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/mm(2). 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+/-0.12x10(-3) mm(2)/second) than normal premenopausal women (0.50+/-0.09x10(-3) mm(2)/second). Mean ADC values were significantly lower both in subjects with reduced BMD (0.41+/-0.10x10(-3) mm(2)/second) and normal BMD (0.43+/-0.08x10(-3) mm(2)/second) compared to normal controls (0.49+/-0.07x10(-3) mm(2)/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.