1 Department of Radiology, Seoul National University Bundang Hospital, 82, Gumi-ro 173 Beon-gil, Bundanggu, Seongnam-si, Gyeonggi-do, Korea.
2 Present address: Korea University Ansan Hospital, Ansan-si, Gyeonggi-do, Korea.
AJR Am J Roentgenol. 2017 Oct;209(4):860-866. doi: 10.2214/AJR.16.17684. Epub 2017 Aug 10.
The objective of this study is to evaluate the effect of the metal artifact reduction algorithm for orthopedic implants (O-MAR) on CT image quality for patients with reverse total shoulder arthroplasty (RTSA), with emphasis placed on the evaluation of bone in the vicinity of prostheses.
Sixty-five patients who underwent CT scanning after RTSA were enrolled in the study. Two radiologists analyzed the images reconstructed with filtered back projection (FBP) with or without O-MAR processing. Images were evaluated to determine the degree of streaking artifacts, the confidence in depicting various structures around the prosthesis, and the presence of pseudolesions. The mean CT number and SD of the selected ROIs placed in the greater tuberosity, glenoid bone, and deltoid muscle were recorded. For measurements from the greater tuberosity and glenoid bone, the frequency with which the measurement met the typical CT number of bone was calculated.
O-MAR images showed less metal streak artifact and noise and provided better visualization of the axillary neurovascular bundle compared with FBP images, with a statistically significant difference (p < 0.001 for all). FBP images were found to be statistically significantly better than O-MAR images, offering better visualization of bone cortex, bone trabeculae, and the bone-prosthesis interface (p < 0.001 for all). Scapular pseudonotching was observed on 4.6% of FBP images and 36.9% of O-MAR images. The pseudocemented appearance was noted on 47.7% of O-MAR images but was not seen on FBP images.
The use of O-MAR improved CT image quality for patients with RTSA in the aspect of metal artifact reduction and soft-tissue profile. However, O-MAR tends to degrade depiction of the bone trabeculae and bone cortex and generate new artifacts, including a pseudocemented appearance and scapular pseudonotching.
本研究旨在评估骨科植入物金属伪影降低算法（O-MAR）对接受反式全肩关节置换术（RTSA）患者 CT 图像质量的影响，重点评估假体附近骨骼的评估。
共纳入 65 例 RTSA 后行 CT 扫描的患者。两位放射科医生分析了滤波反投影（FBP）重建和 FBP 联合 O-MAR 处理后的图像。评估图像的条纹伪影程度、对假体周围各种结构的描绘信心以及伪影的存在。记录放置在大结节、肩胛骨关节盂和三角肌选定 ROI 的平均 CT 值和标准差。对大结节和肩胛骨关节盂的测量值，计算测量值符合典型骨 CT 值的频率。
O-MAR 图像的金属条纹伪影和噪声较少，与 FBP 图像相比，腋窝神经血管束的可视化效果更好，差异有统计学意义（p < 0.001）。FBP 图像在骨皮质、骨小梁和骨-假体界面的可视化效果明显优于 O-MAR 图像，差异有统计学意义（p < 0.001）。在 4.6%的 FBP 图像和 36.9%的 O-MAR 图像上观察到肩胛骨假性切迹。在 47.7%的 O-MAR 图像上观察到伪骨水泥外观，但在 FBP 图像上未见。
O-MAR 可改善 RTSA 患者的 CT 图像质量，在减少金属伪影和软组织轮廓方面有改善。然而，O-MAR 会降低骨小梁和骨皮质的显示，产生新的伪影，包括伪骨水泥外观和肩胛骨假性切迹。
