DePippo P S, Ascher E, Scheinman M, Yorkovich W, Hingorani A
Department of Surgery, Maimonides Medical Center, Brooklyn, NY, USA.
Cardiovasc Surg. 1999 Jan;7(1):27-32. doi: 10.1016/s0967-2109(98)00096-9.
Magnetic resonance angiography is a useful technique to determine the patency of the circle of Willis when compared with conventional four-vessel angiography. The purpose of this study is to determine whether the integrity of the circle of Willis, assessed by magnetic resonance angiography, provides adequate collateral cerebral circulation during carotid endarterectomy and correlates with internal carotid artery back pressure. Over a recent 20-month period, 35 patients were studied preoperatively with magnetic resonance angiography of the carotid bifurcations of the circle of Willis and the vertebrobasilar system. All patients underwent standard carotid endarterectomy with intraoperative measurement of internal carotid artery back pressure. Patients with an internal carotid artery back pressure < 50 mmHg had an intraluminal shunt placed. Deficiencies in branches of the circle of Willis, the carotid bifurcation and the vertebrobasilar system determined by magnetic resonance angiography were correlated with internal carotid artery back pressure using Fisher's exact test. Only one patient had a completely intact circle of Willis. Eleven of 16 patients (69%) who had an internal carotid artery back pressure < 50 mmHg had an occluded A1 segment of the anterior cerebral artery combined with an occluded posterior communicating artery, whereas only five of 19 patients (26%) who had an internal carotid artery back pressure > 50 mmHg had similar findings (P < 0.03). Severity of occlusive disease of the contralateral internal carotid artery and the basilar artery did not independently predict internal carotid artery back pressure. An occluded anterior branch of the circle of Willis in combination with an occluded posterior branch of the circle of Willis is associated with an internal carotid artery back pressure < 50 mmHg. Although magnetic resonance angiography of the circle of Willis may provide valuable anatomic information, it is not sufficiently accurate to predict the need for carotid shunting and therefore its use cannot be justified on a routine basis.
与传统的四血管造影相比，磁共振血管造影是确定 Willis 环通畅性的一种有用技术。本研究的目的是确定通过磁共振血管造影评估的 Willis 环完整性在颈动脉内膜切除术期间是否能提供足够的脑侧支循环，并与颈内动脉背压相关。在最近的 20 个月期间，对 35 例患者进行了术前 Willis 环颈动脉分叉和椎基底系统的磁共振血管造影研究。所有患者均接受标准的颈动脉内膜切除术，并在术中测量颈内动脉背压。颈内动脉背压<50 mmHg 的患者放置了腔内分流器。使用 Fisher 精确检验将磁共振血管造影确定的 Willis 环、颈动脉分叉和椎基底系统分支的缺陷与颈内动脉背压相关联。只有 1 例患者的 Willis 环完全完整。16 例颈内动脉背压<50 mmHg 的患者中有 11 例（69%）大脑前动脉 A1 段闭塞并伴有后交通动脉闭塞，而 19 例颈内动脉背压>50 mmHg 的患者中只有 5 例（26%）有类似表现（P<0.03）。对侧颈内动脉和基底动脉闭塞性疾病的严重程度不能独立预测颈内动脉背压。Willis 环前支闭塞并伴有 Willis 环后支闭塞与颈内动脉背压<50 mmHg 相关。虽然 Willis 环的磁共振血管造影可能提供有价值的解剖学信息，但它不足以准确预测是否需要颈动脉分流，因此其常规使用是不合理 的。
