MAGNETIC-RESONANCE BONE DENSITOMETRY - COMPARISON OF DIFFERENT METHODS BASED ON SUSCEPTIBILITY

RATIONALE AND OBJECTIVES. Three different magnetic resonance technique s for the assessment of the density of trabecular bone are presented a nd compared. METHODS. All methods are based on the susceptibility diff erence between marrow and bony components, Localized spectroscopic (PR ESS single voxel spectroscopy) and two different imaging approaches (F LASH gradient echo imaging and MAGSUS imaging) are demonstrated to be sensitive to the trabecular structures on application to the distal fe mur of a healthy volunteer. This region was chosen because a continuou s rarefication of the trabecular density from the epiphysis to the met aphysis occurs physiologically. In addition, results from the heel-bon es of five young healthy volunteers were compared with data from three patients with severe osteoporosis. RESULTS. All methods allowed diffe rentiation between the two groups. Advantages and disadvantages of the methods concerning spatial resolution, preparation and measuring time , necessity of postprocessing, problems with shim adjustment, and occu rrence of several chemical shift components are reported. The MAGSUS t echnique combines simple application and avoidance of postprocessing f or at least qualitative assessment of bone density with sufficient spa tial resolution. CONCLUSIONS. A reliable assessment of osteoporosis by magnetic resonance is possible in peripheral marrow regions of adults , Further studies are needed to establish standard measuring protocols .