FET-PET for malignant glioma treatment planning

Radiother Oncol. 2011 Apr;99(1):44-8. doi: 10.1016/j.radonc.2011.03.001. Epub 2011 Mar 30.


Background and purpose: The aim of this study was to compare MRI-based morphological gross tumour volumes (GTVs) to biological tumour volumes (BTVs), defined by the pathological radiotracer uptake in positron emission tomography (PET) imaging with (18)F-fluoroethyltyrosine (FET), subsequently clinical target volumes (CTVs) and finally planning target volumes (PTVs) for radiotherapy planning of glioblastoma.

Patients and methods: Seventeen patients with glioblastoma were included into a retrospective protocol. Treatment-planning was performed using clinical target volume (CTV=BTV+20mm or CTV=GTV+20mm+inclusion of the edema) and planning target volume (PTV=CTV+5mm). Image fusion and target volume delineation were performed with OTP-Masterplan®. Initial gross tumour volume (GTV) definition was based on MRI data only or FET-PET data only (BTV), secondarily both data sets were used to define a common CTV.

Results: FET based BTVs (median 43.9 cm(3)) were larger than corresponding GTVs (median 34.1cm(3), p=0.028), in 11 of 17 cases there were major differences between GTV/BTV. To evaluate the conformity of both planning methods, the index (CTV(MRT)∩CTV(FET))/(CTV(MRT)∪CTV(FET)) was quantified which was significantly different from 1 (0.73 ± 0.03, p<0.001).

Conclusion: With FET-PET-CT planning, the size and geometrical location of GTVs/BTVs differed in a majority of patients. It remains open whether FET-PET-based target definition has a relevant clinical impact for treatment planning.

MeSH terms

  • Aged
  • Biopsy
  • Brain Neoplasms / diagnostic imaging
  • Brain Neoplasms / pathology
  • Brain Neoplasms / radiotherapy*
  • Contrast Media
  • Female
  • Glioma / diagnostic imaging*
  • Glioma / pathology
  • Glioma / radiotherapy*
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Neoplasm Staging
  • Positron-Emission Tomography
  • Radiopharmaceuticals*
  • Radiotherapy Planning, Computer-Assisted / methods*
  • Radiotherapy, Conformal
  • Retrospective Studies
  • Statistics, Nonparametric
  • Tomography, X-Ray Computed
  • Treatment Outcome
  • Tyrosine / analogs & derivatives*


  • Contrast Media
  • Radiopharmaceuticals
  • (18F)fluoroethyltyrosine
  • Tyrosine