Objective By using high-resolution magnetic resonance angiography to display the vascular wall imaging so as to evaluate the relationship between plaque characteristics and postoperative in-stent restenosis(ISR)in patients with middle cerebral artery stenosis.Methods A total of 66 patients with symptomatic atherosclerotic middle cerebral artery stenosis,who were admitted to the Affiliated Hospital of Chengde Medical College of China from January 2019 to March 2023,were enrolled in this study.Before stent implantation,all the 66 patients completed high-resolution magnetic resonance angiography.According to the postoperative imaging follow-up results,the patients were divided into ISR group and non-ISR group.The preoperative plaque characteristics,which were assessed by high-resolution magnetic resonance imaging,were compared between the two groups.Results ISR group had 14 patients and non-ISR group had 52 patients.Most of the plaques were located in the inferior lateral wall(37.8％)and the ventral lateral wall(28.7％),in which no statistically significant difference existed between the two groups(P＞0.05).Compared with non-ISR group,in ISR group the negative remodeling degree was obviously higher and the difference between the two groups was statistically significant(x2=6.026,P=0.049).The plaque load in ISR group and non-ISR group was 79.09±8.82 and 69.46±10.49 respectively,and the difference between the two groups was statistically significant(t=3.143,P=0.003).The homocysteine level in ISR group and non-ISR group was(16.02±4.24)mol/L and(12.05±3.34)mol/L respectively,and the difference between the two groups was statistically significant(t=3.717,P＜0.001).In ISR group,there were more significantly contrast-enhanced plaques(78.5％vs.42.3％),with statistically significant difference(x2=6.311,P=0.043).Multivariate logistic regression analysis showed that plaque load(OR=1.225,95％CI:1.040-1.443,P=0.015)and homocysteine level(OR=1.676,95％CI:1.150-2.442,P=0.007)were the independent risk factors for ISR.ROC curve analysis showed that in predicting ISR,the AUC,specificity and sensitivity of the plaque load were 0.765(95％CI:0.622-0.908,P=0.002),0.731 and 0.714 respectively,which of the homocysteine level were 0.767(95％CI:0.623-0.911,P=0.002),0.942 and 0.500 respectively.The combination use of plaque load and homocysteine level could achieve the best predictive effect,its AUC,specificity and sensitivity were 0.887(95％CI:0.794-0.981,P＜0.001),0.904 and 0.714 respectively.Conclusion The plaque load assessed by high-resolution magnetic resonance imaging and the homocysteine level have higher specificity and sensitivity in predicting ISR in patients with middle cerebral artery stenosis.