Predictive value of the velocity of collateral filling in patients with acute ischemic stroke

The velocity of collateral filling can be assessed in dynamic time-resolved computed tomography (CT) angiographies and may predict initial CT perfusion (CTP) and follow-up lesion size. We included all patients with an M1 +/- internal carotid artery (ICA) occlusion and follow-up imaging from an existing cohort of 1791 consecutive patients who underwent multimodal CT for suspected stroke. The velocity of collateral filling was quantified using the delay of time-to-peak (UP) enhancement of the M2 segment distal to the occlusion. Cerebral blood volume (CBV) and mean transit time (MU)-CBV mismatch were assessed in initial CTP. Follow-up lesion size was assessed by magnetic resonance imaging (MRI) or non-enhanced CT (NECT). Multivariate analyses were performed to adjust for extent of collateralization and type of treatment. Our study comprised 116 patients. Multivariate analysis showed a short collateral blood flow delay to be an independent predictor of a small CBV lesion (P < 0.001) and a large relative mismatch (P < 0.001) on initial CTP, of a small follow-up lesion (P < 0.001), and of a small difference between initial CBV and follow-up lesion size (P = 0.024). Other independent predictors of a small lesion on follow-up were a high morphologic collateral grade (P = 0.001), lack of an additional ICA occlusion (P = 0.009), and intravenous thrombolysis (P = 0.022). Fast filling of collaterals predicts initial CTP and follow-up lesion size and is independent of extent of collateralization.