Boos Johannes, Sawicki Lino Morris, Lanzman Rotem Shlomo, Thomas Christoph, Aissa Joel, Schleich Christoph, Heusch Philipp, Antoch Gerald, Kröpil Patric
University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Dusseldorf, Germany
University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Dusseldorf, Germany.
Acta Radiol. 2017 Jan;58(1):70-76. doi: 10.1177/0284185116633911. Epub 2016 Mar 2.
Artifacts from metallic implants can hinder image interpretation in computed tomography (CT). Image quality can be improved using metal artifact reduction (MAR) techniques.
To evaluate the impact of a MAR algorithm on image quality of CT examinations in comparison to filtered back projection (FBP) in patients with hip prostheses.
Twenty-two patients with 25 hip prostheses who underwent clinical abdominopelvic CT on a 64-row CT were included in this retrospective study. Axial images were reconstructed with FBP and five increasing MAR levels (M30-34). Objective artifact strength (OAS) (SI-SI) was assessed by region of interest (ROI) measurements in position of the strongest artifact (SI) and in an osseous structure without artifact (SI) (in Hounsfield units [HU]). Two independent readers evaluated subjective image quality regarding metallic hardware, delineation of bone, adjacent muscle, and pelvic organs on a 5-point scale (1, non-diagnostic; 5, excellent image quality). Artifacts in the near field, far field, and newly induced artifacts due to the MAR technique were analyzed.
OAS values were: M34: 243.8 ± 155.4 HU; M33: 294.3 ± 197.8 HU; M32: 340.5 ± 210.1 HU; M31: 393.6 ± 225.2 HU; M30: 446.8 ± 224.2 HU and FBP: 528.9 ± 227.7 HU. OAS values were significantly lower for M32-34 compared to FBP (P < 0.01). For overall subjective image quality, results were: FBP, 2.0 ± 0.2; M30, 2.3 ± 0.8; M31, 2.6 ± 0.5; M32, 3.0 ± 0.6; M33, 3.5 ± 0.6; and M34, 3.8 ± 0.4 (P < 0.001 for M30-M34 vs. FBP, respectively). Increasing MAR levels resulted in new artifacts in 17% of reconstructions.
The investigated MAR algorithm led to a significant reduction of artifacts from metallic hip implants. The highest MAR level provided the least severe artifacts and the best overall image quality.
金属植入物产生的伪影会妨碍计算机断层扫描（CT）中的图像解读。使用金属伪影减少（MAR）技术可提高图像质量。
与滤波反投影（FBP）相比，评估MAR算法对髋关节假体患者CT检查图像质量的影响。
本回顾性研究纳入了22例植入25个髋关节假体且接受了64排CT临床腹部盆腔扫描的患者。轴向图像采用FBP及五个逐渐增加的MAR水平（M30 - 34）进行重建。通过在最强伪影位置（SI）和无伪影的骨质结构（SI）（以亨氏单位[HU]表示）进行感兴趣区（ROI）测量来评估客观伪影强度（OAS）（SI - SI）。两名独立阅片者以5分制（1分，非诊断性；5分，图像质量极佳）评估关于金属硬件、骨骼、相邻肌肉及盆腔器官的主观图像质量。分析了近场、远场的伪影以及MAR技术新产生的伪影。
OAS值分别为：M34：243.8 ± 155.4 HU；M33：294.3 ± 197.8 HU；M32：340.5 ± 210.1 HU；M31：393.6 ± 225.2 HU；M30：446.8 ± 224.2 HU以及FBP：528.9 ± 227.7 HU。与FBP相比，M32 - 34的OAS值显著更低（P < 0.01）。总体主观图像质量结果为：FBP，2.0 ± 0.2；M30，2.3 ± 0.8；M31，2.6 ± 0.5；M32，3.0 ± 0.6；M33，3.5 ± 0.6；M34，3.8 ± 0.4（M30 - M34与FBP相比，P均< 0.001）。MAR水平增加导致17%的重建图像出现新伪影。
所研究的MAR算法显著减少了金属髋关节植入物产生的伪影。最高的MAR水平产生的伪影最不严重，总体图像质量最佳。
