Predictive value of technetium-99m sestamibi in patients with multiple myeloma and potential role in the follow-up

Technetium-99m 2-methoxyisobutylisonitrile (Tc-99m-MIBI or setamibi) has re cently been proposed for use in the evaluation of multiple myeloma (MM). Th e aims of this study were to investigate its potential predictive value in patients with MM and its possible role in the follow-up. Thirty patients wi th MM who had undergone two Tc-99m-MIBI scintigraphic studies at least 2 mo nths apart constituted the study group; 22 of them received chemotherapy in the interval between the two scans. The scans were classified as showing p attern N when only physiological uptake was present, pattern D when diffuse bone marrow uptake was observed, pattern F when areas of focal uptake of t he tracer were evident, and pattern F+D when both D and F patterns were obs erved. Comparative Tc-99m-MIBI scintigraphy was considered indicative of di sease progression when there was a worsening of the pattern (i.e. from N to D, or from N or D to F or to F+D) or an increase in the pattern D semiquan titative score. It was considered indicative of disease improvement when th e opposite trend was observed; otherwise, it was considered to document a s table condition. A significant association was observed between the baselin e scintigraphic pattern and clinical status at follow-up in the group of pa tients evaluated after chemotherapy (chi (2)=16.7, P<0.05). A negative base line Tc-99m-MIBI scintigram showed a high predictive accuracy (100%) for re mission, while the presence of pattern F or F+D was often associated with a less favourable outcome. A multivariate analysis showed that Tc-99m-MIBI u ptake pattern has an added value in relation to known prognostic variables such as C-reactive protein. Tc-99m-MIBI scintigraphy patterns at follow-up were significantly associated with the clinical status evaluated after chem otherapy (<chi>(2)=32.6, P<0.0001). Considering pattern N as indicating rem ission, pattern D stable condition, and pattern F or F+D progressive diseas e, a high concordance between scintigraphic findings and clinical status wa s found in the 22 patients undergoing chemotherapy (91%), Variation in Tc-9 9m-MIBI findings comparing baseline and follow-up evaluations was significa ntly associated with clinical status both in patients undergoing chemothera py (<chi>(2)=26.5, P<0.0005) and in those not undergoing chemotherapy (<chi >(2)=8.0, P<0.005). In conclusion, the results of this study suggest a prog nostic value of Tc-99m-MIBI scintigraphy in patients with MM and a potentia l role during the follow-up.