Prognostic value of 18 F-FET PET imaging in re-irradiation of high-grade glioma: Results of a phase I clinical trial

Radiother Oncol. 2016 Oct;121(1):132-137. doi: 10.1016/j.radonc.2016.08.014. Epub 2016 Sep 9.


Background and purpose: Positron emission tomography (PET) provides quantitative metabolic information and potential biomarkers of treatment outcome. We aimed to determine the prognostic value of early 18F-fluoroethyl-tyrosine (18F-FET) PET scans acquired during re-irradiation for recurrent high-grade glioma (HGG).

Material and methods: A phase I clinical trial of re-irradiation of HGG was carried out. MRI and 18F-FET PET were used for target delineation and follow-up. Images were acquired at baseline, during radiotherapy and 4weeks post-treatment and compared by measuring the metabolically active biological tumor volume (BTV) and maximal activity (Tmax/B). Correlations with outcomes were assessed by multivariate Cox regression analysis.

Results: Thirty-one patients were included and all patients have died. The median overall survival was 7.0 mos. Both baseline BTV and baseline MRI volume (necrotic/cystic cavities subtracted) were prognostic for overall survival (OS) in multivariate analysis (HR=1.3 p<0.01 and HR=1.3 p<0.01, respectively). Early changes in BTV and Tmax/B were observed but they carried no independent prognostic information.

Conclusions: Baseline biological tumor volume (BTV) defined by 18F-FET PET was prognostic for OS in multivariate analysis, as was MRI volume (necrotic/cystic cavities subtracted). Tumor volume may aid in identifying patients whose life expectancy is too short to warrant re-irradiation.

Keywords: High-grade glioma; MRI; Metabolic imaging; Positron emission tomography; Prognostic markers; Re-irradiation.

Publication types

  • Clinical Trial, Phase I

MeSH terms

  • Adult
  • Aged
  • Brain Neoplasms / diagnostic imaging*
  • Brain Neoplasms / radiotherapy*
  • Dose-Response Relationship, Radiation
  • Female
  • Glioma / diagnostic imaging*
  • Glioma / radiotherapy*
  • Humans
  • Magnetic Resonance Imaging / methods
  • Male
  • Middle Aged
  • Positron-Emission Tomography / methods
  • Prognosis
  • Prospective Studies
  • Radiopharmaceuticals*
  • Re-Irradiation / methods
  • Treatment Outcome
  • Tumor Burden
  • Tyrosine / analogs & derivatives*


  • Radiopharmaceuticals
  • (18F)fluoroethyltyrosine
  • Tyrosine