18F-fluoro-ethyl-tyrosine positron emission tomography for grading and estimation of prognosis in patients with intracranial gliomas

Eur J Radiol. 2015 May;84(5):955-62. doi: 10.1016/j.ejrad.2015.01.022. Epub 2015 Feb 7.

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.

Keywords: Brain tumor surgery; FET-PET; Glioblastoma; Glioma; MRI; Survival.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Area Under Curve
  • Brain Neoplasms / diagnostic imaging*
  • Brain Neoplasms / pathology
  • Female
  • Follow-Up Studies
  • Glioma / diagnostic imaging*
  • Glioma / pathology
  • Humans
  • Male
  • Middle Aged
  • Neoplasm Grading
  • Positron-Emission Tomography* / methods
  • Prognosis
  • ROC Curve
  • Radiopharmaceuticals*
  • Tyrosine / analogs & derivatives*

Substances

  • O-(2-fluoroethyl)tyrosine
  • Radiopharmaceuticals
  • Tyrosine