Volumetric Changes in Hippocampal Subfields and Memory Performance After Fractionated Brain Radiation Therapy

Vollständiger Abstract

Worum geht es in dieser Arbeit?

Abstract Background The hippocampus comprises discrete anatomic subfields subserving different components of memory. We evaluated longitudinal, dose-dependent volumetric changes in hippocampal subfields after fractionated RT and determined their associations with verbal and visuospatial memory performance. Methods Eighty-nine adults with primary brain tumors received fractionated RT on a prospective clinical trial. High-resolution 3D volumetric MRI and memory tests were obtained at baseline and 3, 6, and 12-months post-RT. Bilateral hippocampi and their thirty-eight subfields were segmented using robust automated parcellation. Linear mixed-effects (LME) models analyzed (1) time-dependent atrophy, (2) dose-volume relationships, and (3) subfield-memory associations at the same timepoint, corrected for multiple comparisons. Results Multiple left and right-sided hippocampal subfields demonstrated significant atrophy at 3, 6, and 12-months post-RT (all p ≤ 0.05). Dose-dependent atrophy was significant at 12 months (p = .01) in the left hippocampus and across all time points in the right (all p ≤ 0.05). Eight right-sided and one left-sided subfield exhibited dose-dependent atrophy across all time points (all p ≤ 0.05). Greater left hippocampal tail and molecular layer volumes were associated with higher verbal memory scores, while greater volumes of multiple right-sided subfields predicted better visuospatial memory performance (all p ≤ 0.05, 𝛽 > 0). Conclusions Fractionated RT induces progressive, dose-related atrophy in discrete hippocampal subfields, with earlier and steeper dose–response curves in right-sided subfields. Higher volumes within multiple left and right-sided subfields were associated with better verbal and visuospatial memory, respectively. Subfield-sparing planning objectives may optimize cognitive outcomes in primary brain tumor patients when hippocampal avoidance is not feasible.