Abstract WP261: Longitudinal Free-Water-Corrected Corticospinal Tract Diffusivity and Functional Outcome After Minimally Invasive ICH Evacuation

Background: Minimally invasive surgery (MIS) for intracerebral hemorrhage (ICH) aims to maximize clot removal while minimizing white matter injury. Preservation of the corticospinal tract (CST) is a key determinant for recovery, but diffusion tensor imaging (DTI) near the hematoma is confounded by edema. Free-water (FW) correction enhances tract-specific assessment and may enable longitudinal tracking of CST integrity after MIS. This study presents a longitudinal analysis evaluating FW-corrected CST diffusion metrics after MIS ICH evacuation, addressing an important gap in tracking white matter repair in hemorrhagic stroke. Objective: To characterize longitudinal changes in FW-corrected CST diffusion metrics after MIS ICH evacuation and evaluate their association with 6-month functional outcome. Methods: Fifteen patients (mean age 58 ± 11; median ICH score = 1) with supratentorial ICH underwent MIS evacuation and DTI at ≤14 days post-op and 6 months. Lesion-masked whole-tract CST reconstructions (Synaptive Modus Plan) yielded FW-corrected fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). Ipsilesional-to-contralesional ratios were calculated. Absolute and percent changes from baseline to 6 months were correlated with 6-month modified Rankin Scale (mRS) and ΔmRS (Spearman). Results: Among the tested diffusion metrics, absolute FA change from baseline to 6 months demonstrated the largest correlation with mRS change (rho = –0.37, p = 0.18, N = 15), followed by FA percent change (rho = –0.31, p = 0.26). MD- and RD-based metrics showed weaker associations (rho between –0.27 and –0.11, all p > 0.3), while single-timepoint values at baseline or 6 months were minimally related to outcome. Conclusion: In this exploratory MIS-ICH cohort, longitudinal FW-corrected FA changes showed the strongest signal of association with functional recovery, though correlations did not reach statistical significance. These findings demonstrate the feasibility of FW-corrected DTI for longitudinal tracking of CST integrity after ICH, and trends suggest further study of FA change as a potential biomarker of white matter repair, supporting further study in larger cohorts.