Guilloz Imaging Department, Central Hospital, University Hospital Center of Nancy, 29 Avenue du Maréchal de Lattre de Tassigny, 54035, Nancy Cedex, France.
Guilloz Imaging Department, Central Hospital, University Hospital Center of Nancy, 29 Avenue du Maréchal de Lattre de Tassigny, 54035, Nancy Cedex, France.
Eur J Radiol. 2020 Jun;127:108970. doi: 10.1016/j.ejrad.2020.108970. Epub 2020 Mar 19.
To compare the performance of different image reconstruction algorithms in the presence of small metal objects of different sizes and at different dose levels.
A fresh bone of bovine femur was drilled with seven drill bits of increasing diameter. CT images with eight different dose levels were acquired and reconstructed with three algorithms: hybrid iterative reconstruction - HIR, Full model-based iterative reconstruction - full MBIR and a single energy metal artifact reduction - SEMAR. Trabecular distortion adjacent to metal was evaluated subjectively with a four-point scale. Edge profile artifacts were evaluated quantitatively by measuring drill bit diameter overestimation and the width of the low-density halo surrounding the drill bit.
Trabecular distortion was higher with full MBIR compared to HIR and SEMAR (P < 0.0001) and increased with drill bits larger than 1.2 mm and with doses lower than 18.1 mGy.cm. Low-density halos size and drill bit diameter overestimation decreased with full MBIR compared to the other two reconstruction algorithms and with SEMAR compared to HIR (P < 0.0001). There was a mean drill bit overestimation of 0.56 ± 0.25 mm for full MBIR versus 0.68 ± 0.09 mm for SEMAR and mean low-density halo diameters of 0.03 mm ± 0.08 for full MBIR versus 0.42 mm ± 0.09 for SEMAR.
Algorithm performance is influenced by dose levels and metal object size and no individual algorithm provides the best overall performance. Full MBIR is better in reducing edge artifacts and SEMAR is the best option for larger metal implants and low dose protocols.
比较不同大小金属物体在不同剂量水平下不同图像重建算法的性能。
用 7 个直径逐渐增大的钻头在牛股骨新鲜骨上钻孔。采集了 8 个不同剂量水平的 CT 图像，并使用 3 种算法进行重建：混合迭代重建（HIR）、全模型迭代重建（full MBIR）和单能金属伪影减少（SEMAR）。使用 4 分制主观评估金属附近的骨小梁变形。通过测量钻头直径高估和钻头周围低密度晕环的宽度，定量评估边缘轮廓伪影。
与 HIR 和 SEMAR 相比，full MBIR 引起的骨小梁变形更高（P<0.0001），且随钻头直径大于 1.2mm 和剂量低于 18.1mGy.cm 而增大。与其他两种重建算法相比，full MBIR 降低了低密度晕环的大小和钻头直径高估，与 HIR 相比，SEMAR 也降低了低密度晕环的大小和钻头直径高估（P<0.0001）。full MBIR 的钻头平均高估为 0.56±0.25mm，SEMAR 为 0.68±0.09mm，full MBIR 的低密度晕环平均直径为 0.03±0.08mm，SEMAR 为 0.42±0.09mm。
算法性能受剂量水平和金属物体大小的影响，没有一种算法能提供最佳的整体性能。full MBIR 更有利于减少边缘伪影，而 SEMAR 是较大金属植入物和低剂量方案的最佳选择。
