Combination of FDG, FET, FET PET and MRI in patients with glioma

309 Objectives: The aim of this study was to compare with the differences of FDG, FET and FLT PET for detection of glioma. Methods: 29 patients(high grade:low grade=22:7) who were newly diagnosed(n=5) or suspicious of recurrence(n=24) were included. Brain MRI with Gd was performed and then FLT, FET and FDG brain PET were succeeded within 1 week for all patients. ROIs corresponding to Gd enhancement in MRI were manually drawn on each PET. Then, maximal SUV(SUVmax) and the respective ratio to the background(BG) were measured. Sensitivity for each modality were evaluated. Abnormal Gd enhancement in MR and abnormal tracer uptake greater than BG on PET scan were regarded as viable tumor. Results: Histological confirmation was performed in 7(newly diagnosed in 5) of 29 patients, and 22 of 29 patients were clinically follow up. The overall sensitivity of FDG, FLT, FET PET and MRI were 55%, 85%, 100% and 100%. Among 24 patients who were suspicious of recurrence, 18 patients were recurred. In patients with FDG negative(n=17) who were suspicious of recurrence, sensitivity of FLT, FET and MR were 77% 100% and 100%, and specificity were 100%, 57% and 67%. In FDG positive case(n=7), all recurred glioms were detected on FLT, FET and MRI. Mean SUVmax of FLT, FET and FDG were 1.26, 2.20 and 6.08. Mean tumor to BG ratio of FLT, FET and FDG were 4.00, 1.90 and 1.17. In recurred patients, mean tumor to BG ratio of FET had statistically significant differences between high grade and low grade(tumor to BG ratio, 2.15 vs. 1.71; p=0.049) but FDG and FLT had no significant differences. Conclusions: Tumor to BG ratio of FET could be useful in grading of glioma. In FDG nagative case, combination of FLT and FET PET could be useful to detection of glioma, considering sensitivity and specificity.