Magnetic Resonance Imaging of the Bone Marrow: Malignant Lymphoma – Multiple Myeloma – Bone Marrow

Abstract

Magnetic resonance imaging (MRI) has become the most applied imaging technique 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 patients with hematologic malignancies by elucidating osseous and extra-osseous components in their relationships to nerves and vessels. Moreover, MRI permits the detection of bone marrow abnormalities before skeletal lesions become evident on plain radiographs, but it cannot reliably predict the histological nature of a marrow lesion, just like bone marrow scintigraphy. Almost every third of the patients who have had negative bone marrow biopsies for malignant lymphoma, will be recognized as suffering from marrow involvement on a subsequent MR imaging procedure. Consequently, the clinical stage IV will 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 depicting all types of marrow involvement. To assess the local extent of the tumor and to search for other thus far hidden foci of the disease, the technique has become an integral part of the staging procedure in patients with solitary plasmacytoma. All three fundamental MR patterns of abnormal bone marrow have been observed in patients with multiple myeloma, the focal one being most frequent. The prognostic significance of the different MR patterns is controversial. MRI identifies patients at high risk for the development of vertebral collapses, but cannot predict the time and precise level of the fracture. The criteria defined for differentiating benign and malignant vertebral collapses at MRI are quite reliable. Quantitative MRI seems to enable monitoring of treatment response. The typical fatty appearance of the irradiated spine is irreversible for doses exceeding 30 Gy and serves as a dependable indicator for the extent of the irradiation field. MRI can direct harvest procedures for autologous bone marrow transplantation to sites of relatively unaffected marrow. In the evaluation of the status of bone marrow after transplantation, quantitative contrast-enhanced MRI seems to be a promising new tool, because the degree and rate of gadolinium chelate uptake depends on the cellularity of the marrow.