Evaluation of whole-abdominal fat volume by 700-slice CT scanning and comparison with the umbilical fat area anthropometric indices

The influence of preoperative fat distribution on post-bariatric surgery body mass index and body weight loss

BACKGROUND

The body weight following bariatric surgery is a primary concern for both healthcare professionals and surgical candidates. However, it remains unclear whether variations in preoperative fat distribution influence weight loss outcomes.

OBJECTIVE

The aim of this study was to evaluate the effect of abdominal fat distribution on postoperative weight loss and body mass index (BMI) reduction, and to clarify the role of different fat depots in weight loss outcomes.

METHODS

Preoperative data from patients with overweight or obesity, along with their weight records at 1, 2 and 5 years following surgery, were retrospectively collected. Multiple levels of abdominal fat areas were measured using computerized tomography imaging. Statistical analyses included Pearson's correlation coefficients, multiple linear regressions, ridge regressions, decision tree regressions and paired t tests to evaluate the associations and influences.

RESULTS

A total of 139 patients were initially included. The statistical analysis results indicated that umbilical subcutaneous adipose tissue (SAT) was an independent factor influencing weight and BMI loss at the 1-year follow-up (n = 67, p < 0.01). Furthermore, umbilical SAT demonstrated significant correlations with sustained BMI reduction over the long term.

CONCLUSION

Umbilical SAT is a significant factor in postoperative weight and BMI loss. Patients with greater SAT may experience more substantial weight and BMI reductions following surgery, offering new insights into personalized weight loss strategies and alternative approaches for assisted weight loss.

Association between body composition and mortality in patients requiring extracorporeal membrane oxygenation support

AIM

To ascertain the association between body composition, including muscle mass and adiposity, and patient mortality in those requiring extracorporeal membrane oxygenation (ECMO) for acute respiratory failure.

MATERIALS AND METHODS

A retrospective study was undertaken of all patients with acute respiratory failure requiring veno-venous (VV) ECMO between January 2015 and December 2019. Automated image segmentation software was used to quantify the cross-sectional area and average radiodensity (in Hounsfield units) of different muscle and fat compartments at the L3 level of whole-body computed tomography (CT) images taken within 48 h of initiation of ECMO support. The primary endpoint was 30-day post-ECMO initiation all-cause mortality. Logistic regression was used to analyse the correlation between CT measurements, co-morbidities, and 30-day survival.

RESULTS

The study included 189 patients (age = 43.8 ± 14.6, sex = 42.3% female). There was no significant association between 30-day survival status and cross-sectional area of muscle or fat. Muscle attenuation (psoas, long spine, and abdominal muscles respectively) at the L3 level were significantly lower in those who died within 30 days of ECMO cannulation (p<0.05). On multivariable analysis including age, sex, and pre-existing respiratory comorbidities, psoas muscle attenuation was an independent predictor of survival at 30 days (OR 0.97; 95% CI 0.94 to 1.00; p=0.047).

CONCLUSIONS

Reduced psoas muscle attenuation is associated with poorer survival outcomes at 30 days post-ECMO cannulation in patients who received VV ECMO support for respiratory failure. Cross-sectional areas of muscle and fat compartments did not correlate with survival outcomes at 30 days even when corrected for height and sex.

CT features of divisional bile ducts in healthy Labrador Retrievers

Computed tomography (CT) is increasingly being used for the study of gallbladder and bile duct diseases. The first step in interpreting CT findings is understanding the cross-sectional anatomy of the structures involved, but there are no published studies describing the CT features of the divisional bile ducts. In dogs, anatomic studies report two common patterns including three or four divisional bile ducts. The aim of this retrospective, descriptive, anatomical study was to describe the size and pattern of the visible divisional bile ducts, based on their location and extension, using contrast-enhanced CT in a group of Labrador Retrievers without evidence of hepatobiliary diseases. The correlation between the biliary duct number and dimensions, and the visceral fat area percentage (VFA%) was also evaluated. The right lateral divisional duct (RLD) was visualized in four of 40 dogs, the left lateral divisional duct (LLD) in nine of 40 dogs, and in 17 of 40 dogs, both were simultaneously visualized. In 10 of 40 dogs, the RLD and LLD were not highlighted. When visible, the RLD has a median diameter of 0.23 cm and a median length of 0.82 cm. The LLD has a median diameter of 0.23 cm and a median length of 2.72 cm. The median diameter of the common bile duct before and after the insertion of divisional bile ducts was 0.23 and 0.25 cm, respectively. No correlation with the VFA% was found. At least one of the divisional bile ducts could be visualized using contrast-enhanced CT in the majority of sampled dogs (75%) .

Optimal cutoff values for visceral fat volume to predict metabolic syndrome in a Korean population

Previous studies have reported the association between visceral fat and metabolic syndrome (MS); however, just few studies have been conducted to evaluate the relationship between actual visceral fat volume (VFV) and MS. This study aimed to obtain 3 dimensional VFV and subcutaneous fat volume (SFV) using abdominal computed tomography (CT) and determine MS-predictive cutoff values.A total of 250 individuals, aged 27 to 80 years, who underwent health screening with abdominal CT between November 2019 and May 2020 were included. The subcutaneous (SFA) and visceral (VFA) fat areas were quantified using axial images obtained at the level of the lowest to the highest part of the umbilicus. The SFV and VFV were quantified from the highest level of the liver dome to the pelvic floor on axial CT images. The Aquarius iNtuition software program (TeraRecon, Foster City, CA) was used to calculate the SFA, VFA, SFV, and VFV. Subcutaneous fat mass and visceral fat mass (VFM) were measured using an adipose tissue density of 0.9 g/mL. We used the modified criteria of MS proposed by the Third National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults and waist circumference of ≥90 cm in men and ≥85 cm in women to define MS. Multivariate analysis of covariance was used to compare the fat areas, volumes, and mass according to the presence of MS and sex. Additionally, a receiver operating characteristic curve analysis was performed to determine the cutoff values for VFV, SFV, VFM, subcutaneous fat mass, VFA, and SFA associated with MS.Of the assessed variables, VFV and VFM had the highest area under the receiver operating characteristic curve value for predicting MS in both men and women: 0.811 (95% confidence interval, 0.743-0.868) for men and 0.826 (95% confidence interval, 0.727-0.900) for women. The MS-predictive cutoff values were 4852 cm3 and 4366.8 g for men and 3101 cm3 and 2790.9 g for women, respectively. Further, large, population-based studies are needed to validate these cutoff values.

Relationships between computed tomography-assessed density, abdominal fat volume, and glucose metabolism after sleeve gastrectomy in Japanese patients with obesity

In this study, we investigated the relationships between body weight (BW), computed tomography (CT)-assessed abdominal adipose tissue, and the glycemic metabolic profile in obese Japanese patients following laparoscopic sleeve gastrectomy (LSG). This study analyzed adipose tissue compartments using CT methods before and 1 year after LSG. Thirty obese patients were studied, and variables measured included visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), density of VAT (VAT-D), and density of SAT (SAT-D). We also examined the parameters in patients according to whether they had type-2 diabetes (T2DM). LSG induced significant losses in BW, SAT, and VAT after LSG. Additionally, SAT-D and VAT-D both increased and fasting plasma glucose (FPG) and HbA1c, but not C-peptide, decreased after surgery. ΔSAT and ΔVAT were positively related, and ΔSAT-D and ΔVAT-D were negatively related to ΔBW and/or FPG. Furthermore, a multivariate regression model showed that total BW loss (TBWL) was closely related to ΔSAT (β = 0.84; p < 0.001) and ΔVAT-D (β = -0.45; p < 0.05) and improvement of FPG was related to ΔVAT (β = 0.61; p < 0.05) after LSG. Finally, ΔFPG was correlated with ΔVAT in 16 T2DM patients (r = 0.58; p < 0.05) but not in non-T2DM patients. TBWL was related to ΔSAT and ΔVAT-D, and improvement of FPG was related to ΔVAT in obese Japanese patients after LSG.

Validation of a DIXON-based fat quantification technique for the measurement of visceral fat using a CT-based reference standard

PURPOSE

The purpose of the study is to determine whether a novel semi-automated DIXON-based fat quantification algorithm can reliably quantify visceral fat using a CT-based reference standard.

METHODS

This was an IRB-approved retrospective cohort study of 27 subjects who underwent abdominopelvic CT within 7 days of proton density fat fraction (PDFF) mapping on a 1.5T MRI. Cross-sectional visceral fat area per slice (cm²) was measured in blinded fashion in each modality at intervertebral disc levels from T12 to L4. CT estimates were obtained using a previously published semi-automated computational image processing system that sums pixels with attenuation - 205 to - 51 HU. MR estimates were obtained using two novel semi-automated DIXON-based fat quantification algorithms that measure visceral fat area by spatially regularizing non-uniform fat-only signal intensity or de-speckling PDFF 2D images and summing pixels with PDFF ≥ 50%. Pearson's correlations and Bland-Altman analyses were performed.

RESULTS

Visceral fat area per slice ranged from 9.2 to 429.8 cm² for MR and from 1.6 to 405.5 cm² for CT. There was a strong correlation between CT and MR methods in measured visceral fat area across all studied vertebral body levels (r = 0.97; n = 101 observations); the least (r = 0.93) correlation was at T12. Bland-Altman analysis revealed a bias of 31.7 cm² (95% CI [- 27.1]-90.4 cm²), indicating modestly higher visceral fat assessed by MR.

CONCLUSION

MR- and CT-based visceral fat quantification are highly correlated and have good cross-modality reliability, indicating that visceral fat quantification by either method can yield a stable and reliable biomarker.

Proposed cut-off value of the intrahepatic lipid content for metabolically normal persons assessed by proton magnetic resonance spectroscopy in a Japanese population

AIMS

To determine the threshold intrahepatic lipid (IHL) content separating metabolically normal from abnormal in a Japanese population based on proton magnetic resonance spectroscopy ((1)H-MRS).

METHODS

A total of 305 Japanese subjects aged 20-69years were investigated. The subjects underwent general examination, blood tests, and (1)H-MRS of the liver after an overnight fast. They completed a questionnaire about daily drinking habits and their daily alcohol intake was calculated.

RESULTS

The median IHL content was 4.7% in men and 1.7% in women, and it increased along with the number of features of metabolic syndrome (MetS). The optimum IHL cut-off value for separating normal subjects from those with at least one feature of MetS was 6.5% in men (AUC of ROC: 0.727, 95%-CI: 0.649-0.804) and 1.8% in women (0.765, 0.685-0.844). Alcohol intake was not correlated with the IHL content according to multiple logistic regression analysis.

CONCLUSION

This study demonstrated a close association of IHL with features of MetS and identified IHL content cut-off values for metabolic normality in Japanese subjects.

Proposed cut-off values of the waist circumference for metabolic syndrome based on visceral fat volume in a Japanese population

Aim/Introduction

Waist circumference (WC) is the most important parameter for diagnosis of metabolic syndrome. The present study was carried out to obtain optimal WC cut‐off values for diagnosis of metabolic syndrome in a Japanese population based on the measurement of total intra‐abdominal visceral fat volume (VFV), which could be expected to reflect visceral obesity more precisely than visceral fat area.

Materials and Methods

A total of 405 Japanese persons undergoing health screening were investigated. visceral fat volume was calculated from the data in 700–800 computed tomography slices from the top of the liver to the floor of the pelvic cavity. Then, receiver operating characteristic analysis was used to determine the cut‐off value of the VFV/height ratio. Subsequently, the corresponding WC value was obtained by linear regression analysis.

Results

The cut‐off value of the VFV/height ratio was 2,317 cm³/m in men and 1,425 cm³/m in women. The sensitivity and specificity of the ratio were 52.9 and 86.4% in men vs 63.4 and 82.2% in women, respectively. The corresponding cut‐off value of WC was 86.0 cm in men and 80.9 cm in women.

Conclusions

The proposed cut‐off values of WC for metabolic syndrome are 85 cm in Japanese men and 80 cm in Japanese women.

Best single-slice location to measure visceral adipose tissue on paediatric CT scans and the relationship between anthropometric measurements, gender and VAT volume in children

OBJECTIVE

Visceral adipose tissue (VAT) is a significant risk factor for obesity-related metabolic diseases. This study investigates (1) the best single CT slice location for predicting total abdominal VAT volume in paediatrics and (2) the relationship between waist circumference (WC), sagittal diameter (SD), gender and VAT volume.

METHODS

A random sample of 130 paediatric abdomen CT scans, stratified according to age and gender, was collected. Three readers measured VAT area at each intervertebral level between T12 and S1 using ImageJ analysis (National Institute of Health, Bethesda, MD) software by thresholding -190 to -30 HU and manually segmenting VAT. Single-slice VAT measurements were correlated with total VAT volume to identify the most representative slice. WC and SD were measured at L3-L4 and L4-L5 slices, respectively. Regression analysis was used to evaluate WC, SD and gender as VAT volume predictors.

RESULTS

Interviewer and intraviewer reliability were excellent (intraclass correlation coefficient = 0.99). Although VAT measured at multiple slices correlated strongly with abdominal VAT, only one slice in females at L2-L3 and two slices in males at L1-L2 and L5-S1 were strongly correlated across all age groups. Linear regression analysis showed that WC was strongly correlated with VAT volume (beta = 0.970, p < 0.001).

CONCLUSION

Single-slice VAT measurements are highly reproducible. Measurements performed at L2-L3 in females and L1-L2 or L5-S1 in males were most representative of VAT. WC is indicative of VAT.

ADVANCES IN KNOWLEDGE

VAT should be measured at L2-L3 in female children and at either L1-L2 or L5-S1 in males. WC is a strong indicator of VAT in children.

Multiparametric body composition analysis and anthropometric empirical indicator: obesity based south Indian perspective

BACKGROUND

Obesity has emerged to be a global threat to mankind. Many abnormalities such as cardiovascular diseases and diabetes emerge as outcomes of obesity.

OBJECTIVES

The present study aimed at bringing out a technique which considers the combinational measurement of all essential anthropometric circumferences and body mass index (BMI), so that the accurate assessment of obesity can be made. To date, BMI has been considered to be the main adiposity index, but the distribution of body fat was not taken into account by BMI. The contradictory outcomes by BMI pertaining to risk factor detection in various ethnicities and populations were witnessed. Also, BMI failed to gauge obesity in muscular body builders who possess small waists and large torsos.

MATERIALS AND METHODS

The study adopted a cross-sectional design and 107 subjects from urban south India participated. The measurements of body composition and anthropometry were shown.

RESULTS

The higher significant difference of ≤ 0.001 was observed in male and female studied population, when AEI (BIA1), AEI (EXTERNAL) and BMI were compared against BFM (measured by both the devices BIA1 and BIA2).

CONCLUSIONS

The results exhibited the prominence of AEI (Anthropometric Empirical Indicator, which is the combinational measurement of all essential anthropometric circumferences and BMI) over BMI. Also, the validity of the effective functioning of low-cost, portable, simple protocol based body composition analyzer on par with the highercost, standard body composition analyzer was demonstrated by the present study.

Relation of visceral and subcutaneous adipose tissue to bone mineral density in chinese women

The relationship between adipose and bone tissues is still being debated. The purpose of our study was to evaluate whether the distribution and volume of abdomen adipose tissue are correlated to trabecular bone mineral density in the lumbar spine. In this cross-sectional study, 320 Chinese women, being divided into two groups according to age ≥55 years and <55 years, were evaluated with quantitative computed tomography (QCT) of the spine to simultaneously evaluate the average trabecular BMD of L2-L4, VAT, and SAT. Possible covariates of height, weight, age, and comorbidities were considered. In the <55-year-old sample, multiple linear regression analyses indicated that VAT volume was negatively correlated to trabecular BMD (P value = 0.0003) and SAT volume had no correlation to trabecular BMD. In contrast, there was no significant correlation between VAT or SAT and BMD in the ≥55-year-old sample. Our results indicate that high VAT volume is associated with low BMD in Chinese women aged <55 years and SAT has no relation with BMD.

Visceral obesity and risk of high grade disease in clinical t1a renal cell carcinoma

PURPOSE

Accurate assessment of disease characteristics is a prerequisite for treatment decision making regarding small renal masses. In this study we evaluate the association between visceral obesity and Fuhrman grade in patients with cT1a renal cell carcinoma.

MATERIALS AND METHODS

We retrospectively collected data on 186 patients with surgically treated cT1a renal cell carcinoma. Single slice computerized tomography was used to measure the area of visceral and subcutaneous adipose tissue. Visceral obesity was calculated as the proportion of visceral adipose tissue to overall adipose tissue. Other analyzed factors included clinical characteristics (age, gender, body mass index and tumor size) and anatomical features of the tumor defined by the R.E.N.A.L. nephrometry score. The association between predictors and high grade disease (Fuhrman grade III or IV) were assessed using logistic regression analyses.

RESULTS

A total of 47 (25.3%) tumors were classified as high grade. The percentage of visceral adipose tissue was higher in male participants but did not correlate with body mass index, age or tumor size. In univariate analyses the percentage of visceral adipose tissue and tumor size were significantly associated with higher Fuhrman grade. Multivariate analysis showed that the percentage of visceral adipose tissue (OR 1.06, p = 0.0018) and tumor size (OR 1.91, p = 0.047) were independent predictors of high grade cancer. Addition of the percentage of visceral adipose tissue to a model including clinical characteristics and anatomical features of the tumor remarkably improved its discriminatory ability (p = 0.0010).

CONCLUSIONS

Increased visceral obesity was found to be strongly associated with higher Fuhrman grade in patients with cT1a renal cell carcinoma. Further studies are needed to confirm these findings and discover the underlying biological mechanism.