结肠模拟息肉CT结肠成像的实验研究

Experiment study of multislice CT colonography in porcine colonic polyp model

目的：研究扫描参数、图像重建参数和后处理方法对CT结肠成像（CTC）图像质量和模拟息肉检出率的影响，以期获得良好图像质量和较高息肉检出率的成像参数及后处理方法的最佳组合。方法：用猪结肠制成大小不等的模拟息肉共计60枚。充气后应用16层螺旋CT进行容积扫描，分别比较不同螺距、不同层厚、不同重叠重建率、不同算法及不同后处理方法对图像质量的影响及息肉的检出率，确定最佳参数组合。结果：准直1．25mm，螺距1．375：1、重建层厚1．25mm、O％重叠重建率和标准算法重建是扫描和重建参数的最佳组合。各种后处理方法中：CTVE、VR＋Raysum、MPR＋轴位和VD对10～12mm组息肉的检出率分别为100％、95％、95％、100％；对5-9．9mm组息肉的检出率分别为95％、75％、80％和95％；对2～4．9mm组息肉的栓出率分别为85％、30％、50％和80％。综合应用以上各种方法对10～12mm组、5～9．9mm组和2-4．9mm组的检出率分别为100％、100％和90％。结论：16层螺旋CT的CTC最佳成像参数应为：准直1．25mm，螺距1．375：1，1．25mm重建层厚，0％重叠重建率和标准算法重建。CTVE和VD对息肉的检出率高于其他后处理方法，CTVE结合其他后处理方法可提高息肉的检出率。

Objective： To evaluate the effects of scanning parameters, reformat modatities and post processing techniques on image quality and the detecting rate of simulated polyps. And select an optimal combination of scanning parameters and post processing technique. Methods：Sixty polyps lesions of varying size were simulated with sutures on the inner face of porcine colon segments. After distending the colon segment with air, the phantoms was examined using muhi-detector row CT with varying combinations of detector collimation and pitch. The CT data were reconstructed with varying post processing techniques polyp depiction was compared in varying pitch, section thickness and method. The detecting rates of CTC affected by different post processing techniques were compared as well. Resuits：The optimal protocol was section thickness 1.25 mm, pitch 1.375：1, overlap reconstruction 0% and standard reconstruction. The effect of varying post processing techniques in polyp detection： the detection rate of CTVE, VR＋Raysum, MPR＋axial image and VD was respectively 100%, 95%, 95% and 100% in 10-12 mm group; the rate was respectively 95%, 75%, 80% and 95% in 5-9.9 mm group; the rate was respectively 85%, 30%, 50% and 80% in 2-4.9 mm group. The rate of all these methods in detecting polyps was 100%, 100% and 90% in 10-12 mm group, 5-9.9 mm group and 2-4.9 mm group, respectively. Conclusion：The optimal protocol of 16-row CTC is section thickness 1.25 mm, overlap reconstruction 0% and standard method. CTVE and VD are superior to other methods in the detection of polyps. Combine CTVE with other methods can improve the detection of polyps.