Analysis of 11C-methionine uptake in low-grade gliomas and correlation with proliferative activity.
OBJECTIVE
The relationship of (11)C-methionine (MET) uptake and tumor activity in low-grade gliomas (those meeting the criteria for World Health Organization [WHO] grade II gliomas) remains uncertain. The aim of this study was to compare MET uptake in low-grade gliomas and to analyze whether MET positron-emission tomography (PET) can estimate tumor viability and provide evidence of malignant transformation.


METHODS
We studied glioma metabolic activity in 49 consecutive patients with newly diagnosed grade II gliomas by using MET PET before surgical resection. On MET PET, we measured tumor/normal brain uptake ratio (T/N ratio) in 21 diffuse astrocytomas (DAs), 12 oligodendrogliomas (ODs), and 16 oligoastrocytomas (OAs). We compared MET T/N ratio among these 3 tumors and investigated possible correlation with proliferative activity, as measured by Mib-1 labeling index (LI).


RESULTS
MET T/N ratios of DA, OD, and OA were 2.11 +/- 0.87, 3.75 +/- 1.43, and 2.76 +/- 1.27, respectively. The MET T/N ratio of OD was significantly higher than that of DA (P < .005). In comparison of MET T/N ratios with the Mib-1 LI, a significant correlation was shown in DA (r = 0.63; P < .005) but not in OD and OA.


CONCLUSIONS
MET uptake in DAs may be closely associated with tumor viability, which depends on increased amino acid transport by an activated carrier-mediated system. DAs with lower MET uptake were considered more quiescent lesions, whereas DA with higher MET uptake may act more aggressively.
Kato
T
T
Chubu Medical Center for Prolonged Traumatic Brain Dysfunction, Kizawa Memorial Hospital, Minokamo City, Gifu, Japan. ttaka1010@gmail.com
Shinoda
J
J
Oka
N
N
Miwa
K
K
Nakayama
N
N
Yano
H
H
Maruyama
T
T
Muragaki
Y
Y
Iwama
T
T
D000328:Adult; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging* / Q000378:metabolism*; D006801:Humans; D008297:Male; D008715:Methionine / Q000493:pharmacokinetics*; D009361:Neoplasm Invasiveness; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic
D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D008715:Methionine