Are Neuroanatomical Changes in Pediatric Medulloblastoma Radiation Specific?

Abstract

Though MRI changes following combined modality treatment of medulloblastoma have been attributed to radiation, the impact of surgery remains unclear. To better distinguish post-surgical versus radiation effects, we compared MRI-derived longitudinal neuroanatomical changes in medulloblastoma (MB) patients treated by both surgery and radiation against cerebellar pilocytic astrocytoma (JPA) patients treated by surgery alone. The 2 treatment cohorts included 14 MB patients (4–18 years; 5 Female; 3 high-risk) and 5 JPA patients (2.8–16.2 years; 4 male), with longitudinal high-resolution T1 axial MR imaging at variable time points since diagnosis (mean follow-up, scans: 379 days, 7 per patient). Robust autosegmentation was used to measure regional cortical thickness and volumes, and subcortical volumes. Relative longitudinal changes for each structure were analyzed with a linear mixed effects model that also included age at surgery and sex. Longitudinal MRI changes were observed across both groups. Corpus callosum subvolumes, including central (P = .019), mid-anterior (P = .026) and mid-posterior (P = .027), and right post-central volume (P = .031) exhibited statistically significant (P < .05) decline over time. Left parahippocampal cortical thickness growth was also significant (P = .042). Despite overall growth with time, MB treatment had an insignificant negative effect on left fusiform (P = .19) and left parahippocampal (P = .19) volumes, while the reverse trend was observed for the left paracentral (P = .16) and left precuneus volumes (P = .15). Additional positive trends with time were observed for right parahippocampal volume (P = .070), right parahippocampal thickness (P = .068), left fusiform (P = .070) and left inferior temporal thickness (P = .083). A negative trend was observed for right superior frontal (P = .091) cortical volume. Treatment cohort, age, and sex had no significant effect overall. The lack of significant longitudinal differences between the irradiated and non-irradiated groups suggests that neuroanatomical changes may not be radiation-specific as previously thought. Further longitudinal imaging analysis may identify early neurocognitive sequelae and may be useful in considering early intervention.