Abstract Body: Background:
Acute stroke lesions become more hypodense on non-contrast CT as the ischemic injury matures. Lesions transition to established infarcts at which time recanalization treatment is thought to be futile, if not harmful. As it is not possible to directly quantify the degree of injury progression, eligibility for treatment is determined using temporal criteria. In this study we used an AI approach to segment and quantify the degree of hypoattenuation of acute stroke lesions on baseline CTs, and explored its impact on clinical outcome following mechanical thrombectomy.

Methods:
Imaging was collected from a multicentric registry (across 4 US and 5 EU sites) of consecutive large vessel occlusion (LVO) stroke patients who underwent mechanical thrombectomy. Baseline NCCT scans were processed using Brainomix 360 to automatically segment the ischemic core. Lesion hypoattenuation was then quantified by in-house software using the mean Net-Water-Uptake (NWU). Multivariate models were used to explore the association between NWU and clinical outcome (3-month modified Rankin scale–mRS), controlling for e-ASPECTS scores, age, and recanalization status. Interaction models were also used to examine the relationship between NWU e-ASPECTS scores.

Results:
Of the 1363 patients included (age: median 70, IQR: 50-79; 571 females), successful recanalization (mTICI 2b-3) was achieved for 1119 patients. Multivariate analysis found NWU (p=<.001, t=4.62; Fig1) to remain an independent predictor of outcome. There was a significant interaction effect between and ASPECTS score (p=0.029, Fig 2), suggesting that degree of hypoattenuation played a larger role in patients with lower aspects value. In subgroup analysis, NWU was not a significant predictor of outcome in patients that did not achieve successful recanalizion (mTICI 0-2a).

Conclusions:
These findings suggest that stroke lesion hypodensity measured using NWU might help identify patients at risk of futile recanalization, and that incorporating this information might be more relevant in patients with lower ASPECTS. The ability to determine treatment eligibility using information extracted from routine imaging would allow safe extension of treatment to patients with unclear onset time, and would account for differences in rates of infarct progression.