18F-FET PET in the diagnosis and prognostication of primary brain tumours

Abstract

Learning Objectives: summarize the recent developments and the current role of 18F-FET PET in brain tumours according to recent literature data describe the current limitations of 18F-FET PET and the need for expertise in the interpretation of PET data. Background(s): Positron emission tomography (PET) is a functional imaging method that has gained pervasive use in the evaluation of brain tumors. PET-tracers currently used for imaging of brain tumors are largely radio labeled amino acid (AA) tracers. These AA are preferentially taken up by tumor cells due to an overexpression of amino acid transporters on their cell surface, while the uptake of the normal brain tissue is relatively low. Numerous studies related to O-(2- [18F] fluoroethyl)-L-tyrosine (18F-FET) positron emission tomography (PET) in brain tumours have been published in the literature (1, 2). Principal findings from selected recently published and relevant articles on the role of 18F-FET PET in neuro-oncology are described. Imaging Findings OR Procedure Details: 18F-FET PET may be useful in the differential diagnosis between brain tumours and nonneoplastic lesions and between low-grade and high-grade gliomas (3, 4). Incorporation of 18F-FET PET into surgical planning allows better demarcation of the extent of resection beyond margins visible with standard MRI (5). For biopsy planning, 18F-FET PET is particularly useful in identifying malignant foci within non-contrast-enhancing gliomas. 18F-FET PET might improve the radiation therapy planning in patients with gliomas. This metabolic imaging method may be useful to evaluate treatment response in patients with gliomas and it improves the differential diagnosis between brain tumours recurrence and posttreatment changes (6). 18F-FET PET may provide useful prognostic information in high-grade gliomas (7). Care must be taken in interpretation of PET data for example [18F]FET signal is physiologically increased in vascular malformations or the venous sinuses, which can mimic tumor extension to the contralateral hemisphere in the case of sinus sphenoidalis (6). Conclusion(s): Based on recent literature data 18F-FET PET may provide additional diagnostic information compared to standard MRI in neuro-oncology. Positron emission tomography has become an important imaging technique to improve the definition of the target volume for irradiation. Multimodality imaging in combination with multidisciplinary team discussion could further improve patient care and facilitate individualised patient management.