Rubinstein D, Escott E J, Mestek M F
University of Colorado Health Sciences Center, Department of Radiology, Denver 80262, USA.
J Trauma. 1996 Feb;40(2):204-10. doi: 10.1097/00005373-199602000-00006.
To determine the computed tomography (CT) appearance of minimally displaced type II odontoid fractures and the optimal protocols to evaluate these fractures by CT.
The CT scans of five patients with minimally displaced type II odontoid fractures and 71 patients without odontoid pathology were reviewed for signs of fracture. A phantom consisting of a cadaver specimen with a type II odontoid fracture was evaluated with several protocols on four CT scanners. The protocols differed in slice thickness and reconstruction algorithm. Helical scanning was also performed, and parasagittal and coronal reformations were created from each image set.
Multiple cortical disruptions longer than 1 mm were demonstrated on the scans of all five patients with type II odontoid fractures. Only three of the 71 patients without odontoid fractures had multiple cortical disruptions, and none were longer than 1 mm. In the phantom study, thinner sections demonstrated cortical disruptions better than thicker sections. Similarly, images reconstructed with a bone reconstruction algorithm demonstrated the cortical disruptions better than images reconstructed with a soft-tissue reconstruction algorithm. Helical scans (1 mm thick) adequately demonstrated the reduced Type II odontoid fracture. Parasagittal and coronal reformations failed to demonstrate a fracture line through the base of the odontoid process on all image sets.
Cortical disruptions greater than 1 mm and multiple cortical disruptions may be the only findings of odontoid fractures and should suggest the diagnosis. Evaluation of potential type II odontoid fractures is improved as CT section thickness is reduced (down to 1 mm) and is also improved by use of a bone reconstruction algorithm. The apparent absence of a fracture line through the base of the odontoid process on parasagittal or coronal reformations does not rule out the diagnosis.
确定轻微移位的Ⅱ型齿状突骨折的计算机断层扫描（CT）表现以及通过CT评估这些骨折的最佳方案。
回顾了5例轻微移位的Ⅱ型齿状突骨折患者和71例无齿状突病变患者的CT扫描图像，以寻找骨折迹象。使用四个CT扫描仪上的几种方案对一个包含Ⅱ型齿状突骨折尸体标本的模型进行了评估。这些方案在切片厚度和重建算法上有所不同。还进行了螺旋扫描，并从每个图像集创建了矢状旁位和冠状位重建图像。
在所有5例Ⅱ型齿状突骨折患者的扫描图像中均显示出多条长度超过1mm的皮质中断。在71例无齿状突骨折的患者中，只有3例有多处皮质中断，且均不超过1mm。在模型研究中，较薄的切片比厚切片能更好地显示皮质中断。同样，用骨重建算法重建的图像比用软组织重建算法重建的图像能更好地显示皮质中断。螺旋扫描（1mm厚）能充分显示移位的Ⅱ型齿状突骨折。在所有图像集上，矢状旁位和冠状位重建均未能显示通过齿状突基底部的骨折线。
大于1mm的皮质中断和多处皮质中断可能是齿状突骨折的唯一表现，应提示诊断。随着CT切片厚度减小（低至1mm），对潜在Ⅱ型齿状突骨折的评估得到改善，使用骨重建算法也可改善评估。矢状旁位或冠状位重建图像上齿状突基底部明显没有骨折线并不能排除诊断。
