CT Angiography Image ASPECTS Shows Superior Correlation with 24-Hour DWI-ASPECTS Compared to NCCT-ASPECTS in Revascularized Emergent Large Vessel Occlusion

Background and Aims: The Alberta Stroke Program Early CT Score (ASPECTS) is a semi-quantitative tool used to estimate infarct core in acute ischemic stroke (AIS). While CT Angiography Source Images (CTA-SI) have shown promise in better predicting infarct core than non-contrast CT (NCCT), limited evidence exists comparing these modalities with final infarct volume assessed by diffusion-weighted imaging (DWI). This study evaluates the interobserver variability and correlation of CTA-SI ASPECTS and NCCT ASPECTS with 24-hour DWI-ASPECTS in patients undergoing successful revascularization for emergent large vessel occlusion (ELVO). Methods: We prospectively evaluated patients with middle cerebral artery (MCA) territory infarcts who underwent NCCT, CTA, and 24-hour DWI imaging. Patients <18 years, those with posterior circulation strokes, failed interventions (TICI <2b), or unavailable follow-up MRI were excluded. ASPECTS was calculated independently on CTA-SI and NCCT by blinded radiologists. Interobserver reliability was assessed using Cronbach's alpha and intraclass correlation coefficients (ICC). Spearman's rank correlation was used to assess association with final infarct core on 24-hour DWI. Results: Out of 332 screened patients, 294 had confirmed AIS; 151 had LVO, and 117 underwent successful revascularization. The cohort had a mean age of 52.4 ± 15.1 years, with males comprising 66%. Cronbach's alpha for interobserver reliability was 0.91 for CTA-SI and 0.83 for NCCT. CTA-SI ASPECTS demonstrated superior concordance (ICC = 0.89) compared to NCCT (ICC = 0.81; p < 0.001). Correlation with 24-hour DWI-ASPECTS was significantly higher for CTA-SI (rho = 0.74) than NCCT (rho = 0.58; p < 0.001). Regional analysis showed CTA-SI ASPECTS outperformed NCCT in most ASPECTS territories except caudate and insula. Conclusion: CTA-SI ASPECTS offers higher interobserver reliability and a stronger correlation with final infarct volume on 24-hour DWI compared to NCCT ASPECTS. Incorporating CTA-SI in acute stroke protocols can enhance infarct core estimation and improve decision-making in emergent revascularization.