Abstract 116: Cortical Thickness Estimation From Clinical T1 Weighted Magnetic Resonance Images To Predict Functional Outcomes After Mechanical Thrombectomy

Abstract

Background: Endovascular treatment (EVT) is the standard of care for acute ischemic stroke caused by large vessel occlusion (LVO). However, successful EVT does not result in functional independence in many patients. This may be due to pre-existing cortical atrophy that might reduce compensatory plasticity and attenuate recovery. Identifying patients who will most benefit from EVT may be possible using baseline cortical thickness measures as a marker of brain health and providing additional prognostic utility for clinical T1-weighted (T1w) MRI. Objective: Estimate hemispheric and regional cortical thickness from clinical T1w-MRI and determine its influence on functional outcomes post successful EVT. Methods: We performed a retrospective analysis of a prospectively maintained Stroke Thrombectomy and Aneurysm Registry (n=602), collected between 2015 - 2021. We selected 213 patients (mean age 67.5 ± 14.6, 49.3% female) who had adequate quality MRI within 14 days of EVT and a record of the modified Rankin scale (mRS) at 90 days post EVT. Clinical T1w images were transformed into high-resolution images using the convolutional neural network SynthSR. Then, FreeSurfer was used to estimate hemispheric and regional mean cortical thickness from the side contralateral to the stroke, to avoid local lesion effects. In addition to hemispheric cortical thickness, we selected the insula, superior frontal gyrus (SFG), and superior temporal gyrus (STG) for the analysis due to their importance in sensorimotor processing, self-awareness, and social cognition respectively which are important during rehabilitation. Results: In an ordinal regression model adjusted for baseline mRS, the cortical thickness of the SFG and the STG was significantly predictive of 90-day mRS (p=0.005 and p=0.003 respectively), while hemispheric and insular cortical thickness were not. After adjusting for confounders and comorbidities, SFG and STG cortical thickness remained significant predictors of 90-day mRS (p<0.001 for both). Conclusions: The correlation between decreased cortical thickness in specific regions and worse functional outcomes elucidates the effects of pre-existing cortical atrophy in key areas of the brain that may be more important than others during recovery.