Visceral Adipose Tissue Measurements Research Articles

Measurement of Visceral Adipose Tissue in Persons With Spinal Cord Injury by Magnetic Resonance Imaging and Dual X-Ray Absorptiometry: Generation and Application of a Predictive Equation

Purpose: Dual energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI) permits quantification of visceral adipose tissue (VAT). However, DXA has not been validated against MRI in persons with chronic spinal cord injury (SCI). A predictive equation was generated from the measurement of VAT by MRI, a “gold” standard to quantitate VAT, compared to that of DXA, a method with several practical advantages. Method: DXA and MRI scans were performed in 27 participants with SCI. MRI multiaxial images were captured for VAT analysis. DXA-VAT was quantified at the android region (DXA-VATANDROID-VOL) using enCore software. Android regions of DXA and MRI were matched using android height. Volumes of multiaxial MRI-VAT and subcutaneous adipose tissue (SAT) were quantified for the android region (MRI-VATANDROID-VOL, MRI-SATANDROID-VOL) and total trunk (MRI-VATANDROID-VOL). Linear regression analysis was used to establish the proposed predication equations. The prediction equations were then applied to an independent sample that consisted of 98 participants with SCI. Bland-Altman analysis was used to determine the limits of agreement. Results: DXA-VATANDROID-VOL predicted 92% of the variance in MRI-VATANDROID-VOL (SEE = 252.5, p < 0.0005) and 85% of the variance in MRI-VATTRUNK-VOL (SEE = 1526.9, p < 0.0005). DXA-SATANDROID-VOL predicted 81.5% of the variance in MRI-SATANDROID-VOL (SEE = 458.2, p < 0.0005). Bland-Altman analysis revealed a high level of agreement between MRI-VATANDROID-VOL and DXA-VATANDROID-VOL (mean bias = 58.45 cm3). A predicted mean DXA-VATANDROID-VOL of 995.2 cm3 was estimated as the population-specific cut-off point for high levels of VAT. Conclusion: DXA-VATANDROID-VOL may accurately predict MRI-VATANDROID-VOL in persons with SCI. The ability of DXA to detect VAT changes in longitudinal studies in persons with SCI should be performed.

Fully convolutional networks for automated segmentation of abdominal adipose tissue depots in multicenter water-fat MRI.

An approach for the automated segmentation of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in multicenter water-fat MRI scans of the abdomen was investigated, using 2 different neural network architectures. The 2 fully convolutional network architectures U-Net and V-Net were trained, evaluated, and compared using the water-fat MRI data. Data of the study Tellus with 90 scans from a single center was used for a 10-fold cross-validation in which the most successful configuration for both networks was determined. These configurations were then tested on 20 scans of the multicenter study beta-cell function in JUvenile Diabetes and Obesity (BetaJudo), which involved a different study population and scanning device. The U-Net outperformed the used implementation of the V-Net in both cross-validation and testing. In cross-validation, the U-Net reached average dice scores of 0.988 (VAT) and 0.992 (SAT). The average of the absolute quantification errors amount to 0.67% (VAT) and 0.39% (SAT). On the multicenter test data, the U-Net performs only slightly worse, with average dice scores of 0.970 (VAT) and 0.987 (SAT) and quantification errors of 2.80% (VAT) and 1.65% (SAT). The segmentations generated by the U-Net allow for reliable quantification and could therefore be viable for high-quality automated measurements of VAT and SAT in large-scale studies with minimal need for human intervention. The high performance on the multicenter test data furthermore shows the robustness of this approach for data of different patient demographics and imaging centers, as long as a consistent imaging protocol is used.

EP03.02: Measurement of visceral adipose tissue during pregnancy are correlated with birthweight: preliminary results

EP03.02: Measurement of visceral adipose tissue during pregnancy are correlated with birthweight: preliminary results

Habitual Sleep Measures are Associated with Overall Body Fat, and not Specifically with Visceral Fat, in Men and Women.

This study aimed to investigate the associations of sleep duration and sleep quality with visceral adipose tissue (VAT) in middle-aged individuals. In this cross-sectional analysis of baseline measurements of the Netherlands Epidemiology of Obesity (NEO) study, participants underwent anthropometry and completed the Pittsburgh Sleep Quality Index (PSQI) for assessing short sleep duration (as sex-specific age-adjusted percentiles) and poor quality (PSQI > 5). VAT was assessed by magnetic resonance imaging in a random subgroup. We performed linear regression analyses to examine associations of short sleep and poor sleep with measures of body fat, adjusted for confounding, including total body fat in models with VAT. A total of 5,094 participants (52% women; mean age of 56 [SD 6] years), 1,947 of whom had VAT measurements, were analyzed. The difference in VAT between poor sleep (PSQI > 5) and good sleep (PSQI ≤ 5) was 7.2cm2 (95% CI: 1.2-13.8) in women and 16.1cm2 (95% CI: 6.2-26.0) in men. These differences attenuated toward the null after the adjustment for total body fat. Similar patterns of associations were observed for short sleep (lowest 10% compared with median 60%). Our results suggest that measures of sleep are not specifically associated with a higher amount of VAT.

Visceral Adipose Tissue Is Associated With Stricturing Crohn's Disease Behavior, Fecal Calprotectin, and Quality of Life.

Visceral adipose tissue (VAT) has been proposed to play a pathogenic role in Crohn's disease (CD); however, prospective clinical data are lacking. The aim was to evaluate whether VAT, beyond body mass index (BMI), is associated with CD behavior, disease activity, quality of life (QoL), or outcomes. Body composition data and clinical, anthropometric, disease activity (fecal calprotectin [FC]), and QoL scores were gathered prospectively on adults with CD at 0, 12, and 24 months. BMI and, VAT metrics (visceral adipose tissue volume [cm3]/height [m2] index and VAT:subcutaneous adipose tissue [SAT] ratio) were calculated. Inflammatory bowel disease-related surgery and hospitalization were recorded over extended follow-up (median, 51 months). Multivariable linear mixed effects and logistic regression analyses were performed. Ninety-seven participants were assessed at baseline (55% male; median age, 31 years), 84 at 12 months, and 72 at 24 months. VAT:SAT was positively associated with stricturing disease behavior (log odds ratio [OR], 1.7; 95% confidence interval [CI], 0.32 to 3; P = 0.01) and elevated FC in patients with ileocolonic disease (β, 1.3; 95% CI, 0.32 to 2.3; P = 0.01). VAT:SAT was associated with lower QoL, particularly in those with ileal disease (β, -12; 95% CI, -19 to -4.5; P = 0.05). However, no prospective associations were observed between serial VAT measurements and time to surgery or hospitalization. No correlations were found between BMI and disease behavior, activity, or QoL. VAT:SAT, rather than BMI, is associated with stricturing CD behavior, elevated FC, and reduced QoL in a disease distribution-dependent manner. Further studies are required to substantiate the role of VAT as a useful biomarker in CD.

Clinical impact of abdominal fat distribution measured by 3-D computed tomography volumetry on post-transplant renal function in recipients after living kidney transplantation: a retrospective study.

Excessive visceral fat may decrease renal function because of metabolic derangements. The aim of this study was to evaluate the impact of abdominal fat distribution on renal function of recipients after kidney transplantation using the visceral adipose tissue (VAT)/subcutaneous adipose tissue (SAT) ratio. Seventy-nine patients underwent living kidney transplantation from 2009 to 2017. Patients without a correct measurement of VAT and SAT, follow-up of < 6months, or with kidney transplant rejection or a virus infection were excluded. VAT and SAT were calculated automatically by 3-D volume analyzer software in recipients prior to living kidney transplantation. Our primary aim was to identify abdominal fat distribution measured by CT associated with renal dysfunction (estimate glomerular filtration rate; eGFR < 45) at 6month post renal transplantation in recipient. Fifty-eight living kidney recipients were included in this retrospective study: 30 for the high VAT/SAT ratio group; 28 for the VAT/SAT low group. Multiple logistic regression analysis showed the VAT/SAT ratio and pre-donor eGFR were associated with eGFR < 45ml/min/1.73m2. An increase in VAT/SAT ratio was associated independently with the incidence of decreased renal function. This finding indicates that adipose tissue distribution is an important predictor of the outcome of living kidney transplantation in recipients.

How to best assess abdominal obesity.

Abdominal obesity, especially the increase of visceral adipose tissue (VAT), is closely associated with increased mortality related to cardiovascular disease, diabetes, and fatty liver disease. This review provides an overview of the recent advances for abdominal obesity measurement. Compared to simple waist circumference, emerging three-dimensional (3D) body-scanning techniques also measure abdominal volume and shape. Abdominal dimension measures have been implemented in bioelectrical impedance analysis to improve accuracy when estimating VAT. Geometrical models have been applied in ultrasound to convert depth measurement into VAT area. Only computed tomography (CT) and MRI can provide direct measures of VAT. Recent advances in imaging allow for evaluating functional aspects of abdominal fat such as brown adipose tissue and fatty acid composition. Waist circumference is a simple, inexpensive method to measure abdominal obesity. CT and MRI are reference methods for measuring VAT. Further studies are needed to establish the accuracy for dual-energy X-ray absorptiometry in estimating longitudinal changes of VAT. Further studies are needed to establish whether bioelectrical impedance analysis, ultrasound, or 3D body scanning is consistently superior to waist circumference in estimating VAT in different populations.

Body adiposity indicators and cardiometabolic risk: Cross-sectional analysis in participants from the PREDIMED-Plus trial

Excess adiposity is associated with poor cardiometabolic (CM) health. To date, several techniques and indicators have been developed to determine adiposity. We aimed to compare the ability of traditional anthropometric, as well as standard and novel DXA-derived parameters related to overall and regional adiposity, to evaluate CM risk. Using the cross-sectional design in the context of the PREDIMED-Plus trial, 1207 Caucasian senior men and women with overweight/obesity and metabolic syndrome (MetS) were assessed. At baseline, anthropometry- and DXA-measured parameters of central, visceral, peripheral and central-to-peripheral adiposity together with comprehensive set of CM risk factors were obtained. Partial correlations and areas under the ROC curve (AUC) were estimated to compare each adiposity measure with CM risk parameters, separately for men and women, and in the overall sample. DXA-derived indicators, other than percentage of total body fat, showed stronger correlations (rho-0.172 to 0.206, p<0.001) with CM risk than anthropometric indicators, after controlling for age, diabetes and medication use. In both sexes, DXA-derived visceral adipose tissue measures (VAT, VAT/Total fat, visceral-to-subcutaneous fat) together with lipodystrophy indicators (Trunk/Legs fat and Android/Gynoid fat) were strongly and positively correlated (p<0.001) with glycated hemoglobin (HbA1c), the triglyceride and glucose index (TyG), triglycerides (TG), the ratio TG/HDL-cholesterol (TG/HDL-C), and were inversely related to HDL-C levels (p<0.001). Furthermore, in AUC analyses for both sexes, VAT/Total fat showed the highest predictive ability for abnormal HbA1c levels (AUC=0.629), VAT for TyG (AUC=0.626), both lipodystrophy indicators for TG (AUCs=0.556), and Trunk/Legs fat for HDL-C (AUC=0.556) and TG/HDL-C (AUC=0.581). DXA regional adiposity measures offer advantages beyond traditional anthropometric and DXA overall adiposity indicators for CM risk assessment in senior overweight/obese subjects with MetS. In particular, in both sexes, visceral adiposity better stratifies individuals at risk for glucose abnormalities, and indicators of lipodystrophy better predict markers of dyslipidemia.

Abbreviated mpMRI protocol for diffuse liver disease: a practical approach for evaluation and follow-up of NAFLD.

Multiparametric magnetic resonance imaging (mpMRI) may help determine the metabolic profile of patients with obesity and metabolic syndrome in addition to their clinical and laboratory biomarkers for diagnosis and monitoring. An abbreviated mpMRI protocol may be a faster, less-costly, and easier to perform alternative for the diagnosis, treatment, and follow-up of patients with NAFLD and for use in clinical trials. To evaluate an abbreviated mpMRI protocol tailored to analyze quantitative imaging features of patients with obesity and NAFLD and assess its use during treatment. This prospective study included patients with obesity and NAFLD to perform a quantitative analysis of liver fat and iron content, stiffness, as well as the visceral adipose tissue (VAT) during the course of a physical exercise-based treatment regimen. Longitudinal improvements in imaging features were observed in patients with good response to treatment, in accordance with improvements in biochemical and anthropometric biomarkers. An abbreviated mpMRI protocol consisting of liver fat and iron quantification, MR elastography, and VAT measurements is a feasible, less-costly, and accessible option for screening and monitoring of patients with obesity, NAFLD, and metabolic syndrome.

Visceral Adiposity in Psoriasis is Associated With Vascular Inflammation by 18F-Fluorodeoxyglucose Positron-Emission Tomography/Computed Tomography Beyond Cardiometabolic Disease Risk Factors in an Observational Cohort Study

ObjectivesThe authors sought to examine the relationship between visceral adipose tissue (VAT) and vascular inflammation (VI) by 18F-Fluorodeoxyglucose (18F-FDG) positron-emission tomography (PET)/computed tomography (CT) in psoriasis (PSO). Furthermore, we evaluated whether treatment of PSO modulated VAT and VI. BackgroundPSO, a chronic inflammatory skin disease, is associated with VI by 18F-FDG PET/CT and increased cardiometabolic risk including adipose tissue dysregulation. Recently, VI was associated with future cardiovascular events; however, the relationship of visceral and subcutaneous adiposity with VI in PSO has yet to be evaluated. MethodsConsecutive PSO patients (N = 77) underwent 18F-FDG PET/CT scans to measure VI and abdominal adiposity. A subset of PSO patients with severe skin disease was scanned at 1 year following PSO treatment (N = 13). ResultsThe cohort was middle aged (51.8 ± 12.6 years), predominantly male (n = 44, 57%), had low cardiovascular risk by Framingham 10-year risk (median 4 years [interquartile range (IQR): 2 to 7 years]), and mild-to-moderate skin disease (5.2 [IQR: 3.0 to 8.5]). PSO disease severity associated with VAT (β = 0.33; p = 0.004) beyond SAT (β = 0.30; p = 0.005). VAT (β = 0.55; p < 0.001), but not SAT (β = 0.15; p = 0.11), associated with VI beyond cardiovascular risk factors. We followed a subset of severe PSO patients treated aggressively for PSO and observed improvement in PSO severity and VAT, which was associated with an improvement in VI at 1 year beyond cardiovascular risk factors (β = 0.53; p = 0.049). ConclusionsVolume-based CT measurement of VAT may capture metabolic risk associated with VI compared to subcutaneous adipose tissue in PSO. PSO treatment associated with a decrease in VAT as well as decrease in VI suggesting VAT as a relevant biomarker related to VI in PSO.

Ethnic Differences in Visceral Adiposity Measured in Early Pregnancy.

To determine if visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) depth in early pregnancy differs by maternal ethnicity. We prospectively evaluated 482 women without pre-pregnancy diabetes. All underwent sonographic measurement of VAT and SAT depth at 11 to 14 weeks' gestation. SAT did not differ between groups, but VAT did. Compared with Canadian-born women (3.9 cm, 95% CI 3.7-4.1), mean VAT depth was higher among Latin American (4.6 cm, 95% CI 4.1-5.2), Sub-Saharan African (5.0 cm, 95% CI 4.0-6.1), and Caribbean (6.0 cm, 95% CI 4.8-7.3) women. Adjusting for age, parity, and 1/height2, the relative risks of having a VAT depth >80th percentile were 1.69 (95% CI 1.05-2.73) for Latin American, 2.24 (95% CI 1.28-3.93) for Sub-Saharan African, and 3.34 (95% CI 1.91-5.84) for Caribbean women, relative to Canadian-born women. Women from these world regions also had a greater percentage of preterm births and emergency CSs. VAT differs appreciably among certain ethnic groups, which may reflect their predisposition to adverse pregnancy outcomes.

Relationships of Clinical and Computed Tomography-Imaged Adiposity with Cognition in Middle-Aged and Older African Americans.

Adiposity depots may differentially affect cognition. African Americans (AA) have higher rates of obesity and dementia but lower visceral adipose tissue (VAT) than whites, yet are underrepresented in studies of adiposity and cognition. Our study compared relations of cognitive function to clinical adiposity measures and computed tomography (CT)-imaged abdominal adiposity in AA. CT-imaged subcutaneous adipose tissue (SAT) and VAT measurements were obtained in the AA cohort of the Genetic Epidemiology Network of Arteriopathy Study (N = 652, mean age 68 ± 8.4 years, 74% females, 59% obese, 82% hypertensive). Clinical adiposity measures included waist circumference (WC) and body mass index (BMI). Global cognition was operationalized as a global cognitive z-score generated from the average of four cognitive domain z-scores. Generalized estimating equations were used to examine cross-sectional associations between individual standardized adiposity measures and cognition, accounting for age, sex, education, smoking status, and familial clustering. A collective model was constructed including multiple supported adiposity measures and age-by-adiposity interactions. In the collective model, higher WC was associated with worse global cognition, β = -0.12 (95%CI: -0.21, -0.03); higher SAT was associated with better cognition, β = 0.09 (0.01, 0.18); higher BMI was associated with worse cognition at younger ages with attenuation at older ages (BMI-by-age-interaction p = .004). VAT was not significantly associated with global cognition, β = -0.03 (-0.07, 0.02). WC may be the simplest and most efficient measure of adiposity to assess with respect to cognition in clinical settings, although studies to determine mechanistic effects of subcutaneous and other adiposity depots on cognition are warranted.

Visceral adipose tissue area measurement at a single level: can it represent visceral adipose tissue volume?

Measurement of visceral adipose tissue (VAT) needs to be accurate and sensitive to change for risk monitoring. The purpose of this study is to determine the CT slice location where VAT area can best reflect changes in VAT volume and body weight. 60 plain abdominal CT images from 30 males[mean age (range) 51 (41-68) years, mean body weight (range) 71.1 (101.9-50.9) kg] who underwent workplace screenings twice within a 1-year interval were evaluated. Automatically calculated and manually corrected areas of the VAT of various scan levels using "freeform curve" region of interest on CT were recorded and compared with body weight changes. The strongest correlations of VAT area with VAT volume and body weight changes were shown in a slice 3 cm above the lower margin of L3 with r values of 0.853 and 0.902, respectively. VAT area measurement at a single level 3 cm above the lower margin of the L3 vertebra is feasible and can reflect changes in VAT volume and body weight. Advances in knowledge: As VAT area at a CT slice 3cm above the lower margin of L3 can best reflect interval changes in VAT volume and body weight, VAT area measurement should be selected at this location.

Impact of Acute Dietary Manipulations on Dual-Energy X-ray Absorptiometry Estimates of Visceral Adipose Tissue

PURPOSE: Dual-energy x-ray absorptiometry (DXA) is viewed as a superior method of body composition assessment, but whole-body DXA scans are impacted by variation in pre-assessment activities, such as eating and drinking. DXA software now allows for estimation of visceral adipose tissue (VAT), which has been implicated in a number of diseases. It is unknown to what extent food and fluid intake affect VAT estimates. In the present analysis, the effects of acute high-carbohydrate (HC) and very low-carbohydrate (VLC) diets on DXA estimates of VAT were examined. METHODS: Male and female adults completed two one-day dietary conditions in random order: a VLC diet (1 - 1.5 g CHO/kg) and a HC diet (9 g CHO/kg). The diets were isocaloric to each other, and all food items were provided to participants. DXA scans were conducted in the morning after an overnight fast and in the afternoon soon after the third standardized meal. VAT volume, mass, and area were obtained, and paired samples t-tests were performed to compare the changes in VAT measures between diets. RESULTS: Fifteen males (age 22 ± 3, BF% 21 ± 5%) and eighteen females (age 21 ± 2, BF% 31 ± 5%) were included in the analysis. The change in VAT volume between the fasted and fed visits was different between diets (HC: +1.6%; VLC: -9.2%, p= .047). There were also trends for differences in VAT mass (p= .089) and area (p= .096) changes between diets. CONCLUSIONS: Within a single day, VAT estimates are differentially affected by isocaloric HC and VLC diets, with VLC consumption leading to reductions in VAT estimates. The content of the diet on the day of a DXA scan can affect estimates of VAT, which could spuriously influence the categorization of an individual’s health risk by DXA VAT estimates. Standardization of food intake prior to scans, preferably in the form of an overnight fast, should be employed to eliminate this important source of error.

Visceral adiposity predicts post-operative Crohn's disease recurrence.

Excessive visceral adipose tissue has been associated with poorer outcomes in patients with inflammatory bowel disease. To determine whether body composition is associated with outcome in a prospective study of post-operative Crohn's disease patients. The POCER study evaluated management strategies for prevention of post-operative Crohn's disease recurrence; subjects were enrolled after resection of all macroscopic Crohn's disease and were randomised to early endoscopy and possible treatment escalation, or standard care. The primary endpoint was endoscopic recurrence at 18 months. 44 subjects with cross-sectional abdominal imaging were studied, and body composition analysis performed using established techniques to measure visceral adipose tissue area, subcutaneous adipose tissue area, and skeletal muscle area. The body composition parameter with the greatest variance was visceral adipose tissue. Regardless of treatment, all subjects with visceral adipose tissue/height2 >1.5 times the gender-specific mean experienced endoscopic recurrence at 18 months (compared to 47%) [relative risk 2.1, 95% CI 1.5-3.0, P = 0.012]. Waist circumference correlated strongly with visceral adipose tissue area (ρ = 0.840, P < 0.001). Low skeletal muscle was prevalent (41% of patients), but did not predict endoscopic recurrence; however, appendicular skeletal muscle indices correlated inversely with faecal calprotectin (ρ = 0.560, P = 0.046). Visceral adiposity is an independent risk factor for endoscopic recurrence of Crohn's disease after surgery. Sarcopenia correlates with inflammatory biomarkers. Measures of visceral adipose tissue may help to stratify risk in post-operative management strategies.

Comparison of Associations of DXA and CT Visceral Adipose Tissue Measures With Insulin Resistance, Lipid Levels, and Inflammatory Markers

Visceral adipose tissue (VAT) measured by computed tomography (CT) is related to insulin resistance, lipids, and serum inflammatory markers. Our objective was to compare the strength of the associations of VAT measured using dual-energy X-ray absorptiometry (DXA-VAT) and CT (CT-VAT) with insulin resistance, serum lipids, and serum markers of inflammation. For 1117 men aged 65 and older enrolled in the Osteoporotic Fractures in Men Study, the cross-sectional associations of DXA-VAT and CT-VAT with homeostasis model assessment of insulin resistance (homa2ir), C-reactive protein, and high-density lipoprotein (HDL) cholesterol were estimated with regression models and compared using a Hausman test. Adjusted for age and body mass index, DXA-VAT was moderately associated with homa2ir (effect size 0.38, 95% confidence interval [CI]: 0.28–0.47) and modestly associated with HDL cholesterol (DXA effect size −0.29, 95% CI: −0.38 to −0.21). These associations were significantly greater than those for CT-VAT with homa2ir (0.30, 95% CI: 0.24–0.37; p value for effect size difference 0.03) and CT-VAT with HDL cholesterol (−0.22, 95% CI: −0.29 to −0.15; p value for difference 0.005). Neither DXA-VAT nor CT-VAT was associated with C-reactive protein after adjustment for age and body mass index (DXA-VAT effect size 0.14, 95% CI: −0.04 to 0.32; CT-VAT effect size 0.08, 95% CI: −0.08 to 0.25; p value for difference 0.35). DXA-VAT has similar or greater associations with insulin resistance and HDL cholesterol as does CT-VAT in older men, confirming the concurrent validity of DXA-VAT. Investigations of how well DXA measurements of VAT predict incident cardiovascular disease events are warranted.

Clinical usefulness of abdominal bioimpedance (ViScan) in the determination of visceral fat and its application in the diagnosis and management of obesity and its comorbidities

Visceral adipose tissue (VAT) has been shown to be profoundly responsible of most of the obesity-associated metabolic derangements. The measurement of VAT usually implies the use of imaging techniques such as magnetic resonance imaging or computed tomography (CT). Our aim was to evaluate the accuracy of the determination of VAT by means of abdominal bioimpedance (BIA) with the ViScan device in comparison with CT and its clinical usefulness in the management of obesity. We studied a sample of 140 subjects (73 males/67 females) with BMI ranging from 17.7 to 50.4kg/m2 to evaluate the accuracy of the ViScan in comparison to CT to determine VAT. To further analyze ViScan's clinical usefulness we studied a separate cohort (n=2849) analyzing cardiometabolic risk factors. Furthermore, we studied the ability of the ViScan to detect changes in VAT after weight gain (n=107) or weight loss (n=335). The study was performed from October 2009 through June 2015. ViScan determines VAT with a good accuracy in individuals with a CT-VAT up to 200cm2, and then with lower precision with increasing body mass, exhibiting a moderate-high correlation with CT-VAT (r=0.75, P<0.001). Importantly, VAT determination with the ViScan exhibits better correlations with several cardiometabolic risk factors such as glucose, triglycerides, HDL-cholesterol and markers of fatty liver than anthropometric measurements such as BMI or waist circumference. ViScan is able to detect VAT variations after body weight changes. Since the possibility of measuring VAT by imaging techniques is not always available, abdominal BIA represents a good alternative to estimate VAT, allowing the identification of patients with increased VAT-related cardiometabolic risk and a better management of obese patients. ClinicalTrials.gov NCT01055626 and NCT01572090.

The clinical importance of quantifying body fat distribution during androgen deprivation therapy for prostate cancer.

Androgen deprivation therapy (ADT) is now considered a mainstay in the treatment of metastatic and locally advanced prostate cancer (PCa). Despite well-established benefits of ADT in relation to overall survival, this treatment has been associated with a number of adverse effects, particularly with regard to key cardiometabolic risk factors including the development of insulin resistance, dyslipidemia and increases in total and regional fat mass. In non-ADT populations, increased levels of visceral adipose tissue (VAT) are thought to be a key mediator of the increased cardiometabolic risk associated with weight gain, but this has received limited attention in men treated with ADT. VAT is best assessed using tools such as computed tomography or magnetic resonance imaging; however, these tools are not readily accessible for the majority of researchers or clinicians. Recent advances allow for a method of estimating VAT using a whole-body dual-energy X-ray absorptiometry (DXA) scan that shows promise as a practical tool for researchers to evaluate changes in body fat distribution during ADT. The aim of this narrative review is to (1) review the available evidence with regard to the relationship between ADT and cardiometabolic risk; (2) discuss the role of body fat distribution on cardiometabolic risk in non-ADT populations, with a particular emphasis on the importance of visceral adiposity; (3) examine the potential influence of ADT on body fat distribution and visceral adiposity and (4) provide an overview of current tools used to measure changes in body fat distribution in men treated with ADT, highlighting the potential utility of a recently developed DXA-derived measure of VAT.

Visceral adiposity and cancer survival: a review of imaging studies

Although obesity is a well-known risk factor for cancer, the association between obesity and cancer survival remains controversial. This is partially due to the inability of conventional obesity measures to directly assess adiposity or adipose tissue distribution. As a metabolic organ, visceral adipose tissue (VAT) secrets a variety of cytokines and cytokine-like factors, potentially affecting cancer survival. The objective of this review was to investigate the influence of imaging-assessed VAT on cancer survival. A total of 22 studies assessing the impact of visceral adiposity on survival were included. Negative associations between VAT and survival were more frequently observed among patients with colorectal (four of six studies) and pancreatic (three of five studies) cancers, compared to higher VAT predicting longer survival in most studies of renal cell carcinoma patients (four of five studies). Methodological limitations, including unstandardised VAT measurement methods, lack of other body composition measurement (i.e. muscle mass), small sample size and heterogeneous cohort characteristics, may explain controversial findings related to the impact of VAT on cancer survival.

Associations between body composition, physical capabilities and pulmonary function in healthy older adults.

There are positive associations between pulmonary function (PF) and fat-free mass as well as muscle strength. Contrarily, negative associations were found with indirect measures of visceral adipose tissue (VAT). We aimed to differentiate between associations of body composition and PF by assessing mediating and moderating effects of physical capabilities. Cross-sectional data were assessed among 40 healthy, free-living elderly (20 males) aged 65.1-81.2 years (mean±s.d. age: 72.2±4.3 years; body mass index: 25.6±3.7 kg/m2). Total and regional skeletal muscle (SM), and adipose tissue (AT) were measured using whole-body magnetic resonance imaging. Muscle strength by handgrip dynamometry, physical activity (PA) by questionnaire, and physical performance by gait speed and sit-to-stand test (STS). Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were assessed by spirometry. Positive associations between height-standardized FVC (FVCI) as well as FEV1 (FEVI), and SM (r=0.435-0.520, P<0.05) were found; subcutaneous AT (SAT) and FVCI correlated negatively (r=-0.374; P<0.05). HGS and PA correlated positively with FEVI (r=0.456-0.608, P<0.05), HGS also with FVCI (r=0.595, P<0.05). Stepwise multiple regression using FVCI and FEVI as dependent variables, and total/thoracic SM, VAT, SAT, HGS, PA and physical performance as independent variables showed that (i) only HGS entered the regression for predicting FVCI (R2=0.351; standard error of estimation (SEE)=0.32 l), and (ii) HGS and PA explained 50% of FEVI (SEE=0.23 l). HGS mediated the relationship between SM and PF; the STS moderated the relationship between SM and FVCI. In healthy elderly, PF is positively associated with SM; physical capabilities mediate and moderate these relationships.