99mTc-MIBI scintigraphy in untreated stage III multiple myeloma: comparison with X-ray skeletal survey and bone scintigraphy.

Technetium-99m 2-methoxyisobutylisonitrile (99mTc-MIBI) is a lipophilic agent that has been proposed as a useful tracer for the detection of disease sites in patients with multiple myeloma (MM). We performed a prospective study to determine the potential of 99mTc-MIBI imaging for the evaluation of the extent of primary disease in patients with advanced stage MM, compared with skeletal survey and bone scintigraphy. Twenty patients with advanced stage MM at initial diagnosis underwent whole-body 99mTc-MIBI imaging, together with contemporaneous skeletal survey and bone scintigraphy. The findings of 99mTc-MIBI imaging were correlated with the results of skeletal survey and bone scan. All 99mTc-MIBI scans were positive for the presence of active MM, whereas skeletal surveys were positive in 18 patients (90%) with osteolytic lesions. Bone scintigraphy demonstrated MM in only 15 patients (75%). In two patients with no detectable lesions on skeletal survey, 99mTc-MIBI imaging revealed uptake in the spine, corresponding to the abnormalities seen on magnetic resonance imaging (MRI). With respect to the localization of bone lesions, 99mTc-MIBI imaging was superior to bone scintigraphy in 15 patients (75%) and had concordant results with bone scintigraphy in four (20%). 99mTc-MIBI imaging is a very sensitive imaging modality for the identification of the extent of disease in patients with advanced MM. It is clearly superior to bone scintigraphy and complements the results of skeletal survey by finding additional disease sites. Hence, in active MM patients, 99mTc-MIBI imaging has the potential to detect bone marrow disease that cannot be detected by skeletal survey and bone scintigraphy.