脑静脉系统流出端影像学特征及其与颅内压增高的关系研究

目的 对比观察颅内压增高与正常压力状态下脑静脉系统流出端的影像学特征,描述该段血管汇入静脉窦前的狭窄形成,结合前期实验结果探讨脑静脉系统参与颅内压调节机制中该血管狭窄节段可能的生物学意义及临床应用价值. 方法 选取40例颅内占位性病变(非血管性疾病)致颅内压增高患者为研究对象,10例正常志愿者作为对照组,磁共振静脉血管成像技术扫描成像,获得脑桥静脉及脑内静脉窦原始影像,以最大强度投影进行图像后处理,记录脑桥静脉汇入静脉窦前即两者交界处的影像学特征.并测量不同压力状态下脑桥静脉的直径.结果 颅内高压患者的脑桥静脉直径大于对照组,并且大部分颅内压增高患者(32/40)可出现影像学上脑静脉流出端磁共振信号的减弱甚至消失,形成影像学上的明显狭窄,而正常志愿者中仅有1例出现类似的信号减弱.结论 脑桥静脉作为脑静脉系统的最后通路,在颅内压增高时形成的狭窄结构提示其可能参与脑静脉系统自身体积变化的被动调节,进而对颅内压的调节发挥重要的作用.压力增高时脑桥静脉直径增加也从另外一方面说明该狭窄结构限制了静脉血液向颅外的顺畅引流,导致静脉血液的淤积并进一步增加了颅内压力.

MRI investigation on outflow segment of cerebral venous system and its significance with increased intracraulai pressure

Objective To measure and compare the imaging (MRI) features of outflow segment of cerebral venous system under increased and normal intracmnial pressure (ICP) and describe the stenosis formed before the venous sinus to explore the possible biological significances and clinical values of cerebral venous system in the regulating of angiostenosis. Methods Forty patients that presented both increased ICP symptoms and more or less hydrocephalus were selected as experimental group and 10 normal volunteers were selected as control group. Both the 2 groups were underwent 2D-TOF MRI with the following parameters: repetition time/echo time, 50/4.9 milliseconds; flip angle, 45°;field of view, 250 min×250 mm; matrix, 256×256 pixels; section thickness, 1.5 mm. The original images and data of the cerebral bridging veins and cerebral venous were recorded, and then, sinus Syngo fast view imaging system was used to process and analyze them. The diameter of cerebral bridging veins under different pressures was measured. Results The diameter of cerebral bridging veins in the experimental group was longer than that in the control group. A short and narrow length in MRI was obviously shown in most increased ICP patients resulting from signal weakness even disappearance at the outflow segment of cerebral venous system, while only 1 volunteer was showed the existence of signal weakness of similar imaging. Conclusion Cerebral bridging veins, the last passageway of the cerebral venous system, can passively influence the intraeranial pressure environment to regulate the level of ICP.The increased length of diameter of cerebral bridging veins under high pressure indicates that stenosis can induce hematomain the vein by limiting the drainage of venous blood.