Microstructural Injury to Corpus Callosum and Intrahemispheric White Matter Tracts Correlate With Attention and Processing Speed Decline After Brain Radiation.
Published on Jan 4, 2021in International Journal of Radiation Oncology Biology Physics7.038
· DOI :10.1016/J.IJROBP.2020.12.046
Abstract Background The corpus callosum (CC) and intra-hemispheric white matter tracts (IHWM) subserve critical aspects of attention and processing speed. We analyzed imaging biomarkers of microstructural injury within these regions and association with attention/processing speed decline post-radiotherapy in primary brain tumor patients. Methods On a prospective clinical trial, 44 primary brain tumor patients underwent cognitive testing and MRI/diffusion-weighted imaging pre-radiotherapy, and 3-, 6-, and 12-months post-radiotherapy. CC (subregions; total) and IHWM tracts (left/right without CC; total) were autosegmented; tumor/tumor bed/edema were censored. Biomarkers included: volume changes (cc); mean diffusivity (MD, higher values indicate WM injury); fractional anisotropy (FA, lower values indicate WM injury). Reliable-change indices measured changes in attention (WAIS-IV digits-forward; D-KEFS-Trail-Making visual-scanning) and processing speed (WAIS-IV coding; D-KEFS-Trail-Making number-sequencing, letter-sequencing), accounting for practice effects. Linear mixed-effects models evaluated associations between 1) mean radiation dose and biomarkers (volume, MD, FA); 2) imaging biomarkers and neurocognitive performance. Statistics were corrected for multiple comparisons. Results Processing speed declined at 6 months (number-sequencing, letter-sequencing; p Conclusions The CC demonstrated radiation dose-dependent atrophy and WM injury. Microstructural injury within the CC and IHWM was associated with attention/processing speed decline after radiotherapy. These areas represent possible avoidance regions for preservation of attention/processing speed.