Double-phase Tc-99m MIBI scintigraphy as a therapeutic predictor in patients with non-Hodgkin's lymphoma

Tc-99m MIBI is a promising agent for the functional characterization of P-glycoprotein expression and the prediction of therapeutic outcome in human tumors. The purpose of this study was to determine whether tumor clearance of Tc-99m MIBI may have a predictive value in the clinical outcome in patients with non-Hodgkin's lymphoma.

Seventeen patients with histologically proved non-Hodgkin's lymphoma underwent Tc-99m MIBI scintigraphy before starting chemotherapy. Early and late images were obtained after the injection of 740 MBq (20 mCi) Tc-99m MIBI. Tumor-to-normal soft tissue ratios were measured on early and late images, and the percentage retention (%R) was calculated. These findings were correlated with other prognostic factors.

Of all 40 tumor lesions, 22 (55%) showed Tc-99m MIBI tumor uptake, whereas the other 18 (45%) lesions had no uptake. According to the location, the diagnostic accuracy of Tc-99m MIBI scans was 66.7% (12 of 18) for lesions of the head and neck, 66.7% (8 of 12) for those of the chest, and 20% (2 of 10) for those of subdiaphragmatic regions (P = 0.037). The mean %R of complete responders was 91.8 +/- 14.8% and for partial responders or nonresponders it was 65.4 +/- 17.7% (P = 0.014). The %R of Tc-99m MIBI showed a significant negative correlation with the serum lactate dehydrogenase level (r = -0.757), the score of the international prognostic index (r = -0.643), and the Ann Arbor stage (r = -0.733).

The slow tumor clearance of Tc-99m MIBI can predict a good response to chemotherapy in patients with non-Hodgkin's lymphoma and differentiate responding and nonresponding tumors early in the course of chemotherapy.