Incremental value of Alberta Stroke Program Early CT Score to collateral score for predicting target mismatch in stroke patients with extended time window or unknown onset time.

Purpose: To evaluate whether Alberta Stroke Program Early CT Score (ASPECTS) could provide incremental value to collateral score, and their integration could be an effective surrogate of CTP in predicting target mismatch.

Material And Methods: One hundred and fifty-nine stroke patients (onset time 6-16 h or with unknown onset time) with MCA and/or ICA occlusion underwent non-contrast computed tomography (NCCT) and CT perfusion (CTP) scan for initial assessment. Simulated single-phase CT angiography (sCTA, peak arterial phase) and multiphase CTA (mCTA) were reconstructed from CTP. ASPECTS was assessed on NCCT and sCTA. Collateral score was evaluated on mCTA. Target mismatch was defined as infarct core volume < 70 mL, the mismatch ratio ≥ 1.8, and the absolute mismatch volume ≥ 15 mL. Pearson correlation analysis, Mann-Whitney U test, chi-square test, and receiver operating characteristic curve analyses were performed.

Results: Median CTA source image (CTA-SI) ASPECTS was significantly lower than NCCT ASPECTS (p = 0.001). NCCT ASPECTS, CTA-SI ASPECTS, and mCTA collateral score correlated significantly with infarct core volume and mismatch ratio (all p < 0.05). Mismatch group showed significantly higher NCCT ASPECTS, CTA-SI ASPECTS, and mCTA collateral score than non-mismatch group (all p < 0.001). NCCT ASPECTS and CTA-SI ASPECTS showed comparable predicting performance with mCTA collateral score (p > 0.05). Adding CTA-SI ASPECTS to mCTA collateral score improved the performance of mCTA in predicting target mismatch (area under curve, 0.905 vs. 0.804, p = 0.003).

Conclusion: ASPECTS can provide incremental information to collateral score in predicting target mismatch. If CTP scan fails, clinical decision based on ASPECTS and collateral score might be reasonable.