Abstract WMP69: Brain Atrophy and White Matter Disease Agreement on NCCT and MRI in Ischemic Stroke

Abstract

Background: NCCT is the most widely used parenchymal imaging for acute stroke. Evaluations of brain frailty measures like atrophy and white matter disease (WMD) are becoming increasingly relevant in stroke outcome prediction but are conventionally thought to be best seen on MRI. We assessed the agreement between baseline NCCT and follow-up MRI ratings of brain atrophy and WMD and compared their predictive validity in relation to 90-day functional outcomes in acute ischemic stroke. Methods: In this post-hoc analysis of baseline NCCT and follow-up MRI data from the Alteplase compared to Tenecteplase (AcT) randomised-controlled trial, expert readers (stroke neurologists and radiologists) assessed atrophy using the global cortical atrophy (GCA), Koedam, and medial temporal lobe atrophy scales. WMD was measured using the Fazekas scale. Binary agreement (none-mild vs. moderate-severe) and agreement across the full range of scores between atrophy and WMD measures on NCCT and MRI were calculated using Gwet’s agreement coefficient (AC1). Logistic regressions and Delong’s test were used to compare the area under the curve (AUC) for the prediction of 90-day modified Rankin score (mRS) 0-1 when using NCCT vs MRI-based ratings for each atrophy and WMD variable. Results: Of 1577 patients included in the AcT trial, 491 had interpretable NCCT+MRI. Binary agreement was substantial (AC1:0.68-0.80) for deep and total WMD scores, Koedam scale and frontal GCA. Almost perfect binary agreement (AC1:0.81-0.97) was found for all other measures. Deep white matter showed a significant difference between NCCT and MRI ratings for predicting 90-day mRS 0-1 (MRI AUC = 0.61 [0.56-0.66], CT AUC = 0.56 [0.50-0.60], p = 0.01, Delong p = 0.02) There was no significant difference in predicting 90-day mRS for the other variables (all p > 0.12, GCA: MRI AUC = 0.54 [0.49-0.60] CT AUC = 0.53 [0.47-0.58], p = 0.58, Delong p = 0.86). Conclusion: NCCT ratings of brain atrophy and WMD by experts have substantial to almost-perfect agreement with MRI atrophy and WMD ratings and achieve similar prediction of 90-day mRS 0-1 functional outcomes in acute stroke patients. This implies that it is reasonable to use NCCT scans to evaluate these brain frailty measures in clinical practice and in stroke trials.