[(18)F]Fluoroethyltyrosine- positron emission tomography-guided radiotherapy for high-grade glioma.
BACKGROUND
To compare morphological gross tumor volumes (GTVs), defined as pre- and postoperative gadolinium enhancement on T1-weighted magnetic resonance imaging to biological tumor volumes (BTVs), defined by the uptake of (18)F fluoroethyltyrosine (FET) for the radiotherapy planning of high-grade glioma, using a dedicated positron emission tomography (PET)-CT scanner equipped with three triangulation lasers for patient positioning.


METHODS
Nineteen patients with malignant glioma were included into a prospective protocol using FET PET-CT for radiotherapy planning. To be eligible, patients had to present with residual disease after surgery. Planning was performed using the clinical target volume (CTV = GTV union or logical sum BTV) and planning target volume (PTV = CTV + 20 mm). First, the interrater reliability for BTV delineation was assessed among three observers. Second, the BTV and GTV were quantified and compared. Finally, the geometrical relationships between GTV and BTV were assessed.


RESULTS
Interrater agreement for BTV delineation was excellent (intraclass correlation coefficient 0.9). Although, BTVs and GTVs were not significantly different (p = 0.9), CTVs (mean 57.8 +/- 30.4 cm(3)) were significantly larger than BTVs (mean 42.1 +/- 24.4 cm(3); p < 0.01) or GTVs (mean 38.7 +/- 25.7 cm(3); p < 0.01). In 13 (68%) and 6 (32%) of 19 patients, FET uptake extended >or= 10 and 20 mm from the margin of the gadolinium enhancement.


CONCLUSIONS
Using FET, the interrater reliability had excellent agreement for BTV delineation. With FET PET-CT planning, the size and geometrical location of GTVs and BTVs differed in a majority of patients.
Weber
Damien C
DC
Department of Radiation Oncology, Geneva University Hospital, Geneva, Switzerland. damien.weber@hcuge.ch
Zilli
Thomas
T
Buchegger
Franz
F
Casanova
Nathalie
N
Haller
Guy
G
Rouzaud
Michel
M
Nouet
Philippe
P
Dipasquale
Giovanna
G
Ratib
Osman
O
Zaidi
Habib
H
Vees
Hansjorg
H
Miralbell
Raymond
R
D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D005260:Female; D005462:Fluorine Radioisotopes; D005910:Glioma / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014443:Tyrosine
D005462:Fluorine Radioisotopes; D019275:Radiopharmaceuticals; D014443:Tyrosine