Scintigraphy with technetium-99m methoxyisobutylisonitrile in multiple myeloma patients: correlation with the International Staging System.

(99m)Tc-2-methoxyisobutylisonitrile ((99m)Tc-MIBI) scintigraphy has been suggested in multiple myeloma (MM) patients. According to the International Staging System (ISS), serum b2-microglobulin (Sbeta(2)M) and serum albumin (SA) are dominant predictive factors and different cut-off values of these factors can separate patients into various stages of the disease. The purpose of this study was to assess the relationship between ISS staging, by Sbeta(2)M and SA, and the (99m)Tc-MIBI scan findings. Twenty-five MM patients have been studied. Eighteen patients were at stage I, three at stage II and four at stage III of MM. (99m)Tc-MIBI scans were obtained and scored according to intensity (I) and extent (E) of the radiotracer uptake. A summed score (S) for the (99m)Tc-MIBI scan was calculated for each patient. A statistically significant negative correlation between E, I and S uptake scores versus the SA levels (P=0.004, 0.049 and 0.018 respectively), as well as a statistically significant positive correlation between E and S scores and the Sbeta(2)M levels (P=0.012 and 0.032) were detected. A statistically significant difference between the E and S uptake scores among the MM patients examined for every stage separately was also found (P=0.007 and 0.024 respectively). The gradual increase of the E and S scores across the three stages of MM was also significant (P=0.003 and 0.021 respectively), despite the relatively small number of patients in stages II and III. In seven patients who died at the end of the follow-up period all three scores were significantly increased as compared to the scores of the patients who remained alive at that time. In conclusion, this study provides additional evidence that (99m)Tc-MIBI scan not only reflects myeloma disease activity in bone marrow but it is also well correlated with the Sbeta(2)M and SA levels according to ISS.