(18)F-Fluorothymidine PET-CT for resected malignant gliomas before radiotherapy: tumor extent according to proliferative activity compared with MRI.
OBJECTIVE
To compare the presence of post-operative residual disease by magnetic resonance imaging (MRI) and [18F]fluorothymidine (FLT)-positron emission tomography (PET)-computer tomography (CT) in patients with malignant glioma and to estimate the impact of 18F-FLT PET on the delineation of post-operative target volumes for radiotherapy (RT) planning.


METHODS
Nineteen patients with post-operative residual malignant gliomas were enrolled in this study. For each patient, 18F- FLT PET-CT and MRI were acquired in the same week, within 4 weeks after surgery but before the initiation of RT. The PET-CT and MRI data were co-registered based on mutual information. The residual tumor volume defined on the 18F-FLT PET (Vol-PET) was compared with that of gadolinium [Gd] enhancement on T1-weighted MRI (Vol-T1) and areas of hyperintensity on T2-weighted MRI (Vol-T2).


RESULTS
The mean Vol-PET (14.61 cm3) and Vol-T1 (13.60 cm3) were comparable and smaller than the mean Vol-T2 (32.93 cm3). The regions of 18F-FLT uptake exceeded the contrast enhancement and the hyperintense area on the MRI in 14 (73.68%) and 8 patients (42.11%), respectively. In 5 (26.32%) of the 19 patients, Vol-PET extended beyond 25 mm from the margin of Vol-T1; in 2 (10.53%) patients, Vol-PET extended 20 mm from the margin of Vol-T2. Vol-PET was detected up to 35 mm away from the edge of Vol-T1 and 24 mm away from the edge of Vol-T2. In 16 (84.21%) of the 19 patients, the Vol-T1 extended beyond the Vol-PET. In all of the patients, at least some of the Vol-T2 was located outside of the Vol-PET.


CONCLUSIONS
The volumes of post-operative residual tumor in patients with malignant glioma defined by 18F-FLT uptake on PET are not always consistent with the abnormalities shown on post-operative MRI. Incorporation of 18F-FLT-PET in tumor delineation may have the potential to improve the definition of target volume in post-operative radiotherapy.
Department of Radiation Oncology, Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan, China; Key Laboratory of Radiation Oncology of Shandong Province, Shandong Cancer Hospital and Institute, Jinan, Shandong, China.
Fen
F
Zhao
Department of Radiation Oncology, Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan, China; Key Laboratory of Radiation Oncology of Shandong Province, Shandong Cancer Hospital and Institute, Jinan, Shandong, China.
Minghuan
M
Li
Department of Radiation Oncology, Duke University Medical Center, Durham, NC, United States of America.
Zhiheng
Z
Wang
Department of Radiation Oncology, Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan, China; Department of Nuclear Medicine, Shandong Cancer Hospital and Institute, Jinan, Shandong, China.
Zheng
Z
Fu
Department of Radiation Oncology, Duke University Medical Center, Durham, NC, United States of America.
Yunfeng
Y
Cui
Department of Radiation Oncology, Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan, China; Department of radiology, Shandong Cancer Hospital and Institute, Jinan, Shandong, China.
Zhaoqiu
Z
Chen
Department of Radiation Oncology, Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan, China; Key Laboratory of Radiation Oncology of Shandong Province, Shandong Cancer Hospital and Institute, Jinan, Shandong, China.
Jinming
J
Yu
D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D015224:Dideoxynucleosides; D005260:Female; D005910:Glioma / Q000175:diagnosis* / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D018365:Neoplasm, Residual; D049268:Positron-Emission Tomography; D011184:Postoperative Period; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden / Q000528:radiation effects
D015224:Dideoxynucleosides; C002854:alovudine