PET/CT using 68Ga-PSMA-617 versus 18F-fluorodeoxyglucose to differentiate low- and high-grade gliomas

Background and purpose To compare and characterize metabolic features of high- and low-grade glioma tumors using Ga-68-PSMA-617 and F-18-FDG positron emission tomography/computed tomography (PET/CT). Methods Thirty patients who underwent both Ga-68-PSMA-617 and F-18-FDG PET/CT over 2 consecutive days and then underwent surgical treatment were retrospectively identified. All tumors were diagnosed histologically. This report includes 16 high-grade glioma (HGG) and 14 low-grade glioma (LGG) tumors. Standard uptake value (SUV) and target to nontarget (T/NT) were quantitatively investigated through the entire tumor region. Statistical analyses were performed using area under the curve (AUC) and comparison of two means. Results SUVmax and SUVmean were the most effective (AUC, 0.96 and 0.94 for PSMA PET; AUC, 0.79 and 0.74 for FDG PET, respectively) for differentiating HGGs from LGGs. These methods distinguished between HGG and LGG effectively (PSMA PET: SUVmax, 5.766 +/- 3.945 vs. 0.7364 +/- 0.5295, p < 0.0001; SUVmean, 1.666 +/- 1.680 and 0.1514 +/- 0.1534, p < 0.0001, respectively) (FDG PET: SUVmax, 11.67 +/- 3.639 and 9.118 +/- 6.612; SUVmean, 5.648 +/- 2.114 and 4.435 +/- 2.872; p = 0.0083, 0.0262, respectively). The Youden index for SUVmax and SUVmean of Ga-68-PSMA-617 and F-18-FDG were 0.82 and 0.79 and 0.54 and 0.61, separately. T/NTmax was helpful for visual inspection of Ga-68-PSMA-617-PET images (T/NTmax: 1.291 +/- 0.9553 in grade II, 5.25 +/- 2.435 in grade III, and 13.61 +/- 13.84 in grade IV). T/NTmax differed significantly between LGG and HGG and between subtypes of LGG. Conclusion PET/CT with Ga-68-PSMA-617 and F-18-FDG may help distinguish between HGG and LGG, and Ga-68-PSMA-617 PET/CT is superior to(18)F-FDG in differentiating HGG and LGG.