颅内血管畸形

ntracranial Vascular Malformations

按病理学分类颅内血管畸形分为：动静脉畸形（包括动静脉瘘），海绵状血管瘤，静脉血管瘤（或静脉发育异常）以及毛细血管扩张症四种不同类型。影像学检查需要观察血管畸形的供血动脉、引流静脉（包括静脉窦是否增粗）、畸形血管本身，也就是畸形血管团、血管内有无血栓，还要观察血流的循环速度，即循环时间的改变、脑组织内是否有出血，以及出血机化形成的钙化，和邻近脑组织内出现的缺血、水肿乃至萎缩等慢性变化。ＣＴ平扫和增强扫描可以观察畸形血管有无染色，供血动脉、引流静脉是否增粗，但是很难区别供血动脉和引流静脉。同样，可以通过打药前后ＣＴ对比观察，显示急性出血、慢性出血，及血肿吸收过程中的变化。ＣＴ可以准确地定位，描绘血肿的形态，显示血肿和占位效应的比例关系，以鉴别畸形血管出血、高血压出血还是肿瘤出血。ＣＴＡ技术可以三维显示动脉、静脉以及血肿之间的关系。磁共振使用不同的脉冲序列，可显示流空效应反映的血管异常，可以评价出血的全过程，即评价血肿内血红蛋白的氧化过程，含氧血红蛋白、脱氧血红蛋白、正铁血红蛋白在不同场强下形成不同的信号强度，磁共振还可评价脑组织内含铁血黄素沉着，为检查脑血管畸形，特别是对判断脑血管畸形合并血肿的不同时期提供了有?

The cerebral vascular malformations are pathologically divided into four types: arteriovenous malformations (including arteriovenous fistula), cavernous angiomas, venous angiomas, and capillary telangiectases. The imaging studies are perormed to observe the feeding artery, draining vein (including venous sinus enlargement), AVM nidus, thrombosis, circulation time, cerebral hemorrhage, calcifications, and the brain chronic changes like cerebral ischemia, edema, and cerebral atrophy. CT study could show the AVM stain and enlargement of feeding arteries and draining veins. However, it is difficult to distinguish the feeding artery and draining vein on CT studies. By comparison CECT and NECT, we can distinguish the acute and chonic hemorrhage, and the changes during hemorrhage absorption. CT study can also he used to locate the vascular malformation, delineate the hematoma, show mass effects, and differentiate the AVM hemorrhage and hypertension hemorrhage. CTA could display the relationship between blood vessels and hematoma. MR studies could display the flow void effect of abnormal vessels by a variety of pulse sequences. MR could also evaluate the metabolic stages of hemoglobin in the hematoma. The oxyhemoglobin, deoxyhemoglobin, methemoglobin, and hemosidin show different signal intensities on both T1WI and T2WI. These signal changes of hematoma provide an effective method in evaluating the AVM and the stage of AVM hematoma. Cerebral angiography shows the detail information on morphology and circulation time of the vascular malformation and is critical for surgical planing. It is the modality of choice in imaging the AVM.