Multi-phase CT-Angiography outperforms angiographic careggi collateral score and predicts functional outcome in acute ischemic stroke

Collaterals are a strong determinant of clinical outcome in acute ischemic stroke (AIS) patients undergoing Endovascular Treatment (EVT). Careggi Collateral Score (CCS) is an angiographic score that demonstrated to be superior to the widely suggested ASITN/SIR score. Multi-phase CT-Angiography (mCTA) could be alternatively adopted for collateral assessment. We investigated whether mCTA had an equivalent predictive performance for functional outcome compared to CCS.

Consecutive AIS patients undergoing EVT for large vessel occlusion within 24 h from onset were analyzed. Receiver operating characteristic curves and multivariable logistic regression were investigated to evaluate the predictive performance of mCTA collateral score (range 0–5) and CCS (range 0–4) for good functional outcome (three-months modified Rankin Scale 0–2).

We included 201 subjects (59.7% females, mean age 75), of whom 96 (47.7%) had good outcome at three-months. Both CCS (OR = 14.4, 95% CI = 6.3–33.8) and mCTA (OR = 23.8, 95% CI = 10.1–56.4) collateral scores were independent predictors of outcome. The AUC of CCS was 0.80 (95% CI 0.73–0.86) and the best cut-off was ≥ 3 (87% sensitivity, 71% specificity), while the AUC of mCTA collateral score was 0.84 (95% CI 0.78–0.90) with an optimal cut-off of ≥ 4 (85% sensitivity, 87% specificity). Patients with good mCTA collaterals experienced smaller (16.6 vs. 63.7 mL, p < 0.001) infarct lesion as compared to those with mCTA poor collaterals.

mCTA discriminative ability for three-months 0–2 mRS was found to be comparable to CCS. mCTA appears a valid, non-invasive imaging modality for evaluating collaterals of AIS patients potentially eligible for EVT.