A comparison study of (11)C-methionine and (18)F-fluorodeoxyglucose positron emission tomography-computed tomography scans in evaluation of patients with recurrent brain tumors.
BACKGROUND
(11)C-methonine ([(11)C]-MET) positron emission tomography-computed tomography (PET-CT) is a well-established technique for evaluation of tumor for diagnosis and treatment planning in neurooncology. [(11)C]-MET reflects amino acid transport and has been shown to be more sensitive than magnetic resonance imaging (MRI) in stereotactic biopsy planning. This study compared fluorodeoxyglucose (FDG) PET-CT and MET PET-CT in the detection of various brain tumors.


METHODS
Sixty-four subjects of brain tumor treated by surgery, chemotherapy, and/or radiotherapy were subjected to [(18)F]-FDG, [(11)C]-MET, and MRI scan. The lesion was analyzed semiquantitatively using tumor to normal contralateral ratio. The diagnosis was confirmed by surgery, stereotactic biopsy, clinical follow-up, MRI, or CT scans.


RESULTS
Tumor recurrence was found in 5 out of 22 patients on [F-18] FDG scan while [(11)C]-MET was able to detect recurrence in 18 out of 22 patients in low-grade gliomas. Two of these patients were false positive for the presence of recurrence of tumor and later found to be harboring necrosis. Among oligodendroglioma, medulloblastoma and high-grade glioma out of 42 patients 39 were found to be concordant MET and FDG scans. On semiquantitative analysis, mean T/NT ratio was found to be 2.96 ± 0.94 for lesions positive for recurrence of tumors and 1.18 ± 0.74 for lesions negative for recurrence of tumor on [(11)C]-MET scan. While the ratio for FDG scan on semiquantitative analysis was found to be 2.05 ± 1.04 for lesions positive for recurrence of tumors and 0.52 ± 0.15 for lesions negative for recurrence of tumors.


CONCLUSIONS
The study highlight that [(11)C]-MET is superior to [(18)F]-FDG PET scans to detect recurrence in low-grade glioma. A cut-off value of target to nontarget value of 1.47 is a useful parameter to distinguish benign from malignant lesion on an [(11)C]-MET Scan. Both [(18)F]-FDG and [(11)C]-MET scans were found to be useful in high-grade astrocytoma, oligodendroglioma, and medulloblastoma.
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Rajnish
R
Sharma
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Maria
M
D'Souza
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Abhinav
A
Jaimini
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Puja Panwar
PP
Hazari
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Sanjeev
S
Saw
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Santosh
S
Pandey
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Dinesh
D
Singh
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Yachna
Y
Solanki
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Nitin
N
Kumar
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Anil K
AK
Mishra
Division of Positron Emission Tomography Imaging and Division of Cyclotron and Radiopharmaceutical Sciences, Molecular Imaging and Research Center, INMAS, New Delhi, India.
Anupam
A
Mondal
[11C]-methonine; [18F]-fluorodeoxyglucose; gliomas; tumor recurrence