Usefulness of [11C]methionine PET in the diagnosis of dysembryoplastic neuroepithelial tumor with temporal lobe epilepsy.
OBJECTIVE
We assessed the diagnostic value of [11C]methionine (MET) positron emission tomography (PET) in the differential diagnosis of dysembryoplastic neuroepithelial tumors (DNETs) among benign tumors associated with temporal lobe epilepsy (TLE).


METHODS
This series consisted of seven TLE patients with benign tumors in the temporal lobe. After MET-PET study, all seven patients underwent tumor resection along with focus excision. The uptake of tracers was evaluated by the lesion-to-contralateral ratio (L/C ratio) and the standardized uptake value (SUV). We also assessed the relation between MET uptake and proliferation capacity observed in the surgical specimens.


RESULTS
Whereas four patients with DNETs did not show high MET uptake visually, the ganglioglioma and gliomas of the remaining three patients were identified as high-MET-uptake lesions. In the DNETs, the SUV ranged from 1.03 to 1.41, and the L/C ratio ranged from 0.99 to 1.14. MET uptake was significantly lower in the patients with DNETs than in the patients with ganglioglioma and brain gliomas (SUV, p = 0.045; L/C ratio, p = 0.0079). The Ki-67 labeling index was 4% in one patient with DNET and 5% in one patient with pleomorphic xanthoastrocytoma (higher labeling index). The higher labeling index was not related to high MET uptake based on the SUV (p = 0.91) and L/C ratio (p = 0.38).


CONCLUSIONS
Negative MET uptake in benign temporal lobe tumors with TLE is consistent with a preoperative diagnosis of DNET.
Maehara
Taketoshi
T
Neurosurgery, Department of Brain Medical Science, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan. maehara.nsrg@tmd.ac.jp
Nariai
Tadashi
T
Arai
Nobutaka
N
Kawai
Kensuke
K
Shimizu
Hiroyuki
H
Ishii
Kenji
K
Ishiwata
Kiichi
K
Ohno
Kikuo
K
D000293:Adolescent; D000328:Adult; D002250:Carbon Radioisotopes / Q000378:metabolism; D003937:Diagnosis, Differential; D004833:Epilepsy, Temporal Lobe / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008715:Methionine / Q000378:metabolism*; D008875:Middle Aged; D018302:Neoplasms, Neuroepithelial / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism; D013724:Teratoma / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism; D014055:Tomography, Emission-Computed / Q000379:methods*
D002250:Carbon Radioisotopes; D008715:Methionine