减影去骨技术在头颈CT血管双期成像中的应用

Bone-Subtraction Dual Phase CT Angiography for Cerebral and Cervical Vessels

目的:比较减影去骨法与手动去骨法对头颈血管CT成像的差异,探讨减影去骨法的应用价值。方法:51例患者30例行脑动脉CTA(12例行脑静脉CTV),另外21例行头颈动脉CT成像。先测试颅底动脉达峰时间,平扫后根据达峰时间行动脉期扫描,必要时立即行静脉期扫描;动脉增强、平扫薄层图像同层相减生成动脉期三维图像,少量残余骨质辅以手动去骨,同样方法处理静脉系统。以手动去骨处理血管增强的原始图像得到动脉(和静脉)三维结构图。观察颈根动脉、颈5椎体-颅内动脉以及脑静脉的完整度,观察颅内血管分支、颅底-颈5椎体动脉的清晰度,计算动脉系统成像后处理消耗的时间,与手动去骨成像对比。结果:减影去骨法显示颈5椎体-颅内动脉的完整性优于手动去骨(χ2=27,P=0.008),前者显示脑静脉的完整度明显好于后者,但两种方法显示颈根部动脉的效果都一般;手动去骨显示颅内动脉分支的清晰度优于减影去骨法(χ2=9,P=0.01),显示颅底-颈5椎体动脉的清晰度差异无显著意义(χ2=5.6,P=0.06);减影去骨处理动脉系统消耗的时间明显少于手动去骨(t=-11.16,P<0.001);总共发现有病变的患者32例,其中减影去骨法对颅底血管狭窄和动脉瘤显示立体效果更好。结论:减影去骨法可显示血管全貌,对病变立体定位更好,但是脑部小血管亮度欠佳,对患者固定要求高。

Objective： To compare the effects of bone-subtraction （BS） CT angiography （CTA） and manual bone elimination （MBE） CTA for the vessels from aortic arch to brain and explore the application value of bone subtraction CT angiography. Methods： 51 patients （21 for cervical and cerebral artery,30 for cerebral vessel）. The arterial peak time in the plane of skull base was determined by test-bolus sequence. The patients were kept stable when plain and enhanced scans （delayed time was the vessel peak time） were taken. Plain images were subtracted by arterial phase images for artery pro cessing, the remaining bone was processed by MBE, the cerebral vein was processed by the same method for 12 patients. The source images were also processed by MBE （assisted by threshold elimination） for artery and vein. The artery （in the collar, from the 5th cervical vertebra to brain） and cerebral vein integrity were evaluated, the details of the vessel from 5th cervical vertebra to the skull base and the vascular branch in the brain were observed,the time of BSCTA for artery was corn pared with that of MBECTA. Results： The integrity of artery from the 5th cervical vertebra to brain processed by BS was better than that by MBE （ 2 27,P 0. 008）,BS surpassed MBE for cerebral vein,the quality of the collar vessel was poor both with MBE and BS. The details of brain vessel branch were found better by MBE than by BS （χ^2=9,P =0. 01） , there was no significant difference between BS and MBE for the artery from 5th cervical vertebra to the skull base processed （χ^2=5.6,P= 0. 06）. BS took less time for the artery thanMBE （t =-11.16,P〈0. 001）. In 32 patients with vascular dis ease,the arterial stenosis and aneurysm near skull base were revealed to be better by BSCTA. Conclusion： Bone-subtraction CT angiography of double phase is suitable for the vessel from the aortic arch to skull base, because the three dimensional full view of vessels can be easily demonstrated and the disease can be shown more clearly than manual elimination of bone, but it depended on patient＇s stability during scanning. For the cerebral vessel, it was not so good as manual method.