Value of Tc-99m sestamibi scintigraphy in the detection of bone lesions inmultiple myeloma: comparison with Tc-99m methylene diphosphonate

Technetium 99m-2-methoxyisobutylisonitrile (Tc-99m MIBI) is a lipophilic ag ent that accumulates preferentially within living malignant cells due to th e higher transmembrane electrical potential as a consequence of the higher metabolic rate than in the surrounding normal cells. It has been effectivel y used to detect malignant tumors at diagnosis and follow-up and has been r eported to be useful in detecting disease lesions in multiple myeloma. We s tudied 28 consecutive patients with multiple myeloma at diagnosis to determ ine the value of Tc-99m MIBI in comparison with Tc-99m methyl ene diphospho nate (MDP), conventional X-rays, computed tomography (CT) scan, and magneti c resonance imaging (MRI). We found 26 patients with obvious osteolytic les ions in X-rays, 22 patients with positive Tc-99m MIBI scans, and 15 patient s with positive Tc-99m MDP scans. There was no coincidence of the positive lesions in the two scans, while in two patients the osteolytic areas were p ositive in the Tc-99m MDP scans, and in one case the osteolytic area was po sitive in the Tc-99m MIBI scan. The intensity of Tc-99m MIBI scans correlat ed with disease activity as determined by lactate dehydrogenase (LDH) (p < 0.05), C-reactive protein (CRP) (p < 0.01), beta (2)-microglobulin (p < 0.0 5), and serum ferritin (p < 0.01). We believe that Tc-99m MIBI scintigraphy can detect bone marrow lesions in myeloma patients that cannot be detected by other imaging methods and that it can be useful especially in solitary myeloma to exclude other involved sites. In addition, it could be a prognos tic factor related to disease activity and multidrug resistance. We believe that a multicenter study is needed to evaluate the usefulness of this agen t.