gms | German Medical Science

Objective: Exact delineation of meningiomas remains difficult in certain critical regions (e.g. skull base, cavernous sinus) with computed tomography (CT) and magnetic resonance imaging (MRI). In the present study we analyzed the diagnostic potential of O-(2-[¹⁸F]-Fluorethyl)-L-tyrosin (FET) PET imaging for tumor delineation.

Method: In 24 patients for which a meningioma was suspected on CT/ MRI a pre-operative FET PET scan was performed. FET scans and MRI were co-registered. Critical regions of interest (ROI) in tumor and tumor-free areas on MRI were defined (pituitary gland, periorbita, tentorium, cavernous sinus, mucosa, bone, dura and brain parenchyma). The tumor/ tissue ratio (T/t) was measured fort the early (3–14 min p.i.) and the late phase of FET up-take (20–40 min p.i.). Furthermore, the time course of activity was correlated with histology.

Results: Delineation of meningioma and critical regions was better in the late as compared to the early phase. A T/t-ratio >1.2 allowed to delineate meningioma tissue from brain/ periorbita/ tentorium and bone in 100% of patients, from pituitary gland and dura in 96%, from mucosa in 88% and for cavernous sinus in 71% of the patients, respectively. The different histological subtypes showed two pattern of time activity curves. However, there was no correlation with WHO grade.

Conclusions: FET PET imaging may delineate meningioma in critical regions, especially periorbita, tentorium/ dura, pituitary gland and bone. It may be helpful for surgical and radiotherapeutical planning in addition to CT and MRI. Further evaluation is warranted.