[11C]-methionine positron emission tomography in the evaluation of pediatric low-grade gliomas.

Background: [ ¹¹ C]-Methionine positron emission tomography (PET; [ ¹¹ C]-MET-PET) is principally used for the evaluation of brain tumors in adults. Although amino acid PET tracers are more commonly used in the evaluation of pediatric brain tumors, data on [ ¹¹ C]-MET-PET imaging of pediatric low-grade gliomas (pLGG) is scarce. This study aimed to investigate the roles of [ ¹¹ C]-MET-PET in the evaluation of pLGGs.
Methods: Eighteen patients with newly diagnosed pLGG and 26 previously treated pLGG patients underwent [ ¹¹ C]-MET-PET met the inclusion and exclusion criteria. Tumor-to-brain uptake ratio (TBR) and metabolic tumor volumes were assessed for diagnostic performances (newly diagnosed, 15; previously treated 26), change with therapy (newly diagnosed, 9; previously treated 7), and variability among different histology ( n  = 12) and molecular markers ( n  = 7) of pLGGs.
Results: The sensitivity of [ ¹¹ C]-MET-PET for diagnosing pLGG, newly diagnosed, and previously treated combined was 93% for both TBR _max and TBR _peak , 76% for TBR _mean , and 95% for qualitative evaluation. TBR _max showed a statistically significant reduction after treatment, while other PET parameters showed a tendency to decrease. Median TBR _max , TBR _peak , and TBR _mean values were slightly higher in the BRAFV600E mutated tumors compared to the BRAF fused tumors. Median TBR _max , and TBR _peak in diffuse astrocytomas were higher compared to pilocytic astrocytomas, but median TBR _mean , was slightly higher in pilocytic astrocytomas. However, formal statistical analysis was not done due to the small sample size.
Conclusions: Our study shows that [ ¹¹ C]-MET-PET reliably characterizes new and previously treated pLGGs. Our study also shows that quantitative parameters tend to decrease with treatment, and differences may exist between various pLGG types.
Competing Interests: Financial disclosure: No potential conflicts of interest relevant to this article exist. Disclaimer: The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
(© The Author(s) 2024. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)