Nimg-103. volumetric changes in gray matter after radiotherapy detected with longitudinal magnetic resonance imaging in glioma patients

Abstract PURPOSE We evaluated volumetric changes in the gray matter (GM) after radiotherapy (RT) and identified factors that were strongly associated with GM volumetric reduction. METHODS A total of 461 magnetic resonance imagings (MRI) from 105 glioma patients treated with postoperative radiotherapy (RT) was retrospectively analyzed. Study patients’ MRIs were collected at five time points: before RT and 1 month, 6 months, 1 year, and 2 years after RT. Using the ‘FastSurfer’ platform, a deep learning-based neuroimaging pipeline, a total of 73 subsites was automatically segmented from longitudinal MRIs and their volumetric changes were calculated. Each subsite was grouped into 10 functional fields. A multivariable linear mixed-effects model was established to identify the potential predictors of volumetric changes. RESULTS The median volumetric changes in the overall, ipsilateral, and contralateral GM were -3.5%, -4.5%, and -2.4% at 2 years after RT. The functional fields of cognition and execution of movement showed the greatest volumetric reductions. In the multivariable linear mixed model, female and the interaction between age and days after RT were significantly associated with GM volume reduction. The GM volume was significantly reduced in patients older than the subsite-specific threshold age at RT (e.g., 45, 50, and 60 years for hippocampus, Broca area, and Wernicke area, respectively). However, there was no significant GM volumetric reduction in patients younger than the threshold age at RT. CONCLUSIONS GM volumetric changes were identified after RT that could lead to long-term treatment sequelae. Particularly for susceptible patients, individualized treatment and prevention strategies are needed.