Uptake and tracer kinetics of O-(2-18F-fluoroethyl)-l-tyrosine in meningiomas: preliminary results.

PurposeO-(2-[18F]Fluoroethyl)-l-tyrosine (18F-FET) is a well-established PET tracer for the imaging of cerebral gliomas, but little is known about 18F-FET uptake in meningiomas. The aim of this study was to explore 18F-FET kinetics and tumour-to-background contrast in meningiomas of various histologies.MethodsA group of 24 patients with suspected cerebral meningioma on MRI/CT had an additional dynamic 18F-FET PET scan prior to surgery. Time–activity curves (TAC) of 18F-FET uptake in the tumours and tumour-to-brain ratios (TBR) for early (3 – 14 min after injection) and late 18F-FET uptake (20 – 40 min after injection) were analysed and compared with histological subtypes and WHO grade. 18F-FET uptake in critical structures in the skull base was also evaluated in terms of tumour-to-tissue (T/Tis) ratio.ResultsTBR of 18F-FET uptake in meningiomas was significantly higher in the early phase than in the late phase (3.5 ± 0.8 vs. 2.2 ± 0.3; P 1.2 in all patients for the periorbita, sphenoidal sinus, pituitary gland, tentorium, bone and brain, in more than 90 % of patients for the mucosa and dura, but in only 63 % of patients for the cavernous sinus.Conclusion18F-FET PET may provide additional information for noninvasive grading of meningiomas and possibly for the discrimination of tumour in critical areas of the skull base. A further evaluation of 18F-FET PET in meningiomas appears to be justified