The role of [(18)F]fluorodopa positron emission tomography in grading of gliomas

PURPOSE: Gliomas are the most commonly occurring brain tumour in adults and there remains no cure for these tumours with treatment strategies being based on tumour grade. All treatment options aim to prolong survival, maintain quality of life and slow the inevitable progression from low-grade to high-grade. Despite imaging advancements, the only reliable method to grade a glioma is to perform a biopsy, and even this is fraught with errors associated with under grading. Positron emission tomography (PET) imaging with amino acid tracers such as [(18)F]fluorodopa ((18)F-FDOPA), [(11)C]methionine ((11)C-MET), [(18)F]fluoroethyltyrosine ((18)F-FET), and (18)F-FDOPA are being increasingly used in the diagnosis and management of gliomas. METHODS: In this review we discuss the literature available on the ability of (18)F-FDOPA-PET to distinguish low- from high-grade in newly diagnosed gliomas. RESULTS: In 2016 the Response Assessment in Neuro-Oncology (RANO) and European Association for Neuro-Oncology (EANO) published recommendations on the clinical use of PET imaging in gliomas. However, since these recommendations there have been a number of studies performed looking at whether (18)F-FDOPA-PET can identify areas of high-grade transformation before the typical radiological features of transformation such as contrast enhancement are visible on standard magnetic resonance imaging (MRI). CONCLUSION: Larger studies are needed to validate (18)F-FDOPA-PET as a non-invasive marker of glioma grade and prediction of tumour molecular characteristics which could guide decisions surrounding surgical resection.