Diverse Patterns and Clinical Significance of 11C-Methionine PET in Dysembryoplastic Neuroepithelial Tumors

Abstract

Purpose: Dysembryoplastic neuroepithelial tumors (DNETs) are slow-growing epilepsy-associated tumors. Low or normal 11 C-methionine (MET) PET uptake helps to differentiate DNETs from other low-grade gliomas. However, diverse MET-PET uptake in DNETs has been observed. The aim of this study is to measure the clinical significance and prognostic value of MET-PET in DNET management. Patients and Methods: Retrospective review of 26 DNET patients was done. Clinical characteristics, radiologic findings, and visual and quantitative MET-PET results were analyzed. PET uptake was calculated as the tumor-to-homotopic mirror ratio (TNR m ) and tumor-to-contralateral cortex ratio (TNR c ). The clinical activity of the tumors at the time of PET was classified into active and quiescent groups. The surgical outcome was defined as a composite of 2 different aspects: tumor progression and/or clinical events such as seizure recurrence or tumor bleeding. Results: Twenty-seven MET-PET examinations (20 initial MET-PET and 7 MET-PET during follow-up) were included. Clinically active tumors at the time of PET presented significantly higher values of TNR m and TNR c than quiescent tumors. High MET-PET uptake by visual grading, TNR m ≥ 1.90, and TNR c ≥ 1.85 exhibited poor prognosis for event-free survival. Conclusions: MET-PET uptake correlates well with the clinical behavior of DNETs at the time of PETexamination. Moreover, High MET-PETuptake is closely related to seizure recurrence if tumors are not entirely resected. Efforts to achieve gross total resection should be made for DNETs with high MET-PET uptake.

A comparison study of dynamic [18F]Alfatide II imaging and [11C]MET in orthotopic rat models of glioblastoma

“…The relatively short half-life of [ 11 C], approximately 20 min, which limits the widespread availability and practical use of [ 11 C]MET (Michaud et al 2020 ). Additionally, the increased uptake of [ 11 C]MET can also be observed in areas of inflammation, infection, and even in some benign brain lesions, which may lead to false positive diagnosis of GBM (Kim et al 2022 ). This is also a challenge in accurately assessing treatment response and identifying tumor recurrence, particularly in radiation encephalopathy or pseudoprogression (Dang et al 2022 ; Pessina et al 2021 ; van Dijken et al 2022 ).…”