脑分水岭梗死MRI、MRA特点及其发病机制的研究

Characteristics of MRI and MRA in Patients with Cerebral Watershed Infarction

目的:探讨脑分水岭梗死(CWI)不同病变模式的MRI、MRA特点及其发病机制。方法:回顾性分析85例CWI患者,将梗死模式分为单纯性CWI、混合性CWI和多发性CWI。比较不同模式的CWI中大脑中动脉(MCA)、颈内动脉(ICA)病变情况。结果:85例CWI患者中,单纯性后分水岭梗死(PWI)6例,单纯性内分水岭梗死(IWI)11例,混合性前分水岭梗死(AWI)4例,混合性PWI 9例,混合性IWI 36例,多发性CWI 19例。MCA重度狭窄率明显高于ICA重度狭窄率(P=0.00)。单纯性IWI、混合性IWI和多发性CWI MCA重度狭窄率明显高于ICA重度狭窄率(P<0.01)。单纯性IWI、混合性AWI、混合性IWI、多发性CWI的MCA重度狭窄率均明显高于单纯性PWI和混合性PWI(P<0.05)。结论:MCA重度狭窄较ICA重度狭窄更易导致CWI,尤其是导致IWI、混合性IWI和多发性CWI;MCA重度狭窄对于前循环(颈内动脉系统)供血区的CWI影响较大;MCA重度狭窄引起狭窄远端的血流动力学障碍和微栓子清除能力下降,可能是导致CWI以及CWI合并皮质区梗死(PI)和/或穿支动脉梗死(PAI)的机制之一。

ObjectiveTo investigate the features of MRI and MRA in detecting different cerebral watershed infarction （CWI） patterns. Methods： Eighty-five CWI patients were retrospectively divided into three types including simple CWI, mixed CWI and multiple CWI. The middle cerebral artery （MCA） and internal carotid artery （ICA） stenosis were evaluated in different CWI patterns. Results： There were 6 patients with simple posterior watershed infarction （PWI）, 11 patients with simple internal watershed infarction （IWI）, 4 patients with mixed anterior water-shed infarction （AWI）, 19 patients with mixed PWI, 36 patients with mixed IWI and 19 patients with multiple CWI. Of the 85 patients, the ratio of severe stenosis of MCA was significantly higher than that of ICA （ P=0.00）. The ratio of severe stenosis of MCA was significantly higher than that of ICA in patients with simple IWI, mixed IWI and multiple CWI （ P〈0.01）. The ratio of severe stenosis of MCA in patients with simple IWI, mixed AWI, mixed IWI and multiple CWI was significantly higher than that in the patients with simple PWI and mixed PWI （ P〈0.05）. Conclusion： Severe stenosis of MCA is more likely to lead CWI than severe stenosis of ICA, especially in patients with IWI, mixed IWI and multiple CWI. Severe stenosis of MAC has a greater effect on CWI of anterior circulation （ICA system）. Hemodynamic abnormality of the far side in patients with severe stenosis of MCA and the declined ability to eliminate micro-embolus may be of important mechanism.