Microstructural injury to corpus callosum and intra-hemispheric white matter tracts correlate with attention and processing speed decline after brain radiation.
Microstructural injury to corpus callosum and intra-hemispheric white matter tracts correlate with attention and processing speed decline after brain radiation. International journal of radiation oncology, biology, physics 2021Abstract
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.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.Processing speed declined at 6 months (number-sequencing, letter-sequencing; p<0.04). Seizures and anti-epileptic drug therapy were associated with lower visual-scanning attention reliable-change indices at 6 months (p=0.039). Higher radiation dose correlated with smaller mid-anterior CC volume (p=0.023), lower FA in posterior CC, anterior CC, and total CC (all p<0.03), and higher MD in anterior CC (p=0.012). Smaller mid-anterior CC and left IHWM volume correlated with worse processing speed (coding, letter-sequencing, number-sequencing, all p<0.03). Higher FA in right, left, and total IHWM correlated with better coding scores (all p<0.01). Lower FA in total IHWM (p=0.009) was associated with worse visual-scanning attention scores. Higher FA in mid-posterior CC (p=0.029) correlated with better digits-forward attention scores.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.
View details for DOI 10.1016/j.ijrobp.2020.12.046
View details for PubMedID 33412257