Determination of brain tumor recurrence using <sup>11</sup>C‐methionine positron emission tomography after radiotherapy
Shigeru Yamaguchi, Kenji Hirata, Michinari Okamoto, Eku Shimosegawa, Jun Hatazawa, Ryuichi Hirayama, Naoki Kagawa, Haruhiko Kishima, Noboru Oriuchi, Masazumi Fujii, Kentaro Kobayashi, Hiroyuki Kobayashi, Shunsuke Terasaka, Ken‐ichi Nishijima, Yuji Kuge, Yoichi M. Ito, Hiroshi Nishihara, Nagara Tamaki, Tohru Shiga
Abstract
Abstract We conducted a prospective multicenter trial to compare the usefulness of 11 C‐methionine (MET) and 18 F‐fluorodeoxyglucose (FDG) positron emission tomography (PET) for identifying tumor recurrence. Patients with clinically suspected tumor recurrence after radiotherapy underwent both 11 C‐MET and 18 F‐FDG PET. When a lesion showed a visually detected uptake of either tracer, it was surgically resected for histopathological analysis. Patients with a lesion negative to both tracers were revaluated by magnetic resonance imaging (MRI) at 3 months after the PET studies. The primary outcome measure was the sensitivity of each tracer in cases with histopathologically confirmed recurrence, as determined by the McNemar test. Sixty‐one cases were enrolled, and 56 cases could be evaluated. The 38 cases where the lesions showed uptake of either 11 C‐MET or 18 F‐FDG underwent surgery; 32 of these cases were confirmed to be subject to recurrence. Eighteen cases where the lesions showed uptake of neither tracer received follow‐up MRI; the lesion size increased in one of these cases. Among the cases with histologically confirmed recurrence, the sensitivities of 11 C‐MET PET and 18 F‐FDG PET were 0.97 (32/33, 95% confidence interval [CI]: 0.85‐0.99) and 0.48 (16/33, 95% CI: 0.33‐0.65), respectively, and the difference was statistically significant ( P < .0001). The diagnostic accuracy of 11 C‐MET PET was significantly better than that of 18 F‐FDG PET (87.5% vs. 69.6%, P = .033). No examination‐related adverse events were observed. The results of the study demonstrated that 11 C‐MET PET was superior to 18 F‐FDG PET for discriminating between tumor recurrence and radiation‐induced necrosis.