Subcutaneous Fat Cross-sectional Area Research Articles

Cervical body composition on radiotherapy planning computed tomography scans predicts overall survival in glioblastoma patients

Background and purposeGlioblastoma (GBM) patients face a strongly unfavorable prognosis despite multimodal therapy regimens. However, individualized mortality prediction remains imprecise. Harnessing routine radiation planning cranial computed tomography (CT) scans, we assessed cervical body composition measures as novel biomarkers for overall survival (OS) in GBM patients. Materials and methodsWe performed threshold-based semi-automated quantification of muscle and subcutaneous fat cross-sectional area (CSA) at the levels of the first and second cervical vertebral body. First, we tested this method’s validity by correlating cervical measures to established abdominal body composition in an open-source whole-body CT cohort. We then identified consecutive patients undergoing radiation planning for recent GBM diagnosis at our institution from 2010 to 2020 and quantified cervical body composition on radiation planning CT scans. Finally, we performed univariable and multivariable time-to-event analyses, adjusting for age, sex, body mass index, comorbidities, performance status, extent of surgical resection, extent of tumor at diagnosis, and MGMT methylation. ResultsCervical body composition measurements were well-correlated with established abdominal markers (Spearman’s rho greater than 0.68 in all cases). Subsequently, we included 324 GBM patients in our study cohort (median age 63 years, 60.8% male). 293 (90.4%) patients died during follow-up. Median survival time was 13 months. Patients with below-average muscle CSA or above-average fat CSA demonstrated shorter survival. In multivariable analyses, continuous cervical muscle measurements remained independently associated with OS. ConclusionThis exploratory study establishes novel cervical body composition measures routinely available on cranial radiation planning CT scans and confirms their association with OS in patients diagnosed with GBM.

Does a "Cushion Effect" Really Exist? A Morphomic Analysis of Vulnerable Road Users with Serious Blunt Abdominal Injury.

Introduction: The severity of injury from motor vehicle crashes (MVCs) depends on complex biomechanical factors, and the bodily features of the injured person account for some of these factors. By assuming that vulnerable road users (VRUs) have limited protection resulting from vehicles and safety equipment, the current study analyzed the characteristics of fat distribution measured by computed tomography (CT) imaging and investigated the existence of a “cushion effect” in VRUs. Materials and Methods: This retrospective study enrolled 592 VRUs involved in MVCs who underwent CT scans. Visceral fat area and subcutaneous fat cross-sectional area were measured and adjusted according to total body area (TBA) and are presented as the visceral fat ratio and the subQ fat ratio (subcutaneous fat ratio). Risk factors for serious abdominal injury (maximum abbreviated injury scale (MAISabd ≥ 3)) resulting from MVCs were determined by univariate and multivariate analysis. Results: MAISabd ≥ 3 was observed in 104 (17.6%) of the patients. The subQ fat ratio at the L4 vertebral level was significantly lower in the MAISabd ≥ 3 group than in the MAISabd < 3 group (24.9 ± 12.0 vs. 28.1 ± 11.9%; p = 0.015). A decreased L4 subQ fat ratio was associated with a higher risk for MAISabd ≥ 3 in multivariate analysis (odds ratio 0.063; 95% CI 0.008–0.509; p = 0.009). Conclusion: The current study supported the “cushion effect” theory, and protection was apparently provided by subcutaneous fat tissue. This concept may further improve vehicle and safety designation in the future.

Association of Thoracic Computed Tomographic Measurements and Outcomes in Patients with Hematologic Malignancies Requiring Mechanical Ventilation.

Rationale: Patients with hematologic malignancies requiring mechanical ventilation have historically experienced poor outcomes.Objectives: We aimed to determine whether body composition characteristics derived from thoracic computed tomographic (CT) imaging were associated with time to liberation from mechanical ventilation.Methods: We evaluated mechanically ventilated patients with hematological malignancies admitted between 2014 and 2018. We included patients with thoracic CT imaging completed between 1 month before and 48 hours after intensive care unit (ICU) admission. We assessed the association of carinal skeletal muscle cross-sectional area (CSA), subcutaneous fat CSA, and fat index (fat/skeletal muscle ratio) with time to liberation from mechanical ventilation within 28 days. We accounted for the competing event of death within 28 days of mechanical ventilation.Results: One hundred fifty-six patients were included; the mean age was 57 years (standard deviation 14) and 39% were female. Thirty-seven percent had received a hematopoietic stem cell transplant, and the median ratio of arterial oxygen tension/pressure to fraction of inspired oxygen was 134 mm Hg (interquartile range [IQR], 92-205). Median skeletal muscle CSA was 68 cm2 (IQR, 54-88) and subcutaneous fat CSA was 38 cm2 (IQR, 27-52). Forty-two percent of patients were liberated from mechanical ventilation within 28 days and 56% died in the ICU. Subcutaneous fat CSA (subdistribution hazard ratio [sHR], 0.81; 95% confidence interval [95% CI], -0.68 to 0.97) and fat index (sHR, 0.81; 95% CI, -0.68 to 0.97) were significantly associated with longer time to liberation from mechanical ventilation. Skeletal muscle CSA was not associated with time to liberation from ventilation (sHR, 1.08; 95% CI, -0.94 to 1.23).Conclusions: Body composition measurements based on thoracic CT scans were associated with time to liberation from ventilation. These could represent novel surrogate markers of physical frailty in patients with hematologic malignancies receiving mechanical ventilation.

Characteristics of Lymphedema in Patients Treated with Mammalian Target of Rapamycin Inhibitors.

Purpose: To investigate the characteristics of lymphedema in patients treated with mammalian target of rapamycin (mTOR) inhibitors and delineate complex decongestive therapy (CDT) outcomes. Methods and Results: We retrospectively analyzed 24 patients with mTOR inhibitor-induced lymphedema and 7 lymphedema patients (control) not treated with mTOR inhibitors, who visited the lymphedema clinic of the department of rehabilitation medicine from March 2016 to December 2019. We comprehensively reviewed clinical features, medication history, associated diseases, lymphoscintigraphy, lower extremity computed tomography venography (LE CTV), and the effect of CDT. By using ImageJ program, we measured the cross-sectional area (CSA) of muscle and subcutaneous fat of mid-thigh image in LE CTV and compared them to a control group not treated with mTOR inhibitors. Seventeen patients on sirolimus and seven patients on everolimus were included, with an approximately equal distribution of stages 2 and 3 lymphedema, and most with pitting edema. Ten patients had breast or gynecological cancer and underwent lymph node dissection. Lymphedema developed after mTOR inhibitor initiation, not postoperatively. Lymphoscintigraphy revealed decreased lymph node uptake and dermal backflow. LE CTV revealed subcutaneous honeycomb-shaped trabecular areas in the affected limbs of seven patients. Patients treated with mTOR inhibitors had a larger mean subcutaneous fat CSA and a smaller mean muscular CSA than controls. Lymphedema improved or remained unchanged after initial CDT. Daily CDT adequately controlled 11 cases, but exacerbation occurred in 5 of 7 poorly compliant patients, and cellulitis occurred in 6 patients. Conclusion: Physicians should identify mTOR inhibitor-related lymphedema early and discuss medication alternatives and CDT with patients.

The impact of disease-related immobilization on thigh muscle mass and strength in older hospitalized patients

BackgroundWe assessed the quantitative changes in muscle mass and strength during 2 weeks of hospitalization in immobile and mobile acutely ill hospitalized older adults.MethodsForty-one patients (82.4 ± 6.6 years, 73.0% females) participated in this prospective longitudinal observational study. Mobility status was defined according to walking ability as described in the Barthel-Index. Functional status, including handgrip strength and isometric knee-extension strength, and mid-thigh magnetic resonance imaging (MRI) measurements of cross-sectional area (CSA) were conducted on admission and at discharge.ResultsTwenty-two participants (54%) were immobile and 19 (46%) mobile. In all, 54.0 and 12.0% were at risk of malnutrition and malnourished, respectively. The median time between baseline and follow-up for MRI scans were 13 days in mobile and immobile participants (P = 0.072). Mid-thigh muscle and subcutaneous fat CSA significantly decreased by 3.9cm2 (5.0%, P = 0.002) and 5.3cm2 (5.7%, P = 0.036) during hospitalization whereas intermuscular fat remained unchanged in immobile subjects. No significant changes were observed in mobile patients. In a regression analysis, mobility was the major independent risk factor for changes in mid-thigh muscle CSA as a percentage of initial muscle area (P = 0.022) whereas other variables such as age (P = 0.584), BMI (P = 0.879), nutritional status (P = 0.835) and inflammation (P = 0.291) were not associated with muscle mass changes. There was a significant decrease in isometric knee extension strength (P = 0.002) and no change in handgrip strength (P = 0.167) in immobile patients whereas both parameters increased significantly over time in mobile patients (P = 0.048 and P = 0.012, respectively).ConclusionsTwo weeks of disease-related immobilization result in a significant loss of thigh muscle mass and muscle strength in older patients with impaired mobility. Concomitantly, there was a significant reduction of subcutaneous adipose tissue in immobile older hospitalized patients whereas no changes were observed in intermuscular fat among these patients. These data highlight the importance of mobility support in maintaining muscle mass and function in older hospitalized patients.

The role of imaging in early detection of patients at risk for neuropathy during primary chemotherapy for ovarian carcinoma.

e18071 Background: Neuropathy is a common adverse event requiring dose reduction or regimen change in patients receiving platinum-taxane chemotherapy for ovarian cancer. Our aim was to determine whether specific biomarkers, such as skeletal muscle, visceral and subcutaneous fat cross-sectional areas, measured using computerized tomography (CT), were associated with the development of neuropathy. Analytic Morphomics, a semi-automated image analysis method, has been used to predict oncologic outcomes with immunotherapy and to identify patients at higher risk for postoperative complications from major cancer surgeries. We hypothesized that patients who required dose reductions or regimen changes would have CT imaging findings that distinguished them from their counterparts who did not require dose reduction or regimen change. Methods: All patients at our institution diagnosed with high-grade ovarian carcinoma between January 1, 2014 and December 31, 2018 were identified retrospectively. Analytic Morphomics was used to extract measures of body composition from CT images at the level of the third lumbar vertebra. Demographic and clinical characteristics were abstracted from the electronic medical record. We analyzed several binary outcomes (neuropathy, delay in chemotherapy, or dose reduction by cycle 1, 3 or 6) and used unpaired, two-tailed t-tests to compare means between each outcome group at each timepoint. Results: Of 156 patients screened for the study, 138 patients were included and had pre-treatment CT scans available and completed six cycles of platinum-taxane chemotherapy. Patients who developed neuropathy in any of the six cycles, or had a change in their chemotherapy regimen by cycle six, had higher mean visceral fat area than those who did not develop neuropathy. This finding was statistically significant throughout three cycles (p = 0.023) and six cycles (p = 0.030). Conclusions: Increased visceral fat on CT imaging was significantly associated with a higher incidence of neuropathy and change in chemotherapy regimen in patients undergoing primary platinum-taxane chemotherapy for ovarian carcinoma. Weight and BMI did not have a significant association with development of neuropathy, dose reduction, or treatment delay. Further study is needed to determine if dose reductions or regimen changes due to neuropathy can be better predicted using morphomics.

Associations between baseline body composition and cancer-specific mortality following neoadjuvant chemotherapy and radical cystectomy for bladder cancer.

e17015 Background: Sarcopenia is a modifiable risk factor independently associated with cancer-specific mortality (CSM) in bladder cancer (BC). Sarcopenic obesity, where obesity is measured by fat mass index [FMI, total body fat (kg)/height(m)2], has been proposed as an additive insult. To date, studies have overwhelmingly been performed in patients treated without neoadjuvant chemotherapy (NAC). Herein, we evaluate associations between baseline skeletal muscle index (SMI), FMI, and CSM in patients treated with NAC and radical cystectomy (RC). Methods: Lumbar SMI (cross sectional area of skeletal muscle/height2, cm2/m2) was measured on a computed tomography (CT) image at the level of the third lumbar vertebral body, within 60 days prior to NAC. Total body FMI was calculated from visceral and subcutaneous fat cross-sectional areas. Patients were classified as being sarcopenic, according to sex-specific consensus definitions: Male: SMI &lt; 55, Female: SMI &lt; 39, and as obese if Male: FMI &gt; 9, Female: &gt; 13. Cancer-specific survival (CSS) was estimated using the Kaplan Meier method. Associations with CSM were summarized with multivariable Cox proportional hazards models. Results: 143 patients had CT scans of sufficient quality (2005-18). There were no significant differences in clinicopathologic characteristics between the study cohort and patients without available imaging (N = 261). Cisplatin-based NAC was given to 125 patients (87%), and 18 (13%) received other regimens. In total, 86 (60%) patients were sarcopenic, 52 (36%) obese, and 25 (17%) both sarcopenic and obese, while 48 (34%) were sarcopenic with normal FMI. Median follow-up was 2.7 years (IQR 1.2-6.2), and 43 patients died from BC. Three-year CSS was 61% (sarcopenic) vs. 77% (p &lt; 0.05). Sarcopenic patients with normal FMI had the worst 3-year CSS (55%) compared to those with sarcopenia and FMI-obesity (79%), normal SMI with FMI-obesity (69%), and normal body composition (88%, p = 0.03). On multivariable analysis, neither FMI (HR: 0.77, 95% CI: 0.47-1.3, p = 0.3) nor SMI was independently associated with CSM (HR: 0.98, 95% CI: 0.96-1, p = 0.07) after adjustment for ASA score, pathologic tumor, and nodal stage. Conclusions: In patients treated with NAC+RC, pretreatment SMI trended towards independently predicting risk of CSM. Patients with sarcopenia and normal fat demonstrated the worst CSS. Further study is warranted on the impact of NAC on body composition and the role of the latter in risk stratification of this high-risk patient population.

Effect of Subcutaneous Tissue on Changes in Thigh Circumference Following Anterior Cruciate Ligament Reconstruction.

Circumference measurements have been used to estimate muscle cross-sectional area (CSA) in clinical settings. Measurements of thigh circumference are affected by muscle and subcutaneous fat (SF). In fact, SF could increase over a short period. Therefore, clarifying the relationship between thigh circumference and muscle and SF following ACL reconstruction is important. This study's primary purpose was to examine pre- and post-operative changes in thigh circumference, thigh muscles and SF CSAs in both legs. Secondary, the relationship between thigh circumference and muscle and SF CSAs was examined to demonstrate that circumference measurements could be used to detect atrophy. Quadriceps, hamstrings, and SF CSAs at 15, 10, and 5 cm proximal to the patella were measured by MRI pre- and 4 weeks postoperatively to examine how reconstruction affected those tissues in the thighs. The results showed increases in SF CSA (r=0.72 at 10 cm, r=0.67 at 15 cm) greatly affected thigh circumference in females on the surgical side. In males, increases in SF CSA (r=0.83) at 15- and 5-cm and decreases in quadriceps muscle CSA (r=0.73) at 5 cm affected thigh circumference on the surgical side. Thigh circumference measurements might not reflect actual muscle CSA in ACL patients.

2058-P: Leptin and Adiponectin Concentrations Independently Predict Future Accumulation of Visceral Adiposity in Nondiabetic Japanese Americans

Objectives: The adipokines leptin and adiponectin are associated with change in body composition and are highly correlated, raising questions about whether they exert independent effects. We investigated whether these two adipokines are independently associated with regional body fat accumulation in a prospective study of Japanese Americans. Methods: Nondiabetic participants between the ages of 34 to 74 years were followed for 5 years to assess change in body composition. Leptin and adiponectin concentrations and single slice CT-measurements of intra-abdominal fat (IAF), abdominal (SCF) and thigh (TF) subcutaneous fat cross-sectional areas were evaluated at baseline and 5 year follow-up study visits. Multiple linear regression analysis was used to estimate the association between leptin and adiponectin and future 5-year accumulation of IAF. Results: 96 men and 95 women without diabetes included in this analysis had the following baseline mean (SD) values: age 45.7 (3.5) years and 46.4 (3.9) years; BMI 25.5 (3.1) kg/m2 and 24.0 (3.9) kg/m2; IAF 78.7 (38.6) cm2 and 62.1 (39.0) cm2; leptin concentration 4.5 (2.3) μg/L and 10.2 (5.2) μg/L; and adiponectin concentration 7.4 (3.2) μg/mL and 10.8 (4.7) μg/mL, respectively. Baseline leptin (β = 1.7722, p=0.014) and adiponectin concentrations (β = -0.4162, p&amp;lt;0.001) were significantly associated with ΔIAF over 5 years in multivariable models adjusting for age, sex, diabetes family history, weight change over 5 years, and baseline measurements of BMI, IAF, abdominal SCF, abdominal circumference, TF, and HOMA-IR. Conclusions: In nondiabetic Japanese Americans, baseline concentrations of leptin and adiponectin were independent predictors of IAF accumulation at 5 years. Higher levels of leptin and adiponectin were associated with greater and lesser accumulation of IAF, respectively. These relationships were independent of age, sex, insulin sensitivity, and body composition. Disclosure S. Song: None. S.E. Kahn: Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Intarcia Therapeutics, Inc., Janssen Pharmaceuticals, Inc., Merck &amp; Co., Inc., Novo Nordisk A/S. Consultant; Self; Neurimmune. Other Relationship; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Merck &amp; Co., Inc., Novo Nordisk A/S. D.L. Leonetti: None. W.Y. Fujimoto: None. E.J. Boyko: None. Funding National Institutes of Health DK31170, HL49293); University of Washington (DK017047, DK035816, RR-000037); VA Puget Sound Health Care System (to E.J.B., S.E.K.)

2057-P: HDL-Cholesterol Concentration Independently Predicts Future Accumulation of Intra-abdominal Fat in Japanese Americans

Background: Both intra-abdominal fat (IAF) and HDL cholesterol (HDL-C) are known to be associated with cardiometabolic health problems, with an inverse correlation between them. However, there is little information about the association between HDL-C concentration with future accumulation of IAF. We conducted a prospective study to evaluate whether baseline HDL-C concentration was associated with the accumulation of CT-measured intra-abdominal fat (IAF) over 5 years. Methods: All participants were Japanese-American men and women between the ages of 34 to 74 years. HDL-C concentration and CT-measurements of IAF, abdominal (SCF) and thigh (TF) subcutaneous fat cross-sectional areas were evaluated at baseline and 5 year follow-up visits. Data were analyzed to determine the association between HDL-C and future 5-year accumulation of IAF. Results: A total of 545 subjects with and without diabetes (296 men, 249 women, and mean age 53.6±11.4 and 54.0±12.0 years, respectively) were included. The mean (SD) HDL-C concentration was 1.3 mmol/L (0.4) in men and 1.7 mmol/L (0.4) in women and mean (SD) IAF was 102 cm2 (53.8) in men and 74.5 cm2 (46.8) in women. Baseline HDL-C concentration was inversely associated with Δ IAF over 5 years using multivariable regression analysis adjusting for age, sex, diabetes family history, weight change over 5 years, and baseline measurements of BMI, IAF, abdominal SCF, abdominal circumference, TF, and HOMA-IR. Conclusions: These results demonstrate that HDL-C concentration predicts significantly future accumulation of IAF over 5 years independent of age, sex, insulin sensitivity, and body composition in nondiabetic Japanese-American men and women. Disclosure S. Song: None. Y. Hwang: None. S.E. Kahn: Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Intarcia Therapeutics, Inc., Janssen Pharmaceuticals, Inc., Merck &amp; Co., Inc., Novo Nordisk A/S. Consultant; Self; Neurimmune. Other Relationship; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Merck &amp; Co., Inc., Novo Nordisk A/S. D.L. Leonetti: None. W.Y. Fujimoto: None. E.J. Boyko: None. Funding National Institutes of Health DK31170, HL49293); University of Washington (DK017047, DK035816, RR-000037); VA Puget Sound Health Care System (to E.J.B., S.E.K.)

Evaluating the “cushion effect” among children in frontal motor vehicle crashes

BackgroundThe “Cushion Effect,” the phenomenon in which obesity protects against abdominal injury in adults in motor vehicle accidents, has not been evaluated among pediatric patients. This work evaluates the association between subcutaneous fat cross-sectional area, quantified using analytic morphomic techniques and abdominal injury. MethodsThis retrospective study includes 119 patients aged 1 to 18years involved in frontal impact motor vehicle accidents (2003–2015) with computed tomography scans. Subcutaneous fat cross-sectional area was measured and converted to age- and gender-adjusted percentiles from population-based normative data. Multivariable analysis determined the risk of the primary outcome, Maximum Abbreviated Injury Scale (MAIS) 2+ abdominal injury, after adjusting for age, weight, seatbelt status, and impact rating. ResultsMAIS 2+ abdominal injuries occurred in 20 (16.8%) of the patients. Subcutaneous fat area percentile was not significantly associated with MAIS 2+ abdominal injury on multivariable logistic regression (adjusted Odds Ratio, 0.86; 95% CI, 0.72–1.03; p=0.10). DiscussionThe “cushion effect” was not apparent among pediatric frontal motor vehicle crash victims in this study. Future work is needed to investigate other analytic morphomic measures. By understanding how body composition relates to injury patterns, there is a unique opportunity to improve vehicle safety design. Level of EvidencePrognosis Study, Level III.

Responsiveness of Infrapatellar Fat Pad Volume Change to Body Weight Loss or Gain: Data from the Osteoarthritis Initiative

Obesity is a potent risk factor for knee osteoarthritis (OA) that is driven by mechanical and potentially endocrine mechanisms, and it affects women more frequently than men. The infrapatellar fat pat (IPFP) represents a potential link between obesity, intra-articular inflammation and structural pathology. Here we investigate whether the IPFP is responsive to body weight loss/gain in women and how its responsiveness to weight change compares to that of subcutaneous fat (SCF) of the thigh. All female participants of the Osteoarthritis Initiative (OAI) with ≥10% weight loss/gain between baseline and a 2-year follow-up were included. Within-subject changes in IPFP volume and SCF cross-sectional areas (CSA) were determined from 3-T magnetic resonance imaging. Linear regression was used to assess the association between change in weight, IPFP volume, and SCF CSA. In the 38 participants with ≥10% weight loss over 2 years (age 59.3 ± 9.1 years, mean loss = 15.9%), there was a significant reduction in IPFP volume (-2.2%, p = 0.02) as well as in SCF CSA (-22%, p < 0.001). In the 34 participants with ≥10% gain (age 61.5 ± 8.7 years, mean gain = 15.9%), there was a significant increase in SCF CSA (+26%, p < 0.001) but not in IPFP volume (0.2%, p = 0.87). Weight change was significantly associated with SCF CSA change (r = 0.76, p < 0.001) but not with IPFP volume change (r = 0.11, p = 0.37). In this first longitudinal, observational study investigating the responsiveness of IPFP and SCF to weight change, IPFP morphology was found responsive to weight loss but not to weight gain. Overall, the responsiveness of the IPFP was substantially less than that of the SCF.

Relationship Of Visceral Fat Accumulation And Arteriosclerosis Risk In Obese Children

PURPOSE: In recent years, there has been increasing attention focused on new factors strongly related to arteriosclerosis such as the ratio of high-density lipoprotein cholesterol (HDL-C) to low-density lipoprotein cholesterol (LDL-C), or the “L/H ratio,” and adiponectin.Therefore, this study compared the relationships between body fat percentage, visceral fat mass and subcutaneous fat mass with arteriosclerosis risk factors in obese and non-obese children. METHODS: Subjects comprised 112 children (age: 7.5 - 12.6 years) who consented to participate in this study. They were divided into an obese group (68 children, age: 9.7±1.5 years) and a non-obese group (44 children, age: 9.6±1.4 years) with an obesity index score of 20% or higher the cutoff for determining obesity. The Bod Pod system was used to measure body density and body fat percentage was then calculated. MRI with 0.2T magnetic field strength was used to calculate visceral fat and subcutaneous fat cross-sectional areas in the horizontal plane between lumbar vertebrae 4 and 5. Venous blood collection was performed during fasting in the early morning. TC, LDL-C, HDL-C, triglycerides, blood glucose level, insulin, HbA1c and adiponectin were analyzed, and L/H ratio and the homeostatic model assessment (HOMA) index were calculated. Systolic and diastolic blood pressure was measured three times and the lowest values for each were used as data. RESULTS: Comparison of the correlation coefficients of test items with body fat percentage, subcutaneous fat area/height and visceral fat area/height in obese children indicated that the correlation coefficient of visceral fat area/height for LDL-C, triglycerides, systolic blood pressure and adiponectin was significantly higher than for the other two indices. Comparison of the correlation coefficients with visceral fat area/height between the obese and non-obese groups indicated that the correlation coefficient was significantly higher for the obese group with regards to TC, LDL-C, insulin, HOMA index, systolic blood pressure and adiponectin. CONCLUSIONS: Results demonstrated that although obese children tend to exhibit subcutaneous fat obesity, visceral fat is more strongly related to arteriosclerosis risk factors than body fat percentage and subcutaneous fat.

Positive effects of brown adipose tissue on femoral bone structure

PurposeRecent studies suggest a link between brown adipose tissue (BAT) and bone. The purpose of our study was to investigate the effects of BAT on femoral bone structure. Materials and methodsWe studied 105 patients (19 m, 86 f. mean age 45.5±16.1years) who underwent F18-FDG positron emission tomography/computed tomography (PET/CT) for benign etiologies (n=20) or follow-up of successfully treated malignancies (n=85); mean time between PET/CT and last form of treatment was 14.8±18.0months. BAT volume by PET/CT; femoral bone structure by CT (total femoral cross-sectional area (CSA), cortical CSA); and thigh muscle CSA and thigh subcutaneous fat CSA by CT was assessed. ResultsThere were positive correlations between BAT volume and total femoral CSA and cortical CSA, independent of age, BMI and history of malignancy (p<0.05). BAT volume correlated positively with thigh muscle CSA and thigh fat CSA (p<0.05). When total femoral CSA was entered as a dependent variable and BAT volume, age and BMI as independent variables in a forward stepwise regression model, BAT volume was the only predictor of total femoral CSA. When femoral cortical CSA was entered as a dependent variable and BAT volume, age and BMI as independent variables, BAT volume was the only predictor of femoral cortical CSA. ConclusionBAT volume is a positive predictor of femoral bone structure and correlates positively with thigh muscle and subcutaneous fat, possibly mediated by muscle. These results provide further evidence of a positive effect of BAT on bone.

477 Apples Are Higher Risk Than Pears: Subcutaneous Fat Measurement Using Analytic Morphomics and the Risk of Infectious Complications in Abdominal Surgeries for Crohn's Disease

BACKGROUND/AIMS: In decision-making for medical vs. surgical therapy in Crohn's disease (CD), it is important to consider the likelihood of serious post-operative complications. Body habitus and BMI have been implicated as important factors for incurring post-operative complications, however these factors have undergone limited studies in CD. AnalyticMorphomics is a novel method of computational image analysis providing quantifiable and reproducible measurements of organs and body tissues. The aim of this study was to determine whether morphomic assessment of body tissues was predictive of major infectious complications following CD-related surgeries. METHODS: We conducted a retrospective review of a large tertiary center's medical records to identify adults with a diagnosis of CD (ICD 555.x) who underwent Crohn's-related abdominal surgery from 2000-2010. Charts were reviewed to verify the diagnosis of CD, medications, demographics, laboratory data, and outcomes. CT scans within 30 days of surgery underwent analytic morphomic analysis for fat and muscle quantification and total body cross-sectional area at several spinal levels. Surgical outcomes of 1) placement of a new post-operative abdominal drain; 2) use of intravenous antibiotics for greater than 10 days; or 3) re-operation within 30 days were considered infectious complications. Logistic regression was used to model these outcomes, focusing on clinical predictors and image-based measures of abdominal fat and muscle. The best models were chosen using pseudo-R^2 in Stata 11. RESULTS: There were 269 subjects identified with complete data on 229 subjects; infectious complications occurred in 23%. Univariate analysis showed hemoglobin, albumin, surgery type, distribution of subcutaneous fat and body area, but not psoas area, BMI, prednisone use, or anti-TNF use were predictors of infectious complications. A multivariate model including hemoglobin, the distribution of subcutaneous fat (differential of fat area between T12 and L3 spinal levels), and admission on a low risk day produced a c-statistic of 0.76. The PPV of the model is 71.4%, and the NPV was 81.4%. CONCLUSIONS: Patients with CD have predictable risk for infectious post-operative complications. Having a higher distribution of subcutaneous fat cross sectional area at T12 compared to L3 (an shaped distribution of abdominal fat) increases risk, along with low hemoglobin, and being admitted on high-risk days of the week (likely a proxy for urgent surgery). The apple distribution of abdominal fat could be a marker of past steroid use, metabolic syndrome, or vascular disease (and poor mesenteric blood flow). This is the first report of the distribution of abdominal fat as a risk factor for infectious complications of CD surgery, and the first application of analytic morphomics to surgery risk in Crohn's disease.

Effects of acute supine rest on mid‐thigh cross‐sectional area as measured by computed tomography

The loss of hydrostatic pressure that occurs as a person moves from the standing to the supine position causes a fluid redistribution that may confound the measurement of thigh cross-sectional area (CSA) if data are obtained while tissue fluid content is in flux. To determine the effects of changing postural position on thigh tissue CSA, mid-thigh axial scans of 13 older women were obtained at 5, 10 and 15 min of supine rest using computed tomography (CT). Scans were analysed for changes in CSA of subcutaneous fat (SF), low density muscle (LDM) and normal density muscle (NDM). A significant decrease from baseline was found in the CSA of NDM at 15 min [2.3+/-0.8 cm2 (+/-SE), 1.6%, P<0.05], with no change in LDM or SF CSA among any of the time intervals. The results of the current study suggest that potential measurement error can be minimized when baseline and follow-up CT-derived images of mid-thigh CSA are obtained within the first 10 min the subject assumes the supine position and that the CSA of NDM and LDM may be affected differently by supine rest.

Measurement of abdominal fat with T1‐weighted MR images

The cross-sectional area of visceral and subcutaneous fat in the abdomen was measured with T1-weighted spin-echo images acquired with a 1.5-T magnetic resonance (MR) imager. Four axial images centered on L-4 were acquired in each patient. Outline regions of interest (ROIs) were drawn manually for subcutaneous and visceral fat. The subcutaneous fat cross-sectional area was calculated from the ROIs drawn around the outer and inner margins of subcutaneous fat. Several adaptive processing methods were evaluated for measuring fat in the complex structure of the viscera. These methods were compared with an existing MR imaging measurement method for abdominal fat in 18 patients. The adaptive method that uses the valley between the fat and nonfat distributions in the average histogram curve was judged best for research evaluations because it reduces the effects of volume averaging while using a more natural division between fat and nonfat data. Another adaptive method that yielded comparable measurements was thought to be more suitable for clinical applications. Cross-sectional area measurements of abdominal fat were compared in 18 nonobese and 17 obese women to illustrate the utility of these measurements.