Investigation of usability of MET PET compared with FDG PET in prostate cancer

1632 Objectives: Primary prostate cancer (PC) was difficult to diagnosis with F-18 Fluorodeoxyglucose (FDG) PET, because physiological accumulation of urinary bladder was disturbing in detecting PC. Our purpose was to investigate of usability of C-11 methionine (MET) PET, which images was no physiological accumulation of urinary bladder, for detecting PC in patients with increased prostate specific antigen (PSA) levels and positive biopsies; no previous study assessed MET PET compared to FDG PET in detecting rate of PC. Methods: Twenty patients (20 men, aged 55-80 years, mean 71.2, PSA level ranged from 5.2 to 3132 ng/ml) with PC by histopathological biopsy (moderate differenciated adenocarcinoma 6, poor differenciated adenocarcinoma 14, and Gleason’s score 5 to 10) were investigated with FDG PET and MET PET. Both PET images were obtained 1 hour (FDG early image: FDGe) and 2 hours (FDG delayed image: FDGd) and 20min (MET PET) after injection of 185 MBq of each tracer with PET camera. The results were then evaluated by the maximum standardized uptake value (SUVmax) in CT fused image. Results: The overall detection rate of MET PET was 60.0% (12/20) that was higher than 40.0% (8/20) of FDG PET. Each SUVmax of MET, FDGe, FDGd uptake in prostate gland was 3.58+/-1.35 (n=12), 4.27+/-2.15 (n=8), 4.88+/-2.82 (n=8). There was no significant correlation with SUVmax and PSA levels and Gleason’s score. Bone metastasis was detected in three patients of PC, the detection rate of MET PET was 100.0% (3/3) that was higher than 66.6% (2/3) of FDG PET. Conclusions: In conclusion, MET PET was considered to be more useful for detecting PC than FDG PET. Additionally MET PET was more superior to FDG PET in detecting bone metastasis. Because the SUVmax of MET PET had no definite correlation with PSA and Gleason’s score, MET PET would reflect another causes example for biological behavior in PC.