Department of Radiology, Chonbuk National University Medical School, Jeonju, Republic of Korea.
Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Republic of Korea.
AJR Am J Roentgenol. 2020 Jun;214(6):1335-1342. doi: 10.2214/AJR.19.22222. Epub 2020 Mar 31.
The clumpy artifact has a high misdiagnosis rate, but the artifact has not been well studied. The aims of this study were to evaluate the frequency and location of clumpy artifacts, the rate of misdiagnosis of clumpy artifacts as gout, and the effects of raising the minimum attenuation value and using a selective photon shield in dual-energy CT (DECT). Forty patients without gout who underwent foot and ankle DECT were enrolled in this study. Images in both sets were randomly assigned a minimum attenuation of 130 HU or 150 HU. Three radiologists independently checked all images for presence, volume, and location of green color-coded pixelation and graded their findings according to a 4-point confidence scale, frequency, and volume. Misdiagnosis rate and misdiagnosis score were compared using the Wilcoxon signed rank and McNemar tests. In set 1, the frequency of clumpy artifacts in DECT with the minimum attenuation set to 130 HU and 150 HU were 81% and 68%, respectively. For all three readers, the misdiagnosis rate and misdiagnosis score decreased when changing the minimum attenuation from 130 HU to 150 HU. In set 2, with the minimum attenuation set to 130 HU, the frequency of the clumpy artifact was 44%; with the minimum attenuation set to 150 HU, no clumpy artifacts were seen. Clumpy artifacts occurred frequently in DECT without a tin filter. Setting the minimum attenuation to the higher value of 150 HU reduced the frequency of clumpy artifacts, and adding a tin filter to DECT greatly reduced their occurrence.
团块状伪影误诊率较高，但尚未得到充分研究。本研究旨在评估团块状伪影的出现频率和位置、将团块状伪影误诊为痛风的比例，以及提高最小衰减值和在双能 CT（DECT）中使用选择性光子屏蔽的效果。本研究纳入了 40 例无痛风的足部和踝关节 DECT 患者。两套图像均随机设定最小衰减值为 130HU 或 150HU。三位放射科医生独立检查所有图像是否存在绿色编码像素化、评估其发现的存在程度、体积和位置，并根据 4 分置信度评分、频率和体积进行分级。采用 Wilcoxon 符号秩和检验和 McNemar 检验比较误诊率和误诊评分。在第 1 组中，将最小衰减值设定为 130HU 和 150HU 时，DECT 中团块状伪影的频率分别为 81%和 68%。对于所有三位读者，当将最小衰减值从 130HU 更改为 150HU 时，误诊率和误诊评分均降低。在第 2 组中，将最小衰减值设定为 130HU 时，团块状伪影的频率为 44%；将最小衰减值设定为 150HU 时，未观察到团块状伪影。无锡滤器的 DECT 中常出现团块状伪影。将最小衰减值设定为较高值 150HU 可降低团块状伪影的频率，在 DECT 中添加锡滤器可大大减少其发生。
