| [Objective] Using magnetic resonance angiography (MRA), we evaluated the cranial and cervical arteries and the hemodynamics of the circle of Willis in the patients with transient ischemic attacks (TIA). Diffusion weighted imaging(DWI) of the brain was also performed. With these methods, we evaluated the mechanism of TIA in terms of vascular morphology and haemodynamics to find out the arteries of high risk in advance.[Materials and Methods] 40 patients conforming to standard of TIA were chosen from the patients who performed MRA examination in our hospital between January 2003 and march 2005. 34 non-cerebrovascular disease subjects and 36 patients with large area brain infarction were also randomly chosen as control subjects from the same patients group mentioned above. MRA was performed with a superconductive GE 1.5T Twin-Speed Infinity with Excite I system equipped with 8NV head and neck coil. The following sequences were performed for all subjects: Three dimensional contrast enhanced MRA (3D CE-MRA), multiple overlapping thin slab acquisition (MOTSA) ,time of flight (TOF) and phase contrast (PC) MRA,and DWI. After postprocessing the data with workstation (AW4.0), the images were analyzed for the relationship between TIA and the degree of stenosis of cranial and cervical arteries as well as thedistribution of the stenosis, the development of the the vessels, DWI findings of the brain, and the development and collateral pattern of the circle of Willis.[Results] Different MRA sequences had their own applicability and advantages, and all the image quality obtained from this study was good enough for the evaluation. Compared with non-cerebrovascular disease subjects, the patients with TIA or large area brain infarctions had higher degree of arterial stenosis and occlusions (.P=0.006), and much more constrictive and occlusive arteries (.PO.001), but there were no significant difference between TIA and large area brain infarction patients (P=0.755). In TIA group,56.58% artery lesions were found within skull and 31.58% were in the cervical region out side the skull. The incidence of dysplastic vertebral arteries (VA) of vertebrobasilar TIA subjects was higher than that of in the non-cerebrovascular disease subjects(P=0.039). The dysplastic VA often had irregular wall and focal stenosis. TIA of internal carotid artery(ICA) system tended to show more ischemic focus on DWI(4/8,50%), and the clinical localization was definite, but not was the case with vertebrobasilar TIA(4/32,12.50%). All ischemic focus on DWI occurred in the areas fed by impaired arteries. The stenotic lesions in the group with non-cerebrovascular disease(75.0%) and in TIA(72.0%) were mainly located in the arteries before the circle of Willis, but only 41.43% was found in the group with large area brain infarction, and there was a significant difference among the three groups (PO.001). There was no significant difference on the types of the circle of Willis among the three groups (P=0.934). Dysplasia or obsence of the first segment (Al) of anterior cerebral artery (ACA) in TIA of ICA system was more common (62.50%), and had a significant difference compared with vertebrobasilar TIA (18.75%)(P<0.05). In the cases of non-cerebrovascular disease subjects, fetal-type posterior cerebral arteries(PCA) accompanying hypoplastic or absent PI were more common (35.29%), and there was a significant difference compared with... |
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