Reader agreement and accuracy of ultrasound features for hepatic steatosis

Abstract

Purpose: The purpose of the study is to assess the reader agreement and accuracy of eight ultrasound imaging features for classifying hepatic steatosis in adults with known or suspected hepatic steatosis.

Methods: This was an IRB-approved, HIPAA-compliant prospective study of adult patients with known or suspected hepatic steatosis. All patients signed written informed consent. Ultrasound images (Siemens S3000, 6C1HD, and 4C1 transducers) were acquired by experienced sonographers following a standard protocol. Eight readers independently graded eight features and their overall impression of hepatic steatosis on ordinal scales using an electronic case report form. Duplicated images from the 6C1HD transducer were read twice to assess intra-reader agreement. Intra-reader, inter-transducer, and inter-reader agreement were assessed using intraclass correlation coefficients (ICC). Features with the highest intra-reader agreement were selected as predictors for dichotomized histological steatosis using Classification and Regression Tree (CART) analysis, and the accuracy of the decision rule was compared to the accuracy of the radiologists' overall impression.

Results: 45 patients (18 males, 27 females; mean age 56 ± 12 years) scanned from September 2015 to July 2016 were included. Mean intra-reader ICCs ranged from 0.430 to 0.777, inter-transducer ICCs ranged from 0.228 to 0.640, and inter-reader ICCs ranged from 0.014 to 0.561. The CART decision rule selected only large hepatic vein blurring and achieved similar accuracy to the overall impression (74% to 75% and 68% to 72%, respectively).

Conclusions: Large hepatic vein blurring, liver-kidney contrast, and overall impression provided the highest reader agreement. Large hepatic vein blurring may provide the highest classification accuracy for dichotomized grading of hepatic steatosis.

Keywords: Hepatic steatosis; Hepatic vein blurring; Liver; Reader agreement; Ultrasound features.

Figure 1

Intra-reader (light green), inter-transducer (teal), and inter-reader (blue) agreement for each imaging feature are shown. For each feature, intra-reader and inter-transducer agreement are both averaged over all readers, and inter-reader agreement is averaged over the two transducers. LHVB = large hepatic vein blurring; MRPVB = main and right portal vein blurring; APPVB = anterior and posterior portal vein blurring; LKC = liver-kidney contrast; PBA = posterior beam attenuation; DD = diaphragm definition; FFS = focal fat sparing; LE = liver echotexture; OI = overall impression

Figure 2

Accuracy, sensitivity, and specificity of the 6C1HD and 4C1 decision rules (light green) applying large hepatic vein blurring for dichotomized hepatic steatosis compared to the radiologists’ overall impression (teal). The decision rules achieved similar or slightly higher accuracy than the radiologists’ overall impression, with lower sensitivity but higher specificity.

Figure 3

a: Scoring spectrum for large hepatic vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. IVC = inferior vena cava; RHV = right hepatic vein; MHV = middle hepatic vein; LHV = left hepatic vein. b: Scoring spectrum for main and right portal vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. MPV = main portal vein; RPV = right portal vein. c: Scoring spectrum for anterior and posterior portal vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. ARPV = anterior right portal vein; PRPV = posterior right portal vein. d: Scoring spectrum for liver kidney contrast. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. L = liver; K = kidney. e: Scoring spectrum for posterior beam attenuation. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. f: Scoring spectrum for diaphragm definition. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. L = liver; K = kidney; D = diaphragm. g: Scoring spectrum for focal fat sparing. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. MPV = main portal vein; RPV = right portal vein. Arrow denotes the area of focal fat sparing. h: Scoring spectrum for liver echotexture. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown.

Figure 3

a: Scoring spectrum for large hepatic vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. IVC = inferior vena cava; RHV = right hepatic vein; MHV = middle hepatic vein; LHV = left hepatic vein. b: Scoring spectrum for main and right portal vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. MPV = main portal vein; RPV = right portal vein. c: Scoring spectrum for anterior and posterior portal vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. ARPV = anterior right portal vein; PRPV = posterior right portal vein. d: Scoring spectrum for liver kidney contrast. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. L = liver; K = kidney. e: Scoring spectrum for posterior beam attenuation. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. f: Scoring spectrum for diaphragm definition. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. L = liver; K = kidney; D = diaphragm. g: Scoring spectrum for focal fat sparing. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. MPV = main portal vein; RPV = right portal vein. Arrow denotes the area of focal fat sparing. h: Scoring spectrum for liver echotexture. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown.

Figure 3

a: Scoring spectrum for large hepatic vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. IVC = inferior vena cava; RHV = right hepatic vein; MHV = middle hepatic vein; LHV = left hepatic vein. b: Scoring spectrum for main and right portal vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. MPV = main portal vein; RPV = right portal vein. c: Scoring spectrum for anterior and posterior portal vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. ARPV = anterior right portal vein; PRPV = posterior right portal vein. d: Scoring spectrum for liver kidney contrast. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. L = liver; K = kidney. e: Scoring spectrum for posterior beam attenuation. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. f: Scoring spectrum for diaphragm definition. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. L = liver; K = kidney; D = diaphragm. g: Scoring spectrum for focal fat sparing. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. MPV = main portal vein; RPV = right portal vein. Arrow denotes the area of focal fat sparing. h: Scoring spectrum for liver echotexture. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown.

Figure 3

a: Scoring spectrum for large hepatic vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. IVC = inferior vena cava; RHV = right hepatic vein; MHV = middle hepatic vein; LHV = left hepatic vein. b: Scoring spectrum for main and right portal vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. MPV = main portal vein; RPV = right portal vein. c: Scoring spectrum for anterior and posterior portal vein blurring. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. ARPV = anterior right portal vein; PRPV = posterior right portal vein. d: Scoring spectrum for liver kidney contrast. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. L = liver; K = kidney. e: Scoring spectrum for posterior beam attenuation. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. f: Scoring spectrum for diaphragm definition. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. L = liver; K = kidney; D = diaphragm. g: Scoring spectrum for focal fat sparing. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown. MPV = main portal vein; RPV = right portal vein. Arrow denotes the area of focal fat sparing. h: Scoring spectrum for liver echotexture. For each scoring grade, the examination with the highest proportion of reads selecting it as that particular score was chosen. Proportions of the 16 reads (2 from each reader) identifying each exam as the corresponding score are shown.