Bone marrow diffusion in osteoporosis: Evaluation with quantitative MR diffusion imaging

Purpose To determine the diffusion of vertebral body marrow with quantitative MR diffusion imaging and to examine whether differences exist between subjects with postmenopausal osteoporosis and premenopausal control subjects. Materials and Methods A total of 44 consecutive women (mean age, 70 years) with documented bone mineral density (BMD) measured by dual energy x‐ray absorptiometry (T‐score) and 20 normal subjects (mean age, 28 years) were examined with echo‐planar diffusion imaging at 1.5 T using b values of 0, 20, 40, 60, 80, 100, 200, 300, 400, and 500 seconds/mm2. Extravascular diffusion (D) and apparent diffusion coefficient (ADC) were calculated and results from both groups compared. Results Both D and ADC values tended to decrease with decreasing BMD. Mean D values were significantly lower in postmenopausal women with reduced BMD (0.42 ± 0.12 × 10–3 mm2/second) than normal premenopausal women (0.50 ± 0.09 × 10–3 mm2/second). Mean ADC values were significantly lower both in subjects with reduced BMD (0.41 ± 0.10 × 10–3 mm2/second) and normal BMD (0.43 ± 0.08 × 10–3 mm2/second) compared to normal controls (0.49 ± 0.07 × 10–3 mm2/second). Conclusion Accumulation of fatty bone marrow associated with osteoporosis is reflected by a decrease in D and ADC. Diffusion imaging may prove useful in the study of osteoporosis. J. Magn. Reson. Imaging 2004;19:222–228. © 2004 Wiley‐Liss, Inc.