The effect of age and demographics on rib shape and orientation
Age-related changes in thoracic skeletal geometry of elderly females.
Dorsal Muscle Attenuation May Predict Failure to Respond to Interleukin-2 Therapy in Metastatic Renal Cell Carcinoma
The Effect of Rib Shape on Stiffness
Application of analytic morphomics for belted elderly occupants in frontal crashes
Reference analytic morphomics population (RAMP): A reference to measure occupant variability for crash injury analysis
Fat Thickness as a Risk Factor for Infection in Lumbar Spine Surgery
Bone mineral density predicts posttransplant survival among hepatocellular carcinoma liver transplant recipients
Modeling female and male rib geometry with logarithmic spirals
Core muscle size and mortality following non-operative management of pelvic fractures
Body Composition Features Predict Overall Survival in Patients With Hepatocellular Carcinoma
Using Analytic Morphomics to Understand Short-Term Convalescence after Radical Cystectomy
Early development of the mouse morphome
Investigating the clinical significance of body composition changes in patients undergoing chemoradiation for oropharyngeal cancer using analytic morphomics
Factors Influencing Specificity and Sensitivity of Injury Severity Prediction (ISP) Algorithm for AACN
Psoas muscle size as a frailty measure for open and transcatheter aortic valve replacement
Analytic morphomics: a novel CT imaging approach to quantify adipose tissue and muscle composition in allogeneic hematopoietic cell translation
Abdominal Adiposity, body composition and survival after liver transplantation
Limitations of the barcelona clinic liver cancer staging system with a focus on transarterial chemoembolization as a key modality of treatment of hepatocellular carcinoma
Sarcopenia and failure to rescue following liver transplantation
Starting a Surgical Home
One-year postoperative resource utilization in sarcopenic patients
Morphomics predicts response to ipilimumab in patients with stage IV melanoma
A Computed tomography study of gender differences in acetabular version and morphology: implications for femoroacetabular impingement
Sarcopenia is associated with autologous transplant-related outcomes in patients with lymphoma
Body fat composition assessment using analytic morphomics predicts infectious complications after bowel resection in Crohn's disease
Predicting Wound Complications with Preoperative CT Scans
Analytic morphomics identifies predictors of new-onset diabetes after liver transplantation
Morphomic analysis as an aid for preoperative risk stratification in patients undergoing major head and neck cancer surgery
Visceral adiposity is negatively associated with bone density and muscle attenuation
Use of analytic morphomics of liver, spleen, and body composition to identify patients at risk for cirrhosis
Effects of aging on osteogenic response and heterotopic ossification following burn injury in mice
Morphomic Factors are Important for Assessing Risk of Cardiovascular Complications in Trauma Patients
Kidney-specific Morphomic Factors are Associated with AKI after Major General Surgery Operations
Image Related Factors Important for AKI Risk Assessment After Colectomies
Cross-sectional area of the abdomen predicts complication incidence in patients undergoing sternal reconstruction
Morphomic analysis for preoperative donor site risk assessment in patients undergoing abdominal perforator flap breast reconstruction: a proof of concept study
Analytic morphomics corresponds to functional status in older patients
Paraspinous muscle as a predictor of surgical outcome
Dorsal muscle group area and surgical outcomes in liver transplantation
Development of a 10-year-old full body geometric dataset for computational modeling
Quantitative detection of cirrhosis: towards the development of computer-assisted detection method
Subcutaneous fat distribution in the human torso
Perioperative changes in trunk musculature on postoperative outcomes
Abdominal wall dynamics after component separation hernia repair
Transsacral screw safe zone size by sacral segmentation variations
Quantification of pediatric and adult cervical vertebra-anatomical characteristics by age and gender for automotive application
Use of morphomic assessment of body composition to quantify risk of surgical-site infection in patients undergoing component separation ventral hernia repair
Morphometric age and mortality after liver transplant
Use of morphomic analysis for preoperative risk stratification in patients undergoing major head and neck cancer surgery
Temporalis muscle morphomics: the psoas of the craniofacial skeleton
Characterization of vertebral angle and torso depth by gender and age groups with a focus on occupant safety
The quantification of liver anatomical changes and assessment of occupant liver injury patterns
Prediction of thoracic injury severity in frontal impacts by selected anatomical morphomic variables through model-averaged logistic regression approach
Cost of major surgery in the sarcopenic patient
Can anatomical morphomic variables help predict abdominal injury rates in frontal vehicle crashes?
Decreased core muscle size is associated with worse patient survival following esophagectomy for cancer
Temporal morphomics as a model for determining preoperative risk of blood transfusion in non-syndromic craniosynostasis patients
Analytic morphometric assessment of patients undergoing colectomy for colon cancer
Analysis of Morphomics Parameters by Gender and BMI Groups: thorax shape and H-point location.
Restrained Male and Female Occupants in Frontal Crashes: Are We Different?
Morphomic Measurement of the Temporalis Muscle and Zygomatic Bone as Novel Predictors of Hospital-Based Clinical Outcomes in Patients with Mandible Fracture
Variation in the femoral bow: a novel high-throughput analysis of 3,922 femurs on cross-sectional imaging
Age-Based Predictive Model of the Pediatric Ribcage
The effect of age on fat and bone properties along the vertebral spine
Abdominal aortic calcification and surgical outcomes in patients with no known cardiovascular risk factors
Novel temporalis muscle and fat pad morphomic analyses aids preoperative risk evaluation and outcome assessment in nonsyndromic craniosynostosis
Novel application of human morphomics to quantify temporal soft tisues in Pierre Robin and Treacher Collins
Quantifying the eyeball test: sarcopenia, analytic morphomics, and liver transplantation
Analytic morphomics, core muscle size, and surgical outcomes
Use of Temporal Morphomic Indices as a Clinically Important Variable in the Diagnosis of Nonsyndromic Craniosynostosis
Worsening central sarcopenia and increasing intra-abdominal fat correlate with decreased survival in patients with adrenocortical carcinoma
Morphomic Analysis of Cervical Facet Angles
Detailed measurement of Vehicle Occupants
Sarcopenia as a Prognostic Factor among Patients with Stage III Melanoma
Development of a quantitative method for the diagnosis of cirrhosis
A quantitative tool to assess degree of sarcopenia objectively in patients with hypercortisolism
Patterns of acetabular femoral head coverage
Surgical site infection and analytic morphometric assessment of body composition in patients undergoing midline laparotomy
Central Adiposity and Surgical Site Infection in Patients Undergoing Midline Laparotomy
Safety Belt & Occupant Factors Influencing Thoracic and Upper Abdominal Injuries in Frontal Crashes
Sarcopenia and Post-Liver Transplant Mortality
Frailty, core muscle size, and mortality in patients undergoing open abdominal aortic aneurysm repair
Analysis of injury trends in frontal University of Michigan CIREN cases in the context of crash tests
Comparison of University of Michigan CIREN cases to existing types of crash tests
Patterns of local and regional variation in ribcage anatomy
Ribcage characterization for FE using automatic CT processing
Factors influencing pediatric Injury Severity Score and Glasgow Coma Scale in pediatric automobile crashes: results from the Crash Injury Research Engineering Network
Patterns of severe injury in pediatric car crash victims: Crash Injury Research Engineering Network database
Structural and material changes in the aging thorax and their role in crash protection for older occupants
Potential applications (and limitations) of 3D imaging data from human crash subjects for biomechanical research
Gender Differences in Hip Anatomy: Possible Implications for Injury Tolerance in Frontal Collisions
The cushion effect
Increased Depth of Subcutaneous Fat is Protective Against Abdominal Injuries in Motor Vehicle Collisions
Journal of Anatomy, (2017), DOI: 10.1111/joa.12632
Elderly populations have a higher risk of rib fractures and other associated thoracic injuries than younger adults, and the changes in body morphology that occur with age are a potential cause of this increased risk. Rib centroidal path geometry for 20 627 ribs was extracted from computed tomography (CT) scans of 1042 live adult subjects, then fitted to a six-parameter mathematical model that accurately characterizes rib size and shape, and a three-parameter model of rib orientation within the body. Multivariable regression characterized the independent effect of age, height, weight, and sex on the rib shape and orientation across the adult population, and statistically significant effects were seen from all demographic factors (P
Traffic Inj Prev., 2017 Mar 23:1-7. DOI 10.1080/15389588.2017.1309526
OBJECTIVE: Both females and the elderly have been identified as vulnerable populations with increased injury and mortality risk in multiple crash scenarios. Particularly in frontal impacts, older females show higher risk to the chest and thorax than their younger or male counterparts. Thoracic geometry plays a role in this increase, and this study aims to quantify key parts of that geometry in a way that can directly inform human body models that incorporate the concept of person age. METHODS: Computed tomography scans from 2 female subject groups aged 20-35 and 65-99 were selected from the International Center for Automotive Medicine scan database representing young and old female populations. A model of thoracic skeletal anatomy was built for each subject from independent parametric models of the spine, ribs, and sternum, along with further parametric models of those components' spatial relationships. Parameter values between the 2 groups are directly compared, and average parameter values within each group are used to generate statistically average skeletal geometry for young and old females. In addition to the anatomic measures explicitly used in the parameterization scheme, key measures of rib cage depth and spine curvature are taken from both the underlying subject pool and from the resultant representative geometries. RESULTS: Statistically significant differences were seen between the young and old groups' spine and rib anatomic components, with no significant differences in local sternal geometry found. Vertebral segments in older females had higher angles relative to their inferior neighbors, providing a quantification of the kyphotic curvature known to be associated with age. Ribs in older females had greater end-to-end span, greater aspect ratio, and reduced out-of-plane deviation, producing an elongated and overall flatter curvature that leads to distal rib ends extending further anteriorly in older individuals. Combined differences in spine curvature and rib geometry led to an 18-mm difference in anterior placement of the sternum between young and old subjects. CONCLUSIONS: This study provides new geometric data regarding the variability in anthropometry of adult females with age and has utility in advancing the veracity of current human body models. A simplified scaffold representation of underlying 3-dimensional bones within the thorax is presented, and the reported young and old female parameter sets can be used to characterize the anatomic differences expected with age and to both validate and drive morphing algorithms for aged human body models. The modular approach taken allows model parameters to hold inherent and intuitive meaning, offering advantages over more generalized methods such as principal component analysis. Geometry can be assessed on a component level or a whole thorax level, and the parametric representation of thorax shape allows direct comparisons between the current study and other individuals or human body models.
RATIONALE AND OBJECTIVES:
To explore whether the sarcopenia body type can help predict response to interleukin-2 (IL-2) therapy in metastatic renal cell carcinoma (RCC).
MATERIALS AND METHODS:
Institutional review board approval was obtained for this Health Insurance Portability and Accountability Act-compliant retrospective cohort study of 75 subjects with metastatic RCC who underwent pretreatment contrast-enhanced computed tomography within 1 year of initiating IL-2 therapy. Cross-sectional area and attenuation of normal-density (31-100 Hounsfield units [HU]) and low-density (0-30 HU) dorsal muscles were obtained at the T11 vertebral level. The primary outcome was partial or complete response to IL-2 using RECIST 1.1 criteria at 6 weeks. A conditional inference tree was used to determine an optimal HU cutoff for predicting outcome. Bonferroni-adjusted multivariate logistic regression was conducted to investigate the independent associations between imaging features and response after controlling for demographics, doses of IL-2, and RCC prognostic scales (eg, Heng and the Memorial Sloan Kettering Cancer Center [MSKCC]).
Most subjects had intermediate prognosis by Heng (65% [49 of 75]) and the MSKCC (63% [47 of 75]) criteria; 7% had complete response and 12% had partial response. Mean attenuation of low-density dorsal muscles was a significant univariate predictor of IL-2 response after Bonferroni correction (P = 0.03). The odds of responding to treatment were 5.8 times higher for subjects with higher-attenuation low-density dorsal muscles (optimal cutoff: 18.1 HU). This persisted in multivariate analysis (P = 0.02). Body mass index (P = 0.67) and the Heng (P = 0.22) and MSKCC (P = 0.08) clinical prognostic scales were not significant predictors of response.
Mean cross-sectional attenuation of low-density dorsal muscles (ie, sarcopenia) may predict IL-2 response in metastatic RCC. Clinical variables are poor predictors of response.
Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.
Morphometry; interleukin-2; metastatic renal cell carcinoma; response prediction; sarcopenia
Stapp Car Crash J. 2016 Nov;60:11-24.
This study investigates the isolated effect of rib shape on the mechanical characteristics of ribs subjected to multiple forms of loading. It aims to measure the variation in stiffness due to shape that is seen throughout the population and, in particular, provide a tool for researchers to better understand the influence of shape on resulting stiffness. A previously published six-parameter shape model of the central axis of human ribs was used. It has been shown to accurately model the overall rib path using intrinsic geometric properties such as size, aspect ratio, and skewness, through shapes based on logarithmic spirals with high curvature continuity. In this study the model was fitted to 19,500 ribs from 989 adult female and male CT scans having demographic distributions matching the US adult population. Mechanical loading was simulated through a simplified finite element model aimed at isolating rib shape from other factors influencing mechanical response. Four loading scenarios were used representing idealized free and constrained loading conditions in axial (body-anterior) and lateral directions. Characteristic rib stiffness and maximum stress location were tracked as simulation output measures. Regression models of rib stiffness found that all shape model parameters added information when predicting stiffness under each loading condition, with their linear combination able to account for 95% of the population stiffness variation due to shape in midlevel ribs for free axial loading, and 92%-98% in other conditions. Full regression models including interactive terms explained up to 99% of population variability. Results allow researchers to better evaluate the differences in stiffness results that are obtained from physical testing by providing a framework with which to explain variation due to rib shape.
International Research Council on Biomechanics of Injury. 2016 Sep. Session S2-9 - Thorax Injury/Injury to the Upper Extremities: IRC-16-105.
In this study, we used analytic morphomics to understand the mechanisms of rib fracture for older occupants in frontal crashes. Analytic morphomics extracts body features from computered tomography scans of people involved in vehicle crashes who have been treated at the University of Michigan, a Level-1 trauma center. Chest injury and rib fracture patterns were examined in belted, front row occupants involved in frontal crashes from the International Center for Automotive Medicine database. Among these occupants, two age groups (younger and older) with the maximum abbreviated injury scale of chest region ≥ 3(MAISthx3+) were categorized. The location of each rib fracture was compared between the groups. Regression analyses were conducted to investigate fracture outcomes considering risk factors including vehicle, demographics, and morphomics. The rib fractures of belted occupants were mainly located under the path of the shoulder belt. For the older group, fracture patterns tended to be located in the anterior region but also bilaterally. Moreover, morphomic factors related to rib shape are the major driver of rib fracture for the older group. The current results for rib shape can highlight the importance of considering these morphomics characteristics when assessing chest injury and creating elderly computer models.
International Research Council on Biomechanics of Injury. 2016 Sep. Session S2-4 - Accident Analysis/Vehicle Technology: IRC-16-80.
Real world crash injuries occur to a large and highly variable population. Analytic Morphomics measures very detailed geometry and material characteristics for tissues, organs, and bones throughout the body using automated processing of medical imaging scans. We analyzed 416 occupants involved in motor vehicle crashes with full crash investigation as well as medical imaging scans and found that morphomic data improved risk stratification for thoracic 3+ injury in both frontal and side impact crashes. We then sought to define the population distribution of the morphomic factors identified to be significantly predictive of crash injury risk to the thorax. Chest, abdomen, and pelvis CT scans were collected from 5,268 patients, aged 16 to 91 years, at the University of Michigan, who were scanned primarily for trauma indications. This curated population, named the Adult Reference Analytic Morphomics Population (RAMP), is representative of typical vehicle occupants in the United States. Customized software was used to perform automated processing of these CT scans and to store detailed body geometry and composition data in an anatomically-indexed format. Quantile regression was performed to generate curves of morphomic factors corresponding to the 5th, 25th, 50th, 75th, and 95th percentiles from ages 16-91 for both men and women respectively. This is a very detailed body composition study based on a large cohort of people.
Orthopedics. 2016 Aug 30:1-5. doi: 10.3928/01477447-20160819-05. [Epub ahead of print]
Body mass index does not account for body mass distribution. This study tested the hypothesis that subcutaneous fat thickness is a better indicator than body mass index of the risk of surgical site infection in lumbar spine procedures performed through a midline posterior approach. Charts were reviewed for previously identified risk factors for surgical site infection (age, diabetes, smoking, obesity, albumin level, multilevel procedures, previous surgery, and operative time) in 149 adult patients who underwent lumbar spine procedures through a midline posterior approach. Subcutaneous fat thickness was measured with a novel automated technique. Regression analysis was used to determine associations between risk factors and fat thickness with surgical site infection. In the study group, 15 surgical site infections occurred (10.1%). Bivariate analysis showed a significant association between surgical site infection and body mass index (P=.01), obesity (P=.02), and fat thickness (P=.002). With multivariate analysis, body mass index and obesity did not show significance, but fat thickness remained significant (P=.026). For every 1-mm thickness of subcutaneous fat there was a 6% (odds ratio, 1.06; 95% confidence interval, 1.02-1.10) increase in the odds of surgical site infection, and patients with fat thickness of greater than 50 mm had a 4-fold increase in the odds of surgical site infection compared with those with fat thickness of less than 50 mm. Body mass index and fat thickness were moderately correlated (r2=0.44). These results confirm the hypothesis that local subcutaneous fat thickness is a better indicator than body mass index of the risk of surgical site infection in lumbar spine procedures. [Orthopedics. 201x; xx(x):exxx-exxx.].
Liver Transpl. 2016 Aug;22(8):1092-8. doi: 10.1002/lt.24458. Epub 2016 Jun 29.
Hepatocellular carcinoma (HCC) is a common indication for liver transplantation (LT). Recent data suggest that body composition features strongly affect post-LT mortality. We examined the impact of body composition on post-LT mortality in patients with HCC. Data on adult LT recipients who received Model for End-Stage Liver Disease exception for HCC between February 29, 2002, and December 31, 2013, and who had a computed tomography (CT) scan any time 6 months prior to LT were reviewed (n = 118). All available CT scan Digital Imaging and Communication in Medicine files were analyzed using a semiautomated high throughput methodology with algorithms programmed in MATLAB. Analytic morphomics measurements including dorsal muscle group (DMG) area, visceral and subcutaneous fat, and bone mineral density (BMD) were taken at the bottom of the eleventh thoracic vertebral level. Thirty-two (27%) patients died during the median follow-up of 4.4 years. The number of HCC lesions (hazard ratio [HR], 2.81; P < 0.001), BMD (HR = 0.90/Hounsfield units [HU]; P = 0.03), pre-LT locoregional therapy (HR = 0.14; P < 0.001), and donor age (HR = 1.05; P < 0.001) were the independent predictors of post-LT mortality. DMG area did not affect post-LT survival. In conclusion, in addition to number of HCC lesions and pre-LT locoregional therapy, low BMD, a surrogate for bone loss rather than DMG area, was independently associated with post-LT mortality in HCC patients. Bone loss may be an early marker of deconditioning that precedes sarcopenia and may affect transplant outcomes. Liver Transplantation 22 1092-1098 2016 AASLD.
J Biomech. 2016 Jul 28. pii: S0021-9290(16)30791-6. doi: 10.1016/j.jbiomech.2016.07.021. [Epub ahead of print]
In this study we present a novel six-parameter shape model of the human rib centroidal path using logarithmic spirals. It provides a reduction in parameter space from previous models of overall rib shape, while simultaneously reducing fitting error by 34% and increasing curvature continuity. Furthermore, the model directly utilizes geometric properties such as rib end-to-end span, aspect ratio, rib "skewness", and inner angle with the spine in its parameterization, making the effects of each parameter on overall shape intuitive and easy to visualize. The model was tested against 2197 rib geometries extracted from CT scans from a population of 100 adult females and males of uniformly distributed ages between 20 and 70. Significant size and shape differences between genders were identified, and shape model utility is demonstrated by the production of statistically average male and female rib shapes for all rib levels. Simulated mechanical loading of the resulting model rib shapes showed that the stiffness of statistically average male and female ribs matched well with the average rib stiffness from each separate population. This in-plane rib shape model can be used to characterize variation in human rib geometry seen throughout the population, including investigation of the overall changes in shape and resultant mechanical properties that ribs undergo during aging or disease progression.
The Orthopaedic Journal at Harvard Medical School. 2016 June;17.
INTRODUCTION The incidence of pelvic fractures in the United States is 13 cases per 10,000 person-years, of which 94% are low-energy fractures in the geriatric population. This cohort has a 20% one-year mortality rate, yet there are limited data predicting post-fracture survival. Core muscle size, a proxy measure of patient frailty, may be one such variable to help risk stratify patients. METHODS We identified 405 patients undergoing non-operative management of a pelvic fracture who had a CT scan of their abdomen/pelvis within 90 days of fracture. We selected for fragility fractures by including females over 50 and males over 65, with an Injury Severity Score (ISS) less than 18. Core muscle size (cross-sectional area of the psoas muscles at L4, normalized to height) was correlated to post-fracture mortality. RESULTS One-hundred and three patients met our selection criteria (82.5% female). Twenty-four patients died within one year of their diagnosis (23.3%). Patients in the lower third of normalized psoas sizes had significantly higher one-year mortality rates compared to patients in the upper third (females: 39.3% vs. 6.9%, p = 0.005' males: 100.0%, p = 0.002). CONCLUSION In non-operatively managed pelvic fractures, our data indicate that decreased core muscle size leads to significantly higher mortality rates. Such objective measures of patient frailty may inform clinical decision-making and improve orthopaedic patient risk stratification.
Clin Transl Gastroenterol. 2016 May 26;7:e172. doi: 10.1038/ctg.2016.31.
OBJECTIVES Existing prognostic models for patients with hepatocellular carcinoma (HCC) have limitations. Analytic morphomics, a novel process to measure body composition using computational image-processing algorithms, may offer further prognostic information. The aim of this study was to develop and validate a prognostic model for HCC patients using body composition features and objective clinical information. METHODS Using computed tomography scans from a cohort of HCC patients at the VA Ann Arbor Healthcare System between January 2006 and December 2013, we developed a prognostic model using analytic morphomics and routine clinical data based on multivariate Cox regression and regularization methods. We assessed model performance using C-statistics and validated predicted survival probabilities. We validated model performance in an external cohort of HCC patients from Parkland Hospital, a safety-net health system in Dallas County. RESULTS The derivation cohort consisted of 204 HCC patients (20.1% Barcelona Clinic Liver Cancer classification (BCLC) 0/A), and the validation cohort had 225 patients (22.2% BCLC 0/A). The analytic morphomics model had good prognostic accuracy in the derivation cohort (C-statistic 0.80, 95% confidence interval (CI) 0.71-0.89) and external validation cohort (C-statistic 0.75, 95% CI 0.68-0.82). The accuracy of the analytic morphomics model was significantly higher than that of TNM and BCLC staging systems in derivation (P=0.001 for both) and validation (P=0.001 for both) cohorts. For calibration, mean absolute errors in predicted 1-year survival probabilities were 5.3% (90% quantile of 7.5%) and 7.6% (90% quantile of 12.5%) in the derivation and validation cohorts, respectively. CONCLUSION Body composition features, combined with readily available clinical data, can provide valuable prognostic information for patients with newly diagnosed HCC.
Bladder Cancer. 2016 Apr 27;2(2):235-240.
BACKGROUND Data from the general surgery literature suggests that patient morphometric data obtained from preoperative imaging may help predict a patient's risk around surgery. OBJECTIVES In this context, we evaluated for associations between psoas muscle area and short-term convalescence following radical cystectomy. METHODS After identifying patients who underwent radical cystectomy at our institution (2008 to 2013), we calculated their psoas muscle area from staging computed tomography scans using established analytic morphomic techniques. We then determined early recovery among patients with high and low psoas muscle area using the validated Convalescence and Recovery Evaluation (CARE) questionnaire-a 27-item survey, divided into four domains (activity, cognitive, gastrointestinal, and pain recovery). Finally, we assessed the relationship between psoas muscle area and changes in CARE scores with nested linear regression models. RESULTS Among the 86 men and among 31 women in our cohort, the median total psoas muscle area was 2,544 mm2 and 1,511 mm2, respectively (P < 0.001 for the comparison). While there was no association between psoas muscle area and recovery in men, women with higher (versus lower) total psoas muscle area had smaller decreases in their pain scores postoperatively and a quicker return to their baseline level (P = 0.05). Activity scores also approached baseline levels faster among women with higher psoas muscle area, although this finding did not reach statistical significance. CONCLUSIONS Psoas muscle area is potentially an important preoperative predictor of recovery for women undergoingradical cystectomy. More broadly speaking, analytic morphomics may represent a novel approach to better understand perioperative risk.
Journal of Craniofacial Surgery, 2016 Apr 19. doi: 10.1097/SCS.0000000000002574.
INTRODUCTION Analytical morphomics focuses on extracting objective and quantifiable data from clinical computered tomography (CT) scans to measure patients' frailty. Studies are currently retrospective in nature; therefore, it would be beneficial to develop animal models for well-controlled, prospective studies. The aim of this study is to develop an in vivo microCT protocaol for the longitudinal acquisition of whole-body images suitable for morphomic analyses of bone. METHODS The authors performed phantom studies on 2 microCT systems (Inveon and CT120) to study tissue radiodensity and further characterize system performance for collecting animal data. The authors also describe their design of a phantom-immobilization device using phantoms and an ovariectomized (OVX) mouse. RESULTS The authors discovered increased consistency along the z-axis for scans acquired on the Inveon compared with CT120, and calibration by individual slice reduces variability. Objects in the field of view had more impact on measurement acquired using the CT120 compared with the Inveon. The authors also found that using the middle 80% of slices for data analysis further decreased variability, on both systems. Moreover, bone-mineral-density calibration using the QCT Pro Mini phantom improved bone-mineral-density estimates across energy spectra, which helped confirm our technique. Comparison of weekly body weights and terminal uterine mass between sham and OVX groups validated our model. DISCUSSION The authors present a refined microCT protocol to collect reliable and objective data. This data will be used to establish a platform for research animal morphomics that can be used to test hypotheses developed from clinical human morphomics.
Springerplus. 2016 Apr 11;5:429. doi: 10.1186/s40064-016-2076-x. eCollection 2016.
BACKGROUND The purpose is to investigate the clinical significance of body morphomics changes in stage III-IV oropharyngeal cancer patients during concurrent chemoradiotherapy (CRT). METHODS Fifty patients who underwent CRT were selected for body composition analyses by either availability of pre/post treatment DEXA scans or a novel CT-based approach of body morphomics analysis (BMA). BMA changes (lean psoas and total psoas area) were compared to total lean body mass changes by DEXA scans using two-sample t tests. Pearson correlation was used to compare the BMA measures to head and neck specific quality of life outcomes. Cox hazards model was used to predict mortality and tumor recurrence. RESULTS Clinically significant declines in total psoas area and lean body mass of similar magnitude were observed in both BMA and DEXA cohorts after CRT. Loss of psoas area (P < 0.05) was associated with greater frailty and mobility issues (3 out of 15 UWQ)L domains). Total psoas area is more sensitive for local recurrence than weight changes and T-stage on multivariate analyses. CONCLUSIONS BMA specifically evaluating psoas area appears to correlate with head and neck cancer quality of life physical domains. Pre- and post-treatment total psoas area at L4 appears prognostic for tumor recurrence.
International Journal of Automotive Engineering. Vol. 7 (2016 Mar 25) No. 1 p. 15-22
To improve the accuracy of Injury Severity Prediction in the event of vehicle crash, a new methodology is proposed using the US vehicle accident database (NASS-CDS). This proposed method is an extension of the base algorithm introduced by Kononen et al. in which, some of the additional variables were introduced and branched logistic regression methodology was used. Results suggest that the proposed branching method has some advantage over the base algorithm due to better linearization of the complex multidimensional non-linear relationship of the input and output variables.
J Thorac Cardiovasc Surg. 2016 Mar;151(3):745-50. doi: 10.1016/j.jtcvs.2015.11.022. Epub 2015 Nov 21
OBJECTIVE To evaluate the use of sarcopenia as a frailty assessment tool for patients with aortic stenosis undergoing surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR). METHODS The study cohort comprised 295 patients who underwent either SAVR (n = 156) or TAVR (n = 139). The mean preoperative Society of Thoracic Surgeons mortality risk score was 4.7%. Preoperative computed tomography (CT) scans were used to calculate gender-standardized total psoas area (TPA), as a validated measure of sarcopenia. RESULTS For the entire cohort, independent predictors of a composite measure of 30-day death, stroke, renal failure, prolonged ventilation, and deep wound infection included preoperative STS major morbidity and mortality risk score (odds ratio [OR], 91.1; P = .02) and TPA (OR, 0.5; P = .024). Two-year survival was 85.7% in patients with sarcopenia, compared with 93.8% in patients without sarcopenia (P = .02). Independent predictors of late survival included TPA (hazard ratio, 0.47; P = .02). Male sex (OR, 0.52; P = .04) and TPA (OR, 0.6; P = .001) were predictive of high resource utilization. A separate analysis by treatment group found that TPA predicted high resource utilization after SAVR (OR, 0.4; P < .001), but not after TAVR (P = .66). CONCLUSIONS CT scan-derived measurement of TPA as an objective frailty assessment tool predicts early morbidity and mortality, high resource utilization, and late survival after treatment for aortic stenosis. The correlation observed between sarcopenia and resource utilization after SAVR versus TAVR suggests that this simple and reproducible risk assessment tool also may help identify those patients who will derive optimal benefit from catheter-based therapy.
Bone Marrow Transplant. 2016 Mar;51(3):446-50. doi: 10.1038/bmt.2015.267. Epub 2015 Nov 9.
Clin Transplant. 2016 Mar;30(3):289-94. doi: 10.1111/ctr.12688. Epub 2016 Feb 13.
BACKGROUND Current measures of obesity do not accurately describe body composition. Using cross-sectional imaging, objective measures of musculature and adiposity are possible and may inform efforts to optimize liver transplantation outcomes. METHODS >Abdominal visceral fat area and psoas muscle cross-sectional area were measured on CT scans for 348 liver transplant recipients. After controlling for donor and recipient characteristics, survival analysis was performed using Cox regression. RESULTS Visceral fat area was significantly associated with post-transplant mortality (p < 0.001; HR = 0.91 per cm(2), 95% CI: 0.88-0.94). Among patients with smaller TPA, the patients with high visceral fat area had 71.8% one-yr survival compared to 81.8% for those with low visceral fat area (p = 0.15). At five yr, the smaller muscle patients with high visceral fat area had 36.9% survival compared to 58.2% for those with low visceral fat area (p = 0.023). CONCLUSIONS Abdominal adiposity is associated with surival after liver transplantation, especially in patients with small trunk muscle size. When coupled with trunk musculature, abdominal adiposity offers direct characterization of body composition that can aid preoperative risk evaluation and inform transplant decision-making.
Clinical Liver Disease. 2016 February; 7(2):32-35.
Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and is one of the leading causes of cancer-related death in the United States. Prognosis of HCC remains poor, driven by advanced tumor burden at diagnosis in two-thirds of cases. Cancer staging systems are important for prognostication and determination of therapy. HCC has unique characteristics for which it is more difficult to use standard cancer staging strategies. First, there is enormous heterogeneity with regard to patient characteristics and HCC biology. Second, in the Western world, the majority of HCC occurs in patients with significant underlying liver disease, making liver function and functional status important in determining outcome. Lastly, tissue diagnosis is not often required, and radiological diagnosis is often the standard. Various staging systems (Table 1) have been proposed to incorporate these variables, but there is no universal worldwide consensus. Two of these staging systems [Barcelona Clinic Liver Cancer (BCLC) and Groupe d'ETUDE et de Traitement du Carcinome Hepatocellulaire (GRETCH)] include performance status, with the BCLC being validated in various geographical settings and with very large data sets. As a result, the BCLC staging system is the most accepted system in the United States, having received the endorsement of both the American Association for the Study of Liver Diseases and the European Association for the Study of Liver Diseases and the European Association for the Study of Liver diseases (Figure 1). Its main advantage is the unique way in which it provides therapy guidelines based on staging, making it a very useful clinical tool.
Clin Transplant. 2015 Dec;29(12):1076-80. doi: 10.1111/ctr.12629. Epub 2015 Oct 15.
INTRODUCTION Sarcopenic liver transplant recipients have higher rates of mortality, but mechanisms underlying these rates remain unclear. Failure to rescue (FTR) has been shown to be a primary driver of mortality following major general and vascular surgery. We hypothesized that FTR is common in sarcopenic liver transplant recipients. METHODS We retrospectively reviewed 348 liver transplant recipients with perioperative CT scans. Analytic morphomic techniques were used to assess trunk muscle size via total psoas area (TPA). One-yr major complication and FTR rates were calculated across TPA tertiles. RESULTS The one-yr complication rate was 77% and the FTR rate was 19%. Multivariate regression showed TPA as a significant predictor of FTR (OR = 0.27 per 1000 mm(2) increase in TPA, p < 0.001). Compared to patients in the largest muscle tertile, patients in the smallest tertile had 1.4-fold higher adjusted complication rates (91% vs. 66%) and 2.8-fold higher adjusted FTR rates (22% vs. 8%). DISCUSSION These results suggest that mortality in sarcopenic liver transplant recipients may be strongly related to FTR. Efforts aimed at early recognition and management of complications may decrease postoperative mortality. Additionally, this work highlights the need for expanded multicenter collaborations aimed at collection and analysis of postoperative complications in liver transplant recipients.
Ann Surg. 2015 Dec;262(6):901-3. doi: 10.1097/SLA.0000000000001250.
J Surg Res. 2015 Nov;199(1):51-5. doi: 10.1016/j.jss.2015.04.074. Epub 2015 Apr 30.
BACKGROUND It is well established that sarcopenic patients are at higher risk of postoperative complications and short-term health care utilization. Less well understood is how these patients fare over the long term after surviving the immediate postoperative period. We explored costs over the first postoperative year among sarcopenic patients. METHODS We identified 1279 patients in the Michigan Surgical Quality Collaborative database who underwent inpatient elective surgery at a single institution from 2006-2011. Sarcopenia, defined by gender-stratified tertiles of lean psoas area, was determined from preoperative computed tomography scans using validated analytic morphomics. Data were analyzed to assess sarcopenia's relationship to costs, readmissions, discharge location, intensive care unit admissions, hospital length of stay, and mortality. Multivariate models were adjusted for patient demographics and surgical risk factors. RESULTS Sarcopenia was independently associated with increased adjusted costs at 30, 90, and 180 but not 365 d. The difference in adjusted postsurgical costs between sarcopenic and nonsarcopenic patients was $16,455 at 30 d and $14,093 at 1 y. Sarcopenic patients were more likely to be discharged somewhere other than home (P < 0.001). Sarcopenia was not an independent predictor of increased readmission rates in the postsurgical year. CONCLUSIONS The effects of sarcopenia on health care costs are concentrated in the immediate postoperative period. It may be appropriate to allocate additional resources to sarcopenic patients in the perioperative setting to reduce the incidence of negative postoperative outcomes.
J Surg Oncol. 2015 Sep;112(4):333-7. doi: 10.1002/jso.24003. Epub 2015 Aug 7.
INTRODUCTION Factors predictive of response to immunotherapy are needed to select appropriate patients. As morphometric analysis can be an objective surrogate for underlying physiology, we explored the possibility that morphomics may predict response among stage IV melanoma patients treated with ipilimumab. METHODS We identified stage IV melanoma patients treated with ipilimumab who had an appropriate CT scan within a 6 month window. Using semi-automated algorithms, we acquired several morphomic measurements. Toxicity and response rate compared by quartile using Fisher's exact test or chi-square, while survival after initiation of ipilimumab was compared by quartile using the log-rank test. RESULTS While there was a significant correlation between toxicity and response (P < .003), morphomics failed to predict either severity of toxicity or specific side effects. Psoas density was significantly associated with response rate, both excluding stable disease (36.4% vs 9.1%, P = .054), and including stable disease (54.5% versus 18.2%, P = 0.045). Survival after initiation of ipilimumab was significantly associated with psoas density (P = 0.04) and visceral fat distance (P = 0.022). DISCUSSION In an exploratory study of patients with metastatic melanoma being treated with ipilimumab, psoas density and spine-fascia distance correlated with response and survival. Pre-treatment morphomic analysis, as a correlate of underlying physiology, may help predict response to immunotherapy.
Arthroscopy. 2015 Jul;31(7):1247-54. doi: 10.1016/j.arthro.2015.02.007. Epub 2015 May 13.
PURPOSE To assess the prevalence of acetabular retroversion in a large population of patients with asymptomatic hips. Furthermore, we sought to identify gender differences in acetabular morphology to address the current thinking that retroversion and pincer-type femoroacetabular impingement (FAI) are more common in women. METHODS We retrospectively reviewed morphologic features of acetabula from a consecutive series of trauma-protocol computed tomography scans of patients without pelvis injury. An automated algorithm determined the acetabular rim profile and center of the femoral head, normalized the frontal plane of the pelvis, and calculated version and coverage. We then compared male and female rim profiles, specifically focusing on version and acetabular wall coverage in the 1-o'clock (anterosuperior), 2-o'clock (central), and 3-o'clock (inferior) positions. RESULTS Of 1,088 patients in the database, 878 had complete data (i.e., age, ethnicity, and body mass index) and were therefore included in the final analysis. Of these, 34.3% were women and 65.7% were men. Mean global acetabular version was 19.1° for men and 22.2° for women (P < .001). Mean acetabular version for men and women was 15.5° and 18.3°, respectively, in the 1-o'clock position; 21.5° and 24.0°, respectively, in the 2-o'clock position; and 20.2° and 24.3°, respectively, in the 3-o'clock position (P < .001 for all 3). True retroversion (<0°) was observed only in the 1-o'clock position. The prevalence of true acetabular retroversion in the 1-o'clock position for men and women was 4.3% and 3%, respectively (P = .36). CONCLUSIONS Mean global and focal acetabular anteversion was greater in women, and the prevalence of focal cephalad retroversion in the 1-o'clock position was not significantly different compared with men. Acetabular retroversion and anterior overcoverage are not more prevalent in women in the anterosuperior acetabulum, where femoroacetabular impingement most commonly occurs. LEVEL OF EVIDENCE Level III, diagnostic study.
Leuk Lymphoma. 2015;56(10):2855-62. doi: 10.3109/10428194.2015.1014359. Epub 2015 Jun 18.
Sarcopenia is associated with treatment-related complications and shorter overall survival in patients with cancer. Psoas area indices were calculated for 121 patients with lymphoma who underwent autologous transplant. Controlling for age, body mass index, comorbidities and performance status for the 73 men included, the hazard ratio (95% confidence interval, CI) for non-relapse mortality was 2.37 (1.01, 5.58), p = 0.048 for every 100 unit decrease in total psoas index and 2.67 (1.04, 6.86), p = 0.041 for every 100 unit decrease in lean psoas index. Men with a lower total psoas index experienced more complications (p = 0.001) and spent more days in hospital (p = 0.03) during the transplant admission. A strong association existed between sarcopenia and number of hospital days in the 100 days following transplant among both men (p < 0.0001) and women (p < 0.0001). Sarcopenia may impact negative outcomes after autologous transplant thereby serving as a potentially modifiable predictor of outcomes and aiding in treatment selection.
Inflamm Bowel Dis. 2015 Jun;21(6):1306-13. doi: 10.1097/MIB.0000000000000360.
BACKGROUND Decisions between medical and surgical management of Crohn's disease (CD) incorporate risk assessments for potential complications of each therapy. Analytic morphomics is a novel method of image analysis providing quantifiable measurements of body tissue composition, characterizing body fat more comprehensively than body mass index alone. The aim of this study was to determine the risk factors associated with postoperative complications in CD, incorporating fat composition analysis using analytic morphomics. METHODS We performed a retrospective review of adults undergoing bowel resection for CD between 2004 and 2011 at a single center. Computed tomography obtained within 30 days prior to surgery underwent morphomic analysis for fat characterization. Postoperative infectious complications were defined as the need for a postoperative abdominal drain, intravenous antibiotics, or reoperation within 30 days. Bivariate and multivariate analyses using logistic regression were used to generate a prediction model of infectious complications. RESULTS A total of 269 subjects met selection criteria; 27% incurred postoperative infectious complications. Bivariate analysis showed hemoglobin, albumin, surgical urgency, high-dose prednisone use, and subcutaneous-to-visceral fat volume distribution as predictors of complications. Body mass index, anti-tumor necrosis factor alpha therapies, and immunomodulator use were not predictors of complication. Multivariate modeling demonstrated a c-statistic of 0.77 and a negative predictive value of 81.1% with surgical urgency (odds ratio = 2.78: 95% confidence interval, 1.46-6.02; P = 0.004), subcutaneous-to-visceral fat distribution (odds ratio = 2.01; 95% confidence interval, 1.20-3.19; P = 0.006), and hemoglobin (odds ratio = 0.69; 95% confidence interval, 0.55-0.85; P = 0.001) as predictors of infectious complication. CONCLUSIONS Fat subtype and distribution are predictive of postoperative infectious complications after bowel resection for CD. Analytic morphomics provides additional body composition detail not captured by body mass index.
Academic Surgical Congress. 2015; Abstract id:ASC20160231.
INTRODUCTION Wound complications – such as incisional hernia, ventral hernia, and wound dehiscence– are common following major abdominal surgery. Despite advances in surgical care, these complications remain prevalent. We hypothesized that analytic morphomics, a novel objective risk assessment tool, would explain the relationship between preoperative tissue composition and postoperative wound complications. METHODS This is an observational study of 1,409 patients undergoing major abdominal surgery and who had a preoperative CT scan, all selected from the Michigan Surgical Quality Collaborative Database. The primary outcome is a composite of local wound complications, including incisional hernia, ventral hernia, wound dehiscence and major wound complications. Analytic morphomic measures of a single slice at the L4 vertebral level were investigated, along with variables related to patient demographics, medical history, admissions status, and comorbid disease. A p < 0.05 threshold in univariate analysis was employed for considering variables to be included in multivariable analysis. RESULTS Wound complications occurred in 11.9% of patients. Analytic morphomic variables associated with wound complications are detailed in the figure. The final, single-slice model was assembled via backwards stepwise selection, and included 4 preoperative variables: subcutaneous fat area @ L4 (odds ratio [OR] = 1.67, 95% confidence interval [Cl] 1.03-2.78, P = 0.040), pack-years (OR = 1.18, 95% CI 0.99-1.38, P = 0.046), albumin (OR = 0.84, 95% CI 0.72-1.00, P = 0.044), and immunosuppressive therapy (OR = 1.97, 95% CI 1.15-3.26, P = 0.010). CONCLUSION Patients with a large subcutaneous fat area have a higher risk of wound complication. This may inform surgeon decision-making in the operating room.
Clin Transplant. 2015 May;29(5):458-64. doi: 10.1111/ctr.12537. Epub 2015 Apr 16.
Among liver transplant recipients, development of post-transplant complications such as new-onset diabetes after transplantation (NODAT) is common and highly morbid. Current methods of predicting patient risk are inaccurate in the pre-transplant period, making implementation of targeted therapies difficult. We sought to determine whether analytic morphomics (using computed tomography scans) could be used to predict the incidence of NODAT. We analyzed peri-transplant scans from 216 patients with varying indications for liver transplantation, among whom 61 (28%) developed NODAT. Combinations of visceral fat, subcutaneous fat, and psoas area were considered in addition to traditional risk factors. On multivariate analysis adjusting for usual risk factors such as type of immunosuppression, subcutaneous fat thickness remained significantly associated with NODAT (OR = 1.43, 95% CI 1.00-1.88, p = 0.047). Subgroup analysis showed that patients with later-onset of NODAT had higher visceral fat, whereas subcutaneous fat thickness was more correlated with earlier-onset of NODAT (using 10 months post-transplant as the cut-off). CONCLUSION Analytic morphomics may be used to help assess NODAT risk in patients undergoing liver transplantation.
J Surg Res. 2015 Mar;194(1):177-84. doi: 10.1016/j.jss.2014.10.002. Epub 2014 Oct 7.
BACKGROUND Patients undergoing major head and neck cancer surgery (MHNCS) may develop significant postoperative complications. To minimize the risk of complications, clinicians often assess multiple measures of preoperative health in terms of medical comorbidities. One emerging method to decrease surgical complications is preoperative assessment of patient frailty measured by specific tissue characteristics. We hypothesize that morphomic characteristics of the temporalis region serve as predictive markers for the development of complications after MHNCS. METHODS We performed a retrospective review of 69 patients with available computed tomography (CT) imaging who underwent MHNCS from 2006-2012. To measure temporalis region characteristics, we used morphomic analysis of available preoperative CT scans to map out the region. All available CT scans had been performed as part of the patient's routine work-up and were not ordered for morphomic analysis. We describe the correlation among temporalis fat pad volume (TFPV), mean zygomatic arch thickness, and incidence of postoperative complications. RESULTS We noted significant difference in the zygomatic bone thickness and TFPV between patients who had medical complications, surgical complications, or total major complications and those who did not. Furthermore, by use of binary logistic regression, our data suggest decreased TFPV and zygomatic arch thickness are stronger predictors of developing postoperative complications than previously studies preoperative characteristics. CONCLUSIONS We describe morphomic analysis of the temporalis region in patients undergoing MHNCS to identify patients at risk for complications. Regional anatomic morphology may serve as a marker to objectively determine a patient's overall health. Use of the temporalis region is appropriate in patients undergoing MHNCS because of the availability of preoperative scans as part of routine work up for head and/or neck cancer.
Am J Clin Nutr. 2015 Feb;101(2):337-43. doi: 10.3945/ajcn.113.081778. Epub 2014 Nov 26.
BACKGROUND The storage of adipose tissue in ectopic compartments is a hallmark attribute linking greater body mass index (BMI) with cardiometabolic diseases. Despite ample evidence to confirm that increased visceral adipose tissue (VAT) deposition occurs with obesity, the interrelations between altered fat partitioning and regional muscle and bone quality are less well understood. OBJECTIVE We examined the association between adiposity and spinal muscle and bone quality across a large, heterogeneous cohort of adults. DESIGN We identified 8833 thoracic or abdominal computed tomography scans from patients in the University of Michigan Health System who were aged 18-64.9 y. We measured trabecular bone densities, cortical bone densities, VAT areas, and subcutaneous adipose tissue (SAT) areas at vertebral levels T7 to L5. Psoas muscle attenuation (an indicator of fat infiltration in muscle) was measured at the L4 level. RESULTS Muscle attenuation as well as trabecular and cortical bone densities revealed negative correlations with BMI, SAT, and VAT. The correlation between BMI and psoas attenuation was -0.321, between BMI and the density of cortical bone was -0.250, and between BMI and trabecular bone was -0.143 (all P < 0.001). However, correlations between VAT and lower muscle attenuation were stronger as were those between VAT and lower bone densities. Inverse correlations between VAT and densities of psoas muscle and cortical and trabecular bone were -0.460, -0.407, and -0.434, respectively (P < 0.001). Even after adjustment for age, sex, and BMI, partial correlations between VAT, muscle attenuation, and bone densities remained significant at -0.250, -0.119, and -0.216, respectively (P < 0.001). CONCLUSIONS Contrary to previous reports that high body mass is associated with increased bone quality, our data show a significant negative association between BMI and muscle and bone densities, suggesting fat infiltration into these tissues. More importantly, correlations between VAT and decreased bone and muscle densities remained statistically significant even after adjustment for age, sex, and BMI.
Clin Gastroenterol Hepatol. 2015 Feb;13(2)360-368.e5. doi: 10.1016/j.cgh.2014.07.042. Epub 2014 Jul 30.
BACKGROUND & AIMS A diagnosis of cirrhosis can be made on the basis of findings from imaging studies, but these are subjective. Analytic morphomics uses computational image processing algorithms to provide precise and detailed measurements of organs and body tissues. We investigated whether morphomic parameters can be used to identify patients with cirrhosis. METHODS In a retrospective study, we performed analytic morphomics on data collected from 357 patients evaluated at the University of Michigan from 2004 to 2012 who had a liver biopsy within 6 months of a computed tomography scan for any reason. We used logistic regression with elastic net regularization and cross-validation to develop predictive models for cirrhosis, within 80% randomly selected internal training set. The other 20% data were used as internal test set to ensure that model overfitting did not occur. In validation studies, we tested the performance of our models on an external cohort of patients from a different health system. RESULTS Our predictive models, which were based on analytic morphomics and demographics (morphomics model) or analytic morphomics, demographics, and laboratory studies (full model), identified patients with cirrhosis with area under the receiver operating characteristic curve (AUROC) values of 0.91 and 0.90, respectively, compared with 0.69, 0.77, and 0.76 for aspartate aminotransferase-to-platelet ratio, Lok Score, and FIB-4, respectively, by using the same data set. In the validation set, our morphomics model identified patients who developed cirrhosis with AUROC value of 0.97, and the full model identified them with AUROC value of 0.90. CONCLUSIONS We used analytic morphomics to demonstrate that cirrhosis can be objectively quantified by using medical imaging. In a retrospective analysis of multi-protocol scans, we found that it is possible to identify patients who have cirrhosis on the basis of analyses of preexisting scans, without significant additional risk or cost.
Stem Cells Dev. 2015 Jan 15;24(2):205-13. doi: 10.1089/scd.2014.0291.
Heterotopic ossification (HO) is a common and debilitating complication of burns, traumatic brain injuries, and musculoskeletal trauma and surgery. Although the exact mechanism of ectopic bone formation is unknown, mesenchymal stem cells (MSCs) capable of osteogenic differentiation are known to play an essential role. Interestingly, the prevalence of HO in the elderly population is low despite the high overall occurrence of musculoskeletal injury and orthopedic procedures. We hypothesized that a lower osteogenicity of MSCs would be associated with blunted HO formation in old compared with young mice. In vitro osteogenic differentiation of adipose-derived MSCs from old (18-20 months) and young (6-8 weeks) C57/BL6 mice was assessed, with or without preceding burn injury. In vivo studies were then performed using an Achilles tenotomy with concurrent burn injury HO model. HO formation was quantified using µCT scans, Raman spectroscopy, and histology. MSCs from young mice had more in vitro bone formation, upregulation of bone formation pathways, and higher activation of Smad and nuclear factor kappa B (NF-κB) signaling following burn injury. This effect was absent or blunted in cells from old mice. In young mice, burn injury significantly increased HO formation, NF-κB activation, and osteoclast activity at the tenotomy site. This blunted, reactive osteogenic response in old mice follows trends seen clinically and may be related to differences in the ability to mount acute inflammatory responses. This unique characterization of HO and MSC osteogenic differentiation following inflammatory insult establishes differences between age populations and suggests potential pathways that could be targeted in the future with therapeutics.
Academic Surgical Congress Abstracts. 2015.
BACKGROUND Motor vehicle crashes (MVCs) are a major cause of traumatic injury in the US, and in- hospital cardiac complications are associated with increased morbidity and mortality in this population. Risk of cardiovascular complications is often difficult to predict using only injury severity and vital signs upon presentation to the trauma center. The utility of analytic morphomics have previously been established in perioperative risk assessment and may provide improved clinical insight in the trauma setting. We hypothesized that morphomic factors may serve as significant predictors of in-hospital cardiac complications for patients involved in MVCs. METHODS Our study included 3,187 MVC adult patients admitted to the University of Michigan Health System who underwent an abdominal CT scan near the time of injury. Exclusion criteria include ISS less than 5 or head-and-neck AIS of 5 or greater. Morphomic factors were measured at the L4 vertebral level using established algorithms. We utilized univariate analysis to determine the relationship of patient demographics, comorbidities, morphomics, and vital signs upon hospital admission with the development of cardiac complications, defined as myocardial infarction (MI), cerebrovascular accident (CVA), and other cardiac events. Injury severity was stratified by mild (5<ISS<16), moderate (16<ISS<25), and severe (ISS>25) trauma. RESULTS Of the 3,187 eligible patients in our study, 121 (3.8%) developed cardiovascular complications. CVA and MI history, bone mineral density, and BMI were significant predictors of cardiovascular events (p<0.05) in mild trauma. Decreased average psoas radiodensity and increased age were found to be significant predictors for cardiovascular events (p<0.01) in moderate trauma. Glasgow Coma Scale and increased anterior body depth were the two most significant predictors of cardiovascular events in severe trauma (p<0.05). Table 1 shows the results of the univariate analysis between the complications and non- complications group for all three levels of trauma. Non-significant predictors of cardiovascular complications across all trauma levels include gender (p=0.17, 1.0, 0.11) and history of diabetes (p=0.37, 0.65, 0.19) or hypertension (p=0.50, 0.07, 0.35). DISCUSSION/CONCLUSION Following a MVC, in-hospital cardiovascular events are serious, life-threatening complications. Psoas radiodensity, bone mineral density, and anterior body depth are significant factors associated with cardiovascular complications. Thus, morphomic factors obtained from cross-sectional imaging are significant predictors of cardiovascular events and may aid clinical decision making for higher risk patients.
BACKGROUND Acute kidney injury (AKI) occurs in approximately 20% of hospitalized adults in the US and is associated with increased morbidity, mortality, and cost for patients of general surgery procedures. Numerous studies have suggested the utility of using patient CT imaging data to predict risk of AKI. Analytic Morphomics, which is a quantitative approach to processing cross-sectional imaging data, has shown utility in evaluating perioperative risk and postoperative outcome. Thus, we hypothesized that individualized morphomic factors would be significantly associated with AKI after major general surgery procedures. METHODS 326 adult patients undergoing major, elective, intra-abdominal general surgery operations from January 2008 to September 2011 were selected. Exclusion criteria include patients undergoing isolated appendectomy or cholecystectomy procedures, patients with a preoperative creatinine value of 1.6 or greater, a history of ESRD, or a prior nephrectomy. Preoperative CT scans within 365 days prior to the operation were analyzed for kidney, vertebral, and fascia-associated parameters such as length, area, volume, and radiodensity. Demographic factors include patient age, gender, and BMI. Univariate analysis was utilized to determine the strength of the association between patient morphomic and demographic factors and development of postoperative AKI as defined by the KDIGO criteria within 30 days of the surgery. RESULTS Of the 238 eligible patients, 31 (13%) developed AKI. Average pixel radiodensity of the total kidney (p<0.001) and kidney parenchyma (p<0.001) were found to be significantly lower for the group that developed postoperative AKI than for those that did not. No significant differences between AKI and non-AKI patients were found for total kidney volume (p=0.19), parenchymal volume (p=0.16), anterior body depth (p=0.32), and patient demographic factors (p>0.15). Table 1 contains the results of the univariate analysis including the means between the AKI and non-AKI group of several factors. CONCLUSION For patients undergoing noncardiac, nonvascular surgical procedures, our analysis showed that kidney pixel radiodensity factors are the most significant in predicting postoperative AKI risk.
INTRODUCTION Acute kidney injury (AKI) occurs in approximately 20% of hospitalized adults and costs the US $10 billion annually. Prolonged hospital stay, cost, and mortality have been shown to be increased in these patients and those requiring renal replacement therapy have an even higher mortality rate. In the setting of colon surgery, a recent large scale study found several associated factors with postoperative AKI including advanced age, chronic renal failure, and total colectomy. However, a surgical decision informed by standard clinical data alone may not be sufficient. We set out to study the relationship between AKI and quantitative kidney morphomic factors from cross-sectional preoperative imaging for patients undergoing colectomies and comparing the results with demographic and intra-operative data. We hypothesized that individualized kidney characteristics would correlate with the risk of postoperative AKI development. METHODS A retrospective review of prospectively gathered data from adult patients undergoing colectomies from 2006-2012 at the University of Michigan was conducted. 390 initial subjects without elevated baseline creatinine values, ESRD, a prior nephrectomy, or renal injury were included. Polycystic kidneys or other kidney abnormalities identified on imaging were excluded resulting in 326 subjects. AKI was defined by the KDIGO criteria within 30 days of injury. Demographic and intraoperative factors were evaluated along with measurements of pertinent kidney morphomic data including volume, surface area, and average Hounsfield Units (HU) which were subjected to univariate analyses. RESULTS Of the 326 patients, 60 developed AKI (18.4%). Of demographic factors, advanced age (p=0.0002) and a higher BMI (p=0.02) were associated with AKI. Comorbidities associated with AKI included hypertension (p=0.008) and diabetes (p=0.013). Interestingly, intraoperative factors including surgical time (p=0.13), blood transfusions (p=0.14), blood loss (p=0.42), and hypotensive episodes (p=0.17) were not significantly associated with AKI. Table 1 shows the results of the univariate analysis of the morphomic factors. CONCLUSION AKI is a serious complication and the prevalence after colorectal surgery at our institution was 18.4%. Our analysis shows that a lower average parenchymal HU was the most significant morphomic factor associated with postoperative AKI. This study is the first to provide information that morphomic analysis can be useful in clinical practice to determine which patients are at risk for developing AKI after a colectomy.
J Surg Res. 2014 Dec;192(2):670-7. doi: 10.1016/j.jss.2014.05.041. Epub 2014 May 24
BACKGROUND Sternal reconstruction with vascularized flaps is central to the management of sternal wound infections and mediastinitis but carries a high risk of complications. There is a need to identify reliable predictors of complication risk to help inform patients and clinicians in preparation for surgery. Unfortunately, body mass index and serum albumin may not be reliable predictors of complication rates. Analytic morphomics provides a robust quantitative method to measure patients' obesity as it pertains to their risk of complications in undergoing sternal reconstruction. METHODS We identified 34 patients with preoperative computed tomography scans of the abdomen from a cohort of sternal reconstructions performed between 1997 and 2010. Using semiautomated analytic morphomics, we identified the patients' skin and fascia layers between the ninth and 12th thoracic spine levels; from these landmarks, we calculated morphomic measurements of the patients' abdomens, including their total body cross sectional area and the cross sectional area of their subcutaneous fat. We obtained the incidence of complications from chart review and correlated the incidence of complications (including seroma, hematoma, recurrent wounds, mediastinitis, tracheostomy, and death) with patients' morphomic measurements. RESULTS We identified 34 patients with preoperative computed tomography scans of the abdomen from a cohort of sternal reconstructions performed between 1997 and 2010. Using semiautomated analytic morphomics, we identified the patients' skin and fascia layers between the ninth and 12th thoracic spine levels; from these landmarks, we calculated morphomic measurements of the patients' abdomens, including their total body cross sectional area and the cross sectional area of their subcutaneous fat. We obtained the incidence of complications from chart review and correlated the incidence of complications (including seroma, hematoma, recurrent wounds, mediastinitis, tracheostomy, and death) with patients' morphomic measurements. CONCLUSIONS Increases in abdominal morphomic measurements correlate strongly with the incidence of complications in patients undergoing sternal reconstruction. This finding may influence preoperative risk stratification and surgical decision making in this patient population.
J Reconstr Microsurg. 2014 Nov;30(9):635-40. doi: 10.1055/s-0034-1376400. Epub 2014 Jun 9
BACKGROUND Morphomics are three-dimensional measurements of aspects of the human anatomy generated by computed tomographic (CT) imaging. The purpose of this study was to generate preliminary data on the efficacy of morphomics, as a potential risk stratification tool, in predicting abdominal donor site wound-healing complications in patients undergoing abdominal perforator flap breast reconstruction. PATIENTS & METHODS In total, 58 consecutive patients undergoing deep inferior epigastric perforator (DIEP) flap breast reconstruction were evaluated. Using preoperative CT scan data, we quantified patients' body area, visceral and subcutaneous fat, fascia area, and body depth between T12 and L4. Associations between morphomic measures and complication rates were examined using t-tests and logistic regression. RESULTS Of the 58 patients, 11 (19%) patients developed a wound dehiscence and 47 (81%) patients healed their abdominal incision without complications. Patients with a dehiscence had a significantly higher body mass index (BMI) (34.32 vs. 29.26 kg/m2, p = 0.014) than patients without a dehiscence. Multiple morphometric measures including higher visceral fat area (p = 0.003) were significant predictors of abdominal donor site wound dehiscence. BMI (odds ratio [OR], 1.16; 95% confidence interval [CI], 1.03–1.32; p = 0.017) and visceral fat area (OR, 1.24; 95% CI, 1.08–1.42; p = 0.002) were independently significant predictors for wound dehiscence in the entire sample. Only visceral fat area retained its predictive ability in patients with a BMI > 30 kg/m2. CONCLUSIONS Morphomic measurements correlate with the likelihood of developing postoperative donor site dehiscence after DIEP flap breast reconstruction. As a proof of concept study, this demonstrates that objective data obtained from CT scans may help in preoperatively assessing the risk for donor site wound healing complications in patients undergoing DIEP flap breast reconstruction.
J Surg Res. 2014 Nov;192(1):19-26. doi: 10.1016/j.jss.2014.06.011. Epub 2014 Jun 11
BACKGROUND Older patients account for nearly half of the United States surgical volume, and age alone is insufficient to predict surgical fitness. Various metrics exist for risk stratification, but little work has been done to describe the association between measures. We aimed to determine whether analytic morphomics, a novel objective risk assessment tool, correlates with functional measures currently recommended in the preoperative evaluation of older patients. MATERIALS & METHODS We retrospectively identified 184 elective general surgery patients aged >70 y with both a preoperative computed tomography scan and Vulnerable Elderly Surgical Pathways and outcomes Assessment within 90 d of surgery. We used analytic morphomics to calculate trunk muscle size (or total psoas area [TPA]) and univariate logistic regression to assess the relationship between TPA and domains of geriatric function mobility, basic and instrumental activities of daily living (ADLs), and cognitive ability. RESULTS Greater TPA was inversely correlated with impaired mobility (odds ratio [OR] = 0.46, 95% confidence interval [CI] 0.25-0.85, P = 0.013). Greater TPA was associated with decreased odds of deficit in any basic ADLs (OR = 0.36 per standard deviation unit increase in TPA, 95% CI 0.15-0.87, P < 0.03) and any instrumental ADLs (OR = 0.53, 95% CI 0.34-0.81; P < 0.005). Finally, patients with larger TPA were less likely to have cognitive difficulty assessed by Mini-Cog scale (OR = 0.55, 95% CI 0.35-0.86, P <0.01). Controlling for age did not change results. CONCLUSIONS Older surgical candidates with greater trunk muscle size, or greater TPA, are less likely to have physical impairment, cognitive difficulty, or decreased ability to perform daily self-care. Further research linking these assessments to clinical outcomes is needed.
J Surg Res. 2014 Nov;192(1):76-81. doi: 10.1016/j.jss.2014.05.057. Epub 2014 May 27.
BACKGROUND Objective measures for preoperative risk assessment are needed to inform surgical risk stratification. Previous studies using preoperative imaging have shown that the psoas muscle is a significant predictor of postoperative outcomes. Because psoas measurements are not always available, additional trunk muscles should be identified as alternative measures of risk assessment. Our research assessed the relationship between paraspinous muscle area, psoas muscle area, and surgical outcomes. METHODS Using the Michigan Surgical Quality Collaborative database, we retrospectively identified 1309 surgical patients who had preoperative abdominal computerized tomography scans within 90 d of operation. Analytic morphomic techniques were used to measure the cross-sectional area of the paraspinous muscle at the T12 vertebral level. The primary outcome was 1-y mortality. Analyses were stratified by sex, and logistic regression was used to assess the relationship between muscle area and postoperative outcome. RESULTS The measurements of paraspinous muscle area at T12 were normally distributed. There was a strong correlation between paraspinous muscle area at T12 and total psoas area at L4 (r = 0.72, P <0.001). Paraspinous area was significantly associated with 1-y mortality in both females (odds ratio = 0.70 per standard deviation increase in paraspinous area, 95% confidence interval 0.50-0.99, P = 0.046) and males (odds ratio = 0.64, 95% confidence interval 0.47-0.88, P = 0.006). CONCLUSIONS Paraspinous muscle area correlates with psoas muscle area, and larger paraspinous muscle area is associated with lower mortality rates after surgery. This suggests that the paraspinous muscle may be an alternative to the psoas muscle in the context of objective measures of risk stratification.
Clin Transplant. 2014 Oct;28(10):1092-8. doi: 10.1111/ctr.12422. Epub 2014 Aug 11.
INTRODUCTION Better measures of liver transplant risk stratification are needed. Our previous work noted a strong relationship between psoas muscle area and survival following liver transplantation. The dorsal muscle group is easier to measure, but it is unclear if they are also correlated with surgical outcomes. METHODS Our study population included liver transplant recipients with a preoperative CT scan. Cross-sectional areas of the dorsal muscle group at the T12 vertebral level were measured. The primary outcomes for this study were one- and five-yr mortality and one-yr complications. The relationship between dorsal muscle group area and post-transplantation outcome was assessed using univariate and multivariate techniques. RESULTS Dorsal muscle group area measurements were strongly associated with psoas area (r = 0.72; p < 0.001). Postoperative outcome was observed from 325 patients. Multivariate logistic regression revealed dorsal muscle group area to be a significant predictor of one-yr mortality (odds ratio [OR] = 0.53, p = 0.001), five-yr mortality (OR = 0.53, p < 0.001), and one-yr complications (OR = 0.67, p = 0.007). CONCLUSION Larger dorsal muscle group muscle size is associated with improved post-transplantation outcomes. The muscle is easier to measure and may represent a clinically relevant postoperative risk factor.
Ann Biomed Eng. 2014 Oct;42(10):2143-55. doi: 10.1007/s10439-014-1078-5. Epub 2014 Aug 13.
The objective of this study was to create a computer-aided design (CAD) geometric dataset of a 10-year-old (10 YO) child. The study includes two phases of efforts. At Phase One, the 10 YO whole body CAD was developed from component computed tomography and magnetic resonance imaging scans of 12 pediatric subjects. Geometrical scaling methods were used to convert all component parts to the average size for a 10 YO child, based on available anthropometric data. Then the component surfaces were compiled and integrated into a complete body. The bony structures and flesh were adjusted as symmetrical to minimize the bias from a single subject while maintaining anthropometrical measurements. Internal organs including the liver, spleen, and kidney were further verified by literature data. At Phase Two, internal characteristics for the cervical spine disc, wrist, hand, pelvis, femur, and tibia were verified with data measured from additional 94 10 YO children. The CAD dataset developed through these processes was mostly within the corridor of one standard deviation (SD) of the mean. In conclusion, a geometric dataset for an average size 10 YO child was created. The dataset serves as a foundation to develop computational 10 YO whole body models for enhanced pediatric injury prevention.
J Digit Imaging. 2014 Oct;27(5):601-9. doi: 10.1007/s10278-014-9696-x.
There are distinct morphologic features of cirrhosis on CT examinations; however, such impressions may be subtle or subjective. The purpose of this study is to build a computer-aided diagnosis (CAD) method to help radiologists with this diagnosis. One hundred sixty-seven abdominal CT examinations were randomly divided into training (n = 88) and validation (n = 79) sets. Livers were analyzed for morphological markers of cirrhosis and logistic regression models were created. Using the area under curve (AUC) for model performance, the best model had 0.89 for the training set and 0.85 for the validation set. For radiology reports, sensitivity of reporting cirrhosis was 0.45 and specificity 0.99. Using the predictive model adjunctively, radiologists' sensitivity increased to 0.63 and specificity slightly decreased to 0.97. This study demonstrates that quantifying morphological features in livers may be utilized for diagnosing cirrhosis and for developing a CAD method for it.
International Research Council on Biomechanics of Injury. 2014 Sep. Session S1-5 - Tissue Biomechanics/Tissue Characterization 2: IRC-14-43.
With obesity becoming a major health issue in recent years and a topic of interest in vehicle occupant safety, there is a need for detailed descriptions of body fat distribution in order to develop accurate models of the human body. In this study subcutaneous fat measurements were obtained from over 17,000 CT scans using planar distance maps from skin surface locations to the fascial envelope. Measures were taken as a map registered by vertebral level (from T6 down to L5, extended to the sacrum) and body location around the body perimeter. Multivariate regression maps were calculated showing the individual effect of demographics on the subcutaneous layer thickness. Regression coefficients were statistically significant, with results showing the progression of 20 years of age producing a migration of 3mm of fat from mid‐abdominal to lower‐ abdominal regions and female occupants having thicker subcutaneous regions compared to males by between 6 and 24mm with accumulation peaks near the buttocks and breasts. Each 20kg of added body weight produce regional fat increases between 2 and 14mm across the torso, with a primary peak near the hips and secondary peak near the lower abdomen.
J Surg Res. 2014 Sep;191(1):106-12. doi: 10.1016/j.jss.2014.03.056. Epub 2014 Mar 22.
BACKGROUND Surgeons often face difficult decisions in selecting which patients can tolerate major surgical procedures. Although recent studies suggest the potential for trunk muscle size, as measured on preoperative imaging, to inform surgical risk, these measures are static and do not account for the effect of the surgery itself. We hypothesize that trunk muscle size will show dynamic changes over the perioperative period, and this change correlates with postoperative mortality risk. METHODS A total of 425 patients who underwent inpatient general surgery were identified to have both a 90-d preoperative and a 90-d postoperative abdominal computed tomography scan. The change in trunk muscle size was calculated using analytic morphomic techniques. The primary outcome was 1-y survival. Covariate-adjusted outcomes were assessed using multivariable logistic regression. RESULTS A total of 82.6% patients (n = 351) experienced a decrease in trunk muscle size in the time between their scans (average 62.1 d). When stratifying patients into tertiles of rate of change in trunk muscle size and adjusting for other covariates, patients in the tertile of the greatest rate loss had significantly increased risk of 1-y mortality than those in the tertile of the least rate loss (P = 0.002; odds ratio = 3.40 95% confidence interval, 1.55-7.47). The adjusted mortality rate for the tertile of the greatest rate loss was 24.0% compared with 13.3% for the tertile of the least decrease. CONCLUSIONS Trunk muscle size changes rapidly in the perioperative period and correlates with mortality. Trunk muscle size may be a critical target for interventional programs focusing on perioperative optimization of the surgical patient.
J Surg Res. 2014 Aug;193(1):497-503. doi: 10.1016/j.jss.2014.08.008. Epub 2014 Aug 9.
BACKGROUND The component separation technique (CST) is an important technique now used frequently in complex ventral hernia repair (VHR). Although this technique has demonstrated superior success rates, there is a paucity of research describing how release of the external obliques coupled with rectus myofascial advancement alters the morphology of the abdominal architecture. In this study, we apply the new concept of analytic morphomics to describe the immediate changes in morphology of the abdomen that take place after VHR by CST. METHODS We identified 21 patients who underwent VHR by CST and received both preoperative and postoperative computed tomography scans between 2004 and 2009 in our clinical database. The surgical technique involved incisional release of the external oblique muscle lateral to the linea semilunaris with rectus abdominis myofascial advancement in all patients. Using semiautomated morphomic analysis, we measured the pre- and post-operative dimensions of the abdominal wall including the anterior-posterior distance from the anterior vertebra-to-skin and fascia along with the circumferential area of the skin and fascial compartments. Paired Student t-tests were used to compare pre- and post-operative values. RESULTS After hernia repair, there was a decrease in the anterior vertebra-to-skin distance (16.6 cm-15.8 cm, P = 0.007). There were also decreases in total body area (968.0 cm(2)-928.6 cm(2), P = 0.017) and total body circumference (113.6 cm-111.4 cm, P = 0.016). The distance from fascia to skin decreased as well, almost to the point of statistical significance (3.3 cm-2.9 cm, P = 0.0505). Interestingly, fascia area and circumference did not decrease significantly after the operation (578.2 cm(2)-572.5 cm(2), P = 0.519, and 89.1 cm-88.6 cm, P = 0.394, respectively). CONCLUSIONS Morphomic analysis can be used to compare and pre- and post-operative changes in patients undergoing abdominal surgery. Our study demonstrates that component separation affects the dimensions of the entire abdomen, but leaves the fascia area and circumference relatively unchanged. These changes in the abdominal wall may help explain the muscular changes observed as a result of this operation and demonstrate that this is a functional operation that restores fascial area. By better defining the effects of this procedure, we can better understand the reason for its clinical success.
J Orthop Res. 2014 June 30;33(2):277-82. doi: 10.1002/jor.22739. Epub 2014 Sep 17
Variations in sacral segmentation may preclude safe placement of transsacral screws for posterior pelvis fixation. We developed a novel automated 3D technique to determine the safe zone size for transsacral screws in the upper two sacral segments in 526 adult pelvis computed tomography scans. Safe zone sizes were then compared by gender and sacral segmentation variations (number of neuroforamen and the presence/absence of lumbosacral transitional vertebrae, ± LSTV). Ten millimeters was used as the safety threshold for a large screw. 3 (0.6%), 366 (70%), and 157 (30%) sacra had 3, 4, or 5 neuroforamen, respectively. Eighty-eight (17%) were +LSTV. Safe zone size depended on gender, number of neuroforamen in -LSTV sacra and presence of LSTV (p < 0.001) but not on the uni- or bilateral nature of the LSTV. 17% of -LSTV sacra were below the safety threshold in S1, 27% in S2, whereas 3% of +LSTV sacra were below in S1, 74% in S2. Of -LSTV sacra that cannot take an S1 screw safely, 77% can do so in S2, leaving only 4% of sacra that cannot accommodate a screw safely in either upper segment. The results demonstrate a predictable pattern of safe zone size based on gender and sacral segmentation variations.
Traffic Inj Prev. 2014 May 27;15(6):572-82. doi: 10.1080/15389588.2013.843774.
OBJECTIVE The cervical anatomy has been shown to affect injury patterns in vehicle crashes. Characterizing the spine anatomy and changes associated with growth and gender is important when assessing occupant protection. In this study, selected cervical characteristics were quantified. METHODS Computed tomography (CT) scans of 750 patients were selected from the University of Michigan trauma database&59; 314 were children and 436 were adults. Four variables were obtained: the maximum spinal canal radius, vertebral body depth, facet angles, and retroversion angles. RESULTS The cervical spine measurements varied with age and gender. The body depth increased nonlinearly with age. The average vertebral body depth at C4 was 9.2 ± 0.38 mm in the 0-3 age group, 15.7 ± 0.29 mm in the 18-29 age group, and 17.2 ± 0.46 mm in the 60+ age group. Pediatric and adult males had larger vertebral body depth than females overall, irrespective of vertebral level (P <.001). Compared to females, the vertebral body depth was 8-9 percent greater in male children and 13-16 percent greater in adult males. The average radius varied with gender, with male children generally having a larger radius than females irrespective of vertebral level (P <.001). Overall, spinal canal radius was smallest in the 0-3 and 60+ age groups and largest in the 18-29 age group. The C4 radius was 5.91 ± 0.17, 6.28 ± 0.14, and 6.73 ± 0.17 mm respectively. The radius was larger in the 4-7 age group than in the 0-3 age group, irrespective of vertebral level (P <.0001). There were nonsignificant radius changes between the 4-7 and 8-11 age groups and the 8-11 and age 12-17 groups, suggesting that the size of the spinal cord reaches near maturation by the age of 7. Facet angles decreased with age in children and increased with age in adults. The average facet angles were largest in the 0-3 age group (P <.1, C2-C6). Adult facet angles were greater in the 60+ age group than in the 18-29 age group (P <.0001, C2-C6). Males had larger facet angles than females overall (P <.01 at C2, C5-C7). The retroversion angles were largest at C6 and C7. They increased with age in children and decreased in the adult population; they were larger (5-22%) in the 18-29 age group than in the 60+ age group (P <.0001, C2-C6). CONCLUSIONS The results obtained in this study help explain variations in cervical anatomical changes associated with age and gender. The information is useful when assessing differences in injury patterns between different segments of the population. Anatomical measurements of the cervical spine should be considered for the development of models used to assess injury mechanisms for various occupant age groups.
Plast Reconstr Surg. 2014 Apr;133(4):559e-66e. doi: 10.1097/PRS.0000000000000009.
BACKGROUND Body mass index does not allow accurate risk stratification for individuals undergoing component separation repair of ventral hernias. The authors hypothesized that tissue morphology measurements (morphomics) of preoperative computed tomography scans stratify the risk of surgical site infection in patients undergoing ventral hernia repair with a component separation technique. METHODS The authors identified 93 patients who underwent component release ventral hernia repair (2004 to 2012). The surgical technique involved release of the external oblique muscle lateral to the linea semilunaris. Using analytic morphomic techniques, the authors measured patients' morphology using routine preoperative computed tomography scans. Two-sample t test was used to evaluate the effect of morphomic and demographic factors on surgical-site infection. Separate logistic regression analyses were performed on these morphomic factors to evaluate their predictive value in assessing the risk of surgical site infection, controlling for demographic covariates. RESULTS Surgical site infections were observed in 31 percent (n = 29) of the population. Subcutaneous fat area, total body area, and total body circumference had increased odds ratios for surgical site infection (p = 0.004, 0.014, and 0.012, respectively), indicating that these measures are better associated with surgical site infection than body mass index. These calculations control for demographic covariates, confirming that these morphomic parameters are predictive of surgical site infection. CONCLUSION Specific morphomic values serve as superior predictors of surgical site infection in patients undergoing component separation technique hernia repair than currently used values such as body mass index. CLINICAL QUESTION/LEVEL OF EVIDENCE Risk, III.
JAMA Surg. 2014 Apr;149(4):335-40. doi: 10.1001/jamasurg.2013.4823.
IMPORTANCE Morphometric assessment has emerged as a strong predictor of postoperative morbidity and mortality. However, a gap exists in translating this knowledge to bedside decision making. We introduced a novel measure of patient-centered surgical risk assessment: morphometric age. OBJECTIVE To investigate the relationship between morphometric age and posttransplant survival. DATA SOURCES Medical records of recipients of deceased-donor liver transplants (study population) and kidney donors/trauma patients (morphometric age control population). STUDY SELECTION A retrospective cohort study of 348 liver transplant patients and 3313 control patients. We assessed medical records for validated morphometric characteristics of aging (psoas area, psoas density, and abdominal aortic calcification). We created a model (stratified by sex) for a morphometric age equation, which we then calculated for the control population using multivariate linear regression modeling (covariates). These models were then applied to the study population to determine each patient's morphometric age. DATA EXTRACTION AND SYNTHESIS All analytic steps related to measuring morphometric characteristics were obtained via custom algorithms programmed into commercially available software. An independent observer confirmed all algorithm outputs. Trained assistants performed medical record review to obtain patient characteristics. RESULTS Cox proportional hazards regression model showed that morphometric age was a significant independent predictor of overall mortality (hazard ratio, 1.03 per morphometric year [95% CI, 1.02-1.04; P < .001]) after liver transplant. Chronologic age was not a significant covariate for survival (hazard ratio, 1.02 per year [95% CI, 0.99-1.04; P = .21]). Morphometric age stratified patients at high and low risk for mortality. For example, patients in the middle chronologic age tertile who jumped to the oldest morphometric tertile have worse outcomes than those who jumped to the youngest morphometric tertile (74.4% vs 93.2% survival at 1 year [P = .03]; 45.2% vs 75.0% at 5 years [P = .03]). CONCLUSIONS & RELEVANCE Morphometric age correlated with mortality after liver transplant with better discrimination than chronologic age. Assigning a morphometric age to potential liver transplant recipients could improve prediction of postoperative mortality risk.
Plast Reconstr Surg. 2014 Mar;133(3 Suppl):131. doi: 10.1097/01.prs.0000444939.16228.9f.
J Surg Res. 2014 Jan;186(1):246-52. doi: 10.1016/j.jss.2013.07.059. Epub 2013 Aug 30.
BACKGROUND The psoas muscle has been shown to predict patient outcomes based on the quantification of muscle area using computed tomography (CT) scans. The accuracy of morphomic analysis on other muscles has not been clearly delineated. In this study, we determine the correlation between temporalis muscle mass, psoas muscle area, age, body mass index (BMI), and gender. METHODS Temporalis and psoas muscle dimensions were determined on all trauma patients who had both abdominal and maxillofacial CT scans at the University of Michigan between 2004 and 2011. Age, BMI, and gender were obtained through chart review. Univariate and multivariate analyses were performed to determine the relative relationship between morphomic data of the temporalis and psoas muscles and the ability of such information to correspond with clinical variables, such as BMI, age, and gender. RESULTS A total of 646 patients were included in the present study. Among the 249 (38.5%) women and 397 (61.5%) men, the average age was 49.2 y. Average BMI was 27.9 kg/m2. Total psoas muscle area directly correlated with mean temporalis muscle thickness (r = 0.57, P < 0.001). There was an indirect correlation between age and psoas muscle area (r = -0.52, P < 0.001) and temporalis muscle thickness (r = -0.36, P < 0.001). Neither psoas nor temporalis measurements correlated strongly with BMI (r = 0.18, P < 0.001; r = 0.14, P = 0.002), although stronger correlations were found in a more "frail," subgroup as defined by a BMI of <20 (r = 0.59, P = 0.002). CONCLUSIONS We demonstrate that dimensions of the temporalis muscle can be quantified and may serve as a proxy for age. Going forward, we aim to assess the utility of temporalis and psoas morphomics in predicting complication rates among trauma patients admitted to the hospital to predict outcomes in the future.
Traffic Inj Prev. 2014;15(1):66-72. doi: 10.1080/15389588.2013.829217.
OBJECTIVE The human body changes as it becomes older. The automotive safety community has been interested in understanding the effect of age on restraint performance. Focus has been placed on characterizing the body's structural changes associated with age and gender. In this study, spine alignment and torso depth were assessed, because both variables have been shown to affect injury risk. METHODS The data was obtained from computed tomography (CT) scans of more than 24,000 patients aged 16 and older. The data consisted of thoracic and lumbar vertebral angles relative to a fixed plane, as well as vertebra-to-front skin and spine-to-back skin distances. Angle measurements were taken in the sagittal plane at each vertebra level from T1 to L5; distance measurements were taken from T6 to L5. The data were analyzed as a function of gender and age with the young group defined as 16 to 29 years old and the older group as 75 and up. RESULTS Vertebral angles were different depending on location. They varied from -24.5 ± 8.9° at T2 to 12.2 ± 5.6° at L1. The vertebral angles also varied with age. Angles in the older male group were 1.74 times larger at T1 and 2.03 times larger at T7 than in the young male group. Similar findings were observed for females. The effect of age and gender was modeled with forward/backward selection using a regression model. The vertebra-to-front skin distance also differed depending on vertebral level. It was highest at T10 at 162.5 ± 30.9 mm and lowest at L4 at 125.3 ± 37.3 mm for the entire study population. On average, males had larger distances than females. The spine-to-back distances were greatest in the lumbar area. The spine-to-back distance increased with lower vertebral level, regardless of age. The vertebral angle and distance data were analyzed for a male subgroup approximating the height and weight of a 50th percentile male dummy. The results showed that the vertebra-to-front skin distance increased with age. There was not a clear trend for the spine-to-back skin distance and L1 vertebral angle. CONCLUSIONS The changes in the vertebral angles, as well as the anterior and posterior spine-to-skin distances along the sagittal plane, were determined as a function of age and gender. The effect was greatest in the mid-thoracic area. Spine alignment and body shape differences need to be considered in human mathematical models used to develop safety countermeasures for the older population, because they may affect the loading path and lead to different seating postures or belt positioning. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.
Stapp Car Crash J. 2013 Nov;57:267-83.
Liver injuries can be significant in vehicle crashes. In this study, the liver anatomy was quantified in both adult and pediatric populations as a function of gender and age. Five anatomical liver measurements were determined using CT scans of 260 normal livers. These measurements include the area and volume, and the length, width, and girth of the liver (IRB HUM00041441). To characterize geometrical shape, an inscribed sphere and circumscribed ellipsoid were fitted on the measurements. In the pediatric population the liver area and volume continuously increased with age. When normalized by patient weight, volume measurements show a decrease in volume with age, suggesting that the liver occupies a smaller proportion of the body with age. In the adult population, liver measurements varied with gender. The superior and inferior locations of the liver were also recorded with respect to the spine. The lower portion was at the L3 in small children and at L2 as children approached puberty. It stayed in that area through the 60+ group, offering more ribcage protection. Liver injury patterns were also assessed in crash occupants. Seventy-two occupants with moderate to severe (AIS 2+) liver injuries were investigated. A new methodology was presented and consisted of quantifying blood volumes. The results were compared to overall liver volume and injury scales. No clear distinction on the injury pattern was observed by age group. Liver injuries were more commonly associated with AIS 2+ thoracic injuries in adults than in children. Most injuries occurred in the right lobe.
Accid Anal Prev. 2013 Nov;60:172-80. doi: 10.1016/j.aap.2013.08.020. Epub 2013 Sep 5.
This study resulted in a model-averaging methodology that predicts crash injury risk using vehicle, demographic, and morphomic variables and assesses the importance of individual predictors. The effectiveness of this methodology was illustrated through analysis of occupant chest injuries in frontal vehicle crashes. The crash data were obtained from the International Center for Automotive Medicine (ICAM) database for calendar year 1996 to 2012. The morphomic data are quantitative measurements of variations in human body 3-dimensional anatomy. Morphomics are obtained from imaging records. In this study, morphomics were obtained from chest, abdomen, and spine CT using novel patented algorithms. A NASS-trained crash investigator with over thirty years of experience collected the in-depth crash data. There were 226 cases available with occupants involved in frontal crashes and morphomic measurements. Only cases with complete recorded data were retained for statistical analysis. Logistic regression models were fitted using all possible configurations of vehicle, demographic, and morphomic variables. Different models were ranked by the Akaike Information Criteria (AIC). An averaged logistic regression model approach was used due to the limited sample size relative to the number of variables. This approach is helpful when addressing variable selection, building prediction models, and assessing the importance of individual variables. The final predictive results were developed using this approach, based on the top 100 models in the AIC ranking. Model-averaging minimized model uncertainty, decreased the overall prediction variance, and provided an approach to evaluating the importance of individual variables. There were 17 variables investigated: four vehicle, four demographic, and nine morphomic. More than 130,000 logistic models were investigated in total. The models were characterized into four scenarios to assess individual variable contribution to injury risk. Scenario 1 used vehicle variables; Scenario 2, vehicle and demographic variables; Scenario 3, vehicle and morphomic variables; and Scenario 4 used all variables. AIC was used to rank the models and to address over-fitting. In each scenario, the results based on the top three models and the averages of the top 100 models were presented. The AIC and the area under the receiver operating characteristic curve (AUC) were reported in each model. The models were re-fitted after removing each variable one at a time. The increases of AIC and the decreases of AUC were then assessed to measure the contribution and importance of the individual variables in each model. The importance of the individual variables was also determined by their weighted frequencies of appearance in the top 100 selected models. Overall, the AUC was 0.58 in Scenario 1, 0.78 in Scenario 2, 0.76 in Scenario 3 and 0.82 in Scenario 4. The results showed that morphomic variables are as accurate at predicting injury risk as demographic variables. The results of this study emphasize the importance of including morphomic variables when assessing injury risk. The results also highlight the need for morphomic data in the development of human mathematical models when assessing restraint performance in frontal crashes, since morphomic variables are more "tangible" measurements compared to demographic variables such as age and gender.
J Am Coll Surg. 2013 Nov;217(5):813-8. doi: 10.1016/j.jamcollsurg.2013.04.042. Epub 2013 Oct 9.
BACKGROUND Sarcopenia is associated with poor outcomes after major surgery. There are currently no data regarding the financial implications of providing care for these high-risk patients. STUDY DESIGN We identified 1,593 patients within the Michigan Surgical Quality Collaborative (MSQC) who underwent elective major general or vascular surgery at a single institution between 2006 and 2011. Patient sarcopenia, determined by lean psoas area (LPA), was derived from preoperative CT scans using validated analytic morphomic methods. Financial data including hospital revenue and direct costs were acquired for each patient through the hospital's finance department. Financial data were adjusted for patient and procedural factors using multiple linear regression methods, and Mann-Whitney U test was used for significance testing. RESULTS After controlling for patient and procedural factors, decreasing LPA was independently associated with increasing payer costs ($6,989.17 per 1,000 mm(2) LPA, p < 0.001). The influence of LPA on payer costs increased to $26,988.41 per 1,000 mm(2) decrease in LPA (p < 0.001) in patients who experienced a postoperative complication. Further, the covariate-adjusted hospital margin decreased by $2,620 per 1,000 mm(2) decrease in LPA (p < 0.001) such that average negative margins were observed in the third of patients with the smallest LPA. CONCLUSIONS Sarcopenia is associated with high payer costs and negative margins after major surgery. Although postoperative complications are universally expensive to payers and providers, sarcopenic patients represent a uniquely costly patient demographic. Given that sarcopenia may be remediable, efforts to attenuate costs associated with major surgery should focus on targeted preoperative interventions to optimize these high risk patients for surgery.
Traffic Inj Prev. 2013 Oct 11;15(6):619-26. doi: 10.1080/15389588.2013.852665.
OBJECTIVE Abdominal injuries resulting from vehicle crashes can be significant, in particular when undetected. In this study, abdominal injuries for occupants involved in frontal impacts were assessed using crash and medical data. METHODS Injury rates and patterns were first assessed with respect to thoracic injuries. A statistical analysis was then conducted to predict abdominal injury outcome using 18 covariate variables, including 4 vehicle, 4 demographic, and 10 morphomic, derived from computed tomography (CT) scans. More than 260,000 logistic regression models were fitted using all possible variable combinations. The models were ranked using the Akaike information criterion (AIC) and combined through the model-averaging approach to produce the optimal predictive model. The performance of the models was then assessed using the area under the curve (AUC). RESULTS The rate of serious thoracic injury was 2.49 times higher than the rate of abdominal injury. The associated odds ratio was 2.31 (P <.01). These results suggest a strong association between serious abdominal and thoracic injuries. The optimal model AUC was 0.646 when using solely vehicle data, 0.696 when combining vehicle and demographic data, 0.866 when combining vehicle and morphomic data, and 0.879 when combining vehicle, demographic, and morphomic data. These results suggest that morphomic variables better predict abdominal injury outcomes than demographic variables. The most important morphomics variables included visceral fat area, trabecular bone density, and spine angulation. CONCLUSION This study is the first to combine vehicle, demographic, and anatomical data to predict abdominal injury rates in frontal crashes.
Dis Esophagus. 2013 Sep-Oct;26(7):716-22. doi: 10.1111/dote.12020. Epub 2013 Jan 25.
Preoperative risk assessment, particularly for patient frailty, remains largely subjective. This study evaluated the relationship between core muscle size and patient outcomes following esophagectomy for malignancy. Using preoperative computed tomography scans in 230 subjects who had undergone transhiatal esophagectomy for cancer between 2001 and 2010, lean psoas area (LPA), measured at the fourth lumbar vertebra, was determined. Cox proportional hazards regression was employed to analyze overall survival (OS) and disease-free survival (DFS) adjusted for age, gender, and stage, and the Akaike information criterion was used to determine each covariate contribution to OS and DFS. Univariate analysis demonstrated that increasing LPA correlated with both OS (P = 0.017) and DFS (P = 0.038). In multivariate analysis controlling for patient and tumor characteristics, LPA correlated with OS and DFS in patients who had not received neoadjuvant treatment (n = 64), with higher LPA associated with improved OS and DFS. Moreover, LPA was of equivalent, or slightly higher importance than pathologic stage. These measures were not predictive among patients (n = 166) receiving neoadjuvant chemoradiation. Core muscle size appears to be an independent predictor of both OS and DFS, as significant as tumor stage, in patients following transhiatal esophagectomy. Changes in muscle mass related to preoperative treatment may confound this effect. Assessment of core muscle size may provide an additional objective measure for risk stratification prior to undergoing esophagectomy.
Plast Reconstr Surg. 2013 Sep;132(3):403e-12e. doi: 10.1097/PRS.0b013e31829ad31f.
BACKGROUND Estimates of blood loss during craniosynostosis surgeries have ranged from 42 to 126 percent of infant's total blood volume. Currently, no risk model has been developed to determine the likelihood of needing a blood transfusion. The authors propose an objective model, based on patients' three-dimensional anatomical characteristics, to stratify the likelihood of needing perioperative packed red blood cells. METHODS High-throughput image analysis from already ordered preoperative computed tomographic scans was used to reconstruct the three-dimensional anatomy of the temporalis muscle and overlying temporal fat pad. Using these morphomic measurements, the authors created a risk assessment model of the amount of packed red blood cells infused based on morphomic variations in temporal soft tissue. RESULTS The authors evaluated 139 infants with nonsyndromic craniosynostosis from the University of Michigan Health System. Results show the need for blood transfusion ranged from 94.1 percent among patients in the smallest quartile for temporal fat pad volume compared with 65.7 percent among the group with the largest quartile for temporal fat pad volume (p = 0.0057). Using multivariable linear regression, temporal fat pad volume (p = 0.012) and fat pad thickness (p = 0.036) were independent predictors for amount of packed red blood cells required. CONCLUSIONS The authors demonstrate that patients with diminished temporal fat pad volume are significantly more likely to need increased packed red blood cell transfusions. In addition, by use of multivariable linear regression, their data suggest that temporal fat pad volume and thickness were independent predictors for the amount of required transfusion of packed red blood cells.
J Surg Oncol. 2013 Sep;108(3):169-75. doi: 10.1002/jso.23366. Epub 2013 Jul 11.
BACKGROUND Analytic morphometrics provides objective data that may better stratify risk. We investigated morphometrics and outcome among colon cancer patients. METHODS An IRB-approved review identified 302 patients undergoing colectomy who had CT scans. These were processed to measure psoas area (PA), density (PD), subcutaneous fat (SFD), visceral fat (VF), and total body fat (TBF). Correlation with complications, recurrence, and survival were obtained by t-tests and linear regression models after adjusting for age and Charlson index. RESULTS The best predictor of surgical complications was PD. PMH, Charlson, BMI, and age were not significant when PD was considered. SF area was the single best predictor of a wound infection. While all measures of obesity correlated with outcome, TBF was most predictive. Final multivariate Cox models for survival included age, Charlson score, nodal positivity, and TBF. CONCLUSIONS Analytic morphometric analysis provided objective data that stratified complications and outcome better than age, BMI, or co-morbidities.
International Research Council on Biomechanics of Injury. 2013 Sep. Session S4-4 - Accident Analysis 2: IRC-13-81.
The automotive safety community is questioning the effect of obesity on the performance and assessment of occupant protection systems. This study analyzed CT scan measurements of 10,952 individuals older than 15 years by Body Mass Index (BMI) and gender, including the H‐point location defined relative longitudinal distance between the centroid of the femoral head and the most posterior skin measurement, vertebra‐to‐front‐skin distance, and spine‐to‐back‐skin distance along the sagittal plane. The distance data was obtained at each vertebra level.The average H‐point location increased with BMI and varied with gender. A regression analysis was fitted on the data. For females, it was equal to 55.90 +2.47*BMI in the normal size group, 86.25+1.30*BMI in the obese group, and 116.25+0.55*BMI mm in the morbidly obese group (p<0.01). For males the corresponding H‐point was 64.12+2.11*BMI, 77.28+1.62*BMI, and 95.13+1.17*BMI mm (p<0.01). The vertebra‐to‐front skin and spine‐ to‐back skin distances also increased with BMI and differed with gender. With the increasing worldwide concern for obese occupant protection, test devices representative of this segment of the population are necessary. Human math models provide the best option for a parametric analysis of protection systems designed and optimized for various BMI and gender groups. The morphomic data was analyzed to represent a 5th percentile female and 50th percentile male dummy. These results will be useful in the modifications of the current human mathematical models to represent obese occupants.
International Research Council on Biomechanics of Injury. 2013 Sep. Session S6-1 - Frontal Impacts: IRC-13-98.
The safety community is questioning the effect of gender on the performance and assessment of occupant protection systems. This study consists of: 1) an investigation of NASS‐CDS data with belted occupants involved in frontal vehicle crashes and 2) a comparison of dummy responses in two matched frontal tests. Because of recent work on a 50th female dummy neck, focus was placed on neck responses. An assessment of cervical facet angles was also carried out from computed tomography (CT) scans of 423 adult patients.The NASS‐CDS data showed that the relative risk of being seriously injured was higher in females than in males for crash severities up to 65 km/h. Females had higher overall risks of serious injury in all body regions except for the head and the abdomen. In 25 to 65 km/h crashes, females were more at risk of spine injuries than males. In the matched tests, the normalized results showed overall higher biomechanical responses in the female than in the male dummy, in particular in the neck region. Airbag interaction with the head/neck complex was noted with the female dummy. The CT scan data indicated that the cervical facet angles increased with age, becoming more horizontal. The increase was greater in females than in males. The quantification of anatomical changes associated with gender is needed to improve physical and/or numerical tools used to assess occupant responses and to understand differences in injury patterns.
J Craniofac Surg. 2013 Sep;24(5):1577-81. doi: 10.1097/SCS.0b013e3182a12e02.
INTRODUCTION Patients with mandibular fracture often have comorbidities and concomitant injuries making the decision for when and how to operate a challenge. Physicians describe "temporalis wasting" as a finding that indicates frailty; however, this is a subjective finding without quantitative values. In this study, we demonstrate that decreased morphomic values of the temporalis muscle and zygomatic bone are an objective measure of frailty associated with increased injury-induced morbidity as well as negative impact on overall hospital-based clinical outcomes in patients with mandible fracture. METHODS Computed tomographic (CT) scans from all patients with a diagnosis of a mandible fracture in the University of Michigan trauma registry and with a hospital admission were collected from the years 2004 to 2011. Automated, high-throughput CT analysis was used to reconstruct the anatomy and quantify morphomic values (temporalis volume, area and thickness, and zygomatic thickness) in these patients using MATLAB v13.0 (MathWorks Inc, Natick, MA, USA). Subsequently, a subset of 16 individuals with a Glasgow Coma Scale of 14 or 15 was analyzed to control for brain injury. Clinical data were obtained, and the association between morphomic measurements and clinical outcomes was evaluated using Pearson correlation for unadjusted analysis and multiple regression for adjusted analysis. RESULTS The mean age of patients in the study was 47.1 years. Unadjusted analysis using Pearson correlation revealed that decreases in zygomatic bone thickness correlated strongly with increases in hospital, intensive care unit, and ventilator days (P < 0.0001, P = 0.0003, and P < 0.0017, respectively). Furthermore, we found that decreases in temporalis mean thickness correlated with increases in hospital and ventilator days (P = 0.0264 and P = 0.0306, respectively). Similarly, decreases in temporalis local mean thickness are significantly correlated with increases in hospital and ventilator days (P = 0.0232 and P = 0.0472, respectively). CONCLUSIONS Decreased thicknesses of the zygomatic bone and temporalis muscle are significantly correlated with higher hospital, ventilator, and intensive care unit days in patients with mandibular fracture receiving reconstructive operations. This morphomic methodology provides an accurate, quantitative means to evaluate craniofacial trauma patient frailty, injury, and outcomes using routinely obtained CT scans. In the future, we plan to apply this approach to determine preoperative risk stratification and assist in surgical planning.
J Orthop Trauma. 2013 June 11;28(1):6-9. doi: 10.1097/BOT.0b013e31829ff3c9.
OBJECTIVES To evaluate femoral radius of curvature in a large sample of computed tomography scans to definitively determine the relationship between radius of curvature and femoral length, age, gender, ethnicity, body mass index and cortical thickness. METHODS A retrospective review was conducted of the electronic medical records and advanced imaging of 1961 patients who underwent pulmonary embolism protocol computed tomography scans between December 1999 and March 2010. The computed tomography scans were imported from the clinical picture archiving and communication system archive into a research image archive and analysis system. Each scan was processed by an automated system that algorithmically determined bony landmarks, adjusted for body position within the scanner and measured the radius of curvature. RESULTS The mean medullary radius of curvature of 3922 femurs was 112 cm (SD = 26 cm). The mean anterior radius of curvature of the femurs was 145 cm (SD = 55 cm). There was a moderately strong positive correlation (0.36-0.39) between femoral length and radius of curvature (P < 0.0001) that was not affected by age, body mass index, cortical thickness, gender, or ethnicity. No significant relationship was found between either gender or ethnicity and radius of curvature independent of femoral length. CONCLUSIONS Differences in radius of curvature based on ethnicity and gender exist primarily because of the variation in average height, and therefore femur length, that exists between ethnic groups and genders. These data may prove useful in the design of safer intramedullary implants that accommodate a greater spectrum of anatomic variation.
International Journal of Automotive Engineering. 2013 May 23. Vol. 5 (2014) No. 1 p. 15-22
Ribcage geometry of 327 boys and girls (aged 1-18) was extracted from CT scans, consisting of three dimensional curves fit through the centroidal path of 6306 individual ribs. Each rib was characterized by 7 parameters describing a rib's in-plane geometry, 2 describing its out-of-plane deviation, and 3 describing the rib orientation relative to anatomical planes. Parameters were predicted by age and gender to fully describe variation in size and shape of rib centroidal geometry as a continuous function following growth throughout childhood. A demographics-based model was also presented describing average ribcage geometry for children of any given age, weight, and height.
SAE Int. J. Trans. Safety 1(2):226-240, 2013, doi:10.4271/2013-01-1244.
The human body changes as it becomes older. The automotive safety community has been interested in understanding the effect of aging on restraint performance. Recent research has been focused on assessing the structural and material changes associated with age. In this study, structural tissue distribution was determined using the computed tomography (CT) scan data of more than 19,000 patients, aged 16 and up. The data consisted of subcutaneous fat cross-sectional area, visceral fat cross-sectional area, and trabecular bone density taken at each vertebral level. The data was quantified as a function of five age groups with the youngest group defined as 16-29 years old and the oldest group as 75 and up. An additional analysis stratified on gender was carried out. Overall, visceral fat increased with age. Compared to the 16-29 group, the visceral fat measured at the L1 level was 1.97 in the 30-44 group, 2.55 in the 45-59 group, 3.33 in the 60-74 group and 3.21 times greater in the 75+ group. Subcutaneous fat also increased with age up to the 60-74-year-old group. The subcutaneous fat measured at L1 level was 1.34 in the 30-44 group, 1.39 in the 45-59 group, 1.38 in the 60-74 group and 1.09 times greater in the 75+ group than in the 16-29 group. A significant association between trabecular bone density and age was found. Trabecular bone density in Hounsfield units (HU) decreased as a function of age, by 2.57*age +0.0056*age2 for females and 2.57*age +0.0082*age2 for males. Gender differences were also observed. Females had 1.43 times more subcutaneous fat and 1.10 times higher trabecular bone density than males at L1, while males had 1.88 times more visceral fat than females. Females gained more subcutaneous fat at L1 as they increased in age up to the 45-59 group and then progressively lost subcutaneous fat. Males and females gained more visceral fat at L1 as they aged up to the 60-74 group. Both consistently lost bone density at L1 as they grew older. The data was also analyzed for a male subgroup approximating the height and weight of a 50th percentile male dummy. Visceral fat increased with age while trabecular bone density decreased. There was an overall-trend for an increase in subcutaneous fat with age. The results obtained in this study provide insight on the quantified effect of bone and fat distribution as a function of age, gender, and vertebral level. Fat and bone distribution needs to be considered in human mathematical models used to develop safety countermeasures for the older population.
Ann Surg. 2013 Apr;257(4):774-81. doi: 10.1097/SLA.0b013e31826ddd5f.
INTRODUCTION In the setting of cardiovascular (CV) risk evaluation before major elective surgery, current risk assessment tools are relatively poor for discriminating among patients. For example, patients with clinical CV risk factors can be clearly identified; but among those without appreciated clinical CV risk, there may be a subset with stigmata of CV disease noted during the preoperative radiographic evaluation. Our study evaluated the relationship between abdominal aortic (AA) calcification measured on preoperative computed tomography (CT) imaging and surgical complications in patients undergoing general elective and vascular surgery. We hypothesized that patients with no known CV risk factors but significant aortic calcification on preoperative imaging will have inferior surgical outcomes. METHODS The study group included 1180 patients from the Michigan Surgical Quality Collaborative (MSQC) database who underwent major general or vascular elective surgery between 2006 and 2009 and who had a CT scan of the abdomen specifically for preoperative planning. AA calcification was measured using novel analytic morphomic techniques and reported as a percentage of the total wall area containing calcification. Patients were divided into cohorts by clinical CV risk and extent of AA calcification. Univariate analysis was used to compare postoperative morbidity between patient cohorts. Multivariate logistic regression analysis was used to compare continuous AA calcification with overall morbidity in patients with no clinical CV risk factors. RESULTS AA calcification was strongly skewed to the right (53.5% had no AA calcification) and was significantly correlated with age (ρ = 0.43, P < 0.001). Unadjusted univariate analysis of morbidity showed no significant differences in complication rates between patients in the clinical CV risk and significant AA calcification (no known CV risk factor) categories. The clinical CV risk (P < 0.001) and significant AA calcification without CV risk factors (P = 0.009) populations both had significantly more infectious and overall complications than patients with no AA calcification and no clinical CV risk. Multivariate logistic regression confirmed that AA calcification was a significant predictor of morbidity in patients with no clinical CV risk factors (odds ratio = 1.35, P = 0.017). DISCUSSION This study suggests that AA calcification may be related to progression of CV disease and surgical outcomes. A better understanding of the complex interaction of patient physiology with overall ability to recover from major surgery, using novel approaches such as analytic morphomics, has great potential to improve risk stratification and patient selection.
J Craniofac Surg. 2013 Jan;24(1):250-5. doi: 10.1097/SCS.0b013e31827006f5.
INTRODUCTION Analytical morphomics is the term we created to describe an innovative, highly automated, anatomically indexed processing of 3D medical imaging data captured during the course of a patients' preoperative CT scan. Our specific aim is to determine the efficacy of craniofacial morphomic indices (CMI) such as temporalis muscle and temporal fat pad morphometric values to predict blood transfusion requirement and hospital stay in a cohort of children with nonsyndromic craniosynostosis (NSC). METHODS High-throughput, semi-automated image analysis was used to reconstruct the 3-dimensional anatomy of the temporalis muscle and temporal fat pad and to quantify CMIs. The prognostic effect of CMI on clinical outcomes were evaluated among all NSC patients and compared across various craniosynostosis subtypes using Wilcoxon nonparametric tests and Kendall's τ to determine significance. RESULTS Using preoperative CT images, we evaluated 117 children with NSC from the University of Michigan Health System. Results demonstrate that increased temporal fat pad volume and local temporalis muscle volume are associated with better clinical outcomes in craniosynostosis patients. More specifically, temporal fat pad volume was shown to be a significant predictor of perioperative blood transfusion requirements (P = 0.0033) and increased temporal muscle volume correlated with decreased hospital stay (P = 0.016) when controlling for other covariates including age, sex, weight, and preoperative hematocrit. In addition, the same significant predictors were found when examining individual subtypes of craniosynostosis. CONCLUSION Our findings demonstrate that maxillofacial CT scans provide a useful quantitative index reflecting general patient health, risk stratification, and probabilities of intervention in addition to their previously established ability to determine the specific pathology of the patient. We demonstrate that temporal morphomics predict the incidence of blood transfusion, hospital stay, and serve as a proxy for fitness in patients undergoing craniosynostosis surgery.
J Craniofac Surg. 2012 June 7;24(1):158-62. doi: 10.1097/SCS.0b013e3182646411.
INTRODUCTION Pierre Robin sequence (PR) and Treacher Collins syndrome (TC) are congenital disorders associated with multiple craniofacial abnormalities. The mandibular malformations linked with these maladies are closely associated with the form and function of the temporalis muscle. Despite these associations, a paucity of research has been directed at quantifying how these malformations affect the tissues of the temporal region. In this paper, we seek to quantify differences in the temporalis muscle and the temporal fat pad using a novel CT-derived analytic program to examine craniofacial morphomic indices within these patient groups in comparison to normal age-matched controls. We posit that the temporalis muscle and temporal fat pad, like other derivatives of the first branchial arch, are hypoplastic in patients with TC and PR compared to age-matched controls. METHODS High-throughput image analysis was used to reconstruct the 3-dimensional (3D) anatomy and quantify morphomic measures of the temporalis muscle and temporal fat pad in children with PR, TC, and age-matched controls. These steps were completed in a semi-automated method using algorithms programmed in MATLAB v13.0. The 3D reconstructions were analyzed in 3 children with PR (6 temporal regions), 3 children with TC (6 temporal regions), and a control group of 19 children (38 temporal regions). We also quantified the same measurements in a localized "core" sample in the area of greatest thickness, providing a more consistent sample of the tissue position. Relationships between the temporal muscle and fat pad values and craniofacial abnormality type were assessed using Wilcoxon nonparametric test using exact distribution, with a P value of less than 0.05 being deemed significant. RESULTS The mean age of our patients was 6.0 years in PR and 4.5 years in TC cohorts. We were able to establish an automated methodology to quantify the temporalis muscle and temporal fat pad based on CT characteristics. Localized temporalis volume and localized temporalis area were significantly smaller in children with PR than in the control group. Total temporalis fat volume and localized temporalis area were significantly less in children with TC than in the control group. When compared to each other, the PR group had small morphomic values compared to TC group. CONCLUSIONS There are significant morphomic differences in the temporalis muscle and the temporal fat pad in children with either PR or TC when compared to age-matched control group which can be measured from pre-existing CT scans. Specifically, both of these test groups show decreases in the morphomic measures of the temporalis region. The quantification of these changes corroborates and objectifies the clinical findings associated with these congenital deformities while simultaneously allowing for preoperative planning. Furthermore, this finding confirms that the hypoplasia seen in these patient populations is not only hypoplasia of the mandible but also of the surrounding functional matrix, which includes the temporalis muscle and temporal fat pad.
Liver Transpl. 2012 Oct;18(10):1136-7. doi: 10.1002/lt.23510.
Ann Surg. 2012 Aug;256(2):255-61. doi: 10.1097/SLA.0b013e31826028b1.
OBJECTIVE Assess the relationship between lean core muscle size, measured on preoperative cross-sectional images, and surgical outcomes. BACKGROUND Novel measures of preoperative risk are needed. Analytic morphomic analysis of cross-sectional diagnostic images may elucidate vast amounts of patient-specific data, which are never assessed by clinicians. METHODS The study population included all patients within the Michigan Surgical Quality Collaborative database with a computerized tomography(CT) scan before major, elective general or vascular surgery (N = 1453). The lean core muscle size was calculated using analytic morphomic techniques. The primary outcome measure was survival, whereas secondary outcomes included surgical complications and costs. Covariate adjusted outcomes were assessed using Kaplan-Meier analysis, multivariate cox regression, multivariate logistic regression, and generalized estimating equation methods. RESULTS The mean follow-up was 2.3 years and 214 patients died during the observation period. The covariate-adjusted hazard ratio for lean core muscle area was 1.45 (P = 0.028), indicating that mortality increased by 45% per 1000 mm(2) decrease in lean core muscle area. When stratified into tertiles of core muscle size, the 1-year survival was 87% versus 95% for the smallest versus largest tertile, whereas the 3-year survival was 75% versus 91%, respectively (P < 0.003 for both comparisons). The estimated average risk of complications significantly differed and was 20.9%, 15.0%, and 12.3% in the lower, middle, and upper tertiles of lean core muscle area, respectively. Covariate-adjusted cost increased significantly by an estimated $10,110 per 1000 mm(2) decrease in core muscle size (P = 0.003). CONCLUSIONS Core muscle size is an independent and potentially important preoperative risk factor. The techniques used to assess preoperative CT scans, namely analytic morphomics, may represent a novel approach to better understanding patient risk.
Ann Plast Surg. 2012 Jul 31;73(1):86-91. doi: 10.1097/SAP.0b013e31826caf8d.
INTRODUCTION Preoperative computed tomography (CT) evaluation of patients with nonsyndromic craniosynostosis (NSC) has focused on the bony cranial vault while ignoring the surrounding soft tissues. In this study, we posit that novel CT-derived temporal muscle and temporal fat pad morphomics (tissue thickness, area, and volume) can be used to calculate temporal morphomic indices (TMIs), which are unique to each NSC subtype (metopic, coronal, and sagittal) and divergent from normal individuals. METHODS High-throughput image analysis was used to reconstruct the 3-dimensional anatomy and quantify a TMI. These steps were completed in a semiautomated method using algorithms programmed in MATLAB v13.0. Differences in TMI across various craniosynostosis subtypes were assessed using Wilcoxon nonparametric tests for both patients with NSC and a control cohort of patients with trauma. RESULTS Using preoperative CT images, we evaluated 117 children with NSC from the University of Michigan Health System and 50 age-matched control patients between 1999 and 2011. Results indicate significant differences in TMI among the normal and NSC groups, with normal patients having significantly higher TMI values than patients with metopic, sagittal, and coronal synostosis. In addition, significant differences were found to exist between each craniosynostosis category. CONCLUSIONS Patients with craniosynostosis demonstrate diminished temporalis muscle and overlying fat pad volume and thickness compared with control patients. The unique changes in temporal morphomics presented in this article demonstrate not only that the bony calvaria is affected by craniosynostosis but also that there exist quantifiable aberrations in the temporalis muscle and temporal fat pad. The methodologies described offer a novel methodology to use pre-existing CT scans to glean additional preoperative information on the soft tissue characteristics of patients with craniosynostosis.
World J Surg. 2012 Jul;36(7):1509-16. doi: 10.1007/s00268-012-1581-5.
BACKGROUND Accurate prediction of survival from adrenocortical carcinoma (ACC) is difficult and current staging models are unreliable. Central sarcopenia as part of the cachexia syndrome is a marker of frailty and predicts mortality. This study seeks to confirm that psoas muscle density (PMD), lean psoas muscle area (LPMA), lumbar skeletal muscle index (LSMI), and intra-abdominal (IA) or subcutaneous fat (SC) can be used in combination to more accurately predict survival in ACC patients. METHODS PMD, LPMA, IA, and SC fat were measured on serial CT scans of patients with ACC. Clinical outcome was correlated with quantitative data from patients with ACC and analyzed. A linear regression model was used to describe the relationship between PMD, LPMA, LSMI, IA, and SC fat, time to recurrence, and length of survival according to tumor stage. RESULTS One hundred twenty-five ACC patients (94 females) were treated from 2005 to 2011. Significant morphometric predictors of survival include PMD, LPMA, and IA fat (p ≤ 0.0001, ≤ 0.0024, <0.0001, respectively) and improve prediction of survival compared to using stage alone. A 100-mm(2) increase in LPMA confers an 8% lower hazard of death. LSMI does not change significantly between stages (p = 0.3196). CONCLUSION Decreased PMD, LPMA, and increased IA fat suggest decreased survival in ACC patients and correlate with traditional staging systems. A more precise prediction of survival may be achieved when staging systems and morphometric measures are used in combination. Serial measurements of morphometric data are possible. The rate of change of these variables over time may be more important than the absolute value.
JSAE Annual Congress. 2012 May; J-GLOBAL ID: 201202221899258995.
Different vertebral facet angles in pediatric versus adult necks may explain their disparate biomechanical tolerance and motion under physical loading. We analyzed CT scans of the neck using novel semi-automated image processing software algorithms to characterize the morphology of each cervical vertebra, including precise measurement of facet angle relative to other vertebral landmarks. We observe clear and very significant changes in facet angle with aging for C2 through C7. These findings are useful, when analyzed in conjunction with vehicle crash and injury data, to identify occupant specific factors that may contribute to motor vehicle crash injury tolerance in live subjects.
JSAE Annual Congress. 2012 May; J-GLOBAL ID: 201202249029876016.
Occupants of vehicles involved in motor vehicle collisions vary substantially in body stature and condition. This variability contributes substantially to differences in injury severity and patterns in the real world. Demographic factors such as age, gender, height and weight are insufficient to describe human variability. We analyzed CT scans of trauma and control populations to measure the anthropometry and tissue quality of different body regions. We observe very significant variability which we have referenced to a large population of 50%ile males. These findings are useful to identify occupant specific factors that contribute to motor vehicle crash injury.
Ann Surg Oncol. 2011 Dec;18(13):3579-85. doi: 10.1245/s10434-011-1976-9. Epub 2011 Aug 6.
BACKGROUND Several hypotheses proposed to explain the worse prognosis for older melanoma patients include different tumor biology and diminished host response. If the latter were true, then biologic frailty, and not age, should be an independent prognostic factor in melanoma. METHODS Our prospective institutional review board (IRB)-approved database was queried for stage III patients with computed tomography (CT) scans at time of lymph node dissection (LND). Psoas area (PA) and density (PD) were determined in semi-automated fashion. Kaplan-Meier (K-M) survival estimates and Cox proportional-hazard models were used to determine PA and PD impact on survival and surgical complications. RESULTS Among 101 stage III patients, PD was significantly associated with both disease-free survival (DFS) (P = 0.04) and distant disease-free survival (DDFS) (P = 0.0002). Cox multivariate modeling incorporating thickness, age, ulceration, and N stage showed highly significant association with PD and both DFS and DDFS. DDFS was significantly associated with Breslow thickness (P = 0.04), number of positive nodes (P = 0.001), ulceration (P = 0.04), and decreasing muscle density (P = 0.01), with hazard ratio of 0.55 [95% confidence interval (CI) 0.35-0.87]. PD also correlated with surgical complications, with odds ratio (OR) of 1.081 [95% CI 1.016-1.150, P = 0.01]. CONCLUSIONS Decreased psoas muscle density on CT, an objective measure of frailty, was as important a predictor of outcome as tumor factors in a cohort of stage III melanoma patients. On multivariate analysis, frailty, not age, was associated with decreased disease-free survival and distant disease-free survival, and higher rate of surgical complications.
Scand J Gastroenterol. 2011 Dec;46(12):1468-77. doi: 10.3109/00365521.2011.613946. Epub 2011 Oct 13.
OBJECTIVE To develop a novel non-invasive, quantitative approach utilizing computed tomography scans to predict cirrhosis. MATERIALS AND METHODS A total of 105 patients (54 cirrhosis and 51 normal) who had CT scans within 6 months of a liver biopsy or were identified through a Trauma registry were included in this study. Patients were randomly divided into the training set (n = 81) and the validation set (n = 24). Each liver was segmented in a semi-automated fashion from a computed tomography scan using Mimics software. The resulting liver surfaces were saved as a stereo lithography mesh into an Oracle database, and analyzed in MATLAB(®) for morphological markers of cirrhosis. RESULTS The best predictive model for diagnosing cirrhosis consisted of liver slice-bounding box slice ratio, the dimensions of the liver bounding box, liver slice area, slice perimeter, surface volume and adjusted surface area. With this model, we calculated an area under the receiver operating characteristic curve of 0.90 for the training set, and 0.91 for the validation set. For comparison, we calculated an area under the receiver operating characteristic curve of 0.70 for our dataset when we used the lab value based aspartate aminotransferase-platelet ratio index, another reported model for predicting cirrhosis. Last, by combining the aspartate aminotransferase-platelet ratio index and our model, we obtained an area under the receiving operating characteristic of 0.95. CONCLUSION This study shows "proof of concept" that quantitative image analysis of livers on computed tomography scans may be utilized to predict cirrhosis in the absence of a liver biopsy.
Surgery. 2011 Dec;150(6)61178-85. doi6 10.1016/j.surg.2011.09.020.
BACKGROUND Muscle weakness and wasting are known manifestations of hypercortisolism (HC). Central sarcopenia is a marker of frailty and predicts mortality. The hypothesis of this study is that central sarcopenia can be used as a marker of disease severity and frailty in patients with HC. METHODS Psoas muscle area and psoas muscle density (PMD) were measured at specific points on CT scans of patients with HC using a defined protocol. We compared 24-hour urine cortisol (24HUC) levels by time point to each CT scan. A linear regression model was used to describe the relationship between 24HUC and morphometric variables. A comparison with matched non-HC patients was performed. RESULTS We identified 45 patients (34 female). The median age was 46 years (range, 14-80); the median 24HUC was 211 mg/dL (range, 9.5-39,500); the median PMD was 50.1 24HUC (range, 20-72). An inverse correlation (-0.29) between 24HUC levels and PMD was noted (P = .045). Intra-abdominal fat was also significantly and positively correlated with 24HUC: 27 non-HC patients matched for age, sex, and body-mass index showed higher (58 vs 51) PMD (P = .0127) compared to those with HC. CONCLUSION PMD and intra-abdominal fat are significantly related to 24HUC levels. Morphometric measures of the overall burden of HC may allow more precise assessment of disease severity.
Stapp Car Crash J. 2011 Nov;55:479-90.
The size and shape of the acetabulum and of the femoral head influence the injury tolerance of the hip joint. The aim of this study is to quantify changes in acetabular cup geometry that occur with age, gender, height, and weight. Anonymized computed tomography (CT) scans of 1,150 individuals 16+ years of age, both with and without hip trauma, were used to describe the acetabular rim with 100 equally spaced points. Bilateral measurements were taken on uninjured patients, while only the uninjured side was valuated in those with hip trauma. Multinomial logistic regression found that after controlling for age, height, weight, and gender, each 1 degree decrease in acetabular anteversion angle (AAA) corresponded to an 8 percent increase in fracture likelihood (p<0.001). Age, weight, and gender were found to influence anteversion angle significantly, with each 10 years in age increasing AAA by 1.07 degrees, each 10 kg of weight decreasing AAA by 0.45 degrees, and being female resulting in 1.42 degrees greater AAA than males. Height was not found to relate significantly to AAA after other anthropometric factors were controlled for. Height, age, and weight, however, correlated with femoral head radius, thus establishing a relationship with acetabular rim size independent of rim shape. A parametric model of the 3D acetabular rim landmark points is reported, allowing for the creation of individualized acetabular geometry for any given age, gender, height, and weight. A custom-built tool to produce such geometry programmatically is also provided.
J Surg Res. 2011 Aug;213(2):236-244. doi: 10.1016/j.jamcollsurg.2011.04.008
BACKGROUND Obesity is a known risk factor for surgical site infection (SSI). Our hypothesis is that morphometric measures of midline subcutaneous fat will be associated with increased risk of SSI and will predict SSI better than conventional measures of obesity. STUDY DESIGN We identified 655 patients who underwent midline laparotomy (2006 to 2009) using the Michigan Surgical Quality Collaborative database. Using novel, semiautomated analytic morphometric techniques, the thickness of subcutaneous fat along the linea alba was measured between T12 and L4. To adjust for variations in patient size, subcutaneous fat was normalized to the distance between the vertebrae and anterior skin. Logistic regression analyses were used to identify factors independently associated with the incidence of SSI. RESULTS Overall, SSIs were observed in 12.5% (n = 82) of the population. Logistic regression revealed that patients with increased subcutaneous fat had significantly greater odds of developing a superficial incisional SSI (odds ratio [OR] = 1.76 per 10% increase, 95% CI 1.10 to 2.83, p = 0.019). Smoking, steroid use, American Society of Anesthesiologists (ASA) classification, and incision-to-close operative time were also significant independent risk factors for superficial incisional SSI. When comparing subcutaneous fat and body mass index (BMI) as the only model variables, subcutaneous fat significantly improved model predictions of superficial incisional SSI (area under the receiver operating characteristic curve [AUC] 0.60, p = 0.023); BMI did not (AUC 0.52, p = 0.73). CONCLUSIONS Abdominal subcutaneous fat is an independent predictor of superficial incisional SSI after midline laparotomy. Novel morphometric measures may improve risk stratification and help elucidate the pathophysiology of surgical complications.
J Surg Res. 2011 Feb;165(2):199-200. doi: 10.1016/j.jss.2010.11.600.
Obesity is a known risk factor for surgical site infection (SSI). Although body mass index (BMI) and body fat percentage are typically used to define obesity, these metrics do not directly assess body composition at the site of the wound. Within this context, measures of adiposity targeted at the surgical site may improve predictions of SSI risk. Such measures can be readily obtained from preoperative cross-sectional imaging. The objective of this study is to determine whether the amount of abdominal fat along the midline is correlated with SSI in patients undergoing procedures requiring midline laparotomy.
SAE International. 2011; #2011-01-1129.
This paper reports on a study that examines the effect of shoulder belt load limiters and pretensioners as well as crash and occupant factors that influence upper torso harm in real world frontal crashes. Cases from the University of Michigan International Center for Automotive Medicine (ICAM) database were analyzed. Additional information was used from other databases including the National Highway Traffic Safety Administration (NHTSA) New Car Assessment Program (NCAP), the Insurance Institute for Highway Safety (IIHS), the National Automotive Sampling System - Crashworthiness Data System (NASS-CDS), and patient data available from the University of Michigan Trauma Center. The ICAM database is comprised of information from real world crashes in which occupants were seriously injured and required treatment at a Level 1 Trauma Center. Cases from the database were included in this study if they met the following criteria: (a) the primary collision involved a frontal type crash and; (b) case occupants were seated in front outboard positions, restrained by 3-point safety belts and deployed frontal airbags. One hundred thirty three (133) case occupants who sustained nearly 1,800 injuries were selected for study from the ICAM database. The study included evaluations of skeletal, organ, and vessel injuries to the upper torso. Potential influencing factors were divided into three general categories: vehicle factors (i.e. seatbelt design); occupant factors; and crash related factors. Considering the challenges and limitations for analysis of field accident data and within the scope of this study, data indicated that: case occupants without shoulder belt load limiters experienced a higher level of upper torso harm in lower severity frontal crashes. The average Delta V for case occupants with shoulder belt load limiters was significantly higher (7.1 km/h, 34% greater crash energy) than that for the case occupants without load limiters. Case occupants with shoulder belt load limiters had significantly fewer clavicle fractures in frontal crashes. For the 62 case occupants with load limiters, the presence or absence of pretensioners did not appear to substantially change the crash severity associated with AIS ≥2 upper torso harm. Lower bone mineral density of the L4 vertebra was indicative of susceptibility to upper torso skeletal injuries. Smaller psoas muscle cross section area was indicative of susceptibility to upper torso internal and skeletal injuries.
J Surg Res. 2010 Aug;211(2):271-278. doi: 10.1016/j.jamcollsurg.2010.03.039
BACKGROUND Surgeons frequently struggle to determine patient suitability for liver transplantation. Objective and comprehensive measures of overall burden of disease, such as sarcopenia, could inform clinicians and help avoid futile transplantations. STUDY DESIGN The cross-sectional area of the psoas muscle was measured on CT scans of 163 liver transplant recipients. After controlling for donor and recipient characteristics using Cox regression models, we described the relationship between psoas area and post-transplantation mortality. RESULTS Psoas area correlated poorly with Model for End-Stage Liver Disease score and serum albumin. Cox regression revealed a strong association between psoas area and post-transplantation mortality (hazard ratio = 3.7/1,000 mm2 decrease in psoas area; p < 0.0001). When stratified into quartiles based on psoas area (holding donor and recipient characteristics constant), 1-year survival ranged from 49.7% for the quartile with the smallest psoas area to 87.0% for the quartile with the largest. Survival at 3 years among these groups was 26.4% and 77.2%, respectively. The impact of psoas area on survival exceeded that of all other covariates in these models. CONCLUSIONS Central sarcopenia strongly correlates with mortality after liver transplantation. Such objective measures of patient frailty, such as sarcopenia, can inform clinical decision making and, potentially, allocation policy. Additional work is needed develop valid and clinically relevant measures of sarcopenia and frailty in liver transplantation.
J Vasc Surg. 2010 June 10-13;53(4):912-7. doi: 10.1016/j.jvs.2010.10.111. Epub 2011 Jan 7.
OBJECTIVES Determining operative risk in patients undergoing aortic surgery is a difficult process, as multiple variables converge to affect overall mortality. Patient frailty is certainly a contributing factor, but is difficult to measure, with surgeons often relying on subjective or intuitive influences. We sought to use core muscle size as an objective measure of frailty, and determine its utility as a predictor of survival after abdominal aortic aneurysm (AAA) repair. METHODS Four hundred seventy-nine patients underwent elective open AAA repair between 2000 and 2008. Two hundred sixty-two patients (54.7%) had preoperative computed tomography (CT) scans available for analysis. Cross-sectional areas of the psoas muscles at the level of the L4 vertebra were measured. The covariate-adjusted effect of psoas area on postoperative mortality was assessed using Cox regression. RESULTS Of the 262 patients, there were 55 deaths and the mean length of follow-up was 2.3 years. Cox regression revealed a significant association between psoas area and postoperative mortality (P = .003). The effect of psoas area was found to decrease significantly as follow-up time increased (P = .008). Among all covariates included in the Cox models (including predictors of mortality such as American Society of Anesthesiologists [ASA] score), the psoas area was the most significant. CONCLUSION Core muscle size, an objective measure of frailty, correlates strongly with mortality after elective AAA repair. A better understanding of the role of frailty and core muscle size may aid in risk stratification and impact timing of surgical repair, especially in more complex aortic operations.
Proceedings of the 21st International Technical Conference on the Enhanced Safety of Vehicles (ESV), 2009. Technical Paper #09-0188-W.
Four-hundred forty two U-M CIREN (University of Michigan Crash Injury Research and Engineering Network) cases have previously been compared to crash tests used in the automotive industry. The comparison demonstrated that the majority of cases were similar in crash configuration and extent to industry crash tests, while smaller proportions either had a greater extent of crash deformation or had different crash configurations than those commonly produced in crash tests. Of the 442 cases, 290 frontal cases were analyzed in greater detail to understand trends in injury causation while considering physical characteristics of occupants (gender, age, body mass index.) Those trends were then evaluated in the context of biomechanics of crash test tools such as Anthropomorphic Test Devices [ATDs] and injury risk curves. Several trends were identified and presented.
Proceedings of the 21st International Technical Conference on the Enhanced Safety of Vehicles (ESV), 2009. Technical Paper #09-185-O.
A comparison of U-M CIREN (University of Michigan Crash Injury Research and Engineering Network) cases to crash tests used in the automotive industry is presented in this paper. 442 U-M CIREN crashes were compared to crash test configurations used throughout the industry. Of those 442 cases, 49% were similar in crash configuration and crash extent to industry crash tests. 32% of the cases were similar to one of the industry crash tests in configuration but had greater extent. 20% of the cases did not match any of the current industry crash tests. This analysis concluded that the majority of injuries in this study occurred in crash configurations similar to existing crash tests while only 20% of cases had crash configurations that were not represented by current crash tests. Any consideration of increasing test severity to address those crashes that produce a greater extent of crash deformation than that produced in crash tests must consider a broader spectrum of collisions including non-injury producing crashes. This analysis must be done in a way that does not increase the risk to the current uninjured population that is not included in the CIREN database.
Japan Society of Automotive Engineers. 2009. JSAE Technical Paper #145-20095232
Standard medical chest and abdomen computed tomography (CT) scans were used to take detailed measurements of human rib geometry and material properties from a wide range of patients. Geometric quantities included rib cross-sectional area, aspect ratio and camber angle. Material-based quantities included rib cross-sectional average density, and inner and outer measurements of cortical bone thickness and cortical bone density. We found very significant local and regional variation both within and between individuals. Proposals are made for the use of these measurements to inform and improve human finite element chest models, allowing them to more accurately represent the human ribcage.
Biomedical Imaging: From Nano to Macro, 2008. ISBI 2008. 5th IEEE International Symposium on 14-17 May 2008. doi: 10.1109/ISBI.2008.4541079.
Standard medical chest and abdominal computed tomography (CT) scans of 46 subjects were analyzed to characterize aspects of human ribcage geometry and bone density. A semi-automatic algorithm was developed to define framework curves for individual ribs. Measurements of this framework were taken to record anthropometric properties of the ribcage such as overall ribcage dimensions and individual rib lengths and angles. Furthermore, the ribcage framework was used to explore the voxel space of the CT images, recording local rib bone cross-sectional density properties. Proposals are made for the use of these measurement techniques to inform and improve human finite element (FE) chest models in terms of global geometry, material properties, and individuality.
J Pediatr Surg. 2006 Nov;41(11):1854-8.
BACKGROUND/PURPOSE Motor vehicle crashes account for more than 50% of pediatric injuries. Triage of pediatric patients to appropriate centers can be based on the crash/injury characteristics. Pediatric motor vehicle crash/injury characteristics can be determined from an in vitro laboratory using child crash dummies. However, to date, no detailed data with respect to outcomes and crash mechanism have been presented with a pediatric in vivo model. METHODS The Crash Injury Research Engineering Network is comprised of 10 level 1 trauma centers. Crashes were examined with regard to age, crash severity (DeltaV), crash direction, restraint use, and airbag deployment. Multiple logistic regression analysis was performed with Injury Severity Score (ISS) and Glasgow Coma Scale (GCS) as outcomes. Standard age groupings (0-4, 5-9, 10-14, and 15-18) were used. The database is biases toward a survivor population with few fatalities. RESULTS Four hundred sixty-one motor vehicle crashes with 2500 injuries were analyzed (242 boys, 219 girls). Irrespective of age, DeltaV > 30 mph resulted in increased ISS and decreased GCS (eg, for 0-4 years, DeltaV < 30: ISS = 10, GCS = 13.5 vs DeltaV > 30: ISS = 19.5, GCS = 10.6; P < .007, < .002, respectively). Controlling for DeltaV, children in lateral crashes had increased ISS and decreased GCS versus those in frontal crashes. Airbag deployment was protective for children 15 to 18 years old and resulted in a lower ISS and higher GCS (odds ratio, 2.1; 95% confidence interval, 0.9-4.6). Front-seat passengers suffered more severe (ISS > 15) injuries than did backseat passengers (odds ratio, 1.7; 95% confidence interval, 0.7-3.4). A trend was noted for children younger than 12 years sitting in the front seat to have increased ISS and decreased GCS with airbag deployment but was limited by case number. CONCLUSION A reproducible pattern of increased ISS and lower GCS characterized by high severity, lateral crashes in children was noted. Further analysis of the specific injuries as a function and the crash characteristic can help guide management and prevention strategies.
J Pediatr Surg. 2006 Feb;41(2):362-7.
BACKGROUND/PURPOS Motor vehicle crashes (MVCs) account for 50% of pediatric trauma. Safety improvements are typically tested with child crash dummies using an in vitro model. The Crash Injury Research Engineering Network (CIREN) provides an in vivo validation process. Previous research suggest that children in lateral crashes or front-seat locations have higher Injury Severity Scale scores and lower Glasgow Coma Scale scores than those in frontal-impact crashes. However, specific injury patterns and crash characteristics have not been characterized. METHODS Data were collected from the CIREN multidisciplinary crash reconstruction network (10 pediatric trauma centers). Injuries were examined with regard to crash direction (frontal/lateral), restraint use, seat location, and change in velocity at impact (DeltaV). Injuries were limited to Abbreviated Injury Scale (AIS) scores of 3 or higher and included head, thoracic, abdominal, pelvic, spine, and long bone (orthopedic) injuries. Standard age groupings (0-4, 5-9, 10-14, and 15-18 years) were used. Statistical analyses used Fisher's Exact test and multiple logistic regressions. RESULTS Four hundred seventeen MVCs with 2500 injuries were analyzed (males = 219, females = 198). Controlling for DeltaV and age, children in lateral-impact crashes (n = 232) were significantly more likely to suffer severe injuries to the head and thorax as compared with children in frontal crashes (n = 185), who were more likely to suffer severe spine and orthopedic injuries. Children in a front-seat (n = 236) vs those in a back-seat (n = 169) position had more injuries to the thoracic (27% vs 17%), abdominal (21% vs 13%), pelvic (11% vs 1%), and orthopedic (28% vs 10%) regions (P < .05 for all). Seat belts were protective for pelvic (5% vs 12% unbelted) and orthopedic (15% vs 40%) injuries (odds ratio = 3, P < .01 for both). CONCLUSION A reproducible pattern of injury is noted for children involved in lateral-impact crashes characterized by head and chest injuries. The Injury Severity Scale scores were higher for children in front-seat positions. Increased lateral-impact safety measures such as mandatory side curtain airbags may decrease morbidity. Furthermore, continued public education for positioning children in the back seat of cars is warranted.
Stapp Car Crash J. 2005 Nov;49:231-49.
The human body undergoes a variety of changes as it ages through adulthood. These include both morphological (structural) changes (e.g., increased thoracic kyphosis) and material changes (e.g., osteoporosis). The purpose of this study is to evaluate structural changes that occur in the aging bony thorax and to assess the importance of these changes relative to the well-established material changes. The study involved two primary components. First, full-thorax computed tomography (CT) scans of 161 patients, age 18 to 89 years, were analyzed to quantify the angle of the ribs in the sagittal plane. A significant association between the angle of the ribs and age was identified, with the ribs becoming more perpendicular to the spine as age increased (0.08 degrees/year, p=0.012). Next, a finite element model of the thorax was used to evaluate the importance of this rib angle change relative to other factors associated with aging. A three-factor, two-level factorial design was used to assess the relative importance of rib cage morphology ("young" and "old" rib angle), thickness of the cortical shell (thick = "young" and thin = "old"), and the bone material properties ("young" and "old") on the force-deflection response and injury tolerance of the thorax. The simulations showed that the structural and material changes played approximately equal roles in modulating the force-deflection response of the thorax. Changing the rib angle to be more perpendicular to the spine increased the effective thoracic stiffness, while the "old" material properties and the thin cortical shell decreased the effective stiffness. The offsetting effects of these traits resulted in similar effective thoracic stiffness for the "elderly" and baseline thoracic models, which is consistent with cadaver data available in the literature. All three effects tended to decrease chest deflection tolerance for rib fractures, though the material changes dominated (a four- to six-fold increase in elements eliminated using a maximum strain criterion). The primary conclusion, therefore, is that an older person's thorax, relative to a younger, does not necessarily deform more in response to an applied force. The tolerable sternal deflection level is, however, much less.
Society of Automotive Engineers. 2004. Paper #2004-01-0331.
Most studies investigating the biomechanics of injury are limited by a paucity of data about the physical characteristics of the subject before the injury occurred. This is particularly the case with live human subjects from real-life cases, where little data except age, gender, height and weight have been available to date. With regard to the injuries themselves, previously available data has generally been descriptive and of insufficient granularity and anatomic specificity to provide insight into the path of force loading through the surrounding tissues or the mechanism of injury. Three-dimensional medical imaging has recently become part of the standard evaluation of injured subjects and a growing pool of this data is becoming available to the biomechanical research community. When reviewed in conjunction with detailed crash and vehicle information, this data can provide invaluable information regarding the baseline physical characteristics that may have affected the subject's injury tolerance as well as insight into injury mechanism. Taken out of the proper context or with improper image processing, portions of this imaging data can be misleading. The objective of this study is to review changes in medical imaging technology over the past two decades as well as changes in its utilization for the standard evaluation of injured patients. Analysis of 3D medical imaging data for biomechanical studies requires image data processing beyond that used during interpretation for clinical purposes; these processes will be reviewed so that members of the biomechanical research community can better understand the potential uses and limitations of this data. The argument will be made for the research community to adopt common standards and procedures. Individual case studies will demonstrate the conditions under which pre-injury body composition data can be extracted from post- injury 3D medical imaging data. Pooled data will demonstrate the association that exists between these body composition data and observed injury tolerance. The implications of this data for the design and validation of finite element models capable of accurately predicting body tolerances to injury will be discussed.
Annual Proceedings of the Association for the Advancement of Automotive Medicine. 2004; 48:287-301.
Male occupants in frontal motor vehicle collisions have reduced tolerance for hip fractures than females in similar crashes. We studied 92 adult pelvic CT scans and found significant gender differences in bony pelvic geometry, including acetabular socket depth and femoral head width. Significant differences were also noted in the presentation angle of the acetabular socket to frontal loading. The observed differences provide biomechanical insight into why hip injury tolerance may differ with gender. These findings have implications for the future design of vehicle countermeasures as well as finite element models capable of more accurately predicting body tolerances to injury.
J Trauma. 2003 Jun;54(6):1090-3.
BACKGROUND The pattern and severity of crash injury depends on a complex interaction of biomechanical factors such as deceleration velocity at impact (delta-V), seat-belt and airbag use, and type of impact. Human body characteristics such as height and weight may play an important role. We hypothesized that body mass index (BMI) will influence crash injury patterns. METHODS The University of Michigan Program for Injury Research and Education database was queried. Three cohorts were analyzed, lean (BMI </= 25 kg/m2), overweight (BMI 25-30 kg/m2), and obese (BMI > 30 kg/m2) RESULTS There were 189 detailed crash cases, with 22 fatalities. There was an increased risk of fatal outcome associated with the obese cohort (adjusted odds ratio, 4.2 compared with lean; p = 0.04). Age, delta-V, seat-belt use, and type of impact were independent predictors of Injury Severity Score (ISS). After adjusting for other modifiers, being overweight was associated with decreased ISS (p = 0.03) and abdominal maximal Abbreviated Injury Scale (mAIS) score (p = 0.008) when compared with the lean cohort. However, the lower extremity mAIS score increased when overweight (p = 0.03) and obese cohorts (p = 0.001) were compared with the lean cohort. CONCLUSION Although no difference in ISS was identified between the lean and obese cohorts, there was an increase in mortality with the obese cohort. The severity of lower extremity injuries increased with increasing BMI. The overweight cohort was associated with lower ISS and abdominal mAIS score compared with the lean cohort. This protection may be attributable to an increase in insulating tissue, or a "cushion effect," without a significant increase in mass and momentum.
Annu Proc Assoc Adv Automot Med. 2003;47:545-59.
The objective of this study was to determine the effect of differences in subcutaneous fat depth on adult injury patterns in motor vehicle collisions. Sixty-seven consecutive adult crash subjects aged 19-65 who received computed tomography of their chest, abdomen and pelvis as part of their medical evaluation and who consented to inclusion in the Crash Injury Research Engineering Network (CIREN) study were included. Subcutaneous fat was measured just lateral to the rectus abdominus muscle in a transverse section taken through the subject at the level of L4. Women had significantly greater subcutaneous fat depth than men. Increased subcutaneous fat depth was associated with significantly decreased injury severity to the abdominal region of females. A similar trend was noted in males although it did not reach statistical significance. Our findings suggest that increased subcutaneous fat may be protective against injuries by cushioning the abdominal region against injurious forces in motor vehicle collisions.
University of Michigan
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