Bone marrow scintigraphy in multiple myeloma. A comparison with bone scintigraphy and skeletal radiology

The radiographic patterns of the skeleton of 73 patients affected by multiple myeloma (MM) were compared to the correspondent scintigraphic findings. Whole body scans were performed using 99m Tc-diphosphonates (bone scintigraphy), and 99m Tc-microcolloids (bone marrow scintigraphy). The results indicate that: a) radiography is more sensitive and accurate than scintigraphy in detecting typical myeloma-related bone lesions; b) bone scintigraphy is useful in detecting alterations in particular locations--i.e., sternum, ribs, scapulae, etc.--which are difficult to demonstrate by plain X-rays; moreover, the recovery of the fractures can be visualized; c) bone marrow scintigraphy is employed to demonstrate the presence of marrow expansion, of cold/hot spots, and relative marrow uptake, related to phagocytic activity. Since in adult men red marrow is confined to the epiphysis of long bones and to the spine, all the diseases affecting bone marrow cause medullary expansion/reduction, which are both easily detected by specific radiopharmaceuticals. The peripheral expansion is clearly documented especially in distal humeri and femora since marrow uptake is included, in healthy adults, in the axial and proximal appendicular skeleton. In spite of its yielding unique information, bone marrow scintigraphy remains an additional technique of bone scan, because of its low diagnostic accuracy.