Tc99m-sestaMIBI uptake in nonsecretory multiple myeloma.

Staging and monitoring of multiple myeloma (MM) is mainly based on monoclonal component quantification; the absence of such a parameter renders difficult follow up of patients with nonsecretory MM (nsMM). In this study our aims were to determine the specificity and sensitivity of Tc99m-sestaMIBI scintigraphy at diagnosis and during follow up of nsMM patients. Nine nsMM patients were prospectively studied at diagnosis and during treatment for a mean time of 33 months (range: 12-65+). Tc99m-sestaMIBI (MIBI) scintigraphy was compared to conventional imaging (CI: X ray with CAT or NMR details) at diagnosis and during follow up. At diagnosis, CI and MIBI were concordant in three patients; CI showed more focal lesions than MIBI in four patients, while MIBI revealed more focal lesions than CI in two patients. During the follow up, MIBI uptake was normal in the four patients who achieved remission. Five patients did not achieve remission: CI and MIBI were concordant in three, while MIBI was falsely negative in two patients. In conclusion, Tc99m-sestaMIBI scintigraphy has high sensitivity (no false positive cases) and 78% specificity (2/9 false negative cases) in tracing active nsMM lesions; it should be considered complementary to CI for monitoring this rare disease.