Background The extent of liver steatosis can be assessed using US attenuation coefficient (AC) algorithms currently implemented in several US systems. However, little is known about intersystem and interoperator variability in measurements. Purpose To assess intersystem and interoperator agreement in US AC measurements for fat quantification in individuals with varying degrees of liver steatosis and to assess the correlation of each manufacturer's AC algorithm results with MRI proton density fat fraction (PDFF). Materials and Methods This prospective study was conducted at Southwoods Imaging, Youngstown, Ohio, September 30-October 1, 2023. Two operators independently obtained AC measurements using eight US systems equipped with an AC algorithm from different manufacturers. On the same day, MRI PDFF measurement was performed by a different operator. Correlation between US AC and MRI PDFF was assessed using a mixed-effects model. Agreement between systems and operators was evaluated using the intraclass correlation coefficient (ICC). Results Twenty-six individuals (mean age, 55.4 years ± 10.7 [SD]; 16 female participants) were evaluated. The correlation of US AC with MRI PDFF was high for five AC algorithms (r range, 0.70-0.86), moderate for two (r = 0.62 for both), and poor for one (r = 0.47). In pairwise comparisons, none of the pairs of systems achieved excellent agreement (overall ICC = 0.33 [95% CI: 0.15, 0.52]). One pair showed good agreement (ICC = 0.79 [95% CI: 0.66, 0.87]), eight pairs showed moderate agreement (ICC range, 0.50 [95% CI: 0.22, 0.69] to 0.73 [95% CI: 0.49, 0.85]), and 19 pairs showed poor agreement (ICC range, 0.11 [95% CI: -0.06, 0.37] to 0.48 [95% CI: 0.20, 0.67]). Interoperator agreement on AC value was excellent for the Samsung Medison algorithm (ICC = 0.90 [95% CI: 0.80, 0.96]), good for the Siemens Healthineers (ICC = 0.76 [95% CI: 0.54, 0.89]) and Canon Medical Systems (ICC = 0.76 [95% CI: 0.16, 0.92]) algorithms, and moderate for the remaining algorithms (ICC range, 0.50 [95% CI: 0.16, 0.73] to 0.74 [95% CI: 0.51, 0.88]). The mean AC value obtained by the two operators did not differ for any system except the system from Canon Medical Systems. Conclusion There was substantial variability in AC values obtained with different US systems, precluding interchangeability between systems for liver steatosis diagnosis and follow-up imaging. Interoperator agreement ranged from moderate to excellent. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Han in this issue.

中文翻译：

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用于量化肝脂肪变性的 US 衰减系数的系统间和操作员间协议。


背景 肝脂肪变性的程度可以使用目前在几个 US 系统中实施的 US 衰减系数 （AC） 算法进行评估。然而，人们对测量中的系统间和操作器间变化知之甚少。目的： 评估不同程度肝脂肪变性个体脂肪定量的 US AC 测量中的系统间和操作者间一致性，并评估每个制造商的 AC 算法结果与 MRI 质子密度脂肪分数 （PDFF） 的相关性。材料和方法 这项前瞻性研究于 2023 年 9 月 30 日至 10 月 1 日在俄亥俄州扬斯敦的 Southwoods Imaging 进行。两名操作员使用八套配备不同制造商的交流算法的美国系统独立获得交流测量结果。同一天，MRI PDFF 测量由不同的操作员进行。使用混合效应模型评估 US AC 和 MRI PDFF 之间的相关性。使用类内相关系数 （ICC） 评估系统和操作员之间的一致性。结果 评估了 26 例个体 （平均年龄 55.4 岁 ± 10.7 [SD];16 例女性参与者）。US AC 与 MRI PDFF 的相关性在五种 AC 算法中为高 （r 范围，0.70-0.86），两种中等 （两种 r = 0.62），一种差 （r = 0.47）。在成对比较中，没有一对系统达到极好的一致性 （总体 ICC = 0.33 [95% CI： 0.15， 0.52]）。1对一致性良好（ICC=0.79 [95% CI：0.66,0.87]），8对一致性中等（ICC范围，0.50 [95% CI：0.22,0.69]至0.73 [95% CI：0.49,0.85]），19对一致性差（ICC范围，0.11 [95% CI：-0.06,0.37] 至 0.48 [95% CI：0.20,0.67]）。 Samsung Medison 算法 （ICC = 0.90 [95% CI： 0.80， 0.96]）的 AC 值操作者间一致性非常好，适合 Siemens Healthineers （ICC = 0.76 [95% CI： 0.54， 0.89]）和佳能医疗系统（ICC = 0.76 [95% CI： 0.16， 0.92]）算法，其余算法的 AC 值一致性中等（ICC 范围，0.50 [95% CI： 0.16， 0.73] 至 0.74 [95% CI： 0.51, 0.88]).除 Canon Medical Systems 的系统外，两名操作员获得的平均 AC 值对于任何系统都没有差异。结论 使用不同 US 系统获得的 AC 值存在很大差异，排除了肝脂肪变性诊断和随访影像学系统之间的互换性。操作员间一致性从中等到极好不等。© RSNA，2024 年本文提供补充材料。另请参见本期 Han 的社论。