螺距的选择对老年慢性阻塞性肺疾病患者成像质量的影响

Effect of different pitch on image quality in old chronic obstructivepulmonary disease with 64-slice CT

目的探讨螺距的选择对64层CT螺旋扫描模式对老年慢性阻塞性肺疾病(COPD)胸部图像质量的影响。方法选择老年(COPD)患者100例,分为两组,A组(50例)采用螺距为0.984、B组(50例)采用螺距为1.375进行胸部CT扫描。使用GE Lightspeed sys#vct 64层CT机,120kV,200mA,层厚5mm,0.8s/r。应用SPSS11.5软件分别对A组和B组的CT图像运动伪影出现率进行χ~2检验,两组间图像质量比较、噪声比较、扫描时间进行t检验。结果 A组患者出现伪影17例,B组4例,较A组减少26%。A组患者平均扫描时间为7s,B组为5.3s,较A组扫描时间平均减少1.7s。结论在进行COPD胸部CT检查中,管电压和管电流恒定不变的情况下选择大螺距扫描,可以减少扫描时间、降低辐射剂量,在保证图像质量的同时,呼吸运动伪影减少,从而达到优化图像的同时降低辐射剂量的目的。

Objective To make a comparison of influence on imaging quality at diff-erent pitch scan modes for old COPD of chest using 64-slice CT. Methods 100 patiants with old COPD were divided into two groups. They underwent CT of tharacic with a pitch of 0.984(group A n=50), or a pitch of 1.375(group B n=50). The study was performed with GE Lightspeed sys # vct 64-sliceCT. All images were obtained at 120 kV tube voltage, 200 mA tube current and 5mm slice thickness. Gantry rotation time was 0.8 s. The motion artifact, image quality and imaging noise were recorded and compared beween groups by student's test (SPSS11.5). Results Compared with Group B, the motion artifact and the scan time in Group A were reduced by 26%, 1.7 s. Conclusion At the same voltage and tube current, a higher pitch (1.375) scan mode can reduce the scan time, the motion artifact and radiation dose without compromising the imaging quality.