Attenuation imaging is a novel, ultrasound-based technique to objectively detect and quantify liver steatosis. In this study, we evaluated the performance and inter-observer variability of attenuation imaging and compared it to a known quantification method of liver fat, the hepatorenal index (HRI). Two observers measured attenuation coefficients (AC) in an attenuation phantom, 20 healthy volunteers and 27 patients scheduled for biopsy for suspected diffuse liver disease. Results were compared with the HRI and histological findings. Both observers were blinded to the results of the biopsy and the measurements of the other observer. Our results showed that patients with moderate (S2, 33-66%) and severe fatty infiltration of the liver (S3, >66%) showed significantly higher ACs in comparison to patients with a liver fat fraction of less than 33% (S0/1). There was no significant difference in AC-values of patients with fatty infiltration of less than 5% (S0) and 5-32% (S1). In the Receiver Operating Characteristic (ROC)-analysis, the area under the curve (AUC)-values for the detection of moderate and severe steatosis were excellent at 0.98. Cut-off values were 0.64 dB/cm/MHz for the detection of S2- and 0.68 dB/cm/MHz for the detection of S3-steatosis. The inter-observer agreement of attenuation imaging was very good with an intraclass correlation coefficient (ICC) of 0.92 in patient and 0.96 in phantom measurements. The ICC decreased with depth in the phantom measurements. In summary, attenuation imaging showed very good inter-observer agreement and is a promising tool for the detection and quantification of moderate and severe hepatic steatosis.

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基于超声的衰减成像用于肝脏脂肪的无创定量——可行性和观察者间变异性的初步研究

衰减成像​​是一种基于超声的新型技术，可客观检测和量化肝脏脂肪变性。在这项研究中，我们评估了衰减成像的性能和观察者间的变异性，并将其与已知的肝脏脂肪定量方法——肝肾指数（HRI）进行了比较。两名观察者测量了衰减体模中的衰减系数 (AC)、20 名健康志愿者和 27 名因疑似弥漫性肝病而计划进行活检的患者。将结果与 HRI 和组织学结果进行比较。两名观察者对活检结果和另一名观察者的测量结果均不知情。我们的结果表明，与肝脏脂肪分数低于 33% 的患者 (S0/ 1）。脂肪浸润小于5%（S0）和5-32%（S1）的患者AC值没有显着差异。在接受者操作特征 (ROC) 分析中，检测中度和重度脂肪变性的曲线下面积 (AUC) 值非常出色，为 0.98。检测 S2- 的截止值为 0.64 dB/cm/MHz，检测 S3-脂肪变性的截止值为 0.68 dB/cm/MHz。衰减成像​​的观察者间一致性非常好，患者组内相关系数 (ICC) 为 0.92，体模测量值为 0.96。在体模测量中，ICC 随着深度而减小。总之，衰减成像显示出非常好的观察者间一致性，是检测和量化中度和重度肝脂肪变性的有前途的工具。