18F-fluoro-ethyl-tyrosine positron emission tomography for grading and estimation of prognosis in patients with intracranial gliomas. Issue 5 (May 2015) - Gempt, Jens
Highlights: The aim of the present study was to evaluate the use of 18 F-FET-PET (FET-PET) for the grading and estimation of prognosis in newly diagnosed patients with intracranial gliomas in a clinical setting. One hundred fifty-two patients (39 WHO II, 26 WHO III, 87 WHO IV) were included. The median T / N ratio of low-grade glioma patients was 1.65 (1.1–3.7), and 3.14 (1.61–8.1, p < 0.001) in high-grade glioma patients. The test of the maximally selected log-rank statistic resulted in a T / N ratio of 1.88 as the cut-off value, with the greatest difference in overall survival between patients with longer and shorter survival. Regarding the prognostic validity for overall survival ROC-curves display an AUC of 0.847 for the 48-month survival for T / N ratio and MRI contrast-enhancement. Our study suggests that FET-PET can predict prognosis and survival in patients harboring intracranial gliomas. Abstract: Introduction: Histopathological examination is the standard for grading and determination of diagnosis in intrinsic brain tumors though the possibility of malignization and tumor heterogeneity always bears the possibility of tumor under-grading or misjudgement regarding the estimation of prognosis. The aim of the present study was to evaluate the use of 18 F-FET-PET (FET-PET) for the grading and estimation of prognosis in newly diagnosed patients with intracranial gliomas in a clinical setting. Methods: Patients who were treated for a newly diagnosed intracranial glioma between January 2007 and May 2012, and had a preoperative FET-PET and MRI scan between were included. The ratio of counts in a tumor VOI (volume of interest) with maximum uptake to the respective counts in a background VOI was calculated to provide the tumor-to-normal ( T / N ) ratio. The clinical and histopathological data (tumor grading, pre- and postoperative neurological status, Karnofsky Performance Status Scale scores, and overall survival rates) were recorded. Results: One hundred fifty-two patients (39 WHO II, 26 WHO III, 87 WHO IV) were included. The median T / N ratio was 2.81 (1.1–8.1). The median T / N ratio of low-grade glioma patients was 1.65 (1.1–3.7), and 3.14 (1.61–8.1, p < 0.001) in high-grade glioma patients. The median survival for patients with WHO III tumors was 22.8 months (95% CI: 15.87%–NA) and 13.23 months (95% CI: 10.83–15.6.%) for patients with WHO IV tumors ( p = 0.0001). For T / N ≤ 1.6, no deaths were recorded; for 1.6 < T / N ≤ 3, median survival was 25.6 months (95% CI: 16.5%–NA), while for T / N > 3, median survival was 14.0 months (95% CI: 11.7–16.2%, p < 0.001). The test of the maximally selected log-rank statistic resulted in a T / N ratio of 1.88 as the cut-off value, with the greatest difference in overall survival between patients with longer and shorter survival. The ROC curve for differentiation of low- vs. high-grade tumors with regard to the T / N ratio showed an area under the curve (AUC) of 0.903. Regarding the prognostic validity for overall survival ROC-curves for 12-month, 24-month and 48-month survival display a higher validity for the WHO-classification than for the imaging modalities though with an AUC of 0.847 for the 48-month survival T / N ratio and MRI contrast-enhancement have a high prognostic value as well. Conclusion: Our study suggests that FET-PET can predict prognosis and survival in patients harboring intracranial gliomas and serves as a valuable tool to supplement the established clinical and histopathological parameters.