Correlation study of MRI intracranial hyperintense vessel sign and internal carotid artery stenosis

Abstract

Objective To evaluate the correlation between intracranial hyperintense vessel sign (HVS) on fluid-attenuated inversion recovery(FLAIR) and the degree of the stenosis of internal carotid artery (ICA).The effect of carotid endarterectomy(CEA) on HVS was assessed.Methods A retrospective analysis of MR FLAIR sequence and cerebral-cervical computed tomography angiography(CTA) was performed in 1 total of 491 patients.Of the 491 patients,41 treated with CEA were evaluated using their pre-and post-operative image data.Patients were divided into ICA stenosis group and non-stenosis group according to the CTA imaging findings.The ICA stenosis group was subdivided into unilateral group and bilateral stenosis group.Furthermore,we measured and graded the ICA of the unilateral stenosis group into seven stenotic degrees,they were＜50％(n=40),50％-＜60％(n=15),60％-＜70％(n=17),70％-＜80％ (n=6),80％-＜90％ (n=7),90％-＜100％ (n=23),100％ (n=24),respectively.Chi square test was used to analyze the occurrence rates of HVS between ICA stenosis and non-stenosis group,and between ICA unilateral and bilateral stenosis group,respectively.Spearman rank correlation was performed to evaluate the correlation between the presence of HVS and stenotic degrees of the ICA.For the 41 patients who underwent CEA,pre-and post-operative image data were compared,focusing on the presence or disappearance of the HVS on MR FLAIR imaging.Results HVS on FLAIR images were observed in 81 of 177 patients(45.76％) with ICA stenosis,and in 59 of 314 patients(18.79％) without ICA stenosis.The occurrence rate of HVS was significantly higher in patients with ICA stenosis than those without ICA stenosis (x2=40.40,P＜0.01).There was no statistical significance in the occurrence rates of HVS between ICA unilateral stenosis group and bilateral stenosis group(x2=0.24,P＞0.05).The occurrence rates of HVS of ICA graded as the seven stenotic degrees were 22.00％(8/40),26.67％(4/15),35.29％(6/17),33.33％ (2/6),42.86％ (3/7),69.57％ (16/23),83.33％ (20/24),respectively.There was a significant positive correlation between the occurrence rates of HVS and the degrees of ICA stenosis(r=0.964,P＜0.01).HVS disappeared in 19(86.36％) out of 22 patients with HVS on pre-operative MR images after CEA in The remaining HVS in 3(13.64％) patients was attributed to the failure of completely recanalization of ICA.Conclusions A close relationship exists between HVS and ICA stenosis.The presence of HVS indicates a high probability of the existence of severe ICA stenosis.A further assessment for ICA stenosis is warranted.HVS disappearance after successful CEA indicates that HVS can be a useful marker for the the evaluation of consequence associated with CEA. Key words: Carotid stenosis; Magnetic resonance imaging