Bone Marrow Diffusion in Osteoporosis: Evaluation with Quantitative MR Diffusion Imaging

Abstract

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.