Determination of total adipose tissue and body fat in women by computed tomography, 40K, and tritium

Effect of aerobic exercise on waist circumference in adults with overweight or obesity: A systematic review and meta-analysis

Excess visceral adiposity contributes to elevated cardiometabolic risk, and waist circumference is commonly used as a surrogate measure of visceral adipose tissue. Although regular aerobic exercise is known to improve abdominal obesity, its effect on waist circumference is unclear. A systematic review and meta-analysis was performed to determine (1) the effect of aerobic exercise on waist circumference in adults with overweight or obesity; (2) the association between any change in waist circumference and change in visceral adipose tissue and/or bodyweight with aerobic exercise interventions; and (3) if reductions in waist circumference with exercise are moderated by clinical characteristics or components of aerobic exercise prescription. Twenty-five randomized controlled trials (1686 participants) were included. Regular aerobic exercise significantly reduced waist circumference by 3.2 cm (95% confidence interval [CI] -3.86, -2.51, p ≤ 0.001) versus control. Change in waist circumference was associated with change in visceral adipose tissue (β = 4.02; 95% CI 1.37, 6.66, p = 0.004), and vigorous intensity produced superior reduction (-4.2 cm, 95% CI -4.99, -3.42, p < 0.0001) in waist circumference compared with moderate intensity (-2.50 cm, 95% CI -3.22, -1.79, p = 0.058). These findings suggest regular aerobic exercise results in modest reductions in waist circumference and associated visceral adipose tissue and that higher intensity exercise may offer superior benefit to moderate intensity.

Measurement of epicardial adipose tissue using non-contrast routine chest-CT: a consideration of threshold adjustment for fatty attenuation

Background

Epicardial adipose tissue (EAT) is known as an important imaging indicator for cardiovascular risk stratification. The present study aimed to determine whether the EAT volume (EV) and mean EAT attenuation (mEA) measured by non-contrast routine chest CT (RCCT) could be more consistent with those measured by coronary CT angiography (CCTA) by adjusting the threshold of fatty attenuation.

Methods

In total, 83 subjects who simultaneously underwent CCTA and RCCT were enrolled. EV and mEA were quantified by CCTA using a threshold of (N30) (− 190 HU, − 30 HU) as a reference and measured by RCCT using thresholds of N30, N40 (− 190 HU, − 40 HU), and N45 (− 190 HU, − 45 HU). The correlation and agreement of EAT metrics between the two imaging modalities and differences between patients with coronary plaques (plaque ( +)) and without plaques (plaque ( −)) were analyzed.

Results

EV obtained from RCCT showed very strong correlation with the reference (r = 0.974, 0.976, 0.972 (N30, N40, N45), P < 0.001), whereas mEA showed a moderate correlation (r = 0.516, 0.500, 0.477 (N30, N40, N45), P < 0.001). Threshold adjustment was able to reduce the bias of EV, while increase the bias of mEA. Data obtained by CCTA and RCCT both demonstrated a significantly larger EV in the plaque ( +) group than in the plaque ( −) group (P < 0.05). A significant difference in mEA was shown only by RCCT using a threshold of N30 (plaque ( +) vs ( −): − 80.0 ± 4.4 HU vs − 78.0 ± 4.0 HU, P = 0.030). The mEA measured on RCCT using threshold of N40 and N45 showed no significant statistical difference between the two groups (P = 0.092 and 0.075), which was consistent with the result obtained on CCTA (P = 0.204).

Conclusion

Applying more negative threshold, the consistency of EV measurements between the two techniques improves and a consistent result can be obtained when comparing EF measurements between groups, although the bias of mEA increases. Threshold adjustment is necessary when measuring EF with non-contrast RCCT.

The HERITAGE Family Study: A Review of the Effects of Exercise Training on Cardiometabolic Health, with Insights into Molecular Transducers

The aim of the HERITAGE Family Study was to investigate individual differences in response to a standardized endurance exercise program, the role of familial aggregation, and the genetics of response levels of cardiorespiratory fitness and cardiovascular disease and diabetes risk factors. Here we summarize the findings and their potential implications for cardiometabolic health and cardiorespiratory fitness. It begins with overviews of background and planning, recruitment, testing and exercise program protocol, quality control measures, and other relevant organizational issues. A summary of findings is then provided on cardiorespiratory fitness, exercise hemodynamics, insulin and glucose metabolism, lipid and lipoprotein profiles, adiposity and abdominal visceral fat, blood levels of steroids and other hormones, markers of oxidative stress, skeletal muscle morphology and metabolic indicators, and resting metabolic rate. These summaries document the extent of the individual differences in response to a standardized and fully monitored endurance exercise program and document the importance of familial aggregation and heritability level for exercise response traits. Findings from genomic markers, muscle gene expression studies, and proteomic and metabolomics explorations are reviewed, along with lessons learned from a bioinformatics-driven analysis pipeline. The new opportunities being pursued in integrative -omics and physiology have extended considerably the expected life of HERITAGE and are being discussed in relation to the original conceptual model of the study.

Sarcopenia: imaging assessment and clinical application

Sarcopenia is a progressive, generalized skeletal muscle disorder characterized by reduction of muscle mass and strength. It is associated with increased adverse outcomes including falls, fractures, physical disability, and mortality, particularly, in elderly patients. Nowadays, sarcopenia has become a specific imaging biomarker able to predict clinical outcomes of patients. Muscle fibre reduction has shown to be an unfavourable pre-operative predictive factor in patients with cancer, and is associated with worse clinical outcomes in terms of postoperative complications, morbidity, mortality, and lower tolerance of chemoradiation therapy. Several imaging modalities, including dual-energy X-ray absorptiometry, CT, MRI, and US can be used to estimate muscle mass and quality to reach the diagnosis of sarcopenia. This article reviews the clinical implications of sarcopenia, how this condition can be assessed through different imaging modalities, and future perspectives of imaging of sarcopenia.

Segmentation and characterization of visceral and abdominal subcutaneous adipose tissue on CT with and without contrast medium: influence of 2D- and 3D-segmentation

Background

Adipose tissue is a valuable biomarker. Although validation and correlation to clinical data have mostly been performed on non-enhanced scans (NES), a previous study has shown conversion of values of contrast enhanced scan (CES) into those of NES to be feasible with segmentation of the entire abdomen (3D-segmentation). In this study we analyzed if density and area of abdominal adipose tissue segmented in a single slice (2D-segmentation) of CES may be converted into that of NES. Furthermore, we compared the precision of conversion between 2D- and 3D-segmentation.

Methods

Thirty-one multi-phasic abdominal CT examinations at identical scan settings were retrospectively included. Exams included NES (n=31), arterial (ART) (n=23), portal-venous (PVN) (n=10), and/or venous scan (VEN) (n=31). Density and area of visceral (VAT) and subcutaneous adipose tissue (SAT) were quantified semi-automatically with fixed thresholds. For conversion of values from CES into those of NES regression analyses were performed and tested. 2D- and 3D-segmentation were compared with respect to conversion accuracy (normalized deviations of converted NES values from original measurements).

Results

After the application of contrast medium 2D-segmented adipose tissue increased in density (max. +5.6±2.4 HU) and decreased in area (max. -10.91%) (10.47%), with few exceptions (P<0.05). This was more pronounced in later scans (VEN ≈ PVN > ART) and more marked in VAT than SAT. Density and area in CES correlated very well with NES, allowing for conversion with only small error. While converted density is slightly more precise applying 3D-segmentation, conversion error of quantity was occasionally smaller with 2D-segmentation.

Conclusions

Contrast medium changes density and quantity of segmented adipose tissue in differing degrees between compartments, contrast phases and 2D- and 3D-segmentation. However, changes are fairly constant for a given compartment, contrast phase and mode of segmentation. Therefore, conversion of values into those of NES may be achieved with comparable precision for 2D- and 3D-segmentation.

Deep Learning-Based Quantification of Visceral Fat Volumes Predicts Posttransplant Diabetes Mellitus in Kidney Transplant Recipients

Background: Because obesity is associated with the risk of posttransplant diabetes mellitus (PTDM), the precise estimation of visceral fat mass before transplantation may be helpful. Herein, we addressed whether a deep-learning based volumetric fat quantification on pretransplant computed tomographic images predicted the risk of PTDM more precisely than body mass index (BMI).

Methods: We retrospectively included a total of 718 nondiabetic kidney recipients who underwent pretransplant abdominal computed tomography. The 2D (waist) and 3D (waist or abdominal) volumes of visceral, subcutaneous, and total fat masses were automatically quantified using the deep neural network. The predictability of the PTDM risk was estimated using a multivariate Cox model and compared among the fat parameters using the areas under the receiver operating characteristic curves (AUROCs).

Results: PTDM occurred in 179 patients (24.9%) during the median follow-up period of 5 years (interquartile range, 2.5–8.6 years). All the fat parameters predicted the risk of PTDM, but the visceral and total fat volumes from 2D and 3D evaluations had higher AUROC values than BMI did, and the best predictor of PTDM was the 3D abdominal visceral fat volumes [AUROC, 0.688 (0.636–0.741)]. The addition of the 3D abdominal VF volume to the model with clinical risk factors increased the predictability of PTDM, but BMI did not.

Conclusions: A deep-learning based quantification of visceral fat volumes on computed tomographic images better predicts the risk of PTDM after kidney transplantation than BMI.

3D-segmentation and characterization of visceral and abdominal subcutaneous adipose tissue on CT: influence of contrast medium and contrast phase

Background

Adipose tissue as part of body composition analysis may serve as a powerful biomarker. Validation of segmented adipose tissue and correlation to clinical data has been performed on non-enhanced scans (NES). As many patients require a contrast enhanced scan (CES) for other aspects of clinical decision making, the utility of CES for body composition analysis would be most useful. Therefore, we analyzed the influence of iodinated contrast medium (ICM) and contrast phase on the characterization and segmentation of adipose tissue.

Methods

Exams of 31 patients undergoing multi-phasic CT at identical scan settings containing an NES were retrospectively included. In addition to NES, patients received an arterial (ART) (n=23), portal-venous (PVN) (n=10), and/or venous scan (VEN) (n=31) after intravenous injection of 90 mL ICM. Density and volume of adipose tissue were quantified semi-automatically with thresholds between -190 HU and -30 HU and recorded separately for visceral (VAT) and subcutaneous adipose tissue (SAT). Density and volume of total adipose tissue (TAT) were computed. For conversion of values from CES into those of NES regression analyses were performed and tested.

Results

Density of adipose tissue increased after application of ICM more on later scans (VEN ≈ PVN > ART) and more markedly in VAT than SAT (VAT > TAT > SAT). Except in SAT on ART, all changes were significant (P<0.001). Measured volume of adipose tissue decreased on all CES (VEN ≈ PVN > ART) (P<0.001), but only reached statistical significance for VAT and TAT (VAT > TAT) on all CES (P<0.05). Density and volume in CES correlate extremely well with NES and may be calculated from one another [root-mean-square error (RMSE): <6 HU; <0.85 dm³].

Conclusions

Density and volume of segmented adipose tissue are altered by the injection of ICM in differing degrees between compartments and contrast phases. However, as the effect of ICM is fairly constant for a given compartment and contrast phase, values may be converted into those of NES with relative precession. This conversion allows body composition analysis to be carried out also in contrast enhanced CT examinations, e.g., for risk stratification and the comparison of the obtained results to previous studies.

Metabolic syndrome in haemodialysis patients: prevalence, determinants and association to cardiovascular outcomes

BACKGROUND

In the general population, metabolic syndrome (MetS) is predictive of major adverse cardiovascular events (MACE). Waist circumference (WC), a component of the MetS criteria, is linked to visceral obesity, which in turn is associated with MACE. However, in haemodialysis (HD) patients, the association between MetS, WC and MACE is unclear.

METHODS

In a cross-sectional study of 1000 HD patients, we evaluated the prevalence and characterised the clinical predictors of MetS. The relationship between MetS and its components, alone or in combination, and MACE (coronary diseases, peripheral arteriopathy, stroke or cardiac failure), was studied using receiver operating characteristics (ROC) curves and logistic regression.

RESULTS

A total of 753 patients were included between October 2011 and April 2013. The prevalence of MetS was 68.5%. Waist circumference (> 88 cm in women, 102 cm in men) was the best predictor of MetS (sensitivity 80.2; specificity 82.3; AUC 0.80; p <  0.05). In multivariate analysis, MetS was associated with MACE (OR: 1.85; 95CI 1.24-2.75; p <  0.01), but not WC alone. There was a stronger association between the combination of abdominal obesity, hypertriglyceridaemia and low high-density lipoprotein cholesterol with MACE after exclusion of impaired fasting glucose and hypertension.

CONCLUSIONS

MetS is frequent and significantly associated with MACE in our haemodialysis cohort and probably in other European dialysis populations as well. In HD patients, a new simplified definition could be proposed in keeping with the concept of the "hypertriglyceridaemic waist".

MRI in the assessment of adipose tissues and muscle composition: how to use it

Body composition analysis based on the characterization of different tissue compartments is currently experiencing increasing attention by a broad range of medical disciplines for both clinical and research questions. However, body composition profiling (BCP) can be performed utilizing different modalities, which all come along with several technical and diagnostic strengths and limitations, respectively. Magnetic resonance imaging (MRI) demonstrates good soft tissue resolution, high contrast between fat and water, and is free from ionizing radiation. This review article represents an overview of imaging techniques for body composition assessment, focussing on qualitative and quantitative methods of assessing adipose tissue and muscles in MRI.

21st Century Advances in Multimodality Imaging of Obesity for Care of the Cardiovascular Patient

Although obesity is typically defined by body mass index criteria, this does not differentiate true body fatness, as this includes both body fat and muscle. Therefore, other fat depots may better define cardiometabolic and cardiovascular disease (CVD) risk imposed by obesity. Data from translational, epidemiological, and clinical studies over the past 3 decades have clearly demonstrated that accumulation of adiposity in the abdominal viscera and within tissue depots lacking physiological adipose tissue storage capacity (termed "ectopic fat") is strongly associated with the development of a clinical syndrome characterized by atherogenic dyslipidemia, hyperinsulinemia/glucose intolerance/type 2 diabetes mellitus, hypertension, atherosclerosis, and abnormal cardiac remodeling and heart failure. This state-of-the-art paper discusses the impact of various body fat depots on cardiometabolic parameters and CVD risk. Specifically, it reviews novel and emerging imaging techniques to evaluate adiposity and the risk of cardiometabolic diseases and CVD.

Metabolic changes with degarelix vs leuprolide plus bicalutamide in patients with prostate cancer: a randomized clinical study

PURPOSE

In a mouse model, degarelix generated the least metabolic consequences via low follicle-stimulating hormone (FSH) levels compared with orchiectomy and leuprolide after 4 months of androgen deprivation therapy (ADT). Here, we comparatively investigated the influence of ADT with degarelix or leuprolide on the development of metabolic syndrome in patients with prostate cancer (PCa).

METHODS

Patients with hormone-naive PCa were recruited. Eligible patients were randomized (1:1) to monthly degarelix or monthly leuprolide for 6 months. Key trial variables were monitored monthly. The primary endpoint was changes in fasting blood sugar (FBS). Secondary endpoints were changes in body weight, abdominal circumference, lipid profiles, and hemoglobin A1c (HbA1c) and FSH levels. Computed tomography was performed to measure subcutaneous and visceral fat areas before and after 6 months of ADT. Data were analyzed using the χ² test, Student's t test, and analysis of variance.

RESULTS

From the 100 patients registered, 85 completed the trial (degarelix: 40 patients; leuprolide: 45 patients). Mean increases in FBS did not differ between the two arms. Similarly, there were no differences between the arms in mean increases in body weight, abdominal circumference, lipid profiles, HbA1c, or subcutaneous and visceral fat areas. Follicle-stimulating hormone levels were significantly lower in the degarelix arm than in the leuprolide arm (p < 0.05).

CONCLUSIONS

Lipid and glucose metabolism did not differ significantly between the arms, while FSH levels were significantly lower in the degarelix arm.

CT-Quantified Adipose Tissue Distribution: Risk or Protective Factor for Complications after Rectal Cancer Surgery?

PURPOSE

Obesity is associated with increased incidence and mortality in rectal cancer (RC). However, an obesity paradox in the sense of a protective effect of obesity is discussed controversially. We evaluated whether adipose tissue distribution has an impact on medical (MC) and surgical complications (SC) after RC surgery.

METHODS

A total of 296 RC patients underwent oncological surgery and multidetector CT with quantification of total (TAT), visceral (VAT), and subcutaneous adipose tissue (SAT). Logistic regressions on SC (anastomotic leakage [n = 26], wound infection [n = 58], bleeding [n = 12], abscess [n = 32], bladder dysfunction [n = 24], burst abdomen [n = 10]), and MC (pulmonary [n = 22], cardiac [n = 18], urinary tract infection [n = 9], sepsis [n = 5]) were performed.

RESULTS

High pelvicVAT was associated with reduced risk for overall SC (OR = 0.915, p = 0.012) and anastomotic leakage (OR = 0.587, p = 0.024, CI: 0.369/0.934). In contrast, CT-quantified obesity was associated with increased risk for wound infection, bladder dysfunction, burst abdomen, overall MC, and cardiac complications (ORs up to 1.423). BMI was not associated with any SC or MC.

CONCLUSION

An obesity paradox with a protective effect of CT-quantified adipose tissue was confirmed for anastomotic leakage and overall SC. In contrast, high adipose tissue was associated with higher risk for other SC and MC. These results show a more complex influence of body composition on MC and SC. CT-quantified obesity is able to provide deeper insights to explain the obesity paradox beyond BMI.

Association of visceral adiposity and insulin resistance with colorectal adenoma and colorectal cancer

BACKGROUND/AIMS

To examine whether visceral adiposity serves as a risk factor for colorectal cancer (CRC) and colorectal adenomas.

METHODS

Two hundred healthy subjects, 200 patients with colorectal adenoma, and 151 patients with CRC (46 with early-stage and 105 with advanced-stage cancers) were enrolled at a tertiary referral hospital. All subjects underwent colonoscopy, and had laboratory data, and computed tomography (CT) scan available for abdominal fat measurement. An abdominal CT scan taken 1 to 4 years (mean interval, 20.6 months) before the diagnosis of CRC was also available in the 42 CRC patients.

RESULTS

The mean areas of visceral adipose tissue (VAT) areas in the control, adenoma, early- and advanced-stage CRC groups were 94.6, 116.8, 110.4, and 99.7 cm2 , respectively (P<0.001). The risk of adenoma positively correlated with VAT area and the visceral-to-total fat ratio (P for trend <0.01), but the risk of CRC did not (P>0.05). The risk of both adenoma and CRC positively correlated with fasting plasma glucose levels (P for trend <0.05). In patients with early-stage cancer (n=17), VAT area decreased when the CT scan at diagnosis was compared with that taken before the diagnosis of CRC, but superficial adipose tissue area did not, so visceral-to-total fat ratio significantly decreased (46.6% vs. 50.7%, respectively, P=0.018).

CONCLUSIONS

VAT area is related to the risk of colorectal adenoma. However, VAT decreases from the early stages of CRC. Impaired fasting glucose has a role in colorectal carcinogenesis.

Body Fatness, Adipose Tissue Compartments, and Biomarkers of Inflammation and Angiogenesis in Colorectal Cancer: The ColoCare Study

BACKGROUND

Adiposity has been linked to both risk and prognosis of colorectal cancer; however, the impact of different fat areas [visceral (VFA) vs. subcutaneous fat area (SFA)] is unclear. We investigated associations between adiposity and biomarkers of inflammation and angiogenesis among patients with colorectal cancer.

METHODS

Preoperative serum samples and computed tomography scans were obtained from 188 patients diagnosed with primary invasive stage I-IV colorectal cancer enrolled in the ColoCare Study. Adiposity was assessed by area-based quantification of VFA, SFA, and VFA:SFA ratio on spinal levels L3/L4 and L4/L5. Circulating levels of inflammation (CRP, SAA, sICAM-1, and sVCAM-1) and angiogenesis (VEGF-A and VEGF-D) were assessed from patient sera on the Meso Scale Discovery platform. Partial correlations and regression analyses, adjusted for age, sex, and tumor stage, were performed.

RESULTS

VFA was moderately correlated with CRP and SAA (CRP: L3/L4 and L4/L5:r = 0.21, P = 0.01; SAA: L3/L4:r = 0.17, P = 0.04). The correlation between SFA and the measured biomarkers were weak (r ≤ 0.13, not significant). The ratio of VFA:SFA at L3/L4 was moderately correlated with VEGF-A (r = 0.28, P = 0.0008) and SAA (r = 0.24, P = 0.006), and less so with CRP (r = 0.18, P = 0.04) and sICAM-1 (r = 0.18, P = 0.04). Similar correlations were found for the VFA:SFA ratio at L4/L5.

CONCLUSIONS

We observed an association between visceral adiposity and biomarkers of inflammation and angiogenesis in colorectal cancer. In particular, the VFA:SFA ratio was correlated with circulating levels of the proangiogenic biomarker VEGF-A.

IMPACT

Our findings support a direct association of visceral adipose tissue with inflammatory and angiogenic processes, which play fundamental roles in the development and progression of colorectal cancer.

The Cutoff Pericardial Adipose Tissue Volume Associated with Metabolic Syndrome

Background

Metabolic syndrome (MS) is a well-known risk factor of cardiovascular diseases that is focused on central obesity. Recent studies have reported the association between pericardial adipose tissue (PAT) volume and MS. However, no studies have demonstrated the cutoff PAT volume that represents the best association with MS.

Methods

The data of 374 subjects were analyzed cross-sectionally to compare PAT, measured on coronary multidetector computed tomography, and various metabolic parameters according to MS. After PAT volumes were divided into tertiles, various metabolic parameters were compared among tertiles; furthermore, the odds ratio for developing MS was calculated. Finally, we demonstrated the cutoff PAT volume that represented the best association with MS by using the receiver-operating characteristic curve.

Results

We found that 27.5% of the subjects had MS, and the mean PAT volume was 123.9 cm³. PAT showed a significant positive correlation with body mass index, waist circumference, and levels of glucose, triglyceride, high-sensitivity C-reactive protein, uric acid, and homocysteine, but a negative correlation with high-density lipoprotein cholesterol. Furthermore, after dividing into tertiles, PAT volume was also significantly associated with various metabolic parameters. The odds ratio for having MS was 4.19 (95% confidence interval, 2.27–7.74) in the top tertile of PAT volumes after adjusting for age, sex, and smoking. The cutoff PAT volume that represented the best association with MS was 142.2 cm³.

Conclusion

PAT was significantly associated with MS and various metabolic parameters. The cutoff PAT volume of 142.2 cm³ showed the best association with MS.

Localization of fat depots and cardiovascular risk

Despite the existing preventative and therapeutic measures, cardiovascular diseases remain the main cause of temporary disability, long-term disability, and mortality. Obesity is a major risk factor for cardiovascular diseases and their complications. However, not all fat depots have the same inflammatory, paracrine, and metabolic activities. In addition, recent studies have indicated that the accumulation of visceral fat, rather than subcutaneous fat, is associated with increased cardiometabolic risk. However, there is also evidence that increasing the area of visceral fat can help protect against lipotoxicity. This review aims to discuss the contemporary literature regarding the characteristics of the visceral, epicardial, and perivascular fat depots, as well as their associations with cardiovascular disease.

Diagnostic imaging of osteoporosis and sarcopenia: a narrative review

Osteoporosis and sarcopenia represent two major health problems with an increasing prevalence in the elderly population. The correlation between these diseases has been widely reported, leading to the development of the term "osteosarcopenia" to diagnose those patients suffering from both diseases. Several imaging methods for the diagnosis and management of osteoporosis exist, with dual-energy X-ray absorptiometry (DXA) being the most commonly used for measuring bone mineral density (BMD). Imaging technique other than DXA is represented by conventional radiography, computed tomography (CT) and ultrasound (US). Similarly, the imaging technologies used to detect loss of skeletal muscle mass in sarcopenia include DXA, CT, US and magnetic resonance imaging (MRI). These methods differ in terms of reliability, radiation exposure and costs. CT and MRI represent the gold standard for evaluating body composition (BC), but are costly and time-consuming. DXA remains the most often used technology for studying BC, being quick, widely available and with low radiation exposure.

Carpal canal lipoma causing lameness in a dog

Carpal canal syndrome, or carpal tunnel syndrome, is the most common entrapment neuropathy in humans and is caused by compression of the median nerve as it courses through the carpal canal. A similar condition has been reported in horses, however there have not been any reported cases of a dog showing lameness secondary to compression within the carpal canal. This report describes the case of a dog exhibiting lameness secondary to a lipoma within the carpal canal. Lameness improved after surgical removal of the mass. This case highlights the need to consider compression of the tendons and nerves in the carpal canal as a cause of forelimb lameness in dogs when pain is localised to the carpus.

Relation of Changes in Body Fat Distribution to Oxidative Stress

Android fat is a surrogate measure of visceral obesity in the truncal region. Both visceral adiposity and oxidative stress (OS) are linked to cardiometabolic risk factors and clinical cardiovascular disease. However, whether body fat distribution (android vs gynoid) is associated with OS remains unknown. We hypothesized that increased android fat will be associated with greater OS. Body fat distribution and markers of OS, including plasma levels of reduced (cysteine and glutathione) and oxidized (cystine and glutathione disulfide) aminothiols, were estimated in 711 volunteers (67% female, 23% black, mean age 48 ± 11) enrolled in the Emory Georgia Tech Predictive Health study. At 1 year, 498 subjects had repeat testing. At baseline, anthropometric and fat distribution indexes, including body mass index, waist circumference, weight/hip ratio, and android and gynoid fat mass correlated with lower plasma concentrations of glutathione and higher cystine levels indicative of higher OS. At 1 year, the change in android but not gynoid fat mass or body mass index negatively correlated with the change in the plasma glutathione level after adjustment for cardiovascular risk factors. Increased body fat, specifically android fat mass, is an independent determinant of systemic OS, and its change is associated with a simultaneous change in OS, measured as plasma glutathione. In conclusion, our findings suggest that excess android or visceral fat contributes to the development of cardiovascular disease through modulating OS.

Body fat composition as predictive factor for treatment response in patients with newly diagnosed multiple myeloma - subgroup analysis of the prospective GMMG MM5 trial

INTRODUCTION/BACKGROUND

Obesity is a well-known risk factor for malignant tumors and increased body mass index (BMI) is correlated to the risk of developing multiple myeloma (MM). The correlation of body fat composition with disease activity, adverse events and treatment response of MM patients has not been investigated yet.

PATIENTS AND METHODS

A subgroup of 108 patients from a single institution enrolled in the prospective GMMG-MM5 trial, who received a whole-body low-dose computed tomography (WBLDCT) before induction therapy, were included in this study. Body fat composition was measured in WBLDCT for each patient, divided in the compartments abdomen, pelvis, thigh and further categorized in subcutaneous (SAT) and visceral adipose tissue (VAT). The correlation of these parameters with disease activity (M protein, plasma cell count, LDH, CRAB-criteria), adverse cytogenetics, adverse events and treatment response were evaluated.

RESULTS

Significant reciprocal correlation was found between adverse cytogenetics and VAT of the abdomen and pelvis, respectively (gain 1q21: p=0.009 and p=0.021; t(4;14): p=0.038 and p=0.042). No correlation of VAT or SAT with adverse events was observed. Significant reciprocal correlation was observed between abdominal (p=0.03) and pelvic (p=0.035) VAT and treatment response. Abdominal VAT remains significant (p=0.034) independently of revised ISS stage and treatment. The BMI did not show a significant correlation with treatment response or investigated cytogenetics.

CONCLUSION

Based on the clinically relevant difference in treatment outcome depending on VAT and SAT, excessive body fat of abdomen and pelvis might be a predictive factor for poor treatment response. Further influences in this context should be considered as well, e.g. chemotherapy dosing and body fat metabolism. Further studies are necessary to investigate this hypothesis.

Impact of preoperative visceral fat proportion on type 2 diabetes in patients with low body mass index after gastrectomy

BACKGROUND

Metabolic surgery is an effective option for treatment of type 2 diabetes. Although body mass index (BMI) has several limitations in differentiating the metabolic risks of the same weight of muscle and fat, it is used as the basis of indication for metabolic surgery.

OBJECTIVES

Since visceral fat is highly associated with metabolic disease, we evaluated the effectiveness of visceral fat proportion (VFP) for predicting metabolic risk preoperatively.

SETTING

University hospital.

METHODS

Fifty-two type 2 diabetes patients with BMI≤35 kg/cm² who underwent gastrectomy for gastric cancer were included. Pre- and postoperative VFPs were measured using abdominal computed tomography. Multivariate logistic regression analysis was performed to estimate the effect of VFP on type 2 diabetes. Receiver operating curve analysis was used to estimate the effectiveness of VFP as a predictor of type 2 diabetes improvement.

RESULTS

Thirty-three of the 52 patients (63%) showed improved type 2 diabetes postoperatively. Low preoperative VFP (odds ratio [OR] = .913; 95% confidence interval [CI] = .835-.999; P = .048) and low glycated hemoglobin level (OR = .357; 95% CI = .172-.742; P = .006) were associated with type 2 diabetes improvement 2 years after gastrectomy. The area under the curve was 70.2%, indicating moderate accuracy.

CONCLUSIONS

Preoperative VFP might be a reasonable predictive factor for type 2 diabetes improvement after gastrectomy for patients with a BMI≤35 kg/cm². High-quality studies of visceral fat for metabolic function are needed in the future.

Cardiometabolic risk improvement in response to a 3-yr lifestyle modification program in men: contribution of improved cardiorespiratory fitness vs. weight loss

Our objective was to examine the respective contributions of changes in visceral adiposity, subcutaneous adiposity, liver fat, and cardiorespiratory fitness (CRF) to the improvements in cardiometabolic risk markers in response to a 3-yr healthy eating/physical activity lifestyle intervention. Ninety-four out of 144 viscerally obese healthy men completed a 3-yr lifestyle intervention. Body weight, body composition, and fat distribution were assessed by anthropometry and DEXA/computed tomography. CRF, adipokines, lipoprotein/lipid profile, and 75 g of oral glucose tolerance were assessed. CRF and visceral and subcutaneous adiposity significantly improved over the 3-yr intervention, with a nadir in year 1 and a partial regain in year 3 Liver fat (estimated by insulin hepatic extraction) stabilized from year 1 to year 3, whereas HOMA-IR, ISI-Matsuda index, and adiponectin continued to improve. Multivariate analysis revealed that both visceral adiposity and estimated liver fat reductions contributed to the improved ISI-Matsuda index observed over 3 yr (r² = 0.28, P < 0.001). Three-year changes in fat mass and CRF were independently associated with changes in visceral fat (adjusted r² = 0.40, P < 0.001), whereas only changes in CRF were associated with changes in estimated liver fat (adjusted r² = 0.18, P < 0.001). A long-term (3 yr) healthy eating/physical activity intervention in men improves several cardiometabolic risk markers over the long term (3 yr) despite a partial body weight regain observed between year 1 and year 3 The improvement in CRF contributes to visceral and estimated liver fat losses over the long term, which in turn explain the benefits of the lifestyle intervention on cardiometabolic risk profile.

An Analysis of Individual Body Fat Depots and Risk of Developing Cancer: Insights From the Dallas Heart Study

OBJECTIVE

To examine the association between specific adipose tissue depots and the risk of incident cancer in the Dallas Heart Study.

PATIENTS AND METHODS

Individuals without prevalent cancer in the Dallas Heart Study underwent quantification of adipose depots: visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue, and liver fat by magnetic resonance imaging, and subcutaneous lower-body fat (LBF) by dual-energy X-ray absorptiometry from January 1, 2000, through December 31, 2002, and were observed for the development of cancer for up to 12 years. Multivariable Cox proportional hazards modeling was performed to examine the association between fat depots and cancer.

RESULTS

Of 2627 participants (median age, 43 years; 69% nonwhite race), 167 (6.4%) developed cancer. The most common primary sites of cancer were the breast (in women) and the prostate (in men). In multivariable models adjusted for age, sex, race, smoking, alcohol use, family history of malignancy, and body mass index, a 1-SD increase in VAT was not associated with increased risk of cancer (hazard ratio [HR], 0.94; 95% CI, 0.77-1.14). In contrast, each 1-SD increase in LBF was associated with a reduced incidence of cancer (HR, 0.69; 95% CI, 0.52-0.92) in the fully adjusted model.

CONCLUSIONS

In this study, adiposity-associated cancer risk was heterogeneous and varied by fat depot: VAT was not independently associated with incident cancer, and LBF seemed to protect against cancer development. Further studies of the adiposity-cancer relationship, including serial assessments, are needed to better elucidate this relationship.

Preliminary study on the assessment of visceral adipose tissue using dual-energy x-ray absorptiometry in chronic obstructive pulmonary disease

Background

Visceral adipose tissue (VAT) was shown to be increased in patients with chronic obstructive pulmonary disease (COPD) compared to control subjects with comparable body mass index (BMI). Our aim was to determine the relation of VAT by dual-energy x-ray absorptiometry (DEXA) in patients with COPD by disease severity, BMI, other indices of body composition and static lung volumes.

Methods

294 COPD patients admitted for rehabilitation were studied. Lung function, static lung volumes and body composition (i.e. BMI, waist circumference, fat-free mass, fat mass and fat distribution between android and gynoid fat mass) were assessed before entering pulmonary rehabilitation. VAT was estimated within the android region by using DEXA. Patients were stratified for gender, BMI (cut-off of 25 kg/m²) and GOLD stage. To assess the impact of VAT on lung volumes, patients were also stratified for VAT less and above 50^th percentile.

Results

Both male and female patients with more severe airflow limitation had significantly lower VAT values, but these differences disappeared after stratification for BMI. VAT was significantly and strongly correlated with other body composition parameters (all p < 0.001). Patients with moderate to severe airflow limitation and lower VAT had increased static lung hyperinflation and lower diffusing capacity for carbon monoxide. Nevertheless, multivariate stepwise regression models including for BMI, age, gender and forced expiratory volume in 1 s (FEV₁) as confounders did not confirm an independent role for VAT on static lung hyperinflation and diffusion capacity.

Conclusion

After stratification for BMI, VAT is comparable in moderate to very severe COPD patients. Furthermore, BMI and demographics, but not VAT, were independent predictors of static lung hyperinflation and diffusing capacity in COPD.

Significance of Epicardial and Intrathoracic Adipose Tissue Volume among Type 1 Diabetes Patients in the DCCT/EDIC: A Pilot Study

INTRODUCTION

Type 1 diabetes (T1DM) patients are at increased risk of coronary artery disease (CAD). This pilot study sought to evaluate the relationship between epicardial adipose tissue (EAT) and intra-thoracic adipose tissue (IAT) volumes and cardio-metabolic risk factors in T1DM.

METHOD

EAT/IAT volumes in 100 patients, underwent non-contrast cardiac computed tomography in the Diabetes Control and Complications Trial /Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study were measured by a certified reader. Fat was defined as pixels' density of -30 to -190 Hounsfield Unit. The associations were assessed using-Pearson partial correlation and linear regression models adjusted for gender and age with inverse probability sample weighting.

RESULTS

The weighted mean age was 43 years (range 32-57) and 53% were male. Adjusted for gender, Pearson correlation analysis showed a significant correlation between age and EAT/IAT volumes (both p<0.001). After adjusting for gender and age, participants with greater BMI, higher waist to hip ratio (WTH), higher weighted HbA1c, elevated triglyceride level, and a history of albumin excretion rate of equal or greater than 300 mg/d (AER≥300) or end stage renal disease (ESRD) had significantly larger EAT/IAT volumes.

CONCLUSION

T1DM patients with greater BMI, WTH ratio, weighted HbA1c level, triglyceride level and AER≥300/ESRD had significantly larger EAT/IAT volumes. Larger sample size studies are recommended to evaluate independency.

The effect of abdominal fat parameters on percutaneous nephrolithotomy success

INTRODUCTION

Obesity has been suggested to lower the success of percutaneous nephrolithotomy (PCNL). However, the relationship between abdominal fat parameters, such as visceral and subcutaneous abdominal adipose tissue, and PCNL success remained unclear. In this study, we aimed to investigate the effect of abdominal fat parameters on PCNL success.

METHODS

A total of 150 patients who underwent PCNL were retrospectively enrolled in this study. Group 1 consisted of patients who had no residual stones or residual stone fragments <3 mm in diameter while group 2 included patients with residual stone fragments ≥3 mm. PCNL procedure was defined as successful if all stones were eliminated or if there were residual stone fragments <3 mm in diameter confirmed by non-contrast computed tomography (NCCT) performed postoperatively. Preoperative NCCT was used to determine abdominal fat parameters.

RESULTS

Group 1 consisted of 117 (78.0%) patients while group 2 included 33 (22.0%) patients. On univariate analysis, stone number, stone surface area (SSA), visceral fat area (VFA), abdominal circumference on computerized tomography (ACCT), and duration of procedure were found to be predictive factors affecting PCNL success. Logistic regression analysis revealed that ACCT and SSA were independent prognostic factors for PCNL success.

CONCLUSIONS

PCNL success was not affected by VFA, subcutaneous fat area (SFA) and body mass index (BMI) in our series. However, ACCT and SSA had negative associations with PCNL success. We conclude that both ACCT and SSA can be used as tools for predicting PCNL outcomes.

CT-based compartmental quantification of adipose tissue versus body metrics in colorectal cancer patients

PURPOSE

While obesity is considered a prognostic factor in colorectal cancer (CRC), there is increasing evidence that not simply body mass index (BMI) alone but specifically abdominal fat distribution is what matters. As part of the ColoCare study, this study measured the distribution of adipose tissue compartments in CRC patients and aimed to identify the body metric that best correlates with these measurements as a useful proxy for adipose tissue distribution.

MATERIALS AND METHODS

In 120 newly-diagnosed CRC patients who underwent multidetector computed tomography (CT), densitometric quantification of total (TFA), visceral (VFA), intraperitoneal (IFA), retroperitoneal (RFA), and subcutaneous fat area (SFA), as well as the M. erector spinae and psoas was performed to test the association with gender, age, tumor stage, metabolic equivalents, BMI, waist-to-height (WHtR) and waist-to-hip ratio (WHR).

RESULTS

VFA was 28.8 % higher in men (p_VFA<0.0001) and 30.5 % higher in patients older than 61 years (p_VFA<0.0001). WHtR correlated best with all adipose tissue compartments (r_VFA=0.69, r_TFA=0.84, p<0.0001) and visceral-to-subcutaneous-fat-ratio (VFR, r_VFR=0.22, p=<0.05). Patients with tumor stages III/IV showed significantly lower overall adipose tissue than I/II. Increased M. erector spinae mass was inversely correlated with all compartments.

CONCLUSION

Densitometric quantification on CT is a highly reproducible and reliable method to show fat distribution across adipose tissue compartments. This distribution might be best reflected by WHtR, rather than by BMI or WHR.

KEY POINTS

• Densitometric quantification of adipose tissue on CT is highly reproducible and reliable. • Waist-to-height ratio better correlates with adipose tissue compartments and VFR than BMI or waist-to-hip ratio. • Men have higher a higher visceral fat area than women. • Patients older than 61 years have higher visceral fat area. • Patients with tumor stages III/IV have significantly lower adipose tissue than those in stages I/II.

Visceral obesity: A new risk factor for stone disease

INTRODUCTION

We examined the relationship between stone disease and the amount of visceral adipose tissue measured with unenhanced computed tomography (CT).

METHODS

We included 149 patients with complaints of flank pain and kidney stones detected by CT, from August 2012 to April 2013. In addition, as the control group we included 139 healthy individuals, with flank pain within the same time period, with no previous history of urological disease and no current kidney stones identified by CT. Patients were analyzed for age, gender, body mass index, amount of visceral and subcutaneous adipose tissue, and serum level of low-density lipoprotein and triglyceride.

RESULTS

There were no differences between groups in terms of gender and age (p = 0.27 and 0.06, respectively). Respective measurements for the stone and control groups for body mass index were 29.1 and 27.6 kg/m(2); for visceral fat measurement 186.0 and 120.2 cm(2); and for subcutaneous fat measurements 275.9 and 261.9 cm(2) (p = 0.01; 0.01 and 0.36, respectively). Using multivariate analysis, the following factors were identified as increasing the risk of kidney stone formation: hyperlipidemia (p = 0.003), hypertension (p = 0.001), and ratio of visceral fat tissue to subcutaneous fat tissue (p = 0.01). Our study has its limitations, including its retrospective nature, its small sample size, possible selection bias, and missing data. The lack of stone composition data is another major limitation of our study.

CONCLUSION

The ratio of visceral to subcutaneous adipose tissue, in addition to obesity, hyperlipidemia, and hypertension, was identified as an emerging factor in the formation of kidney stones.

Visceral adipose tissue influences on coronary artery calcification at young and middle-age groups using computed tomography angiography

Purpose:

The purpose of the study was to evaluate the impact of excessive visceral adipose tissue (VAT) on subclinical coronary atherosclerosis and coronary artery calcifications (CAC) in young and middle-age groups using multislice computed tomography.

Methods:

This study is a single center, cross-sectional study. Eligible patients (n = 159), who under the age of 61 years, with chest pain and mild to moderate probability to have coronary artery disease (CAD) were enrolled. Coronary calcium score and epicardial adipose tissue (EAT) were measured at the level of the left main coronary artery while VAT was measured at the level of the iliac crest.

Results:

The average age was (48 ± 8 years). The mean VAT was (38 ± 21 cm²) with no significant difference between men and women (38 ± 22 vs. 37 ± 19 P = 0.8) respectively. Student's t-test analysis showed significantly higher VAT in patients with detectable CAC than patients with no CAC (48 ± 24 vs. 33 ± 18 P = 0.00002), respectively. Univariate regression analysis showed that VAT and EAT, are strong predictor for CAC (hazard ratio [HR] 1.034, 95% confidence interval [CI: 1.016–1.052]. P <0.001 and [HR] 1.344, 95% CI: [1.129–1.601] P = 0.001), respectively.

Conclusion:

Excessive VAT is significantly associated with positive CAC. VAT can strongly predict subclinical CAD in individuals at young and middle-age groups.

CPAP therapy induces favorable short-term changes in epicardial fat thickness and vascular and metabolic markers in apparently healthy subjects with obstructive sleep apnea-hypopnea syndrome (OSAHS)

BACKGROUND

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is an independent risk factor for hypertension, coronary artery disease, and diabetes mellitus. Epicardial fat has been recently recognized as a new risk factor and active participant on cardiometabolic risk. The aim of this study was to assess an independent relationship between sleep apnea severity, metabolic and vascular markers, and epicardial fat, at baseline and after 3 months of continuous positive airway pressure (CPAP) therapy.

MATERIALS AND METHOD

Our study group consisted of 48 patients with suspected OSAHS and no prior history of cardiovascular disease or diabetes mellitus. All patients underwent full overnight polysomnography. Thickness of epicardial and visceral adipose tissue, brachial artery flow-mediated dilation (FMD), carotid intima media thickness (cIMT), pulse wave velocity (PWV), plasma C-reactive protein (CRP) levels, fasting glucose levels, HbA1c, homeostatic model assessment of insulin resistance index (HOMA), and lipid profile were measured at baseline and after 3 months of CPAP use in patients with moderate to severe OSAHS.

RESULTS

In OSAHS patients (Apnea-hypopnea index (AHI) ≥15/h, N = 28), epicardial fat correlated with fasting glucose (rho = 0.406, p = 0.04) and HOMA (rho = 0.525, p = 0.049) but was not associated with visceral fat (rho = 0.126, p = 0.595). Epicardial adipose tissue (EAT) (p = 0.022) increased across AHI severity along with PWV (p = 0.045) and carotid intima media thickness (IMT) (p = 0.034) while FMD (p = 0.017) decreased. Therapy with CPAP reduced both epicardial (p < 0.001) and visceral fat (p = 0.001). Alterations in epicardial fat across the follow-up were associated with changes in PWV (p = 0.026) and HOMA (p = 0.037) independently of major confounders.

CONCLUSIONS

Epicardial fat thickness was associated with OSA severity and may be an additional marker of cardiovascular risk as well as of future diabetes in these patients. CPAP therapy reduced epicardial fat, suggesting its potentially beneficial role in reducing cardiometabolic risk in OSA patients.

Visceral adipose tissue measured by computed tomography and high-grade prostate cancer after radical prostatectomy

We assessed the association between obesity measurements including visceral adipose tissue (VAT), measured by computed tomography, and the risk of high-grade prostate cancer after radical prostatectomy. We investigated 296 patients who were diagnosed with prostate cancer and underwent radical prostatectomy. Data extracted from medical records included age, body mass index (BMI), VAT, pretreatment prostate-specific antigen (PSA) levels and Gleason score (GS). We performed logistic regression to examine the association between indicators of obesity and a higher GS (⩾4+3). Among the 296 patients, 107 (36%) had a higher GS. After controlling for age and PSA, BMI was not associated with GS (odds ratio, OR=1.039, 95% confidence interval, CI=0.943-1.145; P=0.437). BMI had different effects on GS depending on VAT. When the data were stratified by the median VAT value, a higher BMI was significantly associated with a higher GS in patients with VAT⩾130.5 cm2 (OR=1.218, 95% CI=1.028-1.443; P=0.022), but not in those with VAT<130.5 cm2 (OR=0.912, 95% CI=0.783-1.062; P=0.236). A higher BMI was associated with an increased risk of high-grade cancer only in patients with more VAT.

Increased visceral adipose tissue as a potential risk factor in patients with embolic stroke of undetermined source (ESUS)

PURPOSE

The etiology of an ischemic stroke remains undetermined in 20-35% of cases and many patients do not have any of the conventional risk factors. Increased visceral adipose tissue (VAT) is a suggested new risk factor for both carotid artery atherosclerosis (CAA) and atrial fibrillation (AF), but its role in the remaining stroke population is unknown. We assessed the amount of VAT in patients with embolic stroke of undetermined source (ESUS) after excluding major-risk cardioembolic sources, occlusive atherosclerosis, and lacunar stroke.

METHODS

Altogether 58 patients (mean age 57.7 ± 10.2 years, 44 men) with ischemic stroke of unknown etiology but without CAA, known AF or small vessel disease underwent computed tomography angiography and assessment of VAT. For comparison VAT values from three different reference populations were used. Conventional risk factors (smoking, hypertension, diabetes, increased total and LDL-cholesterol, decreased HDL-cholesterol) were also registered.

RESULTS

Mean VAT area was significantly higher in stroke patients (205 ± 103 cm2 for men and 168 ± 99 cm2 for women) compared to all reference populations (P < 0.01). 50% of male and 57% of female patients had an increased VAT area. In male patients, VAT was significantly higher despite similar body mass index (BMI). Increased VAT was more common than any of the conventional risk factors.

CONCLUSION

Increased VAT was found in over half of our patients with ESUS suggesting it may have a role in the pathogenesis of thromboembolism in this selected group of patients.

Increased plasma levels of retinol-binding protein 4 with visceral obesity is associated with cardiovascular risk factors

Aims/Introduction:  Visceral obesity has been suggested to be an independent risk factor for cardiovascular disease (CVD); the role of adipokines in the risk for CVD is less clear. Aim of this study was to investigate the relationship between parameters of visceral obesity and index of CVD risk factors.

Materials and Methods:  A cross‐sectional analysis of healthy males (n = 116) and females (n = 175) for evaluation of clinical, laboratory and anthropometric parameters were undertaken. Abdominal subcutaneous (SAT) and visceral adipose tissues (VAT) were measured by computed tomography. Adipokines, including retinol‐binding protein 4 (RBP4) and adiponectin, were determined. The risk for CVD was estimated using the 10‐year Framingham Coronary Heart Disease Risk Point scale (Framingham score).

Results:  The Framingham score was increased in subjects with metabolic syndrome, and significantly increased with various indices of obesity, traditional risk factors of CVD, C‐reactive protein (CRP) and RBP4, but decreased with adiponectin. With multiple linear regression analysis, the Framingham score independently associated with age, smoking status, body mass index, triglyceride and RBP4. The magnitude of the Framingham score showed a linear trend of increase with CRP, VAT and RBP4 (all P < 0.001), but of decrease with SAT and adiponectin (all P < 0.05) at stratified levels of obesity.

Conclusions:  RBP4 is increased with visceral fat accumulation and associated with CVD risk factors independent of obesity or traditional risk factors. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00213.x, 2012)

Association of serum C1q/TNF-Related Protein-9 (CTRP9) concentration with visceral adiposity and metabolic syndrome in humans

BACKGROUND

C1q/TNF-Related Protein (CTRP) family members are novel adipokines that have anti-inflammatory, immunomodulatory, glucose-regulating and vascular effects. However, the metabolic effects of CTRP9 remain unclear in humans.

OBJECTIVES

The aims of this study were to investigate whether serum CTRP9 concentrations are associated with glucose tolerance, metabolic parameters and abdominal fat accumulation. In addition, the authors investigated whether the aforementioned effects of CTRP9 are independent of serum adiponectin levels.

METHODS

A total of 221 subjects (140 men and 81 women), 25-72 years of age (mean age 46.0 years), were randomly selected from two different study populations. The normal glucose tolerance group (n=120) was selected from one study population and the prediabetes/type 2 diabetes group (n=101) was selected from the other study population. Serum CTRP9, total adiponectin concentrations and abdominal fat via computed tomography scan were measured in all subjects.

RESULTS

Subjects in the lower serum CTRP9 tertile were older, had metabolically unhealthy profiles and had lower serum total adiponectin levels when compared with subjects in the middle or upper serum CTRP9 tertiles. In addition, serum CTRP9 concentration were inversely correlated with age, blood pressure, fasting glucose, homeostasis model assessment for insulin resistance, total cholesterol, triglyceride and low-density lipoprotein cholesterol levels (all P<0.01) and positively correlated with serum total adiponectin levels (P=0.03). In terms of abdominal fat accumulation, serum CTRP9 concentrations were inversely correlated with visceral fat amount (P<0.01), but no correlation was observed with subcutaneous fat amount. Finally, serum CTRP9 was inversely associated with the presence of metabolic syndrome, independent of age, sex, body mass index, smoking status, total cholesterol, visceral fat and serum total adiponectin concentrations (odds ratio per 1 s.d. 0.47; 95% confidence interval 0.32-0.70; P<0.01).

CONCLUSIONS

Serum CTRP9 concentrations were positively associated with favorable glucose or metabolic phenotypes and absence of metabolic syndrome, independent of serum total adiponectin concentrations.

Direct Determination of Lean Body Mass by CT in F-18 FDG PET/CT Studies: Comparison with Estimates Using Predictive Equations

PURPOSE

The purpose of this study was to estimate lean body mass (LBM) using CT (LBM CTs) and compare the results with LBM estimates of four different predictive equations (LBM PEs) to assess whether LBM CTs and LBM PEs can be used interchangeably for SUV normalization.

METHODS

Whole-body F-18 FDG PET/CT studies were conducted on 392 patients. LBM CT1 is modified adipose tissue-free body mass, and LBM CT2 is adipose tissue-free body mass. Four different PEs were used for comparison (LBM PE1-4). Agreement between the two measurement methods was assessed by Bland-Altman analysis. We calculated the difference between two methods (bias), the percentage of difference, and the limits of agreement, expressed as a percentage.

RESULTS

For LBM CTs vs. LBM PEs, except LBM PE3, the ranges of biases and limits of agreement were -3.77 to 3.81 kg and 26.60-35.05 %, respectively, indicating the wide limits of agreement and differing magnitudes of bias. For LBM CTs vs. LBM PE3, LBM PE3 had wider limits of agreement and greater positive bias (44.28-46.19 % and 10.49 to 14.04 kg, respectively), showing unacceptably large discrepancies between LBM CTs and LBM PE3.

CONCLUSION

This study demonstrated that there are substantial discrepancies between individual LBM CTs and LBM PEs, and this should be taken into account when LBM CTs and LBM PEs are used interchangeably between patients.

Ethnic difference in liver fat content: a cross-sectional observation among Japanese American in Hawaii, Japanese in Japan, and non-Hispanic whites in United States

BACKGROUND

We recently reported that Japanese had higher liver fat at a lower level of BMI compared with non-Hispanic whites (NHW).

OBJECTIVE

We hypothesize that ethnic difference in fat storage capacity contributes to this ethnic difference in liver fat.

DESIGN

To examine this, we assessed liver fat among 244 Japanese-American aged 40-49, using regional computed-tomography images, along with metabolic variables.

RESULTS

Despite the similar BMI between Japanese-Americans and NHW men, Japanese-Americans had more liver fat (liver to spleen attenuation ratio: 1.03 ± 0.22 for Japanese-Americans, and 1.07 ± 0.15 for NHW men; p < 0.05) and tended to have a greater disposition for fatty liver with an increase in BMI than NHW, indicating a clear difference between the two groups. In addition, liver fat is less in Japanese-Americans compared with Japanese men (1.03 ± 0.22 vs. 1.01 ± 0.16; p < 0.05), despite of a much higher BMI. These ethnic differences support the hypothesis that higher fat storage capacity indeed seems to be associated with less liver fat. In all the groups, liver fat content strongly correlated with triglycerides, homeostasis model assessment-insulin resistance, and C-reactive protein (CRP). Nevertheless, these metabolic variables were worse in Japanese-Americans, despite of less liver fat, compared with Japanese. Moreover, CRP levels were least among Japanese with highest liver fat, and highest among NHW men with least liver fat, despite of a strong positive association between CRP and fatty liver within each population.

CONCLUSIONS

Fat content in the liver is intermediate for Japanese-Americans compared with Japanese and NHW men, which supports the hypothesis of less fat storage capacity among Japanese, closely linked to ethnic difference in predisposition to fatty liver.

Comparison of gross body fat-water magnetic resonance imaging at 3 Tesla to dual-energy X-ray absorptiometry in obese women

OBJECTIVE

Improved understanding of how depot-specific adipose tissue mass predisposes to obesity-related comorbidities could yield new insights into the pathogenesis and treatment of obesity as well as metabolic benefits of weight loss. We hypothesized that three-dimensional (3D) contiguous "fat-water" MR imaging (FWMRI) covering the majority of a whole-body field of view (FOV) acquired at 3 Tesla (3T) and coupled with automated segmentation and quantification of amount, type, and distribution of adipose and lean soft tissue would show great promise in body composition methodology.

DESIGN AND METHODS

Precision of adipose and lean soft tissue measurements in body and trunk regions were assessed for 3T FWMRI and compared to dual-energy X-ray absorptiometry (DXA). Anthropometric, FWMRI, and DXA measurements were obtained in 12 women with BMI 30-39.9 kg/m(2) .

RESULTS

Test-retest results found coefficients of variation (CV) for FWMRI that were all under 3%: gross body adipose tissue (GBAT) 0.80%, total trunk adipose tissue (TTAT) 2.08%, visceral adipose tissue (VAT) 2.62%, subcutaneous adipose tissue (SAT) 2.11%, gross body lean soft tissue (GBLST) 0.60%, and total trunk lean soft tissue (TTLST) 2.43%. Concordance correlation coefficients between FWMRI and DXA were 0.978, 0.802, 0.629, and 0.400 for GBAT, TTAT, GBLST, and TTLST, respectively.

CONCLUSIONS

While Bland-Altman plots demonstrated agreement between FWMRI and DXA for GBAT and TTAT, a negative bias existed for GBLST and TTLST measurements. Differences may be explained by the FWMRI FOV length and potential for DXA to overestimate lean soft tissue. While more development is necessary, the described 3T FWMRI method combined with fully-automated segmentation is fast (<30-min total scan and post-processing time), noninvasive, repeatable, and cost-effective.

Relationship of epicardial fat volume to coronary plaque, severe coronary stenosis, and high-risk coronary plaque features assessed by coronary CT angiography

BACKGROUND

Associations of epicardial fat volume (EFV) measured on noncontrast cardiac CT (NCT) include coronary plaque, myocardial ischemia, and adverse cardiac events.

OBJECTIVES

This study aimed to define the relationship of EFV to coronary plaque type, severe coronary stenosis, and the presence of high-risk plaque features (HRPFs).

METHODS

We retrospectively evaluated 402 consecutive patients, with no prior history of coronary artery disease, who underwent same day NCT and coronary CT angiography (CTA). EFV was measured on NCT with the use of validated, semiautomated software. The coronary arteries were evaluated for coronary plaque type (calcified [CP], noncalcified [NCP], or partially calcified [PCP]) and coronary stenosis severity ≥70% with the use of coronary CTA. For patients with NCP and PCP, 2 high-risk plaque features were evaluated: low-attenuation plaque and positive remodeling.

RESULTS

There were 402 patients with a median age of 66 years (range, 23-92 years) of whom 226 (56%) were men. The EFV was greater in patients with CP (112 ± 55 cm(3) vs 89 ± 39 cm(3)), PCP (110 ± 57 cm(3) vs 98 ± 45 cm(3)), and NCP (115 ± 44 cm(3) vs EFV 100 ± 52 cm(3)). In the 192 patients with PCP or NCP, on multivariable analysis, after adjusting for conventional cardiovascular risk factors, EFV was an independent predictor of ≥70% coronary artery stenosis (odds ratio [OR], 3.0; 95% CI, 1.3-6.6; P = 0.008), any high-risk plaque features (OR, 1.7; 95% CI, 0.9-3.4; P = 0.04), and low attention plaque (OR, 2.4; 95% CI, 1.1-5.1; P = 0.02) but not of positive remodeling.

CONCLUSIONS

EFV is greater in patients with CP, PCP, and NCP. In patients with NCP and PCP, EFV is significantly associated with severe coronary stenosis, high-risk plaque features, and low attenuation plaque.

Pathophysiology of human visceral obesity: an update

Excess intra-abdominal adipose tissue accumulation, often termed visceral obesity, is part of a phenotype including dysfunctional subcutaneous adipose tissue expansion and ectopic triglyceride storage closely related to clustering cardiometabolic risk factors. Hypertriglyceridemia; increased free fatty acid availability; adipose tissue release of proinflammatory cytokines; liver insulin resistance and inflammation; increased liver VLDL synthesis and secretion; reduced clearance of triglyceride-rich lipoproteins; presence of small, dense LDL particles; and reduced HDL cholesterol levels are among the many metabolic alterations closely related to this condition. Age, gender, genetics, and ethnicity are broad etiological factors contributing to variation in visceral adipose tissue accumulation. Specific mechanisms responsible for proportionally increased visceral fat storage when facing positive energy balance and weight gain may involve sex hormones, local cortisol production in abdominal adipose tissues, endocannabinoids, growth hormone, and dietary fructose. Physiological characteristics of abdominal adipose tissues such as adipocyte size and number, lipolytic responsiveness, lipid storage capacity, and inflammatory cytokine production are significant correlates and even possible determinants of the increased cardiometabolic risk associated with visceral obesity. Thiazolidinediones, estrogen replacement in postmenopausal women, and testosterone replacement in androgen-deficient men have been shown to favorably modulate body fat distribution and cardiometabolic risk to various degrees. However, some of these therapies must now be considered in the context of their serious side effects. Lifestyle interventions leading to weight loss generally induce preferential mobilization of visceral fat. In clinical practice, measuring waist circumference in addition to the body mass index could be helpful for the identification and management of a subgroup of overweight or obese patients at high cardiometabolic risk.

Sedentary behaviour, visceral fat accumulation and cardiometabolic risk in adults: a 6-year longitudinal study from the Quebec Family Study

Background

Sedentary behaviour has recently emerged as a unique risk factor for chronic disease morbidity and mortality. One factor that may explain this relationship is visceral adiposity, which is prospectively associated with increased cardiometabolic risk and mortality. The objective of the present study was to determine whether sedentary behaviour was associated with increased accumulation of visceral fat or other deleterious changes in cardiometabolic risk over a 6-year follow-up period among adult participants in the Quebec Family Study.

Methods

The current study included 123 men and 153 women between the ages of 18 and 65. Total sedentary time and physical activity were assessed by self-report questionnaire. Cross-sectional areas of visceral and subcutaneous abdominal adipose tissue were assessed using computed tomography. Cardiometabolic biomarkers including fasting insulin, glucose, blood lipids, HOMA-Insulin Resistance, and oral glucose tolerance were also measured. All variables of interest were collected at both baseline and follow-up.

Results

After adjustment for age, sex, baseline BMI, physical activity, energy intake, smoking, education, income and menopausal status, baseline sedentary behaviour was not associated with changes in visceral adiposity or any other marker of cardiometabolic risk. In the longitudinal model which adjusted for all studied covariates, every 15-minute increase in sedentary behaviour from baseline to follow-up was associated with a 0.13 cm increase in waist circumference (95% CI = 0.02, 0.25). However, there was no association between changes in sedentary behaviour and changes in visceral adiposity or other markers of cardiometabolic risk.

Conclusion

These results suggest that neither baseline sedentary behaviour nor changes in sedentary behaviour are associated with longitudinal changes in visceral adiposity in adult men and women. With the exception of waist circumference, the present study did not find evidence of a relationship between sedentary behaviour and any marker of cardiometabolic risk in this population.

VAT=TAAT-SAAT: innovative anthropometric model to predict visceral adipose tissue without resort to CT-Scan or DXA

OBJECTIVE

To investigate whether a combination of a selected but limited number of anthropometric measurements predicts visceral adipose tissue (VAT) better than other anthropometric measurements, without resort to medical imaging.

HYPOTHESIS

Abdominal anthropometric measurements are total abdominal adipose tissue indicators and global measures of VAT and SAAT (subcutaneous abdominal adipose tissue). Therefore, subtracting the anthropometric measurement the more correlated possible with SAAT while being the least correlated possible with VAT, from the most correlated abdominal anthropometric measurement with VAT while being highly correlated with TAAT, may better predict VAT.

DESIGN AND METHODS

BMI participants' range was from 16.3 to 52.9 kg m(-2) . Anthropometric and abdominal adipose tissues data by computed tomography (CT-Scan) were available in 253 patients (18-78 years) (CHU Nord, Marseille) and used to develop the anthropometric VAT prediction models.

RESULTS

Subtraction of proximal thigh circumference from waist circumference, adjusted to age and/or BMI, predicts better VAT (Women: VAT = 2.15 × Waist C - 3.63 × Proximal Thigh C + 1.46 × Age + 6.22 × BMI - 92.713; R(2) = 0.836. Men: VAT = 6 × Waist C - 4.41 × proximal thigh C + 1.19 × Age - 213.65; R(2) = 0.803) than the best single anthropometric measurement or the association of two anthropometric measurements highly correlated with VAT. Both multivariate models showed no collinearity problem. Selected models demonstrate high sensitivity (97.7% in women, 100% in men). Similar predictive abilities were observed in the validation sample (Women: R(2) = 76%; Men: R(2) = 70%). Bland and Altman method showed no systematic estimation error of VAT.

CONCLUSION

Validated in a large range of age and BMI, our results suggest the usefulness of the anthropometric selected models to predict VAT in Europides (South of France).

Effects of abdominal fat distribution parameters on severity of acute pancreatitis

BACKGROUND

Obesity is a well-established risk factor for acute pancreatitis. Increased visceral fat has been shown to exacerbate the pro-inflammatory milieu experienced by patients. This study aimed to investigate the relationship between the severity of acute pancreatitis and abdominal fat distribution parameters measured on computed tomography (CT) scan.

METHODS

Consecutive patients admitted to Cork University Hospital with acute pancreatitis between January 2005 and December 2010 were evaluated for inclusion in the study. An open source image analysis software (Osirix, v 3.9) was used to calculate individual abdominal fat distribution parameters from CT scans by segmentation of abdominal tissues.

RESULTS

A total of 214 patients were admitted with pancreatitis between January 2005 and December 2010. Sixty-two of these patients underwent a CT scan and were thus eligible for inclusion. Visceral fat volume was the volumetric fat parameter that had the most significant association with severe acute pancreatitis (P = 0.003). There was a significant association between visceral fat volume and subsequent development of systemic complications of severe acute pancreatitis (P = 0.003). There was a strong association between mortality and visceral fat volume (P = 0.019). Multivariate regression analysis, adjusted for gender, did not identify any individual abdominal fat distribution index as an independent risk factor for severe acute pancreatitis.

CONCLUSIONS

Overall, estimation of abdominal fat distribution parameters from CT scans performed on patients with acute pancreatitis indicates a strong association between visceral fat, severe acute pancreatitis, and the subsequent development of systemic complications. These data suggest that visceral fat volume should be incorporated into future predictive scoring systems.

Optimal CT Number Range for Adipose Tissue When Determining Lean Body Mass in Whole-Body F-18 FDG PET/CT Studies

PURPOSE

The aim of this study was to define an optimal CT number range applicable to adipose tissue (AT) measurement in modern PET/CT systems.

METHODS

CT number (in Hounsfield units, HU) was measured in three different pure AT compartments in 53 patients. CT number range for AT was determined in three different ways, including pixel histogram analysis, to take the effect of partial volume averaging into account. The effect of changing the CT number range for AT on the total AT volume was investigated.

RESULTS

The lower limits for CT number for pure subcutaneous AT, retroperitoneal AT, and visceral AT were -140, -140, and -130 HU, respectively. The corresponding upper limits were -70, -71, and -52 HU. The CT number range for AT using three methods when considering partial volume averaging was -144 to -141 HU to -30 to -33 HU, showing similar values between the three methods. The optimal CT number range for AT based on these data was -140 to -30 HU. Increases in total AT volume of 7.5 % and 1.8 % were found when the upper or lower limit was extended using 10 HU intervals, respectively, compared with the reference range of -140 to -30 HU.

CONCLUSION

This study demonstrated that the optimal CT number range of AT that is applicable to modern PET/CT systems can be defined as -140 to -30 HU. The use of this CT number range of AT allowed lean body mass to be determined in whole-body F-18 FDG PET/CT studies.

Comparison of SUVs Normalized by Lean Body Mass Determined by CT with Those Normalized by Lean Body Mass Estimated by Predictive Equations in Normal Tissues

PURPOSE

Standardized uptake values (SUVs) normalized by lean body mass (LBM) determined by CT were compared with those normalized by LBM estimated using predictive equations (PEs) in normal liver, spleen, and aorta using (18)F-FDG PET/CT.

METHODS

Fluorine-18 fluorodeoxyglucose (F-FDG) positron emission tomography/computed tomography (PET/CT) was conducted on 453 patients. LBM determined by CT was defined in 3 ways (LBMCT1-3). Five PEs were used for comparison (LBMPE1-5). Tissue SUV normalized by LBM (SUL) was calculated using LBM from each method (SULCT1-3, SULPE1-5). Agreement between methods was assessed by Bland-Altman analysis. Percentage difference and percentage error were also calculated.

RESULTS

For all liver SULCTs vs. liver SULPEs except liver SULPE3, the range of biases, SDs of percentage difference and percentage errors were -0.17-0.24 SUL, 6.15-10.17 %, and 25.07- 38.91 %, respectively. For liver SULCTs vs. liver SULPE3, the corresponding figures were 0.47-0.69 SUL, 10.90-11.25 %, and 50.85-51.55 %, respectively, showing the largest percentage errors and positive biases. Irrespective of magnitudes of the biases, large percentage errors of 25.07-51.55 % were observed between liver SULCT1-3 and liver SULPE1-5. The results of spleen and aorta SULCTs and SULPEs comparison were almost identical to those for liver.

CONCLUSION

The present study demonstrated substantial errors in individual SULPEs compared with SULCTs as a reference value. Normalization of SUV by LBM determined by CT rather than PEs may be a useful approach to reduce errors in individual SULPEs.

Dual-energy X-ray absorptiometry for quantification of visceral fat

Obesity is the major risk factor for metabolic syndrome and through it diabetes as well as cardiovascular disease. Visceral fat (VF) rather than subcutaneous fat (SF) is the major predictor of adverse events. Currently, the reference standard for measuring VF is abdominal X-ray computed tomography (CT) or magnetic resonance imaging (MRI), requiring highly used clinical equipment. Dual-energy X-ray absorptiometry (DXA) can accurately measure body composition with high-precision, low X-ray exposure, and short-scanning time. The purpose of this study was to validate a new fully automated method whereby abdominal VF can be measured by DXA. Furthermore, we explored the association between DXA-derived abdominal VF and several other indices for obesity: BMI, waist circumference, waist-to-hip ratio, and DXA-derived total abdominal fat (AF), and SF. We studied 124 adult men and women, aged 18-90 years, representing a wide range of BMI values (18.5-40 kg/m(2)) measured with both DXA and CT in a fasting state within a one hour interval. The coefficient of determination (r(2)) for regression of CT on DXA values was 0.959 for females, 0.949 for males, and 0.957 combined. The 95% confidence interval for r was 0.968 to 0.985 for the combined data. The 95% confidence interval for the mean of the differences between CT and DXA VF volume was -96.0 to -16.3 cm(3). Bland-Altman bias was +67 cm(3) for females and +43 cm(3) for males. The 95% limits of agreement were -339 to +472 cm(3) for females and -379 to +465 cm(3) for males. Combined, the bias was +56 cm(3) with 95% limits of agreement of -355 to +468 cm(3). The correlations between DXA-derived VF and BMI, waist circumference, waist-to-hip ratio, and DXA-derived AF and SF ranged from poor to modest. We conclude that DXA can measure abdominal VF precisely in both men and women. This simple noninvasive method with virtually no radiation can therefore be used to measure VF in individual patients and help define diabetes and cardiovascular risk.

Assessment of analytical methods used to measure changes in body composition in the elderly and recommendations for their use in phase II clinical trials

It is estimated that in the next 20 years, the amount of people greater than 65 years of age will rise from 40 to 70 million, and will account for 19% of the total population. Age-related decreases in muscle mass and function, known as sarcopenia, have been shown to be related to functional limitation, frailty and an increased risk of morbidity and mortality. Therefore, with an increasing elderly population, interventions that can improve muscle mass content and/or function are essential. However, analytical techniques used for measurement of muscle mass in young subjects may not be valid for use in the elderly. Therefore, the purpose of this review is to examine the applied specificity and accuracy of methods that are commonly used for measurement of muscle mass in aged subjects, and, to propose specific recommendations for the use of body composition measures in phase II clinical trials of function-promoting anabolic therapies.

Characterization of mesothelioma and tissues present in contrast-enhanced thoracic CT scans

PURPOSE

The purpose of this study was to characterize the Hounsfield unit (HU) distributions of mesothelioma and other tissues present in contrast-enhanced thoracic CT scans, to compare the HU distributions of mesothelioma, muscle, and liver by scanner and reconstruction filter/kernel combination, and to assess interpatient HU distribution variability.

METHODS

The database consisted of 28 contrast-enhanced thoracic CT scans from different patients. For each scan, regions of interest were manually outlined within each of 13 tissues, including mesothelioma. For each tissue, the empirical percentiles in HU values were calculated along with the interpatient variability. The HU distributions of select tissues were compared across three different scanner and reconstruction filter/kernel combinations.

RESULTS

The HU distributions of blood-containing tissues demonstrated substantial overlap, as did the HU distributions of pleural effusion, mesothelioma, muscle, and liver. The HU distribution of fat had the least overlap with the other tissues. Fat and muscle had the lowest interpatient HU variability and the narrowest HU distributions, while blood-containing tissues had the highest interpatient HU variability. A soft-tissue reconstruction filter/kernel yielded the narrowest HU distribution, and fat with artifact had the widest HU distribution.

CONCLUSIONS

Characterization of tissues in CT scans enhances the understanding of those tissues' HU distributions. Due to their overlapping HU distributions and close spatial proximity to one another, separating pleural effusion, mesothelioma, muscle, and liver from one another is a difficult task based on HU value thresholding alone. The results illustrate the wide distributions and large variability that exist for tissues present in clinical thoracic CT scans.

Interscan reproducibility of computer-aided epicardial and thoracic fat measurement from noncontrast cardiac CT

BACKGROUND

Epicardial fat volume (EFV) measured from noncontrast CT is associated with coronary atherosclerosis and increased risk of major adverse cardiovascular events. Interscan reproducibility of EFV quantification from noncontrast CT has not been reported.

OBJECTIVE

We evaluated the interscan (intrascanner and interscanner) reproducibility of EFV and thoracic fat volume (TFV) measurements from noncontrast CT.

METHODS

We studied 25 consecutive patients who were scanned twice with 4-slice multidetector CT (MDCT), with 120 kVp, 2.5-mm slice thickness (intrascanner) and 23 consecutive patients who were scanned with MDCT and electron beam CT (EBCT) with 3-mm slice thickness (interscanner). For each scan, EFV and TFV were measured from user-defined range of CT slices covering the heart by experienced imaging cardiologists. Voxels within -30 to -190 HU within the epicardial contours was quantified as EFV. TFV was quantified within the heart range automatically. Repeatability coefficient (RC), defined as 1.96 × SD of the differences between pairs of repeated measures, was determined.

RESULTS

Correlations for interscan measurements of EFV and TFV were high for both intrascanner (MDCT-MDCT) and interscanner (EBCT-MDCT) data (correlation coefficient ≥0.98). RC values were lowest (4.3% for EFV and 5.4% for TFV) for intrascanner same-observer measurement. For intrascanner cross-observer measurement, RC values were 10.7% for EFV and 9.0% for TFV. For interscanner data, RC values ranged from 6.8% to 8.2%.

CONCLUSION

Epicardial and thoracic fat measurements with the use of either MDCT or EBCT are highly reproducible.

Increased pericardial fat volume measured from noncontrast CT predicts myocardial ischemia by SPECT

OBJECTIVES

We evaluated the association between pericardial fat and myocardial ischemia for risk stratification.

BACKGROUND

Pericardial fat volume (PFV) and thoracic fat volume (TFV) measured from noncontrast computed tomography (CT) performed for calculating coronary calcium score (CCS) are associated with increased CCS and risk for major adverse cardiovascular events.

METHODS

From a cohort of 1,777 consecutive patients without previously known coronary artery disease (CAD) with noncontrast CT performed within 6 months of single photon emission computed tomography (SPECT), we compared 73 patients with ischemia by SPECT (cases) with 146 patients with normal SPECT (controls) matched by age, gender, CCS category, and symptoms and risk factors for CAD. TFV was automatically measured. Pericardial contours were manually defined within which fat voxels were automatically identified to compute PFV. Computer-assisted visual interpretation of SPECT was performed using standard 17-segment and 5-point score model; perfusion defect was quantified as summed stress score (SSS) and summed rest score (SRS). Ischemia was defined by: SSS - SRS ≥4. Independent relationships of PFV and TFV to ischemia were examined.

RESULTS

Cases had higher mean PFV (99.1 ± 42.9 cm(3) vs. 80.1 ± 31.8 cm(3), p = 0.0003) and TFV (196.1 ± 82.7 cm(3) vs. 160.8 ± 72.1 cm(3), p = 0.001) and higher frequencies of PFV >125 cm(3) (22% vs. 8%, p = 0.004) and TFV >200 cm(3) (40% vs. 19%, p = 0.001) than controls. After adjustment for CCS, PFV and TFV remained the strongest predictors of ischemia (odds ratio [OR]: 2.91, 95% confidence interval [CI]: 1.53 to 5.52, p = 0.001 for each doubling of PFV; OR: 2.64, 95% CI: 1.48 to 4.72, p = 0.001 for TFV). Receiver operating characteristic analysis showed that prediction of ischemia, as indicated by receiver-operator characteristic area under the curve, improved significantly when PFV or TFV was added to CCS (0.75 vs. 0.68, p = 0.04 for both).

CONCLUSIONS

Pericardial fat was significantly associated with myocardial ischemia in patients without known CAD and may help improve risk assessment.