Sahani Dushyant, Saini Sanjay, D'Souza Roy V, O'Neill Mary Jane, Prasad Srinivasa R, Kalra Mannudeep K, Halpern Elkan F, Mueller Peter
Division of Abdominal Imaging and Intervention, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA.
J Comput Assist Tomogr. 2003 Mar-Apr;27(2):105-9. doi: 10.1097/00004728-200303000-00001.
The purpose of this study was to compare the performance of low helical pitch acquisition (3:1) and high helical pitch acquisition (6:1) for routine abdominal/pelvic imaging with multislice computed tomography (CT).
Three hundred eighty-four patients referred for abdominal/pelvic CT were examined in a breath-hold on a multislice CT scanner (LightSpeed QX/I; General Electric Medical Systems, Milwaukee, WI). Patients were randomized and scanned with pitch of 3:1 or 6:1 using a constant 140 peak kV and 280-300 mA. Images were reconstructed at a 3.75-mm slice thickness. Direct comparison between the two pitches was possible in a subset of 40 patients who had a follow-up scan performed with the second pitch used in each patient. A comparison was also performed between standard dose CT using a pitch of 6:1 and 20% reduced radiation dose CT using a pitch of 3:1. Two readers performed a blind evaluation using a three-point scale for image quality, anatomic details, and motion artifacts. Statistical analysis was performed using a rank sum test and the Wilcoxon signed rank test.
Overall image quality mean scores were 2.5 and 2.3 for a pitch of 3:1 and a pitch of 6:1, respectively (P = 0.134). Likewise, mean anatomic detail and motion artifact scores were 2.5 and 2.6 for a 3:1 pitch and 2.3 and 2.5 for a 6:1 pitch, respectively (P > 0.05). In patients with a direct comparison of the two pitches (with the standard radiation dose as well as with a 20% reduction in milliamperes), no statistically significant difference in the performance of the two pitches was observed (P > 0.05).
Image quality with a high pitch (6:1) is acceptable for routine abdominal/pelvic CT.
本研究旨在比较多层螺旋计算机断层扫描（CT）在常规腹部/盆腔成像中低螺距采集（3:1）和高螺距采集（6:1）的性能。
384例接受腹部/盆腔CT检查的患者在多层CT扫描仪（LightSpeed QX/I；通用电气医疗系统公司，威斯康星州密尔沃基）上屏气扫描。患者被随机分组，使用恒定的140峰值千伏和280 - 300毫安，以3:1或6:1的螺距进行扫描。图像重建层厚为3.75毫米。在40例患者的子集中可以直接比较两种螺距，这些患者在后续扫描中使用了各自之前使用的第二种螺距。还对使用6:1螺距的标准剂量CT和使用3:1螺距且辐射剂量降低20%的CT进行了比较。两名阅片者使用三点量表对图像质量、解剖细节和运动伪影进行盲法评估。使用秩和检验和Wilcoxon符号秩检验进行统计分析。
螺距为3:1和6:1时，总体图像质量平均得分分别为2.5和2.3（P = 0.134）。同样，螺距为3:1时解剖细节和运动伪影平均得分分别为2.5和2.6，螺距为6:1时分别为2.3和2.5（P > 0.05）。在对两种螺距进行直接比较的患者中（包括标准辐射剂量以及毫安数降低20%的情况），未观察到两种螺距性能上的统计学显著差异（P > 0.05）。
高螺距（6:1）的图像质量对于常规腹部/盆腔CT是可接受的。
