The dynamic changes of glymphatic function at different post-radiotherapy stages in patients with nasopharyngeal carcinoma.

Abstract

The aim of this study was to investigate the dynamic changes of glymphatic function during the different pre-symptomatic phases of Radiation-induced Brain Injury (RBI). In this cross-sectional study, a total of 108 NPC patients (85 in the post-RT and 23 in the pre-RT group) and 33 healthy controls (HCs) were included. The post-RT group was further divided into three subgroups based on the time interval between RT and MRI scanning: 36 patients in post-RT_{0-6 months}, 25 patients in post-RT_{7-12 months}, and 24 patients in post-RT_{＞12 months}. Glymphatic function was assessed using the diffusion tensor imaging along the perivascular space (DTI-ALPS) index. DTI-ALPS _{whole brain}, DTI-ALPS _lesion-side, and DTI-ALPS _{non-lesion-side} index were calculated for all NPC patients; DTI-ALPS _{whole brain} index was calculated for HCs. Differences in the DTI-ALPS index among groups were evaluated using one-way analysis of variance with Bonferroni post hoc tests. Pearson correlation analysis was conducted to investigate the relationship between radiotherapy dose and the DTI-ALPS index. We observed a tendency of reduced DTI-ALPS _{whole brain}, DTI-ALPS _lesion-side, and DTI-ALPS _{non-lesion-side} index in post-RT groups compared to pre-RT group and HCs (p < 0.05). Specifically, the DTI-ALPS _{whole brain} index exhibited dynamic change patterns at different post-RT stages (p < 0.001): pre-RT (1.875 ± 0.323), post-RT_{0-6 months} (1.646 ± 0.213), post-RT_{7-12 months} (1.823 ± 0.307), and post-RT_{＞12 months} (1.720 ± 0.250) groups. This trend was consistent for both DTI-ALPS _lesion-side index (p = 0.003) and DTI-ALPS _{non-lesion-side} index (p = 0.016). These findings demonstrated that the glymphatic system underwent a dynamic process of damage, repair, and eventual homeostasis disruption at different pre-symptomatic stages of RBI. Future longitudinal studies could further elucidate the temporal dynamics of these changes.