Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, 80, Guro-dong, Guro-gu, Seoul 152-703, Republic of Korea.
Eur J Radiol. 2011 Dec;80(3):e258-62. doi: 10.1016/j.ejrad.2010.11.023. Epub 2010 Dec 15.
To evaluate the value of the fade-out sign in the diagnosis of fatty liver (FL) on hepatic ultrasound (US).
We evaluated 127 patients who underwent hepatic US, including 70 patients with FL and 57 normal control subjects. US images were qualitatively evaluated for the presence of the fade-out sign. This sign was considered present if there was a dark band on the deep portion of the liver on the harmonic image when compound sonography (CS) was converted to tissue harmonic CS mode. The degrees of FL were classified into mild, moderate, and severe. The distribution of lengths of dark bands in three groups was examined, and a multiple comparison of the average dark band length was carried out using one-way ANOVA.
The fade-out sign was seen in 55 of 70 FL patients (78.6%) compared to 3 of 57 control subjects (5.3%) (p<0.001). The sensitivity, specificity, accuracy, and positive predictive value of the fade-out sign for the US diagnosis of FL were 78%, 94%, 85.8%, and 94.8%, respectively. Among the 70 FL, there were 28 mild FL (mean length of dark band; 8.3 mm±8.2), 31 moderate FL (mean; 28 mm±6.3), and 11 severe FL (mean; 51 mm±8.3). There were significant differences in band length according to severity (p<0.01).
The fade-out sign on hepatic harmonic US was frequently present in FL. As fat infiltration increased, the fade-out sign lengthened. The fade-out sign offers a specific and new sign of FL.
评估超声肝衰减征在诊断脂肪肝（FL）中的价值。
我们评估了 127 例接受肝脏超声检查的患者，包括 70 例 FL 患者和 57 例正常对照组。对超声图像进行定性评估，以确定是否存在肝衰减征。当复合超声（CS）转换为组织谐波 CS 模式时，如果在谐波图像上肝脏深部出现暗带，则认为存在该征。将 FL 程度分为轻度、中度和重度。检查三组暗带长度的分布，并使用单因素方差分析对平均暗带长度进行多重比较。
与 57 例对照组（5.3%）相比，70 例 FL 患者中有 55 例（78.6%）出现肝衰减征（p<0.001）。肝衰减征对超声诊断 FL 的敏感性、特异性、准确性和阳性预测值分别为 78%、94%、85.8%和 94.8%。在 70 例 FL 中，有 28 例轻度 FL（暗带平均长度；8.3 mm±8.2）、31 例中度 FL（平均；28 mm±6.3）和 11 例重度 FL（平均；51 mm±8.3）。根据严重程度，暗带长度有显著差异（p<0.01）。
肝谐波超声上的肝衰减征在 FL 中经常出现。随着脂肪浸润的增加，肝衰减征变长。肝衰减征提供了 FL 的一个特异且新的征象。
