Quantitative comparison and evaluation of software packages for assessment of abdominal adipose tissue distribution by magnetic resonance imaging

Abdominal adipose tissue and type 2 diabetic kidney disease: adipose radiology assessment, impact, and mechanisms

Diabetic kidney disease (DKD) is a significant healthcare burden worldwide that substantially increases the risk of kidney failure and cardiovascular events. To reduce the prevalence of DKD, extensive research is being conducted to determine the risk factors and consequently implement early interventions. Patients with type 2 diabetes mellitus (T2DM) are more likely to be obese. Abdominal adiposity is associated with a greater risk of kidney damage than general obesity. Abdominal adipose tissue can be divided into different fat depots according to the location and function, including visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), perirenal adipose tissue (PAT), and renal sinus adipose tissue (RSAT), which can be accurately measured by radiology techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI). Abdominal fat depots may affect the development of DKD through different mechanisms, and radiologic abdominal adipose characteristics may serve as imaging indicators of DKD risk. This review will first describe the CT/MRI-based assessment of abdominal adipose depots and subsequently describe the current studies on abdominal adipose tissue and DKD development, as well as the underlying mechanisms in patients of T2DM with DKD.

Abdominal fat quantification using convolutional networks

OBJECTIVES

To present software for automated adipose tissue quantification of abdominal magnetic resonance imaging (MRI) data using fully convolutional networks (FCN) and to evaluate its overall performance-accuracy, reliability, processing effort, and time-in comparison with an interactive reference method.

MATERIALS AND METHODS

Single-center data of patients with obesity were analyzed retrospectively with institutional review board approval. Ground truth for subcutaneous (SAT) and visceral adipose tissue (VAT) segmentation was provided by semiautomated region-of-interest (ROI) histogram thresholding of 331 full abdominal image series. Automated analyses were implemented using UNet-based FCN architectures and data augmentation techniques. Cross-validation was performed on hold-out data using standard similarity and error measures.

RESULTS

The FCN models reached Dice coefficients of up to 0.954 for SAT and 0.889 for VAT segmentation during cross-validation. Volumetric SAT (VAT) assessment resulted in a Pearson correlation coefficient of 0.999 (0.997), relative bias of 0.7% (0.8%), and standard deviation of 1.2% (3.1%). Intraclass correlation (coefficient of variation) within the same cohort was 0.999 (1.4%) for SAT and 0.996 (3.1%) for VAT.

CONCLUSION

The presented methods for automated adipose-tissue quantification showed substantial improvements over common semiautomated approaches (no reader dependence, less effort) and thus provide a promising option for adipose tissue quantification.

CLINICAL RELEVANCE STATEMENT

Deep learning techniques will likely enable image-based body composition analyses on a routine basis. The presented fully convolutional network models are well suited for full abdominopelvic adipose tissue quantification in patients with obesity.

KEY POINTS

• This work compared the performance of different deep-learning approaches for adipose tissue quantification in patients with obesity. • Supervised deep learning-based methods using fully convolutional networks  were suited best. • Measures of accuracy were equal to or better than the operator-driven approach.

Initial experience with the graphical user interface for laser parameters setting of a new thulium fibre laser source device for urinary pathologies treatment

BACKGROUND AND OBJECTIVE

We aimed to evaluate the concordance between the pre-settings ranges of thulium fibre laser (TFL) (Coloplast TFL Drive, Denmark) with easy-to-use graphical user interface and the laser settings used by a high-volume endo-urologist during surgical procedures.

MATERIALS AND METHODS

In October 2022, we prospectively collected data of 67 patients who underwent TFL Drive (Coloplast, Denmark) for the management of urinary stones. Urothelial tumour (upper tract urinary cancer (UTUC) and bladder) 200 and 150 μm laser fibres were used for procedures. Stones characteristics (size and density) tumours and stenosis localizations, laser-on time (LOT), and laser settings were recorded. We also assessed the ablation speed (mm3/s), laser power (W), and Joules/mm3 values for each lithotripsy.

RESULTS

A total 67 patients took part in the study. Median age was 52 (15-81) years. 55 (82%), 8 (12%), and 4 (6%) patients presented urinary stones, urothelial tumour, and stenosis, respectively. Median stone volume was 438 (36-6027) mm3 and median density was 988 (376-2000) HU. Median pulse energy was 0.6 (0.3-1.2), 0.8 (0.5-1) and 1 J for urinary stones, urothelial tumour and stenosis respectably. Endoscopically stone-free rate was 89%. Graphical user interface and surgeon accordance with the safety range were observed in 93.2%, 100% and 100% for urinary stones, UTUC and stenosis, respectively.

CONCLUSION

During endoscopic procedures for urinary stones treatment, it is frequently needed to change laser parameters. These new TFL and GUI technology parameters remained in the pre-set security range in 94.1% of procedures.

Comparison of CT and Dixon MR Abdominal Adipose Tissue Quantification Using a Unified Computer-Assisted Software Framework

PURPOSE

Reliable and objective measures of abdominal fat distribution across imaging modalities are essential for various clinical and research scenarios, such as assessing cardiometabolic disease risk due to obesity. We aimed to compare quantitative measures of subcutaneous (SAT) and visceral (VAT) adipose tissues in the abdomen between computed tomography (CT) and Dixon-based magnetic resonance (MR) images using a unified computer-assisted software framework.

MATERIALS AND METHODS

This study included 21 subjects who underwent abdominal CT and Dixon MR imaging on the same day. For each subject, two matched axial CT and fat-only MR images at the L2-L3 and the L4-L5 intervertebral levels were selected for fat quantification. For each image, an outer and an inner abdominal wall regions as well as SAT and VAT pixel masks were automatically generated by our software. The computer-generated results were then inspected and corrected by an expert reader.

RESULTS

There were excellent agreements for both abdominal wall segmentation and adipose tissue quantification between matched CT and MR images. Pearson coefficients were 0.97 for both outer and inner region segmentation, 0.99 for SAT, and 0.97 for VAT quantification. Bland-Altman analyses indicated minimum biases in all comparisons.

CONCLUSION

We showed that abdominal adipose tissue can be reliably quantified from both CT and Dixon MR images using a unified computer-assisted software framework. This flexible framework has a simple-to-use workflow to measure SAT and VAT from both modalities to support various clinical research applications.

The relationships between physical activity, lumbar multifidus muscle morphology, and low back pain from childhood to early adulthood: a 12-year longitudinal study

We investigated the longitudinal associations between physical activity (PA), lumbar multifidus morphology, and impactful low back pain (LBP) in young people. Nine-year-old children were recruited from 25 primary schools and followed up at age 13, 16, and 21 years. We measured PA with accelerometers at age 9, 13, and 16; quantified patterns of lumbar multifidus intramuscular adipose tissue (IMAT) change from 13 to 16 years using magnetic resonance imaging; and recorded LBP and its impact with standardised questionnaires and interviews. Associations were examined with crude and adjusted logistic or multinomial models and reported with odds ratios (OR) or relative risk ratios (RRR). We included data from 364 children (mean[SD] age = 9.7[.4] years). PA behaviour was not associated with LBP. Having persistently high IMAT levels at age 13 and 16 was associated with greater odds of LBP (OR[95% CI] = 2.98[1.17 to 7.58]). Increased time in moderate and vigorous intensity PA was associated with a lower risk of higher IMAT patterns (RRR[95% CI] = .67[.46 to .96] to .74[.55 to 1.00]). All associations became non-significant after adjusting for sex and body mass index (BMI). Future studies investigating the relationships between PA behaviour, lumbar multifidus IMAT, and impactful LBP should account for potential confounding by sex and BMI.

β-cell function in black South African women: exploratory associations with insulin clearance, visceral and ectopic fat

The role of ectopic fat, insulin secretion and clearance in the preservation ofβ-cell function in black African women with obesity who typically present with hyperinsulinaemia is not clear. We aim to examine the associations between disposition index (DI, an estimate of β-cell function), insulin secretion and clearance and ectopic fat deposition. This is a cross-sectional study of 43 black South African women (age 20-35 years) with obesity (BMI 30-40 kg/m2) and without type 2 diabetes that measured the following: DI, insulin sensitivity (SI), acute insulin response (AIRg), insulin secretion rate (ISR), hepatic insulin extraction and peripheral insulin clearance (frequently sampled i.v. glucose tolerance test); pancreatic and hepatic fat, visceral adipose tissue (VAT) and abdominal s.c. adipose tissue (aSAT) volume (MRI), intra-myocellular (IMCL) and extra-myocellular fat content (EMCL) (magnetic resonance spectroscopy). DI correlated positively with peripheral insulin clearance (β 55.80, P = 0.002). Higher DI was associated with lower VAT, pancreatic fat and soleus fat, but VAT explained most of the variance in DI (32%). Additionally, higher first phase ISR (P = 0.033) and lower hepatic insulin extraction (P = 0.022) were associated with lower VAT, independent from SI, rather than with ectopic fat. In conclusion, peripheral insulin clearance emerged as an important correlate of DI. However, VAT was the main determinant of a lower DI above ectopic fat depots. Importantly, VAT, but not ectopic fat, is associated with both lower insulin secretion and higher hepatic insulin extraction. Prevention of VAT accumulation in young black African women should, therefore, be an important target for beta cell preservation.

Both intermuscular fat and LVEF decline promote heart failure symptoms in cancer survivors

Background

Approximately 20% of cancer survivors treated with chemotherapy experience worsening heart failure (HF) symptoms post-cancer treatment. While research has predominantly investigated the role of cardiotoxic treatments, much less attention has focused on other risk factors, such as adiposity. However, emerging data in cancer survivors indicates that adiposity may also impact a variety of cardiovascular outcomes. Methods: In a prospective study of 62 patients diagnosed with cancer followed for 24 months from cancer diagnosis through to survivorship (post-cancer treatment), we ascertained baseline fat depots including intermuscular fat (IMF) of the erector spinae muscles; and pre- and post-cancer treatment left ventricular ejection fraction (LVEF) and HF symptoms at baseline and 24-months, respectively. Linear regression was used to model independent variables in relation to HF symptoms at 24-months.

Results

Baseline IMF and LVEF change over 24-months significantly interacted to predict HF score at 24-months. The highest HF symptom score was observed for participants who experienced high IMF at baseline and a high decline in LVEF over 24-months (HF score = 11.0) versus all other categories of baseline IMF and LVEF change.

Conclusions

Together IMF and LVEF decline may play an important role in the worsening of HF symptoms in cancer survivors. The finding that IMF at cancer diagnosis led to elevated HF scores post-treatment suggests that IMF may be a potential target for intervention studies.

Assessing lumbar paraspinal muscle cross-sectional area and fat composition with T1 versus T2-weighted magnetic resonance imaging: Reliability and concurrent validity

Purpose

Studies using magnetic resonance imaging to assess lumbar multifidus cross-sectional area frequently utilize T1 or T2-weighted sequences, but seldom provide the rationale for their sequence choice. However, technical considerations between their acquisition protocols could impact on the ability to assess lumbar multifidus anatomy or its fat/muscle distinction. Our objectives were to examine the concurrent validity of lumbar multifidus morphology measures of T2 compared to T1-weighted sequences, and to assess the reliability of repeated lumbar multifidus measures.

Methods

The lumbar multifidus total cross-sectional area of 45 patients was measured bilaterally at L4 and L5, with histogram analysis determining the muscle/fat threshold values per muscle. Images were later re-randomized and re-assessed for intra-rater reliability. Matched images were visually rated for consistency of outlining between both image sequences. Bland-Altman bias, limits of agreement, and plots were calculated for differences in total cross-sectional area and percentage fat between and within sequences, and intra-rater reliability analysed.

Results

T1-weighted total cross-sectional area measures were systematically larger than T2 (0.2 cm²), with limits of agreement <±10% at both spinal levels. For percentage fat, no systematic bias occurred, but limits of agreement approached ±15%. Visually, muscle outlining was consistent between sequences, with substantial mismatches occurring in <5% of cases. Intra-rater reliability was excellent (ICC: 0.981–0.998); with bias and limits of agreement less than 1% and ±5%, respectively.

Conclusion

Total cross-sectional area measures and outlining of muscle boundaries were consistent between sequences, and intra-rater reliability for total cross-sectional area and percentage fat was high indicating that either MRI sequence could be used interchangeably for this purpose. However, further studies comparing the accuracy of various methods for distinguishing fat from muscle are recommended.

A 4-week exercise and protein program improves muscle mass and physical functioning in older adults - A pilot study

BACKGROUND

Prehabilitation might attenuate common surgery-induced losses in muscle mass and physical performance. Beneficial effects of physical exercise with protein supplementation have been reported in older adults, but typically after an intervention of at least 12 weeks. The time-window for pre-surgery training is often limited to around 30 days, and it is not known if it is possible to achieve comparable results in such a short time window.

OBJECTIVES

The aim of this study was to pilot-test the effectiveness of a controlled four-week combined exercise and protein supplementation program on skeletal muscle-related outcomes in a Dutch older adult population.

DESIGN

This study was a one-armed pilot trial.

PARTICIPANTS

Seventeen older men and women, aged 55-75y, not scheduled for surgery.

INTERVENTION

A 4-week intervention program consisting of a twice-weekly supervised resistance and high-intensity aerobic exercise training of 75 min, combined with daily protein supplementation (2 doses of 15.5 g/day at breakfast and lunch).

MEASUREMENT

After two and four weeks, isometric quadriceps maximal voluntary contraction (MVC) was assessed via Biodex and quadriceps cross-sectional area (CSA) via magnetic resonance imaging. Other outcome measures were handgrip strength, chair rise time and maximal aerobic capacity (VO₂-max), as assessed from a submaximal exercise test.

RESULTS

Compliance to the supervised training sessions (99.3%) and the protein supplementation (97%) was very high. The 4-week exercise and protein program led to an increase in quadriceps CSA of 2.3 ± 0.7 cm² (P = 0.008) in the dominant leg and 3.2 ± 0.7 cm² (P < 0.001) in the non-dominant leg. Isometric quadriceps MVC increased in the dominant leg (Δ14 ± 4 Nm, P = 0.001) and in the non-dominant leg (Δ17 ± 5 Nm, P = 0.003). Chair rise test time improved with -3.8 ± 0.5 s (P < 0.0001), and VO₂-max improved with 3.3 ± 1.1 ml/min/kg (P = 0.014). We observed no changes in body weight and handgrip strength.

CONCLUSION

A 4-week exercise and protein intervention led to improvements in muscle-related outcomes in older adults with low levels of physical activity.

Preoperative assessment of skeletal muscle mass during magnetic resonance enterography in patients with Crohn's disease

Measurement of the psoas muscle area has been applied to estimate lean muscle mass as a surrogate marker of sarcopenia, but there is a paucity of evidence regarding the influence of sarcopenia on clinical outcomes following inflammatory bowel disease surgery. The aim of this study was to evaluate the association between MRI enterography defined sarcopenia and postoperative complications in patients undergoing elective ileocaecal resection for Crohn’s disease. To obtain cross sectional area measurement of the psoas muscle, the freehand area tool was used to trace the margin of each psoas muscle at the level of L4, with the sum recorded as Total Psoas Area (TPA). The total cross sectional muscle area of the abdominal wall was recorded as Skeletal Muscle Area (SMA), while myosteatosis was measured by normalising the psoas muscle intensity with the mean intensity of the cerebrospinal fluid. The primary outcome was the incidence of 30-day postoperative complications in patients in the lowest quartile of TPA and SMA. 31 patients were included and ten patients (32.25%) developed postoperative complications within 30 days of surgery. The cut-off values for the lowest quartile for TPA were 11.93 cm² in men and 9.77 cm² in women, including a total of 8 patients (25.8%) with 5 patients in this group (62.5%) developing postoperative complications and 3 patients (37.5%) Clavien-Dindo class ≥ 3 complications. The cut-off values for the lowest quartile for SMA were 73.49 cm² in men and 65.85 cm² in women, with 4 patients out of 8 (50%) developing postoperative complications. Psoas muscle cross sectional area and skeletal mass area can be estimated on Magnetic Resonance Enterography as surrogate markers of sarcopenia with high inter-observer agreement.

Sub-cutaneous Fat Mass measured on multislice computed tomography of pretreatment PET/CT is a prognostic factor of stage IV non-small cell lung cancer treated by nivolumab

Introduction: Our aim was to explore the prognostic value of anthropometric parameters in patients treated with nivolumab for stage IV non-small cell lung cancer (NSCLC). Methods: We retrospectively included 55 patients with NSCLC treated by nivolumab with a pretreatment ¹⁸FDG positron emission tomography coupled with computed tomography (PET/CT). Anthropometric parameters were measured on the CT of PET/CT by in-house software (Anthropometer3D) allowing an automatic multi-slice measurement of Lean Body Mass (LBM), Fat Body Mass (FBM), Muscle Body Mass (MBM), Visceral Fat Mass (VFM) and Sub-cutaneous Fat Mass (SCFM). Clinical and tumor parameters were also retrieved. Receiver operator characteristics (ROC) analysis was performed and overall survival at 1 year was studied using Kaplan-Meier and Cox analysis. Results: FBM and SCFM were highly correlated (ρ = 0.99). In ROC analysis, only FBM, SCFM, VFM, body mass index (BMI) and metabolic tumor volume (MTV) had an area under the curve (AUC) significantly higher than 0.5. In Kaplan-Meier analysis using medians as cut-offs, prognosis was worse for patients with low SCFM (<5.69 kg/m²; p = 0.04, survivors 41% vs 75%). In Cox univariate analysis using continuous values, BMI (HR = 0.84, p= 0.007), SCFM (HR = 0.75, p = 0.003) and FBM (HR = 0.80, p= 0.004) were significant prognostic factors. In multivariate analysis using clinical parameters (age, gender, WHO performance status, number prior regimens) and SCFM, only SCFM was significantly associated with poor survival (HR = 0.75, p = 0.006). Conclusions: SCFM is a significant prognosis factor of stage IV NSCLC treated by nivolumab.

Sarcopenia and Inflammatory Bowel Disease: A Systematic Review

BACKGROUND

Sarcopenia is associated with increased morbidity and mortality in oncologic and transplant surgery. It has a high incidence in chronic inflammatory states including inflammatory bowel disease (IBD). The validity of existing data in IBD and of sarcopenia's correlation with surgical outcomes is limited.

METHODS

We performed a systematic review to assess the correlation of sarcopenia with the requirement for surgery and surgical outcomes in patients with IBD. Observational studies of patients with IBD in whom an assessment of sarcopenic status/skeletal muscle index was undertaken, a proportion of whom proceeded to surgical management, were selected.

RESULTS

A total of 5 studies with a combined 658 IBD patients met the inclusion criteria. The majority (70%) had a diagnosis of Crohn's disease. Median (range) body mass index and skeletal muscle index were reported in 4 studies and were 16.58 (13.66-22.50) kg/m2 and 44.52 (42.90-50.64) cm2/m2, respectively. Forty-two percent of IBD patients had sarcopenia. Notably, none of the studies assessed both the anatomical and functional component required for a correct assessment of sarcopenia. Three studies noted that sarcopenic IBD patients had a higher probability of requiring surgery. The rate of major complications (Clavien-Dindo grade ≥IIIa) was significantly higher in patients with sarcopenia. Improved perioperative nutrition management may mitigate the risk of complications.

CONCLUSION

Many IBD patients are young, may be malnourished, and commonly require emergent surgery. There is considerable heterogeneity in the assessment of sarcopenia. Sarcopenia is common in the IBD population and can predict the need for surgical intervention. Sarcopenia correlates with an increased rate of major postoperative complications. Improved perioperative intervention may diminish this risk. A formal assessment, screening by a dedicated IBD dietician, and preoperative physical therapy may facilitate early intervention.

Body composition and sarcopenia: The next-generation of personalized oncology and pharmacology?

Body composition has gained increasing attention in oncology in recent years due to fact that sarcopenia has been revealed to be a strong prognostic indicator for survival across multiple stages and cancer types and a predictive factor for toxicity and surgery complications. Accumulating evidence over the last decade has unraveled the "pharmacology" of sarcopenia. Lean body mass may be more relevant to define drug dosing than the "classical" body surface area or flat-fixed dosing in patients with cancer. Since sarcopenia has a major impact on patient survival and quality of life, therapeutic interventions aiming at reducing muscle loss have been developed and are being prospectively evaluated in randomized controlled trials. It is now acknowledged that this supportive care dimension of oncological management is essential to ensure the success of any anticancer treatment. The field of sarcopenia and body composition in cancer is developing quickly, with (i) the newly identified concept of sarcopenic obesity defined as a specific pathophysiological entity, (ii) unsolved issues regarding the best evaluation modalities and cut-off for definition of sarcopenia on imaging, (iii) first results from clinical trials evaluating physical activity, and (iv) emerging body-composition-tailored drug administration schemes. In this context, we propose a comprehensive review providing a panoramic approach of the clinical, pharmacological and therapeutic implications of sarcopenia and body composition in oncology.

MRI adipose tissue and muscle composition analysis-a review of automation techniques

MRI is becoming more frequently used in studies involving measurements of adipose tissue and volume and composition of skeletal muscles. The large amount of data generated by MRI calls for automated analysis methods. This review article presents a summary of automated and semi-automated techniques published between 2013 and 2017. Technical aspects and clinical applications for MRI-based adipose tissue and muscle composition analysis are discussed based on recently published studies. The conclusion is that very few clinical studies have used highly automated analysis methods, despite the rapidly increasing use of MRI for body composition analysis. Possible reasons for this are that the availability of highly automated methods has been limited for non-imaging experts, and also that there is a limited number of studies investigating the reproducibility of automated methods for MRI-based body composition analysis.

Quantitative MRI evaluation of whole abdomen adipose tissue volumes in healthy volunteers-validation of technique and implications for clinical studies

OBJECTIVE

To explore "whole abdomen" MRI methods for quantifying adipose tissue volumes and to establish associations with body mass index (BMI) and measurement reproducibility-relative to existing "partial abdomen" methods.

METHODS

15 healthy volunteers were scanned on a 3T MRI scanner using a double-echo three-point-Dixon gradient echo sequence. Whole abdomen volumes were acquired via three separate scans ("supine 1", "supine 2" and "prone"). Segmentation was applied to derive (i) "whole abdomen" visceral (VAT) and subcutaneous adipose tissue (SCAT) volumes, and (ii) "partial abdomen" volumes at the lumbar spine (L3 to L5). Root-mean-square coefficients of variation (RMS CoV) were calculated to quantify the variability of each measurement.

RESULTS

"Whole abdomen" measurements were found to correlate better with BMI (r2max = 0.74) than "partial abdomen" volumes (r2max = 0.66). Total adipose tissue (TAT) measurements correlated better with BMI (r2max = 0.74) than SCAT (r2max = 0.43) or VAT (r2max = 0.33) for both methods. Scan-to-scan RMS CoV's for "whole abdomen" VAT and SCAT measurements were 4.16 and 3.61% compared to 6.31 and 5.07% for "partial abdomen" measurements.

CONCLUSION

"Whole abdomen" measures of abdominal adiposity are better correlated with BMI and demonstrate better scan-to-scan reproducibility than "partial abdomen" measures. It is recommended that "whole abdomen" measures be used in longitudinal MRI radiology investigations, where small volume changes may occur. Advances in knowledge: Whole abdomen adipose tissue volumes can be measured and quantified using commercial MRI sequences and post-processing software. These methods are better correlated with BMI and are more reproducible than partial abdomen measures.

Optimization of region-of-interest sampling strategies for hepatic MRI proton density fat fraction quantification

BACKGROUND

Clinical trials utilizing proton density fat fraction (PDFF) as an imaging biomarker for hepatic steatosis have used a laborious region-of-interest (ROI) sampling strategy of placing an ROI in each hepatic segment.

PURPOSE

To identify a strategy with the fewest ROIs that consistently achieves close agreement with the nine-ROI strategy.

STUDY TYPE

Retrospective secondary analysis of prospectively acquired clinical research data.

POPULATION

A total of 391 adults (173 men, 218 women) with known or suspected NAFLD.

FIELD STRENGTH/SEQUENCE

Confounder-corrected chemical-shift-encoded 3T MRI using a 2D multiecho gradient-recalled echo technique.

ASSESSMENT

An ROI was placed in each hepatic segment. Mean nine-ROI PDFF and segmental PDFF standard deviation were computed. Segmental and lobar PDFF were compared. PDFF was estimated using every combinatorial subset of ROIs and compared to the nine-ROI average.

STATISTICAL TESTING

Mean nine-ROI PDFF and segmental PDFF standard deviation were summarized descriptively. Segmental PDFF was compared using a one-way analysis of variance, and lobar PDFF was compared using a paired t-test and a Bland-Altman analysis. The PDFF estimated by every subset of ROIs was informally compared to the nine-ROI average using median intraclass correlation coefficients (ICCs) and Bland-Altman analyses.

RESULTS

The study population's mean whole-liver PDFF was 10.1 ± 8.9% (range: 1.1-44.1%). Although there was no significant difference in average segmental (P = 0.452) or lobar (P = 0.154) PDFF, left and right lobe PDFF differed by at least 1.5 percentage points in 25.1% (98/391) of patients. Any strategy with ≥4 ROIs had ICC >0.995. 115 of 126 four-ROI strategies (91%) had limits of agreement (LOA) <1.5%, including four-ROI strategies with two ROIs from each lobe, which all had LOA <1.5%. 14/36 (39%) of two-ROI strategies and 74/84 (88%) of three-ROI strategies had ICC >0.995, and 2/36 (6%) of two-ROI strategies and 46/84 (55%) of three-ROI strategies had LOA <1.5%.

DATA CONCLUSION

Four-ROI sampling strategies with two ROIs in the left and right lobes achieve close agreement with nine-ROI PDFF.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:988-994.

Increase of Intra-abdominal Adipose Tissue in Pediatric Crohn Disease

BACKGROUND AND OBJECTIVE

Recent evidence points toward an active immunological role of intra-abdominal adipose tissue in Crohn disease (CD). We quantified the abdominal adipose tissue compartments using magnetic resonance imaging (MRI) in 27 pediatric patients with CD compared with 14 controls undergoing MRI examination for other reasons.

METHODS

Total (TAAT), subcutaneous (SCAT) and intra-abdominal (IAAT) adipose tissue areas were measured by semiautomatic segmentation on a transverse slice centered on the umbilicus (mean ± standard deviation in square centimeter) using standard T1-weighted sequences. IAAT/TAAT and IAAT/height ratios were calculated and analyzed for associations with disease duration, phenotype, or therapy.

RESULTS

Patients with CD (median age 15.0 years, range 7.7-17.9, 18/27 boys, median disease duration 29 months, range 0-136) compared to controls (median age 13.9 years, range 3.3-17.8, 4/14 boys) had higher IAAT area (42.3 ± 21.0 vs 28.7 ± 11.6, P = 0.0494) but similar SCAT and TAAT areas (104.6 ± 72.8 vs 96.5 ± 50.8, P = 0.8170 and 146.9 ± 87.3 vs 125.3 ± 61.5, P = 0.7417, respectively). IAAT/TAAT ratio was higher in patients with CD compared to controls (0.32 ± 0.10 vs 0.24 ± 0.04, P = 0.0081). Patients with disease duration >2 years (n = 14) had higher IAAT/TAAT ratio than those with shorter disease and controls (0.35 ± 0.10 vs 0.28 ± 0.08, P = 0.0288 and 0.24 ± 0.04, P = 0.0009, respectively). In these patients, increased IAAT/height ratio was associated with complicated disease (P = 0.043, r = 0.573). No association was found between IAAT/TAAT ratio and actual disease activity or therapy.

CONCLUSIONS

IAAT is increased in pediatric CD and correlates with disease duration. Assessment of IAAT accumulation may be considered in future MRI scores for inflammation and bowel damage in CD and during follow-up of different therapeutic interventions.

Novel Body Shape Descriptors for Abdominal Adiposity Prediction Using Magnetic Resonance Images and Stereovision Body Images

OBJECTIVE

The purpose of this study was to design novel shape descriptors based on three-dimensional (3D) body images and to use these parameters to establish prediction models for abdominal adiposity.

METHODS

Sixty-six men and fifty-five women were recruited for abdominal magnetic resonance imaging (MRI) and 3D whole-body imaging. Volumes of abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were measured from MRI sequences by using a fully automated algorithm. The shape descriptors were measured on the 3D body images by using the software developed in this study. Multiple regression analysis was employed on the training data set (70% of the total participants) to develop predictive models for VAT and SAT, with potential predictors selected from age, BMI, and the body shape descriptors. The validation data set (30%) was used for the validation of the predictive models.

RESULTS

Thirteen body shape descriptors exhibited high correlations (P < 0.01) with abdominal adiposity. The optimal predictive equations for VAT and SAT were determined separately for men and women.

CONCLUSIONS

Novel body shape descriptors defined on 3D body images can effectively predict abdominal adiposity quantified by MRI.

Subtraction of subcutaneous fat to improve the prediction of visceral adiposity: exploring a new anthropometric track in overweight and obese youth

BACKGROUND

The efficiency of traditional anthropometric measurements such as body mass index (BMI) or waist circumference (Waist C) used to replace biomedical imaging for assessing visceral adipose tissue (VAT) is still highly controversial in youth.

HYPOTHESIS AND OBJECTIVES

We evaluated the most accurate model predicting VAT in overweight/obese youth, using various anthropometric measurements and their correlation with different body fat compartments, especially by testing, for the first time in youth, the hypothesis that subtracting the anthropometric measurement the most highly correlated with subcutaneous abdominal adipose tissue (SAAT) and less correlated possible with VAT from an anthropometric abdominal measurement highly correlated with visceral and total abdominal adipose tissue (TAAT), predicts VAT with higher accuracy.

SUBJECTS AND METHODS

VAT and SAAT data resulted from magnetic resonance imaging (MRI) analysis performed on 181 boys and girls (7-17 y) from Diabetes & Endocrinology Care Paediatrics Clinic in Luxembourg. Height, weight, abdominal diameters, waist, hip, and thigh circumferences were measured with a view to developing the anthropometric VAT predictive algorithms.

RESULTS

In girls, subtracting proximal thigh circumference (Proximal Thigh C), the most closely correlated anthropometric measurement with SAAT, from Waist C, the most closely correlated anthropometric measurement with VAT was instrumental in improving VAT prediction, in comparison with the most accurate single VAT anthropometric surrogate. [Formula: see text] Residual analysis showed a negligible estimation error (5 cm² ). In boys, Waist C was the best VAT predictor.

CONCLUSIONS

Subtraction of abdominal subcutaneous fat is important to predict VAT in overweight/obese girls.

Effects of visceral adipose tissue reduction on CVD risk factors independent of weight loss: The Look AHEAD study

OBJECTIVES

To determine if the reduction of visceral adipose tissue (VAT) volume by lifestyle intervention improved risk factors for cardiovascular disease (CVD) independent of weight loss amount.

DESIGN

Ancillary study of randomized-controlled trial.

SETTING

Data analysis using multivariable regression models.

PARTICIPANTS

Participants of the Look AHEAD (Action for HEAlth in Diabetes) Fatty Liver Ancillary Study.

MAIN OUTCOME MEASURES

Correlations between changes in VAT and in CVD risk factors, while adjusting for weight loss and treatment (intensive lifestyle intervention [ILI] vs. diabetes support and education [DSE]).

RESULTS

Of 100 participants analyzed, 52% were women, and 36% were black, with a mean age of 61.1 years. In the DSE group, mean weight and VAT changed by 0.1 % (p=0.90) and 4.3% (p=0.39), respectively. In the ILI group, mean weight and VAT decreased by 8.0% (p<0.001) and 7.7% (p=0.01), respectively. Across both groups, mean weight decreased by 3.6% (p<0.001), and mean VAT decreased by 1.2% (p=0.22); the decrease in VAT was correlated with the increase in HDL-cholesterol (HDL-C; R=-0.37; p=0.03). There were no correlations between changes in VAT and blood pressure, triglycerides, LDL-C, glucose, or HbA1c. After adjusting for age, race, gender, baseline metabolic values, fitness, and treatment group, changes in HDL-C were not associated with changes in VAT, while weight changes were independently associated with decrease in glucose, HbA1c, and increase in HDL-C.

CONCLUSIONS

VAT reduction was not correlated with improvements of CVD risk factors in a sample of overweight and obese adults with type 2 diabetes after adjusting for weight loss.

Visceral adiposity predicts post-operative Crohn's disease recurrence

BACKGROUND

Excessive visceral adipose tissue has been associated with poorer outcomes in patients with inflammatory bowel disease.

AIM

To determine whether body composition is associated with outcome in a prospective study of post-operative Crohn's disease patients.

METHODS

The POCER study evaluated management strategies for prevention of post-operative Crohn's disease recurrence; subjects were enrolled after resection of all macroscopic Crohn's disease and were randomised to early endoscopy and possible treatment escalation, or standard care. The primary endpoint was endoscopic recurrence at 18 months. 44 subjects with cross-sectional abdominal imaging were studied, and body composition analysis performed using established techniques to measure visceral adipose tissue area, subcutaneous adipose tissue area, and skeletal muscle area.

RESULTS

The body composition parameter with the greatest variance was visceral adipose tissue. Regardless of treatment, all subjects with visceral adipose tissue/height² >1.5 times the gender-specific mean experienced endoscopic recurrence at 18 months (compared to 47%) [relative risk 2.1, 95% CI 1.5-3.0, P = 0.012]. Waist circumference correlated strongly with visceral adipose tissue area (ρ = 0.840, P < 0.001). Low skeletal muscle was prevalent (41% of patients), but did not predict endoscopic recurrence; however, appendicular skeletal muscle indices correlated inversely with faecal calprotectin (ρ = 0.560, P = 0.046).

CONCLUSIONS

Visceral adiposity is an independent risk factor for endoscopic recurrence of Crohn's disease after surgery. Sarcopenia correlates with inflammatory biomarkers. Measures of visceral adipose tissue may help to stratify risk in post-operative management strategies.

Relationships between fatty infiltration in the thigh and calf in women with knee osteoarthritis

BACKGROUND

In individuals with knee osteoarthritis (OA), fatty infiltration into thigh muscle is associated with poor physical performance and strength. However, it is not known whether this also occurs in the calf and if this impacts physical function.

AIMS

We investigated the relationships between volumes of intramuscular fat (intraMF), intermuscular fat (IMF), subcutaneous fat (SCF), lean muscle and muscle adiposity, in the thighs compared to the calves of women with knee OA.

METHODS

MRI scans of the thigh and calf were acquired from 20 women over 55 years with knee OA (3.0T Discovery MR750, GE Healthcare). Axial IDEAL (iterative decomposition of water and fat with echo asymmetry and least-squares estimation) fat-separated images were segmented to quantify intraMF, IMF, SCF and lean muscle volumes (SliceOmatic 5.0, Tomovision). Correlation and linear regression analyses were run.

RESULTS

We found a positive relationship between thigh and calf intraMF (R ² = 0.592; B = 5.49; p = 0.001), muscle adiposity (R ² = 0.539; B = 0.567; p = 0.001), and SCF volume (R ² = 0.699; B = 12.847; p = 0.001), controlling for waist-to-hip ratio. Relationships between thigh and calf IMF (R ² = 0.239; B = 7.743; p = 0.061), lean muscle (R ² = 0.245; B = 4.149; p = 0.047) and combined intraMF and IMF volume (R ² = 0.242; B = 6.162; p = 0.044) were not significant.

DISCUSSION

Although a correlation exists between thigh and calf muscle adiposity, intraMF and SCF, this does not hold true for IMF or lean muscle. A greater amount of intraMF infiltration occurs in the thigh compared to the calf of women with knee OA.

CONCLUSION

The calf and thigh may both be involved in pathologic changes in muscle composition in knee OA.

Quantifying Abdominal Adipose Tissue and Thigh Muscle Volume and Hepatic Proton Density Fat Fraction: Repeatability and Accuracy of an MR Imaging-based, Semiautomated Analysis Method

Purpose To determine the repeatability and accuracy of a commercially available magnetic resonance (MR) imaging-based, semiautomated method to quantify abdominal adipose tissue and thigh muscle volume and hepatic proton density fat fraction (PDFF). Materials and Methods This prospective study was institutional review board- approved and HIPAA compliant. All subjects provided written informed consent. Inclusion criteria were age of 18 years or older and willingness to participate. The exclusion criterion was contraindication to MR imaging. Three-dimensional T1-weighted dual-echo body-coil images were acquired three times. Source images were reconstructed to generate water and calibrated fat images. Abdominal adipose tissue and thigh muscle were segmented, and their volumes were estimated by using a semiautomated method and, as a reference standard, a manual method. Hepatic PDFF was estimated by using a confounder-corrected chemical shift-encoded MR imaging method with hybrid complex-magnitude reconstruction and, as a reference standard, MR spectroscopy. Tissue volume and hepatic PDFF intra- and interexamination repeatability were assessed by using intraclass correlation and coefficient of variation analysis. Tissue volume and hepatic PDFF accuracy were assessed by means of linear regression with the respective reference standards. Results Adipose and thigh muscle tissue volumes of 20 subjects (18 women; age range, 25-76 years; body mass index range, 19.3-43.9 kg/m²) were estimated by using the semiautomated method. Intra- and interexamination intraclass correlation coefficients were 0.996-0.998 and coefficients of variation were 1.5%-3.6%. For hepatic MR imaging PDFF, intra- and interexamination intraclass correlation coefficients were greater than or equal to 0.994 and coefficients of variation were less than or equal to 7.3%. In the regression analyses of manual versus semiautomated volume and spectroscopy versus MR imaging, PDFF slopes and intercepts were close to the identity line, and correlations of determination at multivariate analysis (R²) ranged from 0.744 to 0.994. Conclusion This MR imaging-based, semiautomated method provides high repeatability and accuracy for estimating abdominal adipose tissue and thigh muscle volumes and hepatic PDFF. ^© RSNA, 2017.

Lean muscle volume of the thigh has a stronger relationship with muscle power than muscle strength in women with knee osteoarthritis

BACKGROUND

Thigh lean muscle and intramuscular fat have been implicated in the impairment of physical function observed in people with knee osteoarthritis. We investigated the relationships of quadriceps and hamstrings intramuscular fat fraction and lean muscle volume with muscle power and strength, controlling for neuromuscular activation, and physical performance in women with knee OA.

METHODS

Women (n=20) 55years or older with symptomatic, radiographic knee osteoarthritis underwent a 3.0T magnetic resonance imaging scan of the thigh of their most symptomatic knee. Axial fat-separated images were analyzed using software to quantify intramuscular fat and lean muscle volumes of the quadriceps and hamstrings. To quantify strength and power of the knee extensors and flexors, participants performed maximum voluntary isometric contraction and isotonic knee extensions and flexions, respectively. Electromyography of the quadriceps and hamstrings was measured. Participants also completed five physical performance tests.

FINDINGS

Quadriceps and hamstrings lean muscle volumes were related to isotonic knee extensor (B=0.624; p=0.017) and flexor (B=1.518; p=0.032) power, but not knee extensor (B=0.001; p=0.615) or flexor (B=0.001; p=0.564) isometric strength. Intramuscular fat fractions were not related to isotonic knee extensor or flexor power, nor isometric strength. No relationships were found between intramuscular fat or lean muscle volume and physical performance.

INTERPRETATION

Muscle power may be more sensitive than strength to lean muscle mass in women with knee osteoarthritis. Thigh lean muscle mass, but neither intramuscular nor intermuscular fat, is related to knee extensor and flexor power in women with knee osteoarthritis.

Automated quantification of abdominal adiposity by magnetic resonance imaging

OBJECTIVES

To develop a fully-automated algorithm to process axial magnetic resonance imaging (MRI) slices for quantifying abdominal visceral, subcutaneous and total adipose tissues, i.e., VAT, SAT, and TAT, without human intervention or prior knowledge.

MATERIALS AND METHODS

Fat regions in single MRI slice or sequence (20 slices) were identified with image processing techniques including region-growing, inhomogeneity correction, fuzzy c-means clustering, and active contours segmentation. The MR images of 85 subjects (60 males and 25 females), whose body mass index (BMI) values ranged from 19.96 to 40.35 kg/m2 , were analyzed using the fully-automated algorithm-the automatic method developed in the research and the widely used semi-automated software (sliceOmatic® Tomovision, Inc.)-the reference method.

RESULTS

The proposed automated method showed good performance against the reference method to quantify adipose tissues in both single umbilical slice and MRI sequence. The square of the Pearson correlation coefficients (R2 ) based on the results generated from the two methods for VAT/SAT/TAT were 0.977/0.998/0.997 for single slice data and 0.995/0.999/0.999 for volumetric data. The intra-class correlation of visceral adipose tissue (VAT) between the three operators was 0.939 in the reference method, which was improved to 0.999 in the automatic method. The adipose tissue measurements in the slice at Lumbar 3 vertebra have the highest correlation with the total fat volumes across the entire abdomen.

CONCLUSION

The fully-automated algorithm presented in the paper provides an accurate and reliable assessment of abdominal fat without human intervention. Am. J. Hum. Biol. 28:757-766, 2016. © 2016Wiley Periodicals, Inc.

Sarcopenia and sarcopenic obesity: do they predict inferior oncologic outcomes after gastrointestinal cancer surgery?

Sarcopenia, or loss of skeletal muscle mass and quality, has been studied as part of aging and adverse health outcomes in elderly patients but has only recently been evaluated as a separate condition in cancer patients and important indicator of adverse outcomes. Currently, its definition and method of assessment are still being debated. Sarcopenia within an increasingly obese population has led to a subgroup with sarcopenic obesity, at even higher risk of adverse outcomes. Yet, sarcopenia often goes undiagnosed in these patients, hidden beneath higher body mass index. Identifying sarcopenic and sarcopenic obese subpopulations would allow for more effective treatment plans and potential avoidance of suboptimal outcomes, as well as the chance to intervene and combat these modifiable risk factors. This review will examine available literature on the definition and methods of evaluating sarcopenia and sarcopenic obesity, summarize the effectiveness of sarcopenia and sarcopenic obesity as predictors of outcomes after gastrointestinal cancer surgery, including colorectal cancer resection, liver resection, and pancreatic resection, and outline strategies to minimize the impact of sarcopenia. It is clear that untreated sarcopenia and sarcopenic obesity can be associated with suboptimal post-operative outcomes, especially infections and disease-free or overall survival.

Oral AGE restriction ameliorates insulin resistance in obese individuals with the metabolic syndrome: a randomised controlled trial

AIMS/HYPOTHESIS

We previously reported that obese individuals with the metabolic syndrome (at risk), compared with obese individuals without the metabolic syndrome (healthy obese), have elevated serum AGEs that strongly correlate with insulin resistance, oxidative stress and inflammation. We hypothesised that a diet low in AGEs (L-AGE) would improve components of the metabolic syndrome in obese individuals, confirming high AGEs as a new risk factor for the metabolic syndrome.

METHODS

A randomised 1 year trial was conducted in obese individuals with the metabolic syndrome in two parallel groups: L-AGE diet vs a regular diet, habitually high in AGEs (Reg-AGE). Participants were allocated to each group by randomisation using random permuted blocks. At baseline and at the end of the trial, we obtained anthropometric variables, blood and urine samples, and performed OGTTs and MRI measurements of visceral and subcutaneous abdominal tissue and carotid artery. Only investigators involved in laboratory determinations were blinded to dietary assignment. Effects on insulin resistance (HOMA-IR) were the primary outcome.

RESULTS

Sixty-one individuals were randomised to a Reg-AGE diet and 77 to an L-AGE diet; the data of 49 and 51, respectively, were analysed at the study end in 2014. The L-AGE diet markedly improved insulin resistance; modestly decreased body weight; lowered AGEs, oxidative stress and inflammation; and enhanced the protective factors sirtuin 1, AGE receptor 1 and glyoxalase I. The Reg-AGE diet raised AGEs and markers of insulin resistance, oxidative stress and inflammation. There were no effects on MRI-assessed measurements. No side effects from the intervention were identified. HOMA-IR came down from 3.1 ± 1.8 to 1.9 ± 1.3 (p < 0.001) in the L-AGE group, while it increased from 2.9 ± 1.2 to 3.6 ± 1.7 (p < 0.002) in the Reg-AGE group.

CONCLUSIONS/INTERPRETATION

L-AGE ameliorates insulin resistance in obese people with the metabolic syndrome, and may reduce the risk of type 2 diabetes, without necessitating a major reduction in adiposity. Elevated serum AGEs may be used to diagnose and treat 'at-risk' obesity.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01363141 FUNDING: The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases (DK091231).

The role of MRI in understanding the underlying mechanisms in obesity associated diseases

Obesity and its possible association with diseases including diabetes and cardiovascular diseases have been studied for decades for its impact on healthcare. Recent studies clearly indicate the need for developing accurate and reproducible methodologies for assessing body fat content and distribution. Body fat distribution plays a significant role in developing an insight in the underlying mechanisms in which adipose tissue is linked with various diseases. Among imaging technologies including computerized axial tomography (CAT or CT), magnetic resonance imaging (MRI), and magnetic resonance spectroscopy (MRS), MRI and MRS seem to be the best emerging techniques and together are being considered as the gold standard for body fat content and distribution. This paper reviews studies up to the present time involving different methodologies of these two emerging technologies and presents the basic concepts of MRI and MRS with required novel image analysis techniques in accurate, quantitative, and direct assessment of body fat content and distribution. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.

Measurement of skeletal muscle area: Comparison of CT and MR imaging

OBJECTIVE

To investigate the intra- and inter-observer agreement and correlation between CT and MR measurements of skeletal muscle area (SMA) in the abdomen.

METHODS

CT and MR images from twelve patients were analyzed by two blinded observers using segmentation software (MITK-3M3, Mint Medical and Slice-O-Matic, Tomovision) to quantify SMA. MR images included T1w "in-phase", T1w "out-of-phase", and T2w sequences. Inter- and intra-observer agreement was assessed using the intraclass correlation coefficient (ICC). Pearson correlation coefficient (r) was used to correlate measurements obtained on MR with CT. CT and MR measurements were compared with Bland-Altman plots.

RESULTS

Intra- and inter-observer agreement for SMA was high for CT and MR. For MR, the measurements on T2w images showed the highest inter-observer agreement (ICC=0.96). CT SMA correlated closely with MR, with T2w images showing the highest correlation (r=0.98; P<0.01). Bland-Altman plots showed a 1.7%-3.9% bias between CT and MR measurements, lowest for T2w images.

CONCLUSIONS

MR SMA measurements are reproducible and correlate closely with CT. The T2w sequence is recommended to quantify SMA on MR images.

Cardiometabolic risk: leg fat is protective during childhood

BACKGROUND

Childhood obesity is associated with early cardiometabolic risk (CMR), increased risk of adulthood obesity, and worse health outcomes. Leg fat mass (LFM) is protective beyond total fat mass (TFM) in adults. However, the limited evidence in children remains controversial.

OBJECTIVE

We investigated the relationship between LFM and CMR factors in youth.

SUBJECTS

A total of 203 overweight/obese children, 7-17-yr-old, followed in the Pediatric Clinic, Luxembourg.

METHODS

TFM and LFM by dual energy x-ray absorptiometry and a detailed set of CMR markers were analyzed.

RESULTS

After TFM, age, sex, body mass index (BMI) Z-score, sexual maturity status, and physical activity adjustments, negative significant partial correlations were shown between LFM and homeostasis model assessment of insulin resistance (HOMA) (variance explained: 6.05% by LFM*; 7.18% by TFM**), fasting insulin (variance explained: 5.71% by LFM*; 6.97% by TFM**), triglycerides (variance explained: 3.96% by LFM*; 2.76% by TFM*), systolic blood pressure (variance explained: 2.68% by LFM*; 4.33% by TFM*), C-reactive protein (variance explained: 2.31% by LFM*; 4.28% by TFM*), and resistin (variance explained: 2.16% by LFM*; 3.57% by TFM*). Significant positive partial correlations were observed between LFM and high-density lipoprotein (HDL) cholesterol (variance explained: 4.16% by LFM*) and adiponectin (variance explained: 3.09% by LFM*) (*p-value < 0.05 and **p-value < 0.001). In order to adjust for multiple testing, Benjamini-Hochberg method was applied and the adjusted significance level was determined for each analysis. LFM remained significant in the aforementioned models predicting HOMA, fasting insulin, triglycerides, and HDL cholesterol (Benjamini and Hochberg corrected p-value < 0.01).

CONCLUSIONS

LFM is protective against CMR in children, at least in terms of insulin resistance and adverse blood lipid profiles.

Validation of a fast method for quantification of intra-abdominal and subcutaneous adipose tissue for large-scale human studies

Central obesity is the hallmark of a number of non-inheritable disorders. The advent of imaging techniques such as MRI has allowed for a fast and accurate assessment of body fat content and distribution. However, image analysis continues to be one of the major obstacles to the use of MRI in large-scale studies. In this study we assess the validity of the recently proposed fat-muscle quantitation system (AMRA(TM) Profiler) for the quantification of intra-abdominal adipose tissue (IAAT) and abdominal subcutaneous adipose tissue (ASAT) from abdominal MR images. Abdominal MR images were acquired from 23 volunteers with a broad range of BMIs and analysed using sliceOmatic, the current gold-standard, and the AMRA(TM) Profiler based on a non-rigid image registration of a library of segmented atlases. The results show that there was a highly significant correlation between the fat volumes generated by the two analysis methods, (Pearson correlation r = 0.97, p < 0.001), with the AMRA(TM) Profiler analysis being significantly faster (~3 min) than the conventional sliceOmatic approach (~40 min). There was also excellent agreement between the methods for the quantification of IAAT (AMRA 4.73 ± 1.99 versus sliceOmatic 4.73 ± 1.75 l, p = 0.97). For the AMRA(TM) Profiler analysis, the intra-observer coefficient of variation was 1.6% for IAAT and 1.1% for ASAT, the inter-observer coefficient of variation was 1.4% for IAAT and 1.2% for ASAT, the intra-observer correlation was 0.998 for IAAT and 0.999 for ASAT, and the inter-observer correlation was 0.999 for both IAAT and ASAT. These results indicate that precise and accurate measures of body fat content and distribution can be obtained in a fast and reliable form by the AMRA(TM) Profiler, opening up the possibility of large-scale human phenotypic studies.

Segmentation and quantification of adipose tissue by magnetic resonance imaging

In this brief review, introductory concepts in animal and human adipose tissue segmentation using proton magnetic resonance imaging (MRI) and computed tomography are summarized in the context of obesity research. Adipose tissue segmentation and quantification using spin relaxation-based (e.g., T1-weighted, T2-weighted), relaxometry-based (e.g., T1-, T2-, T2*-mapping), chemical-shift selective, and chemical-shift encoded water-fat MRI pulse sequences are briefly discussed. The continuing interest to classify subcutaneous and visceral adipose tissue depots into smaller sub-depot compartments is mentioned. The use of a single slice, a stack of slices across a limited anatomical region, or a whole body protocol is considered. Common image post-processing steps and emerging atlas-based automated segmentation techniques are noted. Finally, the article identifies some directions of future research, including a discussion on the growing topic of brown adipose tissue and related segmentation considerations.

Fully automatic and nonparametric quantification of adipose tissue in fat-water separation MR imaging

Despite increasing demand and research efforts, currently there is no consensus on the protocol for automated and reliable quantification of adipose tissue (AT) and visceral adipose tissue (VAT) using MRI. The purpose of this study was to propose a novel computational method with enhanced objectiveness for the quantification of AT and VAT in fat-water separation MRI. 3T data from IDEAL were acquired for the fat-water separation. Fat tissues were separated from nonfat regions (background air, bone, water, and other nonfat tissues) using K-means clustering (K = 2). From the binary fat mask, arm regions were separated from body based on the relative size of connected component. AT was obtained from the binary body fat mask. With the initial contour as the outer boundary of body fat, the subcutaneous adipose tissue (SAT) and VAT were separated using deformable model driven by a specifically generated deformation field pointing to the inner boundary of SAT. The proposed method was tested on 16 patients with dyslipidemia and evaluated by comparing the correlation with semi-automatic segmentation results. Good robustness was also observed in the proposed method from the Bland-Altman plots. Compared to other established fat segmentation methods, the proposed method is highly objective for fat-water separation MRI with minimal variability induced by subjective parameter settings.

Elevated serum advanced glycation endproducts in obese indicate risk for the metabolic syndrome: a link between healthy and unhealthy obesity?

CONTEXT

Although obesity can predispose to the metabolic syndrome (MS), diabetes, and cardiovascular disease, not all obese subjects develop MS, hence the need for new indicators of risk for this syndrome. Advanced glycation end products (AGEs) correlate with factors involved in the MS, including inflammation and insulin resistance (IR). Because AGEs can be derived from food and are modifiable, it is important to determine whether they are a risk factor for MS.

OBJECTIVE

The objective of this study was to assess the association of endogenous and exogenous AGEs with MS criteria.

DESIGN

The following data were collected in a cross-sectional study of subjects with and without the MS: serum AGEs (sAGEs) and mononuclear cell AGEs, metabolites, pro- and antiinflammatory markers, body fat mass measures, including abdominal magnetic resonance imaging, and caloric and dietary AGE (dAGE) consumption.

SETTING

The study was conducted in the general community.

PARTICIPANTS

Participants included 130 MS and 139 non-MS subjects of both sexes, older than 50 years.

RESULTS

sAGEs ((ϵ)N-carboxymethyllysine, methylglyoxal) were markedly elevated in obese persons with more than one other MS criteria but not in obese without MS criteria. sAGEs directly correlated with markers of IR (HOMA) and inflammation (leptin, TNFα, RAGE) and inversely with innate defenses (SIRT1, AGE receptor 1 [AGER1], glyoxalase-I, adiponectin). sAGEs correlated with dAGEs but not with calories, nutrient consumption, or fat mass measures. Consumption of dAGE, but not of calories, was markedly higher in MS than in non-MS.

CONCLUSION

High sAGEs, a modifiable risk factor for IR, may indicate risk for the MS, type 2 diabetes, and cardiovascular disease. High dietary AGE consumption and serum AGE levels may link healthy obesity to at-risk obesity.

Accuracy and reproducibility of adipose tissue measurements in young infants by whole body magnetic resonance imaging

PURPOSE

MR might be well suited to obtain reproducible and accurate measures of fat tissues in infants. This study evaluates MR-measurements of adipose tissue in young infants in vitro and in vivo.

MATERIAL AND METHODS

MR images of ten phantoms simulating subcutaneous fat of an infant's torso were obtained using a 1.5T MR scanner with and without simulated breathing. Scans consisted of a cartesian water-suppression turbo spin echo (wsTSE) sequence, and a PROPELLER wsTSE sequence. Fat volume was quantified directly and by MR imaging using k-means clustering and threshold-based segmentation procedures to calculate accuracy in vitro. Whole body MR was obtained in sleeping young infants (average age 67±30 days). This study was approved by the local review board. All parents gave written informed consent. To obtain reproducibility in vivo, cartesian and PROPELLER wsTSE sequences were repeated in seven and four young infants, respectively. Overall, 21 repetitions were performed for the cartesian sequence and 13 repetitions for the PROPELLER sequence.

RESULTS

In vitro accuracy errors depended on the chosen segmentation procedure, ranging from 5.4% to 76%, while the sequence showed no significant influence. Artificial breathing increased the minimal accuracy error to 9.1%. In vivo reproducibility errors for total fat volume of the sleeping infants ranged from 2.6% to 3.4%. Neither segmentation nor sequence significantly influenced reproducibility.

CONCLUSION

With both cartesian and PROPELLER sequences an accurate and reproducible measure of body fat was achieved. Adequate segmentation was mandatory for high accuracy.

Liver transplantation arrests and reverses muscle wasting

Muscle wasting, sarcopenia, is common in advanced cirrhosis and predicts adverse outcomes while awaiting and following liver transplantation. Frequent post-transplant worsening of sarcopenia has attracted recent interest. It is unknown whether this serious problem is an expected metabolic consequence of transplantation or results from confounding conditions such as recurrent allograft liver disease or avoidable post-transplant complications. To clarify this question, we studied pre- and post-transplant muscle mass in a retrospective cohort of 40 patients transplanted for three diseases - alcoholic cirrhosis, non-alcoholic steatohepatitis cirrhosis, and primary sclerosing cholangitis cirrhosis - in whom allograft disease recurrence was monitored and excluded, and who lacked common post-transplant muscle wasting complications such as sepsis, renal failure, ischemia, and cholestasis. We measured skeletal muscle index (SMI) using computed tomography before and 12-48 months after transplant. SMI as a categorical variable significantly improved, from 18 patients above the normal cutoff pre-transplant to 28 post-transplant (p = 0.008). SMI increases were greatest in patients with the lowest pre-transplant SMI (p < 0.01). As a continuous variable, mean SMI remained stable, with a non-significant trend toward improvement. We conclude that after liver transplantation sarcopenia does not progress but is arrested and frequently improves in the absence of confounding conditions.

Quantification of abdominal fat depots in rats and mice during obesity and weight loss interventions

Background & Aims

Obesity is a leading healthcare issue contributing to metabolic diseases. There is a great interest in non-invasive approaches for quantitating abdominal fat in obese animals and humans. In this work, we propose an automated method to distinguish and quantify subcutaneous and visceral adipose tissues (SAT and VAT) in rodents during obesity and weight loss interventions. We have also investigated the influence of different magnetic resonance sequences and sources of variability in quantification of fat depots.

Materials and Methods

High-fat diet fed rodents were utilized for investigating the changes during obesity, exercise, and calorie restriction interventions (N = 7/cohort). Imaging was performed on a 7T Bruker ClinScan scanner using fast spin echo (FSE) and Dixon imaging methods to estimate the fat depots. Finally, we quantified the SAT and VAT volumes between the L1–L5 lumbar vertebrae using the proposed automatic hybrid geodesic region-based curve evolution algorithm.

Results

Significant changes in SAT and VAT volumes (p<0.01) were observed between the pre- and post-intervention measurements. The SAT and VAT were 44.22±9%, 21.06±1.35% for control, −17.33±3.07%, −15.09±1.11% for exercise, and 18.56±2.05%, −3.9±0.96% for calorie restriction cohorts, respectively. The fat quantification correlation between FSE (with and without water suppression) sequences and Dixon for SAT and VAT were 0.9709, 0.9803 and 0.9955, 0.9840 respectively. The algorithm significantly reduced the computation time from 100 sec/slice to 25 sec/slice. The pre-processing, data-derived contour placement and avoidance of strong background–image boundary improved the convergence accuracy of the proposed algorithm.

Conclusions

We developed a fully automatic segmentation algorithm to quantitate SAT and VAT from abdominal images of rodents, which can support large cohort studies. We additionally identified the influence of non-algorithmic variables including cradle disturbance, animal positioning, and MR sequence on the fat quantification. There were no large variations between FSE and Dixon-based estimation of SAT and VAT.

Validation of anthropometric indices of adiposity against whole-body magnetic resonance imaging--a study within the German European Prospective Investigation into Cancer and Nutrition (EPIC) cohorts

Background

In epidemiological studies, measures of body fat generally are obtained through anthropometric indices such as the body mass index (BMI), waist (WC), and hip circumferences (HC). Such indices, however, can only provide estimates of a person’s true body fat content, overall or by adipose compartment, and may have limited accuracy, especially for the visceral adipose compartment (VAT).

Objective

To determine the extent to which different body adipose tissue compartments are adequately predicted by anthropometry, and to identify anthropometric measures alone, or in combination to predict overall adiposity and specific adipose tissue compartments, independently of age and body size (height).

Methods

In a sub-study of 1,192 participants of the German EPIC (European Prospective Investigation into Cancer and Nutrition) cohorts, whole-body MRI was performed to determine adipose and muscle tissue compartments. Additional anthropometric measurements of BMI, WC and HC were taken.

Results

After adjusting for age and height, BMI, WC and HC were better predictors of total body volume (TBV), total adipose tissue (TAT) and subcutaneous adipose tissue (SAT) than for VAT, coronary adipose tissue (CAT) and skeletal muscle tissue (SMT). In both sexes, BMI was the best predictor for TBV (men: r = 0.72 [0.68–0.76], women: r = 0.80 [0.77–0.83]) and SMT (men: r = 0.52 [0.45–0.57], women: r = 0.48 [0.41–0.54]). WC was the best predictor variable for TAT (r = 0.48 [0.41–0.54]), VAT (r = 0.44 [0.37–0.50]) and CAT (r = 0.34 [0.26–0.41]) (men), and for VAT (r = 0.42 [0.35–0.49]) and CAT (r = 0.29 [0.22–0.37]) (women). BMI was the best predictor for TAT (r = 0.49 [0.43–0.55]) (women). HC was the best predictor for SAT (men (r = 0.39 [0.32–0.45]) and women (r = 0.52 [0.46–0.58])).

Conclusions

Especially the volumes of internal body fat compartments are poorly predicted by anthropometry. A possible implication may be that associations of chronic disease risks with the sizes of internal body fat as measured by BMI, WC and HC may be strongly underestimated.

Visceral abdominal obesity measured by CT scan is associated with an increased risk of Barrett's oesophagus: a case-control study

OBJECTIVE

Abdominal obesity has been associated with increased risk of Barrett's oesophagus (BE) but the underlying mechanism is unclear. We examined the association between visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) and the risk of BE.

DESIGN

A case-control study among eligible patients scheduled for elective oesophagastroduodenoscopy (EGD) and in a sample of patients eligible for screening colonoscopy recruited at the primary care clinic. All cases with definitive BE and a random sample of controls without BE were invited to undergo standardised mid-abdomen non-contrast computerised axial tomography images, which were analysed by semiautomated image segmentation software. The effect of VAT and SAT surface areas and their ratio (VAT to SAT) on BE were analysed in logistic regression models.

RESULTS

A total of 173 BE cases, 343 colonoscopy controls and 172 endoscopy controls underwent study EGD and CT scan. Participants with BE were more than twice as likely to be in the highest tertile of VAT to SAT ratio (OR: 2.42 (1.51 to 3.88) and adjusted OR 1.47 (0.88 to 2.45)) than colonoscopy controls, especially for those long (≥3 cm) segment BE (3.42 (1.67 to 7.01) and adjusted OR 1.93 (0.92 to 4.09)) and for white men (adjusted OR 2.12 (1.15 to 3.90)). Adjustment for gastroesophageal reflux disease (GERD) symptoms and proton pump inhibitors (PPI) use attenuated this association, but there was a significant increase in BE risk even in the absence of GERD or PPI use.

CONCLUSIONS

Large amount of visceral abdominal fat relative to subcutaneous fat is associated with a significant increase in the risk of BE. GERD may mediate some but not all of this association.

Reproducibility of ultrasonography for assessing abdominal fat distribution in a population at high risk of diabetes

Background:

Visceral fat plays an important role in the development of metabolic disease independently of the effect of overall abdominal fat. Ultrasonography is an accessible method of accurately assessing abdominal fat distribution in epidemiological studies, but few details about the reproducibility of this method have been published.

Objective:

The aim of this study was to investigate the reproducibility of ultrasonography in the assessment of abdominal fat distribution in a population at high risk of type 2 diabetes.

Design and Methods:

Ultrasonography was used to estimate visceral and subcutaneous abdominal fat. Intra- and interobserver variation, short-term variation and variation between estimates in the fasting and non-fasting state were examined in three samples of 30, 33 and 23 participants from the ADDITION-PRO study. A variance components model was used to calculate intra- and interobserver variation, and Bland–Altman plots were drawn for all three substudies.

Results:

Coefficients of variation for intra- and interobserver variation were in the range 3.4–6.1%, except for interobserver variation for subcutaneous fat (9.5%). Short-term variation over a median of 35 days had a coefficient of variation of 15%. The effect of a meal was primarily on the visceral estimates and did not extend beyond the first postprandial hour. Non-fasting visceral estimates were larger than fasting estimates.

Conclusion:

Both visceral and subcutaneous fat can be estimated with ultrasonography with adequate intra- and interobserver reproducibility by clinical researchers with limited training, making it a feasible method of assessing abdominal fat distribution in epidemiological studies.

Whole body fat: content and distribution

Obesity and its co-morbidities, including type II diabetes, insulin resistance and cardiovascular diseases, have become one of the biggest health issues of present times. The impact of obesity goes well beyond the individual and is so far-reaching that, if it continues unabated, it will cause havoc with the economies of most countries. In order to be able to fully understand the relationship between increased adiposity (obesity) and its co-morbidity, it has been necessary to develop proper methodology to accurately and reproducibly determine both body fat content and distribution, including ectopic fat depots. Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS) have recently emerged as the gold-standard for accomplishing this task. Here, we will review the use of different MRI techniques currently being used to determine body fat content and distribution. We also discuss the pros and cons of MRS to determine ectopic fat depots in liver, muscle, pancreas and heart and compare these to emerging MRI techniques currently being put forward to create ectopic fat maps. Finally, we will discuss how MRI/MRS techniques are helping in changing the perception of what is healthy and what is normal and desirable body-fat content and distribution.

Intrahepatic fat is increased in the neonatal offspring of obese women with gestational diabetes

OBJECTIVES

To assess precision magnetic resonance imaging in the neonate and determine whether there is an early maternal influence on the pattern of neonatal fat deposition in the offspring of mothers with gestational diabetes mellitus (GDM) and obesity compared with the offspring of normal-weight women.

STUDY DESIGN

A total of 25 neonates born to normal weight mothers (n = 13) and to obese mothers with GDM (n = 12) underwent magnetic resonance imaging for the measurement of subcutaneous and intra-abdominal fat and magnetic resonance spectroscopy for the measurement of intrahepatocellular lipid (IHCL) fat at 1-3 weeks of age.

RESULTS

Infants born to obese/GDM mothers had a mean 68% increase in IHCL compared with infants born to normal-weight mothers. For all infants, IHCL correlated with maternal prepregnancy body mass index but not with subcutaneous adiposity.

CONCLUSION

Deposition of liver fat in the neonate correlates highly with maternal body mass index. This finding may have implications for understanding the developmental origins of childhood nonalcoholic fatty liver disease.

Software for automated MRI-based quantification of abdominal fat and preliminary evaluation in morbidly obese patients

PURPOSE

To present software for supervised automatic quantification of visceral and subcutaneous adipose tissue (VAT, SAT) and evaluates its performance in terms of reliability, interobserver variation, and processing time, since fully automatic segmentation of fat-fraction magnetic resonance imaging (MRI) is fast but susceptible to anatomical variations and artifacts, particularly for advanced stages of obesity.

MATERIALS AND METHODS

Twenty morbidly obese patients (average BMI 44 kg/m(2) ) underwent 1.5-T MRI using a double-echo gradient-echo sequence. Fully automatic analysis (FAA) required no user interaction, while supervised automatic analysis (SAA) involved review and manual correction of the FAA results by two observers. Standard of reference was provided by manual segmentation analysis (MSA).

RESULTS

Average processing times per patient were 6, 6+4, and 21 minutes for FAA, SAA, and MSA (P < 0.001), respectively. For VAT/SAT assessment, Pearson correlation coefficients, mean (bias), and standard deviations of the differences were R = 0.950, +0.003, and 0.043 between FAA and MSA and R = 0.981, +0.009, and 0.027 between SAA and MSA. Interobserver variation and intraclass correlation were 3.1% and 0.996 for SAA, and 6.6% and 0.986 for MSA, respectively.

CONCLUSION

The presented supervised automatic approach provides a reliable option for MRI-based fat quantification in morbidly obese patients and was much faster than manual analysis.

Automatic intra-subject registration-based segmentation of abdominal fat from water-fat MRI

PURPOSE

To develop an automatic registration-based segmentation algorithm for measuring abdominal adipose tissue depot volumes and organ fat fraction content from three-dimensional (3D) water-fat MRI data, and to evaluate its performance against manual segmentation.

MATERIALS AND METHODS

Data were obtained from 11 subjects at two time points with intermediate repositioning, and from four subjects before and after a meal with repositioning. Imaging was performed on a 3 Tesla MRI, using the IDEAL chemical-shift water-fat pulse sequence. Adipose tissue (subcutaneous--SAT, visceral--VAT) and organs (liver, pancreas) were manually segmented twice for each scan by a single trained observer. Automated segmentations of each subject's second scan were generated using a nonrigid volume registration algorithm for water-fat MRI images that used a b-spline basis for deformation and minimized image dissimilarity after the deformation. Manual and automated segmentations were compared using Dice coefficients and linear regression of SAT and VAT volumes, organ volumes, and hepatic and pancreatic fat fractions (HFF, PFF).

RESULTS

Manual segmentations from the 11 repositioned subjects exhibited strong repeatability and set performance benchmarks. The average Dice coefficients were 0.9747 (SAT), 0.9424 (VAT), 0.9404 (liver), and 0.8205 (pancreas); the linear correlation coefficients were 0.9994 (SAT volume), 0.9974 (VAT volume), 0.9885 (liver volume), 0.9782 (pancreas volume), 0.9996 (HFF), and 0.9660 (PFF). When comparing manual and automated segmentations, the average Dice coefficients were 0.9043 (SAT volume), 0.8235 (VAT), 0.8942 (liver), and 0.7168 (pancreas); the linear correlation coefficients were 0.9493 (SAT volume), 0.9982 (VAT volume), 0.9326 (liver volume), 0.8876 (pancreas volume), 0.9972 (HFF), and 0.8617 (PFF). In the four pre- and post-prandial subjects, the Dice coefficients were 0.9024 (SAT), 0.7781 (VAT), 0.8799 (liver), and 0.5179 (pancreas); the linear correlation coefficients were 0.9889, 0.9902 (SAT, and VAT volume), 0.9523 (liver volume), 0.8760 (pancreas volume), 0.9991 (HFF), and 0.6338 (PFF).

CONCLUSION

Automated intra-subject registration-based segmentation is potentially suitable for the quantification of abdominal and organ fat and achieves comparable quantitative endpoints with respect to manual segmentation.