| PrefaceThree - dimensional CT angiography ( 3D - CTA) is a recent de-veloping technique of medical imaging, combing the fast data - acqui-sition capacity of spiral CT with the graphic - processing capabilities of modern computer workstations. The post - process methods of 3D -CTA include shaded surface display ( SSD) maximum intensity pro-jection ( MIP ) multi - planar reconstruction ( MPR) shade volume rendering (SVR) and virtual endoscopy (VE) ,et al.In addition to 3D visualization of vascular structures, this new technique simultaneously offers precise information about the topo-graphic relationships between vessels and the surrounding anatomic landmarks. The application of VE for cranial arteries was rare relative-ly , only study on cerebral aneurysms was more deep - going. The ap-plication of VE for observing cranial arteries and their branches of pa-tients with cerebral infarctions was not reported in domestic and a-broad. This experiment applicates combined VE MPR MIP and SVR to observe cranial arteries and their branches in patients with cerebral infarctions, and research the internal aspect of cranial arteries and its branches, and evaluate the clinical value of multi - slice helical CT three - dimensional angiography as an assistant method for diagnosingcerebral infarctions.Materials and Methods\ We reviewed 26 patients with cerebral infarctions. The mean ageof the patients was 50. 85 years ( range 18-69 years) . This group consisted of 18 men and 8 women. All these patients underwent 3D -CTA. Original data was acquired by Multi - slice helical CT - Aquilion (Toshiba) .-scan speed 0. 5s/rot,image slice thickness 1.0mm, heli-cal pitch 0.5. Contrast media ( Angiografin) was injected intravenously (1.0-2. OmL/kg) at speed of 2. 5 - 3. 0mL/s, delay time was 15 -23s,reconstruction interval 0. 5mm,reconstruction slice thickness 1. Omm. Source images were processed using a workstation SGI02, the images post - processing software was ALATOVIEW, Version 1. 21. The reconstructed images were then processed into MPR, MIP, SVR and Fly - around/Fly - through images. The standard threshold CT values employed for delineating blood vessels were 90 Hu as the lower limit and 350 - 400 Hu as the upper limit, and were adjusted in ac-cordance with the degree of enhancement. Images of 3D - CTA were analysed by 3 radiologists and 2 neurologists.Results17 middle cerebral arteries ( MCA) occlusion or stenosis were de-tected , and 2 posterior cerebral arteries ( PGA) occlusion or stenosis were detected. 1 vertebral artery ( VA) stenosis was detected by 3D -CTA. There are not abnormal vessels in 6 cases, 5 of them were lacu-nar infarctions. No anterior cerebral artery (AC A) occlusion or steno-sis was detected. Large vessel occlusion and the relationships between the circle - of - Willis and surrounding structures were clearly and dis-played surely. Thrombus and calcification were not found on the vessel wall by fly - through. The artery wall was almost smooth.There are 2 patients were diagnosed multiple sclerosis by conven-tional CT scan or MRI, they were diagnosed definitely by 3D - CTA , 1 of those was diagnosed definitely Moyamoya disease.All Coronal, axial and sagittal sections could 3D display the posi-tion and shape and size of the area of infarction by MPR, and could localize precisely in each brain lobe. The pathologic vessel was tortu-ous and stretching, and the terminal was occluded centripetally.The degree of stenosis was demonstrated by MIP clearly and no thrombus or calcification.In the different direction of coronal, axial and sagittal sections, the ACA, MCA, PCA and vertebrobasilar artery were display clearly by SVR, but the lenticulostriate artery was observed rarely.The observation by Fly - around is similar to that of SVR, exag-gerating the serious stenosis to be occlusion. Fly - around is very use-ful in three - dimensional perception. It can detect more vessel bran-ches than SVR, can observe anterior inferior cerellar artery ( AICA) and right AC...
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