Patterns of failure for patients with glioblastoma following O-(2-[ 18 F]fluoroethyl)-L-tyrosine PET- and MRI-guided radiotherapy

Radiother Oncol. 2017 Mar;122(3):380-386. doi: 10.1016/j.radonc.2017.01.002. Epub 2017 Jan 19.


Background and purpose: To evaluate the patterns of failure following clinical introduction of amino-acid O-(2-[18F]fluoroethyl)-L-tyrosine (FET)-PET-guided target definition for radiotherapy (RT) of glioblastoma patients.

Materials and methods: The first 66 consecutive patients with confirmed histology, scanned using FET-PET/CT and MRI were selected for evaluation. Chemo-radiotherapy was delivered to a volume based on both MRI and FET-PET (PETvol). The volume of recurrence (RV) was defined on MRI data collected at the time of progression according to RANO criteria.

Results: Fifty patients were evaluable, with median follow-up of 45months. Central, in-field, marginal and distant recurrences were observed for 82%, 10%, 2%, and 6% of the patients, respectively. We found a volumetric overlap of 26%, 31% and 39% of the RV with the contrast-enhancing MR volume, PETvol and the composite MRPETvol, respectively. MGMT-methylation (p=0.03), larger PETvol (p<0.001), and less extensive surgery (p<0.001), were associated with larger PETvol overlap.

Conclusion: The combined MRPETvol had a stronger association with the recurrence volume than either of the modalities alone. Larger overlap of PETvol and RV was observed for patients with MGMT-methylation, less extensive surgery, and large PETvol on the RT-planning scans.

Keywords: FET-PET; Glioma; MRI; Radiotherapy; Recurrence patterns.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Brain Neoplasms / radiotherapy*
  • Disease Progression
  • Female
  • Glioblastoma / radiotherapy*
  • Humans
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged
  • Neoplasm Recurrence, Local / diagnostic imaging*
  • Positron Emission Tomography Computed Tomography / methods
  • Positron-Emission Tomography / methods*
  • Radiology, Interventional / methods
  • Radiopharmaceuticals
  • Radiotherapy, Image-Guided / methods
  • Retrospective Studies
  • Treatment Failure
  • Tyrosine / analogs & derivatives*


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