Bone marrow uptake of thallium-201 before and after therapy in multiple myeloma

We describe a patient with multiple myeloma who was found to have diffuse bone marrow uptake of 201Tl. Magnetic resonance (MR) imaging of the lumbar spine demonstrated abnormal low signal intensity on T1-weighted images and abnormal high signal intensity on T2-weighted images. The bone marrow consisted of 68% plasma cells, and the serum immunoglobulin (Ig)G concentration was 7900 mg/dL. After receiving chemotherapy, the percentage of plasma cells and serum IgG concentration declined and there was a decrease in the bone marrow uptake of 201Tl. However, the MR abnormalities in the lumbar spine showed no change after chemotherapy. This patient illustrates a limitation of the use of MR imaging for evaluation of disease state in patients with multiple myeloma, and demonstrates the potential usefulness of 201Tl imaging in these patients.