The Application Of Circle Of Willis By Three-dimensional Time-of-flight Magnetic Resonance Angiograms

Objective: Middle cerebral artery(MCA)is one of the main causes of cerebral ischemia or cerebral infarction,circle of Willis as a compensatory pathway of collateral circulation,its compensation potential is related to its integrity.3D-TOF MRA can be used to observe patients of the circle of Willis in morphological and anatomical variation,to measure the anterior communicating artery diameter,and to explore the existence of the middle cerebral artery arteriosclerosis level,age and gender differences.Methods:1 Random extraction and retrospective analysis of 629 patients with conventional magnetic resonance imaging and 3D-TOF MRA in our hospital for the basic information such as age,sex,clinical symptoms and signs were recorded.2 According to the original MRA data collected,the writer make MIP reconstruction,and rotate it in any direction,in order to clearly show the relationship between the distribution of the blood vessels and vascular,classify the circle of Willis into Type?(complete circle of Willis),Type?(circle of Willis with complete anterior circulation and incomplete posterior circulation),Type ?(circle of Willis with incomplete anterior circulation and complete posterior circulation),Type ?(circle of Willis with incomplete anterior and posterior circulation),and analyses statistically whether there is a brain artery hardening level,age and gender differences between different types.3 Screen for open ACo A patients,measuring the left,middle and right vascular diameter in the original cross-sectional MRA segment images,take the average value is as the blood vessel diameter,with the unit of mm,accurate to 2 decimal places.Each vessel is measured two times and the average results is used as the final data of vessel diameter.4 Combined with the axis of the original image with the reconstruction of Axial,coronal and sagittal plane MIP images to track and assess the brain artery and its branches,according to the vascular morphology,shape,blood flow signal changes and distal vascular display degree evaluation and comprehensive analysis,Degree of stenosis of intracranial artery is divided into four levels: level 0,level 1,level 2,level 3.Level 0: controlled group,full continuous display,clear and sharp edges,signal basically uniform,No overlap phenomenon;level 1: mild atherosclerosis with arterial lumen thickness not uniform,edge uneven,a "beaded" change;Level 2: moderate arteriosclerosis with Segmental stenosis of the lumen of the artery,decreased distal branches,poor development and few of them showing the artery blood flow interruption although the distal end of the still developing;Level 3: severe arteriosclerosis,with artery interrupted and distal developing with distal collateral vessel formation.Age group is devided into group1(under 40 years)and group 2(40-60 years,including 60 years old)and group 3(> 60 years).Results:1 Among the 629 patients,Willis Type?is the least,accounting for 3.3%(21),Type?39.7%(250),Type 4.6%?(29),and Type 52.3% ?(329).2 Circle of Willis type proportion in the distribution of the middle cerebral artery atherosclerosis level is of no statistical difference(P=0.621),and Type is the most,Type? ?is the least.3 The ciecle of Willis type proportion in age distribution is of statistical difference(P=0.002).Type?,the proportion ?40 is the largest(13%).40-60 is less(3.2%)and >60 is the least(1.5%);Type?,the proportion 40-60 is the largest(41.9%).?40 is less(40.7%)and >60 is the least(37%);Type,the ?proportion ?40 is the largest(5.6%).>60 is less(4.9%)and >60 is the least(4.2%);Type ?,the proportion >60 is the largest(56.6%).40-60 is less(50.6%)and ?40 is the least(40.7%).In the age under or equal to 40 years old,Type?and Type ?proportion are the same and most,up to 40.7%,Type ? is the least,5.6%;in the age between 40-60 years old and older than 60 years old,Type ?is the most and type I is the least.4 Circle of Willis type proportion in gender distribution is of statistical difference(P= 0.004),although Type is still the most and Type? ?is the least,however,Type?and Type ?proportion in male is more than that in female and Type?and Type proportion in female is more than that in male.?5 ACoA diameter in the brain artery hardening level is of no statistical difference(P=0.781).level 0,level 1,level 2 and 3 ACoA diameter are respectively(1.22±0.36)mm,(1.19±0.32)mm,(1.19±0.31)mm and(1.20± 0.33)mm.6 ACoA diameter in age is of no statistical difference(P=0.112).Group 1,group 2 and group3 ACoA diameter are respectively(1.19±0.39)mm,(1.15 ±0.32)mm and(1.24±0.33)mm.7 ACo A diameter in gender is of no statistical difference in gender(P=0.053),the male and female ACo A diameter are respectively(1.16±0.31)mm and(1.23±0.34)mm.Conclusion:1 Circle of Willis type composition ratio is different,the Type ?is the main and has low completeness rate of anterior circulation and posterior circulation.2 There is no statistical difference in the distribution of circle of Willis type composition in the different levels of the middle cerebral artery.Type ?is the most and Type?is the least.3 There is statistical difference in the distribution of circle of Willis type composition in the different age levels,that is,different ages of circle of Willis type composition ratio is different.4 There is statistical difference in the distribution of circle of Willis type composition in gender.Type?and Type ?in male accounts for more proportion than in the female.Type?and Type ?in male accounts for less proportion than in the female.But on the general,Type ?is the msot and Type?is the least.5 There is no statistical difference of the ACoA diameter in the level of middle cerebral artery atherosclerosis,age and gender.