PREDICTING MALIGNANCY GRADE WITH PET IN NON-HODGKINS-LYMPHOMA

Our goal was to determine whether PET with C-11-methionine and/or (18) FDG could predict malignancy grade in non-Hodgkin's lymphoma (NHL). Me thods: Twenty-three patients with high-grade, low-grade or transformed low-grade NHL were investigated. Standardized uptake values (SUV), tr ansport rate and mass influx values were calculated both for the whole tumor [mean regions of interest, (ROI)] and for the tumor area with t he highest levels of activity, comprising four contiguous pixels withi n each tumor and designated as a hot spot. Results: Both C-11-methioni ne and (18)FDG detected all tumors. In addition, (18)FDG discriminated between high- and low-grade NHL, whereas C-11-methionine did not. Wit h (18)FDG, three transformed low-grade NHLs behaved in an intermediate manner. All quantitative uptake values correlated well with each othe r for both tracers, except for the mean ROI SUV and transport rate of C-11-methionine. Quantifications of mean ROI uptake and hot spots were strongly correlated. Conclusion: The results of this study together w ith previous findings from other studies indicate that (18)FDG but not C-11-methionine can predict malignancy grade in NHL. Further studies with a larger series of patients are needed.