大脑中动脉分叉部动脉瘤分型与双干型血管分支关系的研究

Study on the relativity between the neck type of middle cerebral artery bifuration aneurysms and the double stem type branches

目的颅内动脉瘤(IA)好发于血管分叉部,提示血管形态学因素与IA形成密切相关。本研究通过回顾大脑中动脉(MCA)分叉部IA病例,探讨MCA分叉部IA分型与其分支的关系。方法回顾性分析117例自2008年1月至2011年12月就诊于温州医学院附属第一医院行头颅多层螺旋CT血管造影(MSCTA)检查诊断为MCA分叉部IA患者的影像学资料,选取双干型MCA分叉部单发IA并经数字减影血管造影(DSA)或手术证实者,符合条件的病例共64例66个IA(其中2例为双侧MCA分叉部IA)。根据瘤颈的位置将分叉部IA分为经典型(C型)和偏侧型(D型)。通过MSCTA后处理图像对IA进行分型,测量患侧MCA两分支起始处的管径、两侧分叉角及两分支间夹角,并计算两分支管径比及两侧分叉角比。将两型IA的分支管径比、两侧分叉角比及两分支间夹角的数值分别进行两独立样本t检验。结果 66个IA中30个为C型IA,36个为D型IA。C型组:分支管径比平均值为1.33±0.35,两侧分叉角比平均值为1.28±0.28,分支夹角平均值为141.70°±19.91°,D型上述参数对应值为1.69±0.41、1.59±0.34、144.17°±18.00°。根据统计结果,两型IA的分支管径比、两侧分叉角比具有统计学差异(t=-3.856,P<0.001;t=-3.953,P<0.001),两分支间夹角差异无统计学意义(t=-0.529,P=0.599)。D型组所有IA均发生于分叉角较小侧,且绝大部分发生于较细分支起始端(35/36)。结论 MCA分叉部血管形态影响分叉部IA的生长部位。MCA分叉部IA中D型更为多见,当分叉部两分支管径及两侧分叉角相差较小时,倾向于发生C型IA,反之则多发生D型IA,并且D型IA倾向于发生在较小分支侧及较小分叉角侧。

Objective There is a high incidence of intracranial aneurysms （IA） at the bifurcations suggesting the vascular morphology is closely related to the formation of intracranial aneurysms. By studying the cases of MCA bifurcation aneurysms retrospectively, discuss the connection between the type of aneurysms and the branches of corresponding bifurcations. Methods The imaging data of the 117 consecutive patients suffer MCA bifurcation aneurysms were studied retrospectively, which were diagnosed by skull multi-slice spiral CT angiography （MSCTA） in The First Affiliated Hospital of Wenzhou Medical College, from January 2008 to December 2011. The cases of MCA bifurcation with two branches and single aneurysm which verified by DSA or surgery were selected. There were 64 cases with 66 aneurysms match the conditions （2 cases had hibateral MCA bifurcation aneurysms）. As for the neck location, the bifurcation aneurysms were classified into Classical neck type（type C） aneurysms and Deviating neck type （ type D） aneurysms. According to the post-processing images, classified the aneurysms, then measure the diameter of daughter arterys （DA） in their initial segment ,the branch angles（Ba） and the angles between them. DA ratio and BA ratios were calculated.Parameters aforementioned of the two types were analyzed with two-tailed independent-samples t test. Results In all 64 causes with 66 aneurysms,there were 30 cases of type C aneurysms and 36 cases of type D aneurysms. Type C group：the average DA ratio was 1.33 ±0. 35 ,the average BA ratios was 1.28 ±0. 28,and the average angles between two DA was 141.70°±19. 91°. The corresponding parameters above-mentioned of type D were 1.69 ±0. 41, 1.59 ±0. 34, 144. 17° ±18.00°. According to statistic results, statistically significant differences were found in the DA ratios and BA ratios between type C and type D （ t = - 3. 856, P 〈0. 001 ; t = - 3. 953, P 〈 0. 001 ）, and no obviously differences was found in the angles between two daughter arteries （ t = - 0. 529, P = 0. 599 ）. Interestingly, in the total 36 cases of type D, all aneurysms existed on the sharp branch angle side, and on the smaller daughter arteries （35/36）. Conclusions The vascular morphology of MCA bifuration influences the site where MCA bifuration aneurysms occur. Type D cases are more common in MCA bifuration aneurysms. Aneurysms with similar size of daugther arteries and branch angles tend to occur type C aneurysms, on the contrary, and the distinct size of daugther arteries and branch angles leading to type D aneurysms. In addition, type D exist more commonly on the side with sharp branch angle and smaller daugther artery.