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Published on: June 2, 2023
CT-based visual grading system for assessment of hepatic steatosis: diagnostic performance and interobserver
Hyo Jung Park1, Kyoung Won Kim2, Heon-Ju Kwon3
1Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-Ro 43-Gil, Songpa-Gu, Seoul, 05505, Republic of Korea.
Insights
A visual grading system (VGS) for hepatic steatosis (HS) on unenhanced CT scans is reliable and reproducible. This simple, non-invasive tool effectively assesses HS, showing high diagnostic performance comparable to quantitative methods.
Area of Science:
- Radiology
- Hepatology
- Medical Imaging
Background:
- Hepatic steatosis (HS) is commonly assessed using unenhanced computed tomography (CT) by comparing liver and vessel attenuation.
- Evaluating the reliability and reproducibility of a CT-based visual grading system (VGS) for HS is crucial for clinical application.
Purpose of the Study:
- To validate a four-point VGS for comprehensive assessment of hepatic steatosis using unenhanced CT images.
- To compare the diagnostic performance of VGS against quantitative indices and pathology as a reference standard.
Main Methods:
- Retrospective validation of a four-point VGS by six reviewers using unenhanced CT scans from 717 potential liver donors.
- Multi-reader multi-case ROC analysis to evaluate VGS and quantitative indices; Fleiss κ statistics for interobserver agreement.
Main Results:
- VGS achieved areas under the ROC curves (AUROCs) > 0.9 for diagnosing total steatosis (TS) ≥30% and macrovesicular steatosis (MaS) ≥10% and ≥30%.
- No significant difference in AUROCs between VGS and quantitative indices (p≥0.1); substantial interobserver agreement (κ=0.61).
- High average-reader sensitivity (0.80-0.93) and specificity (0.81-0.94) for detecting HS thresholds.
Conclusions:
- The CT-based VGS is a reliable and reproducible method for assessing hepatic steatosis.
- VGS offers a simple, non-invasive approach for comprehensive HS evaluation.
- The system demonstrates significant diagnostic performance, supporting its clinical utility.
Background:
Hepatic steatosis (HS) can be comprehensively assessed by visually comparing the hepatic and vessel attenuation on unenhanced computed tomography (CT). We aimed to evaluate the reliability and reproducibility of a CT-based visual grading system (VGS) for comprehensive assessment of HS.
Methods:
In this retrospective study, a four-point VGS based on the visual comparison of liver and hepatic vessels was validated by six reviewers with diverse clinical experience using the unenhanced CT images of 717 potential liver donors. The diagnostic performance of VGS and quantitative indices (difference and ratio of the hepatic and splenic attenuation) to diagnose HS were evaluated using multi-reader multi-case receiver operating characteristics (ROC) analysis (reference: pathology). The interobserver agreement was assessed using Fleiss κ statistics.
Results:
Using the VGS, all six reviewers showed areas under the ROC curves (AUROCs) higher than 0.9 for diagnosing total steatosis (TS) ≥ 30%, macrovesicular steatosis (MaS) ≥ 30%, and MaS ≥ 10%. No difference was noted between the AUROCs of the VGS and quantitative indices (p ≥ 0.1). The reviewers showed substantial agreement (Fleiss κ, 0.61). Most discrepancies occurred between the two lowest grades of VGS (81.5%; 233/283), in which most subjects (97.0%; 226/233) had a MaS < 10%. The average-reader sensitivity and specificity of the VGS were 0.80 and 0.94 to detect TS ≥ 30% and 0.93 and 0.81 to detect MaS ≥ 10%.
Conclusion:
VGS was reliable and reproducible in assessing HS. It may be useful as a non-invasive and simple tool for comprehensive HS assessment.
