Abstract: Objective To study the unique correlation between vertebrobasilar artery dominance (VAD), basilar artery dolichoectasia (BADE) and posterior circulation infarction, and to explore various imaging indicators of morphological changes of vertebrobasilar artery system to distinguish patients with new posterior circulation infarction(PCI) and anterior circulation infarction (ACI). 
Methods Fifty patients with new PCI were selected as the research group, and 50 inpatients with new ACI during the same period were selected as the control group. The related indexes of VAD and BADE in the two groups were retrospectively analyzed, risk factors related to PCI were screened, and the screened indexes were inserted into ROC curve to identify the optimal cut-off value to distinguish the patients with new ACI and PCI. 
Results There was a significant difference between PCI group and ACI group in the basic artery length (BAL), the proportion of patients with VAD or basal curvature (P＜0.05). Logistic analysis showed that grade 2 and grade 3 of the diameter difference (D value) of bilateral vertebral artery were independent risk factors for PCI (P＜0.05). The ROC curve showed that the D value could distinguish the new ACI and PCI, with the optimal cutoff value of 0.41 mm, AUC of 0.753, specificity of 0.78, and sensitivity of 0.66. 
Conclusion VAD increases the risk of PCI, and the risk is greatly increased when D value is above level 2. Patients with cerebral infarction when his D value is greater than 0.41 mm are more likely to experience PCI. 

Key words: vertebrobasilar insufficiency, posterior circulation infarction, anterior circulation infarction