Clinical impact of 11C-methionine PET on expected management of patients with brain neoplasm

We retrospectively examined the clinical efficacy of C-11-methionine positron emission tomography (C-11-MET PET) in patients with brain neoplasm, especially whether the C-11-MET PET changed the clinical management and whether the change was beneficial or detrimental. This study reviewed 89 C-11-MET PET scans for 80 patients (20 scans for initial diagnosis of brain tumor and 69 scans for differentiating tumor recurrence from radiation necrosis). Final diagnosis and the effect on the intended management were obtained from the questionnaire to the referring physicians or directly from the medical records. The diagnostic sensitivity, specificity, and accuracy for the C-11-MET PET were evaluated. Regarding the management impact, the rate of scans that caused changes in intended management was also evaluated. Moreover, the occurrence of scans having detrimental diagnostic impact (DDI) and beneficial diagnostic impact (BDI) were evaluated. Sensitivity, specificity, and accuracy of C-11-MET PET was 87.8, 80.0, and 85.9%. The intended management was changed in 50.0% of the scans. DDI and BDI were observed in 4.3 and 36.2% of the total relevant scans, respectively. C-11-MET PET can provide useful information in initial diagnosis and differentiating tumor recurrence from radiation necrosis. The intended management was changed in half of the scans. Since a few cases did not receive the requisite treatment due to false-negative results of C-11-MET PET, management decision should be made carefully, especially in the case of a negative scan.