H-1 MR spectroscopy of the lumbar spine in bone demineralization of patients suffering from diffuse multiple myeloma or osteoporosis.

Purpose: To evaluate the role of in vivo H-1 MR spectroscopic determination of relaxation times and of fat and water content to differentiate between infiltration of multiple myeloma or osteoporosis in patients with roentgeno logic unclear demineralization of the lumbar spine. Patients, Materials and Methods: Ten patients each with osteoporotic reduction of bone mineral den sity (BMD), histologically proven multiple myeloma who showed only diffuse tumor manifestations without tumor compression fractures in the spine, and volunteers were investigated. Osteoporosis was confirmed by dual-energy X-r ay absorptiometry (DXA) (Hologic QDR 2000 device, Siemens Medical Systems). The MR investigations were performed with a 1.5 T whole body system (Gyros can S15/ACS II, Philips Medical Systems). Localized MR spectra from a cubic volume of about 8 cm(3) were acquired by the PRESS technique. Chemical shi ft selective T-1 relaxation times were obtained from an IR series, T-2 was measured by variation of the interval between the first and the second echo in the volume selection scheme. Statistical analysis was done using the Kr usKal-Wallis test and the Mann-Whitney test with the software SPSS. Results : There were highly significant differences in T-2 values and fat content b etween patients with osteoporosis and multiple myeloma. T-2 values were dec reased in osteoporosis (37 ms and 59 ms vs. 44 ms and 70 ms in plasmocytoma ) and fat content was decreased in multiple myeloma (20% vs 31% and 34% in volunteers and osteoporosis). Between volunteers and patients with osteopor osis the differences in the T-2 of the fat component was significantly diff erent. Conclusions: In our preliminary experience MRS is helpful in the dif ferential diagnosis of bony demineralization. It enables a differentiation between osteoporosis and diffuse multiple myeloma. T-2 value measurements m ay be helpful in the diagnostic trial of osteoporosis.