Department of Radiology, Inje University Busan Paik Hospital, Busan, Korea.
Korean J Radiol. 2021 Aug;22(8):1341-1351. doi: 10.3348/kjr.2020.0548. Epub 2021 May 26.
To compare the quality of various polychromatic and monochromatic images with or without using an iterative metal artifact reduction algorithm (iMAR) obtained from a dual-energy computed tomography (CT) to evaluate total knee arthroplasty.
We included 58 patients (28 male and 30 female; mean age [range], 71.4 [61-83] years) who underwent 74 knee examinations after total knee arthroplasty using dual-energy CT. CT image sets consisted of polychromatic image sets that linearly blended 80 kVp and tin-filtered 140 kVp using weighting factors of 0.4, 0, and -0.3, and monochromatic images at 130, 150, 170, and 190 keV. These image sets were obtained with and without applying iMAR, creating a total of 14 image sets. Two readers qualitatively ranked the image quality (1 [lowest quality] through 14 [highest quality]). Volumes of high- and low-density artifacts and contrast-to-noise ratios (CNRs) between the bone and fat tissue were quantitatively measured in a subset of 25 knees unaffected by metal artifacts.
iMAR-applied, polychromatic images using weighting factors of -0.3 and 0.0 (P and P, respectively) showed the highest image-quality rank scores (median of 14 for both by one reader and 13 and 14, respectively, by the other reader; < 0.001). All iMAR-applied image series showed higher rank scores than the iMAR-unapplied ones. The smallest volumes of low-density artifacts were found in P, P, and iMAR-applied monochromatic images at 130 keV. The smallest volumes of high-density artifacts were noted in P. The CNRs were best in polychromatic images using a weighting factor of 0.4 with or without iMAR application, followed by polychromatic images using a weighting factor of 0.0 with or without iMAR application.
Polychromatic images combined with iMAR application, P and P, provided better image qualities and substantial metal artifact reduction compared with other image sets.
比较使用或不使用迭代金属伪影降低算法(iMAR)获得的双能 CT 评估全膝关节置换术的各种多色和单色图像的质量。
我们纳入了 58 例(28 例男性,30 例女性;平均年龄[范围]:71.4[61-83]岁)接受全膝关节置换术后行双能 CT 检查的患者。CT 图像集由多色图像集组成,这些图像集使用权重因子 0.4、0 和-0.3 线性混合 80 kVp 和锡过滤 140 kVp,以及单色图像 130、150、170 和 190 keV。这些图像集在应用和不应用 iMAR 的情况下获得,共创建了 14 个图像集。两位读者对图像质量进行了定性评分(1[最低质量]至 14[最高质量])。在未受金属伪影影响的 25 例膝关节中,对高、低密度伪影体积和骨与脂肪组织之间的对比噪声比(CNR)进行了定量测量。
应用 iMAR 的、权重因子为-0.3 和 0.0 的多色图像(分别为 P 和 P)显示出最高的图像质量评分(一位读者评分中位数均为 14,另一位读者分别为 13 和 14;<0.001)。所有应用 iMAR 的图像系列的评分均高于未应用 iMAR 的图像系列。低密度伪影体积最小的是 P、P 和应用 iMAR 的 130 keV 单色图像。高密度伪影体积最小的是 P。应用或不应用 iMAR,权重因子为 0.4 的多色图像的 CNR 最佳,其次是应用或不应用 iMAR 的权重因子为 0.0 的多色图像。
与其他图像集相比,结合 iMAR 应用的多色图像 P 和 P 提供了更好的图像质量和大量的金属伪影减少。