螺旋CT容积漫游技术在枢椎骨折螺钉内固定术后评价中的价值

Value of helical CT volume rendering technique in post-operative evaluation of screw fixation of axis fractures

目的探讨螺旋CT容积漫游技术(volume rendering technique, VRT)在枢椎骨折螺钉内固定术后评价中的价值. 方法收集2002年2月-2004年5月经皮枢椎骨折螺钉内固定术后患者共21例,其中枢椎体骨折6例,齿状突骨折5例,枢椎体及齿状突联合骨折10例;同时合并寰枢关节脱位7例.内固定术后均摄X线片、螺旋CT薄层扫描、多平面重建(multiple planar reformatting, MPR)及VRT成像. 结果本组经枢椎体与寰椎侧块钛合金双枚螺钉内固定10例,经枢椎体与齿状突单枚螺钉内固定11例.VRT成像能清晰显示螺钉轨道全径、螺钉位置及固定角度,并优于X线片及MPR成像.多角度VRT成像显示,齿状突与寰椎侧块间距不对称4例,6例经枢椎体与寰椎侧块内固定的单枚螺钉向内侧偏斜,偏斜范围2～5 mm. 结论 VRT成像能消除内固定螺钉伪影,清晰显示螺钉轨道全径,可为枢椎骨折螺钉内固定术后疗效评价提供重要的影像学依据.

Objective To explore the value of helical CT volume rendering technique (VRT) in post-operative evaluation of screw fixation of axis fractures. Methods There were 21 cases of screw fixation of axis fractures between February 2002 and May 2004 in the study including six cases with fractures on axis body, five on odontoid process and 10 on axis body and odontoid process. All cases received X-ray plain film, helical CT scanning, multi-planar reformatting (MPR) and VRT. Results Screw fixation through axis body and massa lateralis atlantis was performed in 10 cases and that through axis body and odontoid process in 11. VRT could clearly display full aperture of screw orbit, location of screw and angle of fixation and hence was superior to X-ray plain film and MPR. Multi-angle VRT displayed asymmetrical space of odontoid process and massa lateralis atlantis in four cases and medial deviation of 2～5 mm of half screw in screw fixation through axis body and massa lateralis atlantis in six. Conclusions VRT can eliminate false shadow of fixation screw, clearly display full aperture of screw orbit and hence supply important imaging evidence for post-operative evaluation of screw fixation of axis fractures.