gms | German Medical Science

Objective: Gliomas account for 30%-50% of all brain tumors. Histopathological examination is the standard for grading and determination of diagnosis in intrinsic brain tumors. The possibility of malignization and tumor heterogenity always bears the possibility of tumor undergrading or misjudgment regarding the estimation of prognosis. Aim of the present study was to evaluate the use of FET-PET for the grading and estimation of prognosis in newly diagnosed patients with intracranial gliomas in a clinical setting.

Method: In this retrospective study we included patients who received a surgical resection or biopsy of a newly diagnosed intracranial glioma and a preoperative FET-PET and MRI scan including sequences with contrast enhancement between January 2007 and May 2012. Ratio of counts in a tumour VOI (with maximal uptake) to the respective counts in a background VOI, derived from a cortical region in the opposite non-tumor-bearing hemisphere, was calculated: T/N ratio. The clinical and histopathological data (tumor grading, pre- and postoperative neurological status, Karnofsky Performance Status Scale and overall survival) were recorded.

Results: 154 patients who underwent resection or biopsy of a newly diagnosed glioma, which had a preoperative MRI and FET-PET were included. Mean patient age was 55 years (range, 18-90). According to histopathological evaluation 39 patients were treated for low-grade gliomas (39 WHO II) and 115 for high-grade gliomas (28 WHO III, 87 WHO IV). Mean Karnofsky-Performance-Status-Scale was 80%, Mean T/N ratio was 3.1 (± 1.656). Mean T/N ratio of low-grade glioma patients was 1.76 (± 0.727), mean T/N ratio of high-grade glioma patients was 3.53 (± 1.64, p<0.05)). Median survival for patients with WHO III tumors was 25.3 month and 13.1 month for patients with WHO IV tumors (p<0.02). A valid estimation of median survival for WHO II tumors for the observation period was not possible (mean survival was 67.7 month). For T/N < 1.6 no death was recorded, for 1.6 < T/N < 3 median survival was 30.3 month and for T/N > 3 median survival was 13.3 month (p<0.02).

Conclusions: Our study suggests that FET-PET can predict prognosis and survival in patients harbouring intracranial gliomas. Stratification of T/N ratio displays estimation of survival similar to the histopathological graduation according to WHO classification. FET-PET might serve as a valuable additional tool to the established clinical and histopathological parameters.