Primary central nervous system (PCNS) tumours are less frequent than brain metastasis but lead to high mortality and morbidity [1]. PCNS tumours are a heterogeneous group including many tumour types whose classifications are constantly evolving [2]. In 2021, the World Health Organization (WHO) classification of PCNS tumours was updated, and the main change was the inclusion of molecular diagnostics in CNS tumour classification [2]. While integration of molecular characteristics is now indispensable for PCNS tumours diagnosis, in the future, many other parameters could be taken into consideration to better characterize brain tumours, including MRI features or molecular imaging with positron emission tomography (PET). Beyond the initial diagnosis, planning surgery and radiotherapy, evaluating treatment response, and diagnosing recurrence in contrast to posttreatment modifications are all challenging and an area of strong interest for PET imaging.

PET is an essential imaging modality in nuclear medicine. The principle relies on the detection of a β+ radioactive tracer that is emitted from the patient after intravenous injection. This noninvasive imaging technique investigates specific molecular mechanisms and is mostly insensitive to blood – brain barrier disruption by FDG and amino acids, in contrast with MRI [3], [4].

Many radiotracers exist, but three types are mainly used in neuro-oncology:

18F-fluorodeoxyglucose (FDG), a radioactive glucose analogue used to evaluate tumour glucose metabolism (FDG uptake usually reflects tumour grade);

amino acid radiotracers, such as 18F-FDOPA, 18F-FET or 11C-methionine, usually used for suspicion of low-grade gliomas;

68Ga conjugated to SSTR ligands that targets somatostatin type 2 receptors, used for meningiomas.

This short review is a summary of the main PET contributions to the diagnosis and management of PCNS tumours, focusing on gliomas, meningiomas and PCNS lymphomas.