NIMG-38. DIAGNOSIS AND TREATMENT OF BRAIN TUMORS USING METHIONINE PET

Abstract INTRODUCTION The usefulness of methionine PET examination in diagnosing brain tumors is widely recognized, and it is a frequently used examination method for distinguishing primary tumors from non-neoplastic lesions and recurrent lesions from radiation necrosis. In addition, during surgery, it has the property of being taken up by actively dividing tumor cells, which is useful for identifying the extent of resection. Method: Methionine PET examination was performed in 228 consecutive cases in our department from January 2021 to April 2023, and medical records and genetic analysis data were retrospectively analyzed. RESULTS Of the 228 cases, 146 cases provided useful data for clinical practice, such as the diagnosis of tumors and the differentiation of recurrent tumors from necrosis. On the other hand, there were 9 cases in which the pathological diagnosis of the resected specimen was “tumor” despite the lack of significant methionine accumulation. The details were astrocytoma, cavernous hemangioma, spinal ependymoma, etc. On the other hand, 26 cases were finally diagnosed as “non-neoplastic disease”. Of these, 13 cases had methionine accumulation. The details of the cases that were finally diagnosed as “non-neoplastic disease” were multiple sclerosis, cerebral infarction, dural arteriovenous fistula, inflammatory disease, etc. There were 12 cases in which a diagnosis of “neoplastic disease” was not revealed after methionine PET examination, and the patient was continuously observed. None of these 12 cases had an acute or malignant course. CONCLUSION Although methionine PET is considered useful for diagnosing neoplastic disease, there are cases in which there is no uptake, especially in astrocytoma, and a certain number of cases in which uptake was observed even in non-neoplastic diseases, so caution is required. In addition, in terms of treatment, it is possible to aim to improve surgical accuracy by integrating methionine PET images with intraoperative MRI and intraoperative molecular analysis techniques, and we report an example of this.