Rubin G D, Leung A N, Robertson V J, Stark P
Department of Radiology, Stanford University School of Medicine, CA 94305-5105, USA.
Radiology. 1998 Sep;208(3):771-6. doi: 10.1148/radiology.208.3.9722858.
To determine if the lower milliampere second setting and shorter acquisition time of subsecond spiral computed tomography (CT) affects the image quality of thoracic CT scans.
In 92 consecutive outpatients referred for thoracic CT, spiral CT (120 kV, 292 mA) was performed with 1-second (n = 45) or 0.75-second (n = 47) scanning time. An equal percentage of patients (70%) in each group received intravenous contrast medium. At six mediastinal and six lung zones, degradation due to motion and noise, respectively, were graded independently on a four-point scale by three blinded radiologists. Statistically significant differences were determine with a two-tailed test.
Mediastinal image quality was significantly better on 0.75-second scans than on 1-seconds scans (P < .001). Regions with the greatest improvement in image quality were around the aortic root, cardiac ventricles, and aortic arch. Lung image quality was also better on 0.75-second scans than on 1-second scans (P = .04). On 0.75- and 1-second scans, respectively, motion-related artifacts were found to degrade image quality 6.2 and 8.7 times more than noise-related artifacts in the mediastinum and 2.6 and 3.9 times more in the lungs.
Subsecond spiral CT is associated with improved clarity and diminished motion artifacts on mediastinal and pulmonary images when compared with 1-second spiral CT.
确定亚秒级螺旋计算机断层扫描（CT）较低的毫安秒设置和更短的采集时间是否会影响胸部CT扫描的图像质量。
在92例连续接受胸部CT检查的门诊患者中，采用螺旋CT（120 kV，292 mA）进行扫描，扫描时间为1秒（n = 45）或0.75秒（n = 47）。每组中相等比例（70%）的患者接受静脉注射造影剂。由三位不知情的放射科医生分别在六个纵隔区和六个肺区，根据运动和噪声导致的图像质量下降情况，采用四分制进行独立评分。采用双侧检验确定统计学上的显著差异。
0.75秒扫描的纵隔图像质量明显优于1秒扫描（P <.001）。图像质量改善最大的区域位于主动脉根部、心室和主动脉弓周围。0.75秒扫描的肺部图像质量也优于1秒扫描（P =.04）。在0.75秒和1秒扫描中，纵隔中与运动相关的伪影导致图像质量下降的程度分别比与噪声相关的伪影高6.2倍和8.7倍，在肺部则分别高2.6倍和3.9倍。
与1秒螺旋CT相比，亚秒级螺旋CT可提高纵隔和肺部图像的清晰度，并减少运动伪影。
