| Background and PurposeIschemic cerebrovascular disease(ICVD)is an important disease that endangers the physical and mental health of middle-aged and elderly people.,TIA and cerebral infarction are its serious clinical manifestations and have attracted more and more researchers' attention.Cerebral infarction is characterized by high morbidity,high mortality,disability,and high recurrence rate,and the morbidity is growing at an annual rate of 8.7%.The main risk of ICVD is stenosis or occlusion of intracranial artery disease,especially the middle cerebral artery(MCA).ICVD often manifests as abnormal changes in cerebral hemodynamics before developing cerebral infarction,understanding the relevant information of cerebral hemodynamics has important guiding significance for early clinical diagnosis,early treatment and prognosis evaluation.Arterial spin labeling(ASL)is a newly developed magnetic resonance perfusion imaging technology in recent years,it does not require the use of exogenous contrast agents,and is non-invasive,non-radiating,safe,simple,and highly repeatable.A series of studies using healthy people or patients with ischemic cerebrovascular disease as subjects show that whether it is global cerebral perfusion or local cortical perfusion,Cerebral blood flow(CBF)quantitative values obtained from 3D-ASL,positron emission tomography(PET),and dynamic susceptibility contrast(DSC)perfusion imaging are well consistent.Due to the slow blood flow in patients with cerebrovascular disease,the arterial transit time(ATT)is difficult to predict,ASL with only a single post-labeling delay(PLD)or inversion time(TI)is difficult to obtain its true CBF value.Multi-delay ASL can set multiple PLD or TI at the same time,calculate ATT and adjust PLD or TI again according to ATT,so as to obtain more accurate blood perfusion information for such patients.Multiple studies have shown that multi-delay ASL is better than ASL of single PLD or TI in the assessment of blood flow in patients with cerebrovascular disease,and the CBF value is more consistent with DSC results.In this study,multi-delay 3D-ASL with 4 TIs was used to evaluate the cerebral perfusion in the main feeding areas of MCA in healthy volunteers and patients with unilateral MCA stenosis or occlusion,to analyze whether the perfusion in the main feeding areas of MCA is different among healthy volunteers at different ages and genders,to investigate the relationship between MCA stenosis and cerebral perfusion changes and the difference in perfusion condition between patients with transient ischemic attack(TIA)and cerebral infarction,to evaluate the value of multi-delay ASL in evaluating perfusion in patients with cerebral arterial stenosis.Materials and MethodsIn this study,all the measurements were carried out by Siemens Prisma 3.0 T magnetic resonance scanner with 64-channel head-neck combined coil.All of the subjects underwent conventional brain sequences,3D TOF-MRA,3D T1 WI structure images,and multi-delay 3D-ASL(TI=1500ms,1990ms,2480ms,2970ms)sequence scans.,while patients also performed MCA 2D high-resolution magnetic resonance(HRMRI)scan.A total of 119 patients with unilateral MCA stenosis or occlusion admitted to our hospital from October 2017 to June 2019 were collected,all of the patients are right-handed;a total of 90 healthy volunteers with age and gender matching the patients were collected,all of the volunteers are right-handed.The MC A stenosis rate of patients was measured according to Samuels standard and method.With reference to the North American Symptomatic Carotid Endarterectomy(NASCET)standard,patients with MCA stenosis or occlusion were divided into 4 groups according to the stenosis rate:mild stenosis group(n=29,stenosis rate 0-49%),Moderate stenosis group(n=26,stenosis rate 50-69%),severe stenosis group(n=33,stenosis rate 70-99%),occlusion group(n=31,stenosis rate 100%),the measurement of MCA stenosis is based on 2D HRMRI TIWI images.The patients were divided into TIA group(n=53)and cerebral infarction group(n=66)according to the presence of infarction in the main feeding areas of MCA on the conventional brain plain scan sequence images.Healthy volunteers were divided into four groups according to age:group A was 18-34 years old(n=23,including 11 males and 12 females);group B was 35-49 years old(n=22,including 11 males and 11 females);group C was 50-64 years old(n=24,including 11 males and 13 females);group D was 65-80 years old(n=21,including 10 males and 11 females),and each group was further divided into male and female groups.Matlab-based SPM 12 software was used to process the ASL-CBF image,and the average CBF of the main feeding areas of MCA on both sides of each subject at 4 TIs was calculated.Statistical software SPSS 21.0 was used for data analysis.The counting data accorded with normal distribution and were expressed by mean±standard deviation(x±s),while the non-normal distribution was expressed by quartile(m[IQR]).Qualitative data are expressed as frequency.The Shapiro-Wilk normality test and homogeneity test of variance were performed on the quantitative data.Paired data samples were compared using paired tests;independent sample t test is used for comparison between two groups of samples of different objects;single factor analysis of variance is used for comparison between groups of samples of different objects;LSD test is used for comparison between groups.Chi-square test or rank sum test was used to compare the differences between qualitative data and ordered data.The test level was set to ?=0.05,and P<0.05 was considered that the difference was statistically significant.Result1.The CBF value of the main feeding areas of the left MCA of healthy volunteers was(54.21±11.40)mL/100g/min,and the right side was(55.44±12.61)mL/100g/min.There were no significant differences in CBF values between the left and right sides of the main feeding areas of MCA in healthy volunteers(P>0.05).2.The CBF value of the main feeding areas of the left MCA of the healthy volunteers 18-34 years old group was(56.55±11.30)mL/100g/min,the right side was(57.94±14.83)mL/100g/min;The CBF value of the main feeding areas of the left MCA of the 35-49 age group was(50.81±10.57)mL/100g/min,and the right side was(53.42±11.89)mL/100g/min;The CBF value of the main feeding areas of the left MCA of the 50-64 year old group was(54.64±8.63)mL/100g/min,and the right side was(57.11±8.49)mL/100 g/min;in the 65-80 years old group,the CBF value of the main feeding areas of the left MCA was(54.73±14.69)mL/100g/min,and the right side was(52.93±14.59)mL/100g/min.There was no statistically significant difference in the CBF value of the main feeding areas among healthy volunteers in different age groups(P>0.05).3.The CBF value of the main feeding areas of the left MCA of the female healthy volunteers was(58.76±11.12)mL/100g/min,the right side was(61.97±1.34)mL/100 g/min;The CBF value of the main feeding areas of the left MCA of the male group was(49.25±9.58)mL/100g/min,and the right side was(48.1±9.83)mL/100g/min.The female CBF value in the main feeding areas of MCA of healthy volunteer was higher than that of male,and the difference was statistically significant(P<0.05).4.In patients with MCA stenosis or occlusion,the CBF value of the main feeding areas of MCA on the affected side was(39.54 ± 12.55)mL/100g/min,and the healthy side was(54.58±9.94)mL/100g/min.The CBF value in the main feeding areas of MCA of the affected side of MCA stenosis or occlusion patients was lower than that of the healthy side,and the difference was statistically significant(P<0.05).5.The CBF value of the main feeding areas of the affected side of MCA of the patients with MCA stenosis or occlusion in mild stenosis group was(49.84±8.60)mL/100g/min,the healthy side was(53.54±8.50)mL/100g/min;The CBF value of the affected side of MCA of the moderate stenosis group was(45.22±7.25)mL/100g/min,and the healthy side was(57.14±8.86)mL/100g/min;The CBF value of the main feeding areas of the affected side of MCA of the severe stenosis group was(36.50±10.00)mL/100g/min,and the healthy side was(56.70±8.36)mL/100g/min;in the occlusion group,the CBF value of the main feeding areas of the affected side of MCA was(28.36±11.31)mL/100g/min,and the healthy side was(51.14±12.55)mL/100g/min.There was no significant difference in the CBF value of the main feeding areas of MCA between the healthy side of MCA stenosis or occlusion patients with different degrees of stenosis(P=0.062).The difference in CBF value between the main feeding areas of MCA of the affected side was statistically significant(P=0.000),and the mean CBF value decreased with increasing stenosis.There was no significant difference in the CBF value of the main feeding areas of MCA in the affected side between the mild stenosis group and the moderate stenosis group(P=0.075),and there was significant difference between the other groups(P<0.05),the greater the difference in stenosis,the greater the difference in CBF.6.The CBF value of the main feeding areas of the affected side of MCA of the patients with MCA stenosis or occlusion in TIA group was(47.65 ± 8.84)mL/100g/min,the healthy side was(55.86±8.32)mL/100g/min;The CBF value of the affected side of MCA of the cerebral infarction group was(33.02±11.26)mL/100g/min,and the healthy side iwas(53.55 ±11.03)mL/100g/min.There was no significant difference in the CBF value of the healthy side of the main feeding areas of MCA between the TIA group and the cerebral infarction group in patients with MCA stenosis or occlusion(P=0.195).The CBF value of the main feeding areas of MCA in the affected side of the TIA group was higher than that in the cerebral infarction group,and the difference was statistically significant(P=0.000).7.In the TIA group of MCA stenosis or occlusion patients,there were 19 cases of mild stenosis,9 cases of moderate stenosis,14 cases of severe stenosis,and 11 cases of occlusion;In the cerebral infarction group,there were 10 cases of mild stenosis,17 cases of moderate stenosis,19 cases of severe stenosis,and 20 cases of occlusion.There was no significant difference in MCA stenosis degrees between the TIA group and the cerebral infarction group in patients with MCA stenosis or occlusion(P=0.065).Conclusion1.The CBF value of normal people's main feeding areas of MCA has no relationship with age,but it is related to gender,and the perfusion of bilateral cerebral hemispheres in female subjects is higher than that in male subjects.2.The decrease of cerebral perfusion level in the corresponding blood supply area of patients with MCA stenosis or occlusion is positively correlated with the degree of cerebral vascular stenosis.3.CBF is an important factor in the development of cerebral infarction in patients with MCA stenosis or occlusion.4.The degree of lumen stenosis is not a decisive factor for the development of cerebral infarction in patients with MCA stenosis or occlusion. |
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