Measurement site influences abdominal subcutaneous and visceral adipose tissue in obese adolescents before and after exercise

A fully convolutional neural network for comprehensive compartmentalization of abdominal adipose tissue compartments in MRI

BACKGROUND

Existing literature has highlighted structural, physiological, and pathological disparities among abdominal adipose tissue (AAT) sub-depots. Accurate separation and quantification of these sub-depots are crucial for advancing our understanding of obesity and its comorbidities. However, the absence of clear boundaries between the sub-depots in medical imaging data has challenged their separation, particularly for internal adipose tissue (IAT) sub-depots. To date, the quantification of AAT sub-depots remains challenging, marked by a time-consuming, costly, and complex process.

PURPOSE

To implement and evaluate a convolutional neural network to enable granular assessment of AAT by compartmentalization of subcutaneous adipose tissue (SAT) into superficial subcutaneous (SSAT) and deep subcutaneous (DSAT) adipose tissue, and IAT into intraperitoneal (IPAT), retroperitoneal (RPAT), and paraspinal (PSAT) adipose tissue.

MATERIAL AND METHODS

MRI datasets were retrospectively collected from Singapore Preconception Study for Long-Term Maternal and Child Outcomes (S-PRESTO: 389 women aged 31.4 ± 3.9 years) and Singapore Adult Metabolism Study (SAMS: 50 men aged 28.7 ± 5.7 years). For all datasets, ground truth segmentation masks were created through manual segmentation. A Res-Net based 3D-UNet was trained and evaluated via 5-fold cross-validation on S-PRESTO data (N = 300). The model's final performance was assessed on a hold-out (N = 89) and an external test set (N = 50, SAMS).

RESULTS

The proposed method enabled reliable segmentation of individual AAT sub-depots in 3D MRI volumes with high mean Dice similarity scores of 98.3%, 97.2%, 96.5%, 96.3%, and 95.9% for SSAT, DSAT, IPAT, RPAT, and PSAT respectively.

CONCLUSION

Convolutional neural networks can accurately sub-divide abdominal SAT into SSAT and DSAT, and abdominal IAT into IPAT, RPAT, and PSAT with high accuracy. The presented method has the potential to significantly contribute to advancements in the field of obesity imaging and precision medicine.

The effect of exercise training on serum concentrations of chemerin in patients with metabolic diseases: a systematic review and meta-analysis

CONTEXT

Elevated serum concentrations of chemerin is a significant factor in the development of metabolic disorders.

OBJECTIVE

This systematic review and meta-analysis evaluated the influence of exercise training on serum concentrations of chemerin in patients with metabolic diseases.

METHODS

Thirteen studies including 463 participants were included and analysed using a random-effects model to calculate weighted mean differences with 95% confidence intervals.

RESULTS

Results indicated that exercise training significantly decreased serum concentrations of chemerin in patients with metabolic diseases when compared with controls. Subgroup analysis showed that exercise training resulted in decreases in serum concentrations of chemerin in men, however, this was not significant in women. Moreover, subgroup analyses based on the type of exercise did not reveal differential effects on serum concentrations of chemerin.

CONCLUSION

Exercise training may produce improvements in serum concentrations of chemerin in patients with metabolic diseases. Further longer-term studies are needed to confirm these findings.

Causative Mechanisms of Childhood and Adolescent Obesity Leading to Adult Cardiometabolic Disease: A Literature Review

The past few decades have shown a worrisome increase in the prevalence of obesity and its related illnesses. This increasing burden has a noteworthy impact on overall worldwide mortality and morbidity, with significant economic implications as well. The same trend is apparent regarding pediatric obesity. This is a particularly concerning aspect when considering the well-established link between cardiovascular disease and obesity, and the fact that childhood obesity frequently leads to adult obesity. Moreover, most obese adults have a history of excess weight starting in childhood. In addition, given the cumulative character of both time and severity of exposure to obesity as a risk factor for associated diseases, the repercussions of obesity prevalence and related morbidity could be exponential in time. The purpose of this review is to outline key aspects regarding the current knowledge on childhood and adolescent obesity as a cardiometabolic risk factor, as well as the most common etiological pathways involved in the development of weight excess and associated cardiovascular and metabolic diseases.

How much abdominal fat do obese patients lose short term after laparoscopic sleeve gastrectomy? A quantitative study evaluated with MRI

Background

This study aimed to elucidate the changes in the amount of abdominal adipose tissue after laparoscopic sleeve gastrectomy in obese Chinese patients over a relatively short follow-up period and to analyze the differences in the effects of surgery between genders.

Methods

Ninety-one patients were enrolled in the study, including 18 males and 73 females. These patients underwent laparoscopic sleeve gastrectomy between November 2017 and November 2019. Before and short term after surgery, the areas of subcutaneous/visceral adipose tissue and the liver proton density fat fraction were calculated with upper abdominal magnetic resonance (MR) examinations.

Results

Approximately 100 days after surgery, the median values of weight loss and body mass index reduction were 23.1 kg and 8.1 kg/m², respectively. The patients achieved a greater absolute loss of subcutaneous adipose tissue index than of visceral adipose tissue index (3.2×10^-3 vs. 1.6×10^-3, P<0.001). The amount of weight loss, body mass index loss and absolute/relative reduction in visceral adipose tissue index were much greater in males than in females (31.7 vs. 21.7 kg, P<0.001; 9.8 vs. 7.9 kg/m², P=0.016; 2.5×10^-3 vs. 1.3×10^-3, P=0.007; 28.2% vs. 20.9%, P=0.029). There was a correlation between decreased amounts in subcutaneous and visceral adipose tissue in sum and weight loss (r=0.282, P=0.032). The absolute/relative reduction in visceral adipose tissue index was also correlated with absolute/relative reduction in liver proton density fat fraction (r=0.283, P=0.013; r=0.372, P=0.001).

Conclusions

The reductions in body weight and visceral fat were more significant in male patients. The sum of absolute reduction in subcutaneous and visceral fat deposits was correlated with weight loss, in all patients enrolled. For severely obese patients, an upper abdominal MR examination could assess the body tissue composition and how it changes after bariatric surgery.

Comparative evaluation of obesity-related parameters in junior sumo wrestlers and children with obesity

[Purpose]

Exercise is a key factor in preventing obesity and metabolic syndrome. Sumo wrestlers increase their body size from childhood for athletic advantage; however, the risk of metabolic syndrome in junior sumo wrestlers is undetermined. Preventive measures against pediatric obesity should be initiated during childhood to prevent obesity in adulthood, considering its high global incidence. We comparatively evaluated the risk factors for metabolic syndrome in junior sumo wrestlers and children with obesity.

[Methods]

We enrolled 70 male children (age 9–17 years [sumo group, n = 14] and 9–14 years [other sports and non-exercise groups, n = 28 each]) and evaluated their anthropometric parameters (height, weight, body mass index z-score, obesity rate, waist circumference, waist to height ratio) and hematological parameters (total, low-density, high-density, and non-high-density lipoprotein-cholesterol; triglycerides; plasma glucose, and glycated hemoglobin levels).

[Results]

The BMI z-score, obesity rate, waist circumference (p < 0.05, along with the non-exercise group), and systolic blood pressure were significantly higher and the high-density cholesterol level was lower in the sumo group than in the other sports group (p < 0.05). The waist to height ratio was significantly higher in the non-exercise group than in the other sports group (p < 0.05). No significant difference was found in other blood lipid, plasma glucose (significantly lower level than the reference range in the sumo group, p < 0.05), and glycated hemoglobin (within the reference range in all groups) levels among the three groups.

[Conclusion]

Junior sumo wrestlers had a larger body size and higher blood pressure than children with obesity who exercised regularly. This provides direction for future research into targeted preventive interventions against metabolic syndrome for junior sumo wrestlers with large body size.

Variation in myokine and adipokine levels according to menstrual cycle following regular resistance exercise

BACKGROUND

The purpose of this study was to analyze the differences between myokine and adipokine factors under stable conditions according to the menstrual cycle (luteal and follicular phases), and investigate the effect of regular resistance exercise on the changes in myokine and adipokine factors according to menstrual cycle in obese female college students.

METHODS

The study participants were female college students with a body fat percentage of 30% or more (n = 20), divided into two groups: luteal phase (n = 12) and follicular phase (n = 8). They performed regular resistance exercise three times a week, 60 minutes daily, for 16 weeks. Parameters measured include body composition via impedance, visceral fat area using computed tomography and myokine and adipokine factors in blood.

RESULTS

Levels of BDNF (p < .05), NGF (p < .01), and adiponectin (p < .01) were significantly increased in the luteal phase group after 16 weeks relative to the baseline values. Leptin (p < .01) was significantly decreased in the luteal phase group after 16 weeks. Weight, body mass index, % fat, and visceral fat area were significantly decreased in both groups after 16 weeks. Muscle mass was significantly increased in both groups after 16 weeks.

CONCLUSIONS

Regular resistance exercise affected the reduction in visceral fat area and had a positive effect on body composition, which might be altered favorably by myokines and adipokines. Thus, the timing of blood collection is very important in obese female college students.

Effects of exercise modality on body composition and cardiovascular disease risk factors in adolescents with obesity: a randomized clinical trial

We compared the effects of aerobic exercise, resistance exercise, and combined aerobic and resistance exercise on total, regional subcutaneous adipose tissue (SAT) and visceral AT (VAT), skeletal muscle (SM), and biomarkers of cardiovascular disease in adolescents. Adolescents with overweight/obesity (N = 118; body mass index ≥ 85th percentile; age, 12-17 years) were randomized to 1 of the following groups for 6 months (3 days/week, 180 min/week): aerobic exercise (n = 38), resistance exercise (n = 40), or combined aerobic and resistance exercise (n = 40). After accounting for age, sex, and baseline value, there was a greater (P < 0.05) reduction in body weight in the aerobic exercise group compared with the resistance exercise group and the combined groups. There were reductions (P < 0.05) in total and regional SAT within the aerobic exercise group only, and the reductions in lower-body SAT were greater (P = 0.02) than the combined group. All groups had reductions (P < 0.01) in VAT, with no group differences. There were significant increases in total and regional SM mass in the resistance exercise and combined group, and not in the aerobic exercise group. Although all exercise modalities are effective in reducing VAT, aerobic exercise is superior at reducing total and regional SAT, but inferior for increasing SM in adolescents with obesity. Despite reductions in VAT, carotid-femoral pulse wave velocity and carotid intima-media thickness did not improve with either exercise. Clinicaltrials.gov identifier: NCT01938950. Novelty Regular exercise (180 min/week) is associated with reductions in visceral fat independent of exercise modality. Resistance exercise alone and combined resistance and aerobic exercise are similarly effective in increasing SM mass.

The Clinical Value and Appropriateness Criteria of Upper Abdominal Magnetic Resonance Examinations in Patients Before and After Bariatric Surgery: a Study of 837 Images

PURPOSE

The abdominal magnetic resonance (MR) examinations have been increasingly applied in patients with obesity. However, few studies analyzed the appropriateness of this examination. This study is aimed to evaluate the feasibility and clinical value of upper abdominal MR in quantification of visceral/subcutaneous adipose tissue (VAT/SAT) and liver fat fraction (LFF) in patients before and after bariatric surgery.

METHODS

All patients who underwent bariatric surgery from November 2017 to November 2019 in the prospectively maintained, IRB-approved database of our institution were queried. The images of all MR studies were retrospectively reviewed and analyzed.

RESULTS

In total, 570 patients with 837 upper abdominal MR examinations were analyzed. The VAT/SAT can be clearly visualized and quantified on fat liver acquisition with volume acceleration-flexible (LAVA-Flex) sequence. The present rate of a single axial slice at the level of the L1-L2 intervertebral disc was 93.1% (779/837). The LFF could be quantitatively evaluated on all of the proton density fat fraction (PDFF) maps (100%, 837/837). Occasional findings may include cholelithiasis, cysts, hepatic hemangioma, and renal angiomyolipoma, which can be clearly diagnosed by MR.

CONCLUSION

The upper abdominal MR is featured by well feasibility and clear clinical value when applying in patients with obesity. We can use the results to do clinical research and evaluate obesity-related disease risks before and after surgery, thus providing suggestions to choose the type of surgery for patients with different risk levels in the future. MR scanning including fat LAVA-Flex images with the inclusion of L1-L2 level and PDFF measurements is suggested for the VAT/SAT/LFF quantification.

TRIAL REGISTRATION

NCT03520699.

Association Between Early Life Weight Gain and Abdominal Fat Partitioning at 4.5 Years is Sex, Ethnicity, and Age Dependent

OBJECTIVE

The aim of this study was to investigate the independent associations between age-specific annual weight gain from birth to age 4 years and fat deposition in metabolically distinct compartments at age 4.5 years in a South Asian longitudinal birth cohort.

METHODS

Volumetric abdominal magnetic resonance imaging with comprehensive segmentation of deep and superficial subcutaneous adipose tissue (SAT) and visceral adipose tissues (VAT) was performed in 316 children (150 boys and 166 girls in three ethnic groups; 158 Chinese, 94 Malay, and 64 Indian) aged 4.5 years. Associations between fat volumes and annual relative weight gain conditional on past growth were assessed overall and stratified by sex and ethnicity.

RESULTS

Conditional relative weight gain had stronger associations with greater SAT and VAT at age 4.5 years in girls than boys and in Indians compared with Malay and Chinese. Overall, the magnitude of association was the largest during 2 to 3 years for SAT and 1 to 2 years for VAT. Despite similar body weight, Indian children and girls had the highest deep and superficial SAT volumes at age 4.5 years (all interactions P < 0.05). No significant sex or ethnic differences were observed in VAT. With increasing BMI, Indian children had the highest tendency to accumulate VAT, and girls accumulated more fat than boys in all depots (all interactions P < 0.001).

CONCLUSIONS

Indian ethnicity and female sex predisposed children to accumulate more fat in the VAT depot with increasing conditional relative weight gain in the second year of life. Thus, 1 to 2 years of age may be a critical window for interventions to reduce visceral fat accumulation.

Estimation of visceral fat in 9- to 13-year-old girls using dual-energy X-ray absorptiometry (DXA) and anthropometry

OBJECTIVES

Accumulation of visceral fat (VF) in children increases the risk of cardiovascular disease and type 2 diabetes, and measurement of VF in children using computed tomography and magnetic resonance imaging (MRI) is expensive. Dual-energy X-ray absorptiometry (DXA) may provide a low-cost alternative. This study aims to determine if DXA VF estimates can accurately estimate VF in young girls, determine if adding anthropometry would improve the estimate and determine if other DXA fat measures, with and without anthropometry, could be used to estimate VF in young girls.

METHODS

Visceral fat was measured at lumbar intervertebral sites (L1-L2, L2-L3, L3-L4 and L4-L5) using 3.0T MRI on 32 young girls (mean age 11.3 ± 1.3 years). VF was estimated using the GE CoreScan application. Measurement of DXA android and total body fat was performed. Weight, height and waist circumference (WC) measurements were also obtained.

RESULTS

Waist circumference and body mass index were both strongly correlated with MRI, although WC was the best anthropometric covariate. Per cent fat (%fat) variables had the strongest correlation and did best in regression models. DXA %VF (GE CoreScan) and DXA android %fat and total body %fat accounted for 65% to 74% of the variation in MRI VF.

CONCLUSION

Waist circumference predicted MRI VF almost as well as DXA estimates in this population, and a combination of WC and DXA fat improves the predictability of VF. DXA VF estimate was improved by the addition of WC; however, DXA android %fat with WC was better at predicting MRI VF.

Anthropometric indices as surrogates for estimating abdominal visceral and subcutaneous adipose tissue: A meta-analysis with 16,129 participants

AIM

To seek anthropometric indices that estimate visceral and subcutaneous adipose tissue (VAT and SAT) by meta-analysis and comparing the predictive efficacy based on different characteristics of participants.

METHODS

PubMed, PubMed Central, Web of Science, China National Knowledge Infrastructure and Wanfang databases were searched for publications containing correlation coefficients of VAT and/or SAT with waist circumference (WC) and/or body mass index (BMI). The overall or subgroup pooled results were analyzed by meta and metafor packages of R with random effects model. MedCalc software was used to compare the correlation coefficients between groups.

RESULTS

Twenty-nine publications were included in this meta-analysis. The correlation coefficients of VAT-WC, VAT-BMI, SAT-WC and SAT-BMI for total studies were between 0.640 and 0.785. The correlation of VAT with WC was larger than that with BMI (Z = 11.664, P < 0.001). Meanwhile, the correlation coefficients of VAT-WC were statistically different among different age groups, areas, ethnicities, body shapes, scanning levels, units and instruments of measuring VAT (P < 0.05). The overall correlation of SAT with BMI was larger than that with WC (Z = 3.805, P < 0.001). The subgroups' correlation coefficients of SAT-BMI showed statistical differences between genders, age groups, areas, ethnicities, body shapes, scanning levels, units (cm² and cm³) and instruments of measuring SAT (P < 0.05).

CONCLUSIONS

WC may be a common and simple surrogate for estimating VAT, and BMI for SAT, especially in Europeans, but not in the aged people.

Effect of Low- Versus High-Intensity Exercise Training on Biomarkers of Inflammation and Endothelial Dysfunction in Adolescents With Obesity: A 6-Month Randomized Exercise Intervention Study

PURPOSE

To investigate the effects of a low- versus high-intensity aerobic training on biomarkers of inflammation and endothelial dysfunction in adolescents with obesity.

METHODS

Sixty-two adolescents with obesity [age = 15 (14) y, body mass index = 34.87 (4.22) kg·m^-2] were randomized to receive either a high-intensity training (HIT, n = 31) or a low-intensity training (LIT, n = 31) for 24 weeks. All participants also received nutritional, psychological, and clinical counseling. Leptin, total and subtype leukocyte counts, tumor necrosis factor-alpha, interleukin-6, myeloperoxidase, soluble intercellular adhesion molecule-1, and soluble vascular cell adhesion molecule-1 were obtained at baseline and after 24 weeks.

RESULTS

HIT reduced neutrophils [from 4.4 (1.9) to 3.6 (1.3) µL^-1 × 10³; P = .01] and monocytes [from 7.2 (2.5) to 5.2 (1.8) µL^-1 × 10²; P < .01], but LIT increased neutrophils [from 4.5 (1.7) to 5.2 (3.3) µL^-1 × 10³; P = .01]. Although tumor necrosis factor-alpha increased in LIT [from 13.3 (7.5) to 17.7 (10.8) pg·mL^-1; P = .01], it decreased in HIT [from 12.4 (7.5) to 11.3 (6.2) pg·mL^-1; P = .01]. No changes in leukocyte counts, soluble intercellular adhesion molecule-1, soluble vascular cell adhesion molecule-1, and homeostasis assessment model for insulin resistance were observed.

CONCLUSIONS

Both HIT and LIT improved the inflammatory profile. The study, however, indicated that the number of biomarkers and the magnitude of changes were higher in the HIT compared with LIT.

The use of magnetic resonance imaging to characterize abnormal body composition phenotypes in youth with Prader-Willi syndrome

INTRODUCTION

Magnetic resonance imaging (MRI) provides detailed assessment of body composition compartments. No studies have employed state-of-the-art MRI methods to accurately examine abdominal adipose tissue (AT) and skeletal muscle in youth with Prader-Willi syndrome (PWS). Therefore, this study aimed to describe AT distribution and skeletal muscle in the abdominal region of youth with PWS using MRI.

METHODS

Anthropometric measures and whole-abdominal T1-weighted MRI were performed in sixteen (5 males and 11 females) youth diagnosed with PWS, and seventeen (10 males and 7 females) youth who did not have PWS (controls). Volume of subcutaneous, visceral, intermuscular, and total AT, and skeletal muscle in the abdominal region were quantified using a semiautomatic procedure. Results were summarized using median and interquartile range (IQR, 25th-75th), and ANCOVA test was used (with age and sex as covariates) to examine differences in body composition compartments between PWS and control group.

RESULTS

PWS group had similar age (10.5, 6.6-13.9 vs. 12.8, 10.0-14.4years; P=0.14) and BMI z-score (0.5, 0.2-1.3 vs. 0.2, -0.3 to 1.0; P=0.33) when compared with controls. Significant differences were observed in absolute volumes of total AT (PWS: 4.1, 2.0-6.6L; control: 2.9, 2.0-4.5L; P=0.01), subcutaneous AT (PWS: 2.8, 1.4-4.8L; control: 1.8, 1.1-3.2L; P=0.01), and intermuscular AT (PWS: 0.3, 0.1-0.4L; control: 0.3, 0.2-0.3L; P<0.005). Visceral AT/subcutaneous AT was lower in PWS (0.4, 0.3-0.5) compared to controls (0.5, 0.4-0.6), P=0.01. In addition, skeletal muscle volume was lower in PWS (1.5, 1.0-2.6L) compared to controls (3.1, 1.6-3.9L), P=0.03. Ratios of abdominal AT compartments to skeletal muscle were all higher in PWS compared to controls (all P<0.005).

CONCLUSIONS

PWS youth have greater abdominal adiposity, particularly subcutaneous AT and intermuscular AT, and lower volume of skeletal muscle compared to controls. The decreased ratio of visceral AT/subcutaneous AT in youth with PWS suggests an improved metabolic profile for the level of adiposity present; however, elevated ratios of AT to skeletal muscle suggest a sarcopenic obesity-like phenotype, which could lead to worse health outcomes.

Effect of Electroacupuncture on Visceral and Hepatic Fat in Women with Abdominal Obesity: A Randomized Controlled Study Based on Magnetic Resonance Imaging

OBJECTIVE

Visceral adipose tissue (VAT) and hepatic fat deposition are the most important risk factors for women's health. Acupuncture, including electroacupuncture (EA), is used to treat obesity throughout the world. The effect of EA is evaluated mainly by body mass index (BMI) and waist circumference (WC). Few studies have assessed its effect in reducing VAT volume and hepatic fat fraction (HFF) based on an exact measurement method such as magnetic resonance imaging (MRI). This study aimed to resolve this issue.

METHODS

Thirty subjects were randomly divided into two groups. The control group (n = 15) did not receive any intervention and maintained a normal diet and their usual exercise habits. The treatment group (n = 15) received EA three times a week for 3 months. BMI and WC were measured using different devices. VAT and HFF were measured by MRI and calculated by related software before and after the intervention.

RESULTS

A marked difference was evident in group that received EA treatment in the following tests. The differences in BMI (U = 21.00, p < 0.001), WC (U = 40.50, p = 0.002), VAT volume (U = 13.00, p < 0.001), and mean HFF (U = 0.00, p < 0.001) before and after the intervention in the treatment group were distinct and significant compared with those of the control group. Three months later, the treatment group showed a lower BMI (W = 91.00, p = 0.001), WC (t = 4.755, p < 0.001), VAT volume (t = 5.164, p < 0.001), and mean HFF (W = 120.00, p = 0.001) compared with pretreatment levels. Compared with the control group, the treatment group showed a lower VAT volume (t = 60.00, p = 0.029) after 3 months of treatment. After 3 months, the control group showed higher mean HFF (t = -2.900, p = 0.012) and VAT volume (W = 11.50, p = 0.006) compared with their initial levels.

CONCLUSION

Based on MRI evaluation, this randomized controlled study proved that EA treatment reduces BMI and WC as well as VAT volume and HFF in women with abdominal obesity.

Age and gender specific estimation of visceral adipose tissue amounts from radiological images in morbidly obese patients

Image-based quantifications of visceral adipose tissue (VAT) volumes from segmented VAT areas are increasingly considered for risk assessment in obese patients. The goal of this study was to determine the power of partial VAT areas to predict total VAT volume in morbidly obese patients (BMI > 40 kg/m²) as a function of gender, age and anatomical landmarks. 130 morbidly obese patients (mean BMI 46.5 kg/m²; 94 females) underwent IRB-approved MRI. Total VAT volumes were predicted from segmented VAT areas (of single or five adjacent slices) at common axial landmark levels and compared with the measured ones (V_VAT-T, about 40 slices between diaphragm and pelvic floor). Standard deviations σ₁ and σ₅ of the respective VAT volume differences served as measures of agreement. Mean V_VAT-T was 4.9 L for females and 8.1 L for males. Best predictions were found at intervertebral spaces L3-L4 for females (σ₅ = 688 ml, σ₁ = 832 ml) and L1-L2 for males (σ₅ = 846 ml, σ₁ = 992 ml), irrespective of age. In conclusion, VAT volumes in morbidly obese patients can be reliably predicted by multiplying the segmented VAT area at a gender-specific lumbar reference level with a fixed scaling factor and effective slice thickness.