PET-based response assessment criteria for diffuse gliomas (PET RANO 1.0): methodological application in [¹⁸F]-FDOPA...

The Response Assessment in Neuro-Oncology (RANO) group recently reported PET-based response assessment criteria for diffuse gliomas (PET RANO 1.0). The objective of this study was to evaluate the methodological application of these criteria for the amino acid [¹⁸F]-FDOPA radiotracer. Patients with confirmed glioma who underwent at least one baseline [¹⁸F]-FDOPA PET scan were retrospectively included. The PET RANO 1.0 criteria were evaluated regarding their methodological application. Patients with at least one follow-up PET scan were evaluated with the PET RANO 1.0 criteria as compared to the routine interpretation of two experts not using the PET RANO 1.0 criteria, defined as the reference. The different PET parameters included in the PET RANO 1.0 criteria were evaluated separately regarding their contribution.

Ninety patients (52.0 ± 15.3 years old, 56% women) were included in this study regards to the methodology of application of the PET RANO 1.0 criteria, with 86% of patients presenting measurable diseases. Among these patients, 65 patients were evaluated for the comparison between the PET RANO 1.0 criteria and the expert interpretation: a concordance of 80%, equivalent for newly diagnosed and recurrent gliomas, as well as IDH-mutant vs. IDH-wildtype gliomas was found. The metabolic tumor volume represented the most contributive parameter (71% of cases) to the definition of response according to the PET RANO 1.0 criteria. Striatum infiltration, post-treatment related effects, measurable diseases criteria and thresholds for PET RANO 1.0 criteria were related to the cases discordances.

The PET RANO 1.0 criteria can be applied with [¹⁸F]-FDOPA imaging, with a reasonable concordance with results of an expert interpretation. Description of discordant cases should help to improve future PET RANO 1.0 criteria updating.