Efficacy of Positron Emission Tomography in distinguishing brain tumours from inflammation

Positron Emission Tomography (PET) enables noninvasive evaluation of brain tumours, most commonly gliomas and metastases. However, the application of PET in distinguishing a tumour from an inflammatory lesion is still uncertain. The principle of this imaging test is based on fundamental differences in the central metabolic pathways in neoplastic and non-neoplastic tissues. 2-deoxy-2-fluoro-D-glucose (FDG) is the most widely used PET marker, whose uptake is closely related to the expression of the glucose transporter (GLUT) in malignant tumours. A limitation of FDG-PET studies is false-positive results, e.g., due to inflammation. This problem may be overcome by the use of different radiotracers targeted at different cellular sites; these include, fluoroethyl-l-tyrosine (FET), C- methionine (c- MET), 13-N ammonia, translocator receptor protein (TSPO) and ligand-11C-PK11195. All markers show variable diagnostic potential, however, more prospective trials are required to prove the efficacy.