The value of collateral circulation classification with 4-dimensional MR angiography in predicting the short-term outcome in patients with acute ischemic stroke

Abstract

Objective To assess the collateral grade based on 4-dimensional magnetic resonance angiography (4D-MRA) in predicting short-term outcome in patients with acute ischemic stroke (AIS) . Methods Forty-seven patients with unilateral MCA stroke were enrolled in this study. All patients underwent multi-modality MRI within 4.5 to 24.0 hours onset of stroke. The collateral grade was assessed through the dynamic MRI angiograms derived from perfusion raw data. The AIS patients were divided into favorable and unfavorable outcome group according to the improvement of national institutes of health stroke scale (NIHSS) score. The differences in baseline data, infarct volume, the ratio of volume of ischemic tissue on perfusion to infarct core on diffusion (rVPD) and collateral grade between the two groups were analyzed. Logistic regression analysis was used to identify variable influencing the short-term clinical outcomes. The Kappa coefficient was used to analyze the consistency of the collateral grade assessed between the two observers. Spearman rank-order correlation test was used to analyze the relationship between the collateral grade, infarct volume, hypoperfusion volume and rVPD. Results The collateral grade used ASITN/SIR based on 4D-MRA was performed in 47 patients. Grade 1 in 4 patients, grade 2 in 21paitients, grade 3 in 16 patients and grade 4 in 6 patients, respectively. The collateral grade had a high consistency among the observers (Kappa=0.806, P<0.01). Of the patients who enrolled the study, the median of infarct volume was 29.63 (4.92, 69.17) ml, the hypoperfusion volume was 73.76 (29.75, 178.42) ml, and the rVPD was 3.1 (1.5, 5.8). It was negatively correlated with initial infarct volume (r=-0.627, P<0.01) and hypoperfusion volume (r=-0.354, P<0.01) . There was a significant positive correlation between the collateral grade and rVPD (r=0.575, P<0.001). There was also significant differences in infarct volume, rVPD, and collateral grade between favorable and unfavorable outcome group (P<0.05). The collateral grade based on 4D-MRA was an independent predictor of favorable clinical outcome (OR=4.419, P<0.05) . Conclusions The collateral circulation classification based on 4D-MRA proved to be a significant predictor of clinical outcome, it can be considered as a reliable method for analyzing the cerebral hemodynamic changes and collateral grade in AIS patients. Key words: Stroke; Magnetic resonance imaging; Collateral circulation