The roles of ¹¹C-acetate PET/CT in predicting tumor differentiation and survival in patients with cerebral glioma

Purpose: This prospective study aimed to evaluate the clinical values of ¹¹C–acetate positron emission tomography/computed tomography (PET/CT) in predicting histologic grades and survival in patients with cerebral glioma. Methods: Seventy-three patients with surgically confirmed cerebral gliomas (19 grade II, 21 grade III, and 33 grade IV) who underwent ¹¹C–acetate PET/CT before surgery were included. Tumor-to-choroid plexus ratio (TCR), which was defined as the maximum standardized uptake value (SUV) of tumors to the mean SUV of choroid plexus, was compared between three World Health Organization (WHO) grade groups. Moreover, metabolic tumor volumes (MTV) were calculated. Progression-free survival (PFS) and overall survival (OS) curves were plotted using the Kaplan–Meier method, and differences in survival between groups were assessed using the log-rank test. Results: Median TCR was 1.20 (interquartile range [IQR], 1.14 to 1.4) in grade II, 1.65 (IQR, 1.26 to 1.79) in grade III, and 2.53 (IQR, 1.93 to 3.30) in grade IV gliomas. Significant differences in TCR were seen among the three WHO grade groups (P < 0.001). In Cox regression analysis including TCR, MTV, molecular markers, and other clinical factors, TCR was prognostic for PFS (P = 0.016) and TCR and MTV were prognostic for OS (P = 0.024 [TCR], P = 0.030 [MTV]). PFS and OS were significantly shorter in patients with a TCR ≥ 1.6 than in those with a TCR < 1.6. OS were significantly shorter in patients with a MTV ≥ 1 than in those with a TCR < 1. Conclusions: TCR on ¹¹C–acetate PET/CT significantly differed between low- and high-grade cerebral gliomas, and it showed the capability to further differentiate grade III from grade IV tumors. TCR and MTV were independent prognostic factors and predicted survival better than did the WHO grade.