Choroid Plexus as the Best Reference Region for Standardized Uptake Value Analysis on C11-Acetate PET/CT for Grading and Predicting Prognosis in Patients with Cerebral Gliomas.

PURPOSE: We aimed to compare different reference regions and select one with the most clinical relevance on C11-acetate (ACE) positron emission tomography/computed tomography (PET/CT) in patients with cerebral glioma.
METHODS: We retrospectively reviewed 51 patients with cerebral glioma who underwent baseline ACE PET/CT at diagnosis. Other than the standardized uptake value (SUV) of the primary tumor, SUVs of the reference regions including the normal gray matter, white matter, choroid plexus, and cerebellum were measured. Then, the SUV ratio (SUVR = tumor SUVmax/reference region SUVmean) was calculated. The effect of patient age on the SUVmean of each reference was examined and the SUVRs of each reference region were compared between grades. age, sex, tumor size, histological grades, SUVR, and the presence of isocitrate dehydrogenase (IDH) mutation were included for survival analyses.
RESULTS: Except for the cerebellum showing a mild negative correlation, we found no correlations between age and SUVmean using the gray matter, white matter, and choroid plexus (r = - 0.280, P = 0.047). Only the SUVR-choroid plexus was able to differentiate between the WHO grades (Grade II vs. III, P = 0.035; grade III vs. IV, P < 0.001; grade II vs. IV, P < 0.001). Multivariate Cox proportional hazards models found that the SUVR-choroid plexus and IDH mutation were statistically significant for predicting OS.
CONCLUSION: Of the different reference regions used for grading cerebral gliomas, the choroid plexus was found to be the most optimal. In addition, the SUV ratio is useful to predict the overall survival in the model with the choroid plexus as a reference region. © Korean Society of Nuclear Medicine 2020.