The value of 99mTc-MIBI whole body scintigraphy in active and in remission multiple myeloma.

Technetium-99m methoxy-isobutyl-isonitrile (99mTc-MIBI) has been proposed as an in-vivo marker of various active malignant diseases. The goal of this study was to evaluate the 99mTc-MIBI whole body scintiscan for the early detection of multiple myeloma (MM), active or in remission. We have studied 43 patients with MM, 32 men and 11 women aged 52+/-10 years. Group A patients had active MM disease (29 cases) and Group B patients had MM disease in remission (14 patients). Plasma proteins, serum immuno-electrophoresis, bone marrow biopsy, whole body 99mTc-MIBI scan and serum bio-chemical tests (ESR, and serum alkaline phosphatase) were carried out in each patient for the diagnosis of active or relapsed disease, or remission. Clinical and laboratory evaluation was made by two oncologists. Scintigraphic images were interpreted by three nuclear physicians who were blinded to the patients' clinical condition. The extension scale of the lesions on scintigraphy (E-score) was categorized into E0-E3. The intensity of radiotracer uptake throughout the skeleton (I-score) was also classified from I0-I3 as compared to the intensity of myocardial uptake. All patients were followed for at least one year and reassessed by the end of the year for confirming active-relapsed disease or remission. One-way analysis of variances and Spearman correlation coefficient were used for statistical data analysis. The sensitivity, specificity, positive and negative predictive values and accuracy of the 99mTc-MIBI scan for determining active or relapsed cases were: 69%, 100%, 100%, 61% and 79%, respectively. There were significant differences in scan pattern, intensity, and extension of the lesions in patients with active-relapsed disease versus those in remission (P<0.001). It is concluded that the pattern of extension and intensity of 99mTc-MIBI uptake in MM patients is associated with disease activity. Hence, in addition to the hematological and pathological findings, the 99mTc-MIBI scan may be considered as a relatively accurate non-invasive technique for the differential diagnosis of active-relapsed from in remission MM.