P14.98 Improving the targeting of Gamma-Knife radiosurgery for recurrent high-grade gliomas (WHO grades III and IV) with 11C-Methionine PET/CT
Abstract BACKGROUND The survival of the patients with high-grade gliomas may be improved through a multidisciplinary approach including stereotactic re-irradiation such as Gamma-Knife at recurrence in a selected population. We report our experience in targeting the hypermetabolic areas of high-grade gliomas using 11C-Methionine PET/CT in selected patients. MATERIAL AND METHODS We retrospectively evaluated the local response in patients treated by Gamma-Knife for recurrent high-grade gliomas in our Institution between 2000 and 2018, targeting the hypermetabolic area with Methionine PET/CT. RESULTS We included 25 patients bearing high-grade gliomas (14 female, 11 male) with a median age of 45 years (5–64). There were 11 WHO grade III gliomas (6 astrocytomas, 5 oligodendrogliomas) and 14 glioblastomas. A total number of 33 Gamma-Knife procedures were performed. In all patients, the targeting was based on the hypermetabolic area as defined by Methionine PET/CT. Four patients were treated concomitantly on 2 or more targets. One patient was treated twice on different targets. We observed a positive response in 29 Gamma-Knife procedures, after a median interval of 2 months (1–33) and no response after 4 procedures (4 glioblastomas). In most cases, progression after Gamma-Knife was observed 4 months after irradiation. CONCLUSION Targeting the hypermetabolic areas with Methionine PET/CT was associated with favorable response in most patients treated by Gamma-Knife radiosurgery for local high-grade gliomas recurrence. Our results must be confirmed by a prospective study with regular and homogeneous morphological and metabolic monitoring.
