MRI‐Measured Bone Marrow Adipose Tissue: Changes During Weight Loss and Its Relationship with DXA‐Measured Bone Mineral

Previous studies suggest that bone marrow adipose tissue (BMAT) plays a role in the pathogenesis of osteoporosis and we reported a strong negative correlation between pelvic BMAT and total body bone mineral density (TBMD) in women. In the present study we evaluated 10 subjects undergoing 12 weeks of weight loss on a low calorie diet [age, 44.3 ± 13.8 yrs; BMI, 31.9 ± 3.1 kg/m 2 ; weight, 87.0 ± 10.1 kg]. Adipose tissue depots were measured with whole‐body MRI [total body (TAT), 43.2 ± 9.3 L; subcutaneous (SAT), 40.2 ± 8.8 L; visceral (VAT), 3.0 ± 1.9 L; total BMAT, 1.49 ± 0.42 L; pelvic BMAT, 0.19 ± 0.12 L]. TBMD (1.23 ± 0.07 g/cm 2 ) was measured by dual‐energy absorptiometry (GE Lunar DPX). Subjects lost weight (5.2 ± 4.1 kg) with significant reductions in TAT, SAT and VAT (all P < 0.05); there was a non‐significant increase in total and pelvic BMAT and a non‐significant decrease in TBMD (p > 0.5). The correlation coefficient between pelvic BMAT and BMD was −0.516 (p=0.13) at baseline and −0.446 (p=0.23) after weight loss thus replicating the previously observed negative association of pelvic BMAT and TBMD. The correlation coefficient between the change in pelvic BMAT and TBMD was 0.298 (p=0.436) without adjustment and 0.266 (p= 0.266) with adjustment for baseline pelvic BMAT and TBMD. BMAT does not appear to decrease as do other adipose tissue depots during weight loss, a finding that needs confirmation in a larger sample.