Magnetic resonance imaging of the bone marrow: Malignant lymphoma - Multiple myeloma - Bone marrow transplantation

Magnetic resonance imaging (MRI) has become the most applied imaging techni que in evaluating lymphomatous diseases, multiple myeloma, myelodysplastic syndromes, and gross therapeutic effects in bone marrow. The tomograms help explain the etiology of pain, palsy, and other clinical symptoms in patien ts with hematologic malignancies by elucidating osseous and extraosseous co mponents in their relationships to nerves and vessels. Moreover, MRI permit s the detection of bone marrow abnormalities before skeletal lesions become evident on plain radiographs, but it cannot reliably predict the histologi cal nature of a marrow lesion, just like bone marrow scintigraphy. Almost e very third of the patients who have had negative bone marrow biopsies for m alignant lymphoma, will be recognized as suffering from marrow involvement on a subsequent MR imaging procedure. Consequently, the clinical stage IV w ill be assigned to a remarkable percentage of patients on the basis of MRI results. In multiple myeloma, MRI has proved to be very reliable for depict ing all types of marrow involvement. To assess the local extent of the tumo r and to search for other thus far hidden foci of the disease, the techniqu e has become an integral part of the staging procedure in patients with sol itary plasmacytoma. All three fundamental MR patterns of abnormal bone marr ow have been observed in patients with multiple myeloma, the focal one bein g most frequent. The prognostic significance of the different MR patterns i s controversial. MRI identifies patients at high risk for the development o f vertebral collapses, but cannot predict the lime and precise level of the fracture. The criteria defined for differentiating benign and malignant ve rtebral collapses at MRI are quite reliable. Quantitative MRI seems to enab le monitoring of treatment response. The typical fatty appearance of the ir radiated spine is irreversible for doses exceeding 30 Gy and serves as a de pendable indicator for the extent of the irradiation field. MRI can direct harvest procedures for autologous bone marrow transplantation to sites of r elatively unaffected marrow. In the evaluation of the status of bone marrow after transplantation, quantitative contrast-enhanced MRI seems to be a pr omising new tool, because the degree and rate of gadolinium chelate uptake depends on the cellularity of the marrow.