三基：磁敏感血管征（Susceptibility Vessel Sign）

GRE序列上大脑中动脉磁敏感血管征和CT上MCA高密度征的意义差不多。最近的研究显示GRE磁敏感征和CT上MCA高密度征都代表了富含红细胞的血栓。

白色血栓是富含血小板的血栓，通常对静脉溶栓有抵抗；然而，红色血栓富含红细胞，对静脉溶栓药物反应更好。

下面是磁敏感血管征的几个例子：

Figure 1: Patient with acute left MCA territory infarct. (a) Unenhanced CT scan shows minimal focal increased density in distal left MCA. (b, c)DWI and apparent diffusion coefficient maps demonstrate acute left MCA territory infarct. (d) MCA cortical branches demonstrate the hyperintense artery sign' on FLAIR images (arrow). (e) SWI image shows susceptibility sign at site of thrombus at distal M1 segment extending into proximal M2 segment (arrow). (f) Distal left MCA occlusion is confirmed on contrast-enhanced MRA (arrow). (d) MRA MIP image confirms the left MCA occlusion

Figure 2: Left PCA occlusion. (a) Unenhanced CT scan shows hypodensity in left PCA territory. (b) DWI image shows acute left PCA territory infarct. (c) SWI images show susceptibility sign in proximal PCA (arrow). (d) Reconstructed volume-rendered images from contrast-enhanced MRA show left PCA occlusion after the origin (arrow)

Figure 3: Right vertebral artery occlusion. (a, b) DWI and ADC maps show acute infarct in right posterior inferior cerebellar artery territory. (c) Right vertebral artery shows susceptibility sign (arrow). (d) Contrast-enhanced MR angiogram volume-rendered technique images show \nocclusion of V4 segment of right vertebral artery (arrow)