Study About The Correlation Of The Abnormal Structure Of Posterior Part Of The Circle Of Willis And VAH With PICA Regional Infarction And White Matter Lesions

Objective: The posterior inferior cerebellar artery(PICA),with its unique anatomical complexity,is of great clinicalimportance.Vertebral artery hypoplasia(VAH)and the abnormal structure of posterior part of the circle of Willis are common in patients with PICA regional infarction,but it is still unclear whether there is a link between them.Therefore this study intends to explore: 1.The etiological classification of PICA regional infarction;2.Association between the posterior part of the circle of Willis and VAH;3.To investigate the correlation between different vascular patterns and PICA regional infarction in different VAH side;4.To investigate the relationship between different vascular patterns and white matter lesions.Methods: We had retrospectively collectioned of the consecutive patients underwent magnetic resonance imaging(MRI)and head and neck CT angiography(CTA)in our hospital from September 2019 to January 2022 and diagnosed with PICA regional infarction as subjects.Head and neck CTA images were processed by Philips workstation post-processing technology.The structure of posterior part of the circle of Willis are usually classified as one of the three variants:an adult configuration,a transitional configuration and a fetal-type posterior circle of Willis(FCW).The subjects with adult and transitional CW configuration were included in the same group.This group we named as “adult “group CW.We defined VA as hypoplastic when VA diameter in the entire course was equal and less than 2.5mm or an asymmetry ratio was equal or less than 1:1.7.According to the CTA images of the head and neck,the vascular pattern was divided into pattern I(simple adult group),pattern II(simple FCW group),pattern Ⅲ(simple VAH group)and pattern Ⅳ(FCW combined with VAH).Automatic segmentation tool WHAT(White matter Hyperintensities Analysis Tools)was used to detect the volume of White matter hyperintensities,which was divided into Periventricular white matter hyperintensity(Pv WMH),Deep white matter hyperintensity(DWMH)and total white matter hyperintensity(TWMH).The clinical basic data and volume of white matter hyperintensity in each group were collected,and finally SPSS 26 software was used for statistical analysis.Results:1.CTA results showed that PICA regional infarction was mainly in pattern Ⅲ(46/150,30.7%).According to TOAST classification,the etiology of infarction in PICA region was mainly large artery atherosclerosis(68/150,45.3%).2.There were 87(58%)cases of VAH among 150 patients,56(37.3%)cases occurred on the right side.There were 105(70%)cases of abnormal structure of posterior part of the circle of Willis,60(40%)cases were FCW among which.Different models of posterior structure variation of the circle of Willis between VAH and normal vertebral artery,FCW was more frequent in individuals with VAH than in those with normal VA(accordingly,47.1% vs 30.2%,P=0.036),it is easy to appear on one side,which had statistical significance.On the contrary,absence/hypoplasia of both PCo A was mostly found in the group with normal VA in comparison with VAH(25.4vs 11.5%,P=0.026).3.We also compared the ipsilateral or contralateral PICA infarcts of VAH in the pattern Ⅲ and the subgroups of pattern Ⅳ.In 87 patients with VAH,2 patients with bilateral VAH were excluded,and finally 85 patients were included for study.The incidence of unilateral cerebellar infarction on the same side of VAH was 69.4% compared to 30.6%on the opposite side.This difference was significant(P=0.031).4.20 cases who with the abnormal structure of anterior part of the circle of Willis was excluded,and 130 patients were included.The MRI images of the head were processed by the automatic white matter segmentation software WHAT,and the results are as follows:there were significant differences in TWMH and DWMH volumes between pattern II and pattern Ⅲ(P<0.05).After controlling age,gender and other related risk factors,the multi-factor linear regression analysis of different vascular patterns and the volume of WMH in different parts showed that vascular pattern II had significant effects on the volume of TWMH(b=-0.23,t=-2.69,P=0.008)and DWMH(b=-0.23,t=-2.74,P=0.007),significant effects of pattern Ⅲ on PVWMH volume(b=0.18,t=2.12,P=0.036).Conclusions:1.PICA regional infarction is more common in patients with VAH,and is prone to occur on the same side of VAH;according to TOAST classification,PICA regional infarction is mainly large artery atherosclerosis;2.VAH occurs more often on the right side and easily merges FCW structure;3.When both VAH and FCW structures were present,they were more common on the same side,while absence/hypoplasia of both PCo A was mostly found in the group with normal VA;4.FCW structure may protect TWMH and DWMH volume distribution under normal structure of anterior part of the circle of Willis,while VAH is a risk factor for PVWMH volume distribution.