多层面螺旋CT结肠仿真内镜的实验研究

Experimental study of multi-slice CT virtual colography in pig colon

目的 探讨MSCT结肠仿真内镜优化的成像参数。方法 猪结肠 8段 ,于肠壁内面模拟病变后行MSCT扫描 ,准直层厚 1.0mm、2 .5mm、5 .0mm ,螺距 1.2 5、1.75及重叠重建率 0 %、5 0 %、70 %分别匹配 ,共 16组图像分别行VC观察。结果 第 1组 (准直层厚 1.0mm ,Pitch 1.2 5 ,重叠重建率 5 0 % )病变检出准确率最高 ,但与第 2～ 4、9～ 12组病变检出率无明显差异 ,其中第 12组 (准直层厚 2 .5mm ,Pitch 1.75 ,重叠重建率 5 0 % )的扫描时间和CTDI最小 ,容积重建法VC的检出准确率高于表面重建法VC。结论 层厚和重叠重建率对MSCTVC的病变检出准确率有明显影响 ,优化参数为 :准直层厚 2 .5mm ,螺距 1.75 ,5 0 %重叠重建 ,容积重建法VC。

Objective To investigate the optimized parameters of multi slice CT virtual colography (MSCT VC). Methods Eight segments of pig colon were resected and cleaned, and simulated polyps with different size were created on the mucosa of colon. Each specimen was scanned with collimation of 1.0 mm, 2.5 mm, 5.0 mm, and pitch of 1.25, 1.75, reconstructed with 0%, 50%, 70% overlap, respectively. The images were classified into 16 groups by different parameters, and VC with volume perspective mode were processed. The accuracy of polyps detection was evaluated in each group. Results Group 1 (collimation 1.0mm, Pitch 1.25, overlap rate 50%) had the maximal accuracy of polyps detection, but there was no significant difference between group 1 and group 2-4, 9-12. Group 12 (collimation 2.5mm, Pitch 1.75, overlap rate 50%) had the least scan time and CTDI, but VC with volume perspective mode was superior to that with surface perspective mode. Conclusion In experimental condition, MSCT VC were significantly affected by the collimation and overlapping rate. The optimized parameters were as follows: collimation 2.5 mm, pitch 1.75 and 50% overlapped reconstruction, and with volume perspective VC.