CT仿真结肠镜技术的实验研究

The experimental study of the technique of CT virtual colonoscopy

目的 分析、优化扫描方式以提高结肠隆起性病变CT仿真结肠镜 (CTVC)成像效果。方法 取长约 2 0cm的猪结肠 16段 ,每段制作直径 2～ 10mm的息肉模型各 6个。结肠适度充气后 ,在不同体位、层厚和螺距、扫描角度下行螺旋CT扫描 ,观察CTVC成像效果。结果 远地壁模拟息肉显示效果优于近地壁 (Uc =5 998,P <0 0 1) ,检出率高于近地壁 ( χ2 =2 7 4 3,P <0 0 1) ;螺距为1 5 ,层厚由 5 0mm向 3 0、2 0mm递减 ,及层厚为 3 0mm ,螺距由 2 0向 1 5、1 0递减 ,图像显示效果渐好 ;结肠纵轴与扫描架平面成 90°时 ,图像显示效果最佳。结论 采用多体位 ,选择合适的层厚和螺距 ( 3 0mm/ 1 5 )、扫描角度能有效提高结肠隆起性病变的CTVC成像效果。

Objective To analyze and optimize scanning mode in order to improve imaging effect of CT virtual colonoscopy(CTVC)for colorectal masses. Methods Sixteen approximately 20-cm-long sections of fresh pig colon were resected as experimental model with 6 artificial mass lesions ranging from 2mm to 10mm in diameter per section.Spiral scanning was performed after appropriately distended by introduction of air at different body positions,collimation and table pitch and orientation of the colon lumen with respect to the gantry.Results The imaging effect of the distal wall was better than that of the proximal wall(uc=5 998, P <0 01).Detection rate was higher than that of the proximal wall(χ 2=27 43, P <0 01).When table pitch was 1 5,the less collimation was from 5 0mm to 2 0mm,the better images were.When collimatin was 3 0mm,the less table pitch was from 2 0 to 1 0,the better images were.At angle of 90° to the gantry,images were the best.Conclusion Use of multi-positions and proper selection of collimation table pitch (3 0mm/1 5),and orientation of the colon lumen with respect to the gantry could improve imaging effect of CTVC for colorectal masses.