l-[METHYL-(11)C] methionine positron emission tomography for target delineation in malignant gliomas: impact on results of carbon ion radiotherapy.
OBJECTIVE
To assess the importance of (11)C-methionine (MET)-positron emission tomography (PET) for clinical target volume (CTV) delineation.


METHODS
This retrospective study analyzed 16 patients with malignant glioma (4 patients, anaplastic astrocytoma; 12 patients, glioblastoma multiforme) treated with surgery and carbon ion radiotherapy from April 2002 to Nov 2005. The MET-PET target volume was compared with gross tumor volume and CTV, defined by using computed tomography/magnetic resonance imaging (MRI). Correlations with treatment results were evaluated between positive and negative extended volumes (EVs) of the MET-PET target for CTV.


RESULTS
Mean volumes of the MET-PET targets, CTV1 (defined by means of high-intensity volume on T2-weighted MRI), and CTV2 (defined by means of contrast-enhancement volume on T1-weighted MRI) were 6.35, 264.7, and 117.7 cm(3), respectively. Mean EVs of MET-PET targets for CTV1 and CTV2 were 0.6 and 2.2 cm(3), respectively. The MET-PET target volumes were included in CTV1 and CTV2 in 13 (81.3%) and 11 patients (68.8%), respectively. Patients with a negative EV for CTV1 had significantly greater survival rate (p = 0.0069), regional control (p = 0.0047), and distant control time (p = 0.0267) than those with a positive EV. Distant control time also was better in patients with a negative EV for CTV2 than those with a positive EV (p = 0.0401).


CONCLUSIONS
For patients with malignant gliomas, MET-PET has a possibility to be a predictor of outcome in carbon ion radiotherapy. Direct use of MET-PET fused to planning computed tomography will be useful and yield favorable results for the therapy.
Mahasittiwat
Pawinee
P
Department of Radiology, Division of Radiation Oncology, Faculty of Medicine Siriraj Hospital, Bangkok, Thailand.
Mizoe
Jun-Etsu
JE
Hasegawa
Azusa
A
Ishikawa
Hiroyuki
H
Yoshikawa
Kyosan
K
Mizuno
Hideyuki
H
Yanagi
Takeshi
T
Takagi
Ryou
R
Pattaranutaporn
Pittayapoom
P
Tsujii
Hirohiko
H
D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000601:surgery; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000601:surgery; D002250:Carbon Radioisotopes; D005260:Female; D005909:Glioblastoma / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008715:Methionine; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods; D047368:Tumor Burden
D002250:Carbon Radioisotopes; D008715:Methionine