Purpose:To investigate the associations between ectopic and serum lipid levels and bone marrow fat, as a marker of stem cell differentiation, in young obese men and women, with the hypothesis that ectopic and serum lipid levels would be positively associated with bone marrow fat. Materials and Methods:The study was institutional review board approved and complied with HIPAA guidelines. Written informed consent was obtained. spectroscopy by using a point-resolved spatially localized spectroscopy sequence at 3.0 T of L4 for bone marrow fat content, of soleus muscle for intramyocellular lipids (IMCL), and liver for intrahepatic lipids (IHL), serum cholesterol level, serum triglyceride level, and measures of insulin resistance (IR). Exercise status was assessed with the Paffenbarger activity questionnaire. Results:There was a positive correlation between bone marrow fat and IHL (r = 0.21, P = .048), IMCL (r = 0.27, P = .02), and serum triglyceride level (r = 0.33, P = .001), independent of BMI, age, IR, and exercise status (P , .05). High-density lipoprotein cholesterol levels were inversely associated with bone marrow fat content, independent of BMI, age, IR, and exercise status (r = 20.21, P = .019). Conclusion:Results of this study suggest that ectopic and serum lipid levels are positively associated with bone marrow fat in obese men and women.q RSNA, 2013

Purpose Women with anorexia nervosa (AN) have increased marrow fat despite severe depletion of body fat. Recent studies have suggested that marrow fat composition may serve as a biomarker for bone quality. The purpose of our study was to investigate marrow fat composition of the femur using proton MR spectroscopy (1H-MRS), and the relationship between measures of marrow fat composition and BMD and body composition in women with AN and normal-weight controls. Materials and Methods 14 women with AN (29.5±1.9 years) and 12 age-matched normal-weight controls underwent 1H-MRS to determine total marrow fat content and marrow fat composition of the femoral diaphysis and soleus intramyocellular lipids und unsaturated muscle lipids. MRI was performed to quantify abdominal fat, thigh fat and muscle. Lumbar spine BMD, fat and lean mass were assessed by DXA. Results Subjects with AN had higher marrow fat content (p<0.05), but similar marrow fat composition (p >0.05) compared to normal-weight controls. There was an inverse association between marrow methylene protons, an estimate of fatty acid (FA) saturated bonds, and lumbar spine BMD (r= -0.52, p=0.008) independent of %ideal body weight (%IBW). Olefinic protons at 5.3 ppm, an estimate of FA unsaturated bonds, were inversely associated with body fat depots, independent of %IBW, and positively associated with soleus unsaturation (p≤0.05). Conclusion Women with AN have higher total femoral marrow fat but similar composition compared to normal-weight controls. The degree of marrow FA saturation correlates inversely with BMD, suggesting that saturated lipids may have negative effects on BMD. The degree of marrow FA unsaturation correlates positively with soleus unsaturation, suggesting that marrow fat composition may be influenced by the same factors as ectopic lipid composition in muscle.

Neck fat compartments expand differently with increasing adiposity, correlate with CVD risk factors, and are associated with metabolic syndrome, most notably NATpost and NATsc in women. Although neck circumference remains an important method to assess metabolic risk, cross-sectional NAT assessment provides further insight into fat accumulation in the neck. This trial was registered at clinicaltrials.gov as NCT02205021.

).q RSNA, 2015 Purpose:To test the performance of dual-energy computed tomography (CT) in the assessment of marrow adipose tissue (MAT) content of the lumbar spine by using proton (hydrogen 1 [ 1 H]) magnetic resonance (MR) spectroscopy as a reference standard and to determine the influence of MAT on the assessment of bone mineral density (BMD). Materials andMethods:This study was institutional review board approved and complied with HIPAA guidelines. Written informed consent was obtained. Twelve obese osteopenic but otherwise healthy subjects (mean age 6 standard deviation, 43 years 6 13) underwent 3-T 1 H MR spectroscopy of the L2 vertebra by using a point-resolved spatially localized spectroscopy sequence without water suppression. The L2 vertebra was scanned with dual-energy CT (80 and 140 kV) by using a dual-source multi-detector row CT scanner with a calibration phantom. Mean basis material composition relative to the phantom was estimated in the L2 vertebra. Volumetric BMD was measured with and without correction for MAT. Bland-Altman 95% limits of agreement and Pearson correlation coefficients were calculated. Results:There was excellent agreement between 1 H MR spectroscopy and dual-energy CT, with a mean difference in fat fraction of 20.02 between the techniques, with a 95% confidence interval of 20.24, 0.20. There was a strong correlation between marrow fat fraction obtained with 1 H MR spectroscopy and that obtained with dual-energy CT (r = 0.91, P , .001). The presence of MAT led to underestimation of BMD, and this bias increased with increasing MAT content (P , .001). Conclusion:Dual-energy CT can be used to assess MAT content and BMD of the lumbar spine in a single examination and provides data that closely agree and correlate with 1 H MR spectroscopy data.q RSNA, 2015