title: FET-PET for malignant glioma treatment planning.
abstract: OBJECTIVE
  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.
  
  
  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).
  
  
  CONCLUSIONS
  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.
authors: Department of Radiation Oncology, Ludwig-Maximilians-University Munich, München, Germany. maximilian.niyazi@med.uni-muenchen.de
authors: Maximilian
authors: M
authors: Niyazi
authors: Julia
authors: J
authors: Geisler
authors: Axel
authors: A
authors: Siefert
authors: Silke Birgit
authors: SB
authors: Schwarz
authors: Ute
authors: U
authors: Ganswindt
authors: Sylvia
authors: S
authors: Garny
authors: Oliver
authors: O
authors: Schnell
authors: Bogdana
authors: B
authors: Suchorska
authors: Friedrich-Wilhelm
authors: FW
authors: Kreth
authors: Jörg-Christian
authors: JC
authors: Tonn
authors: Peter
authors: P
authors: Bartenstein
authors: Christian
authors: C
authors: la Fougère
authors: Claus
authors: C
authors: Belka
mesh_terms: D000368:Aged; D001706:Biopsy; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D003287:Contrast Media; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014443:Tyrosine / Q000031:analogs & derivatives*
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; C545932:(18F)fluoroethyltyrosine; D014443:Tyrosine