摘要
脑动脉硬化是指脑部血管弥漫性粥样硬化、管腔狭窄及小血管闭塞所致的脑部血供减少而引起的脑部病变，此为中枢神经系统常见病。其病因与发病机理至今仍尚未完全阐明，一般认为是各种综合因素造成血管内膜受损，内膜下条状脂质浸润，内膜增生，脂质堆积，形成泡沫细胞，然后死亡，产生细胞外胆固醇沉积在内膜并形成粥样斑块，由此导致血管壁缺血、玻璃样变、坏死、闭塞或破裂出血等。ＣＴ、ＭＲＩ对脑动脉硬化的诊断极有帮助。主要表现是：１脑底动脉纤曲、扩张，管壁增厚、钙化；２．脑萎缩；３．白质脑病；４．多发性基底节区腔隙性脑梗塞；５．皮质下无症状性脑梗塞；６．脑室周围高信号灶；７．脑梗塞、脑出血后遗改变等。一般将脑出血按时间长短分为急性期、亚急性期、慢性期。各期血肿一般都有较典型的ＣＴ和ＭＲＩ表现，因此用ＣＴ、ＭＲ诊断脑出血一般困难不大。而困难在于鉴别合并脑肿瘤、脑血管异常的脑出血。
Cerebral atherosclerosis is the common disorder of CNS, which is produced by diffuse vascular atherosclerosis, vessel lumen stenosis, small vessel occlusion and reduced blood supply. The pathogenesis and mechanism of cerebral atherosclerosis still remain controversial. The major theory involved in the complex factors, including injury and cellular proliferation. Atherogenesis is initiated by focal endothelial change of subtal intimal injury that leads to platelet aggregation. Endothelial injury permits increased permeability to macromolecules such as LDL. Moncytederived macrophages and smooth muscle cells are recruited to the intima where they proliferate and accumulate fatty eatens, becoming lipid - filled foam cells. As these cells died, their detritus produces the extracellular cholesterol deposits that form the atherosclerosis plaque, which results in vascular ischemia, necrosis, stenosis, occlusion, rupture and hemorrhage, etc. CT and MRI play an important role in the diagnosis of cerebral atherosclerosis, main manifestations include the following: 1. vessel ectasias, elongation and tortuousity, vessel wall thickening and calcifications, 2. cerebral atrophy, 3. leukoencephalopathy, 4. multiple lacunar infarcts in the basal ganglia, 5. subcortical silent brain infarcts, 6. periventricular hyperintensity (PVH), 7. cerebral infarction, or hemorrhage and their complications. Cerebral hemorrhage is usllally divided into acute, subacute and chronic hemorrhage according to hemorrhagic time. It can be diagnosed accurately by CT and MRI because of the typical appearance of hemorrhage in different stage. However, sometimes it is difficult to differenciate cerebral hemorrhage from brain tumor and vascular malformation with hemorrhage, we should take it into account.
出处
《中国医学计算机成像杂志》
CSCD
2000年第1期37-39,共3页
Chinese Computed Medical Imaging
