18F-FAPI-42 PET/MRI in the Evaluation of Glioma Recurrence

BACKGROUND: This study aims to evaluate the diagnostic value of 18 F-FAPI-42 PET in differentiating glioma recurrence from treatment-related changes, with comparative analyses against 11 C-MET PET and contrast-enhanced MRI (CE-MRI). PATIENTS AND METHODS: In this prospective study, patients with suspected glioma recurrence underwent concurrent 18 F-FAPI-42 PET/MRI, 11 C-MET PET/MRI, and CE-MRI examinations. Diagnostic performance for differentiating tumor recurrence was evaluated and compared across imaging modalities using McNemar test. Wilcoxon rank-sum tests were used to assess differences in SUVmax and tumor-to-background ratios (TBR) between glioma recurrence and treatment-related changes. Receiver operating characteristic curve analysis was performed to determine optimal cutoff values and compare the diagnostic efficacy of SUVmax and TBR through area under the curve (AUC) metrics. RESULTS: Among the 76 suspected glioma recurrence patients, 59 were diagnosed with recurrence and 17 had treatment-related changes. When distinguishing between recurrence and treatment-related changes, the accuracy and sensitivity of 18 F-FAPI-42 PET were comparable to those of 11 C-MET PET and CE-MRI (accuracy: 80.26% vs 86.84% vs 78.95%, respectively, all P > 0.05; sensitivity: 89.83% vs 93.22% vs 98.31%, respectively, all P > 0.05), but the specificity of 18 F-FAPI-42 PET was significantly higher than that of CE-MRI (47.06% vs 11.76%, P = 0.031). The semiquantitative analysis of PET parameters showed that SUVmax and TBR of 18 F-FAPI-42 PET and 11 C-MET PET in glioma recurrence were significantly higher than treatment-related changes (all P < 0.05). The diagnostic performance of 18 F-FAPI-42 PET TBR is outstanding (AUC: 0.940), higher than 11 C-MET SUVmax and TBR (AUC: 0.842 and 0.851, P = 0.099 and 0.080), and significantly better than 18 F-FAPI-42 SUVmax (AUC: 0.668, P < 0.001). CONCLUSIONS: The diagnostic efficacy of 18 F-FAPI-42 PET for glioma recurrence is comparable to 11 C-MET PET, and its specificity superior to CE-MRI. 18 F-FAPI-42 PET has a high TBR and advantages in delineating glioma boundaries, which may provide valuable information for therapeutic decision-making.