Yasaka Koichiro, Furuta Toshihiro, Kubo Takatoshi, Maeda Eriko, Katsura Masaki, Sato Jiro, Ohtomo Kuni
1 Department of Radiology, Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
2 Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Acta Radiol. 2017 Sep;58(9):1085-1093. doi: 10.1177/0284185116684675. Epub 2017 Jan 9.
Background Abdominal computed tomography (CT) without arm elevation is associated with degraded image quality due to streak artifacts. Purpose To compare the degree of streak artifacts in abdominal CT images without arm elevation between full iterative reconstruction (IR), hybrid IR, and filtered back projection (FBP) using two commercially available scanners. Material and Methods First, a phantom study simulating CT examination without arm elevation was performed. Second, unenhanced axial images of 33 patients (17 and 16 patients for each vendor) who underwent CT without arm elevation were reconstructed with full IR, hybrid IR and FBP. A radiologist placed 50 parallel lines with lengths of 50 pixels vertical to the streaks and quantitatively evaluated the images for streak artifacts in the phantom study. Two radiologists evaluated the images of patients for streak artifacts (on the liver and the kidney) and diagnostic acceptability using a four-point scale. Results The phantom study indicated that full IR algorithms were more effective than FBP in reducing streak artifacts. In the clinical patient study, streak artifacts were significantly more reduced with full IR compared with FBP in both the liver and kidney ( P < 0.012). Streak artifact reduction was limited with hybrid IR. Model-based iterative reconstruction (MBIR) (one of the full IR algorithms) provided diagnostically more acceptable image quality ( P < 0.016) compared with FBP. Conclusion In abdominal CT without arm elevation, full IR enabled a more efficient streak artifact reduction compared with FBP and MBIR was associated with diagnostically more acceptable images.
不抬高手臂进行腹部计算机断层扫描（CT）时，由于条纹伪影会导致图像质量下降。目的：使用两台商用扫描仪比较全迭代重建（IR）、混合IR和滤波反投影（FBP）在不抬高手臂的腹部CT图像中条纹伪影的程度。材料与方法：首先，进行一项模拟不抬高手臂的CT检查的体模研究。其次，对33例未抬高手臂进行CT检查的患者（每个供应商各17例和16例）的未增强轴向图像分别采用全IR、混合IR和FBP进行重建。一名放射科医生在体模研究中垂直于条纹放置50条长度为50像素的平行线，并对图像的条纹伪影进行定量评估。两名放射科医生使用四点量表对患者的图像（肝脏和肾脏上的）条纹伪影和诊断可接受性进行评估。结果：体模研究表明，全IR算法在减少条纹伪影方面比FBP更有效。在临床患者研究中，与FBP相比，全IR在肝脏和肾脏中均显著减少了条纹伪影（P < 0.012）。混合IR减少条纹伪影的效果有限。与FBP相比，基于模型的迭代重建（MBIR）（全IR算法之一）提供了诊断上更可接受的图像质量（P < 0.016）。结论：在不抬高手臂的腹部CT中，与FBP相比，全IR能更有效地减少条纹伪影，且MBIR与诊断上更可接受的图像相关。
