Ultrasound-derived fat fraction: a novel approach for assessing Wilson's disease-related hepatic steatosis.

BACKGROUND AND OBJECTIVES

Ultrasound-derived fat fraction (UDFF) is a novel, non-invasive, rapid, and cost-effective technology that assesses liver fat content in various hepatic diseases. Its use in evaluating hepatic steatosis in Wilson’s disease (WD) remains largely unexplored. This study aimed to verify the clinical utility and measurement consistency of UDFF in assessing hepatic steatosis in WD, investigate the relationship between BMI and the severity of hepatic steatosis in WD patients, and determine if UDFF is an effective indicator for this condition.

METHODS

This retrospective study involved 89 patients diagnosed with WD. The demographic characteristics, body mass index (BMI), conventional ultrasound examination, liver shear wave elastography, and ultrasound-derived fat fraction (UDFF) detection data were collected and statistically analyzed. The degree of hepatic steatosis was evaluated using the visual scoring method known as the Hamaguchi score. The Bland-Altman plot was used to analyze the intra-observer and inter-observer consistency of UDFF measurements. The Spearman correlation analysis was conducted to explore the correlations among BMI, UDFF, and the Hamaguchi score. Additionally, confounding factors were included to analyze whether UDFF was an independent influencing factor for WD hepatic steatosis. The receiver operating characteristic (ROC) curve was utilized to determine the cutoff value of UDFF for diagnosing WD hepatic steatosis and its diagnostic efficacy.

RESULTS

The Bland-Altman analysis showed bias values of 5.7% and 1.1% for intra-observer variability of a junior and a senior sonologist, respectively, and 14.9% for inter-observer variability. Univariate analysis showed no significant correlation between BMI and the Hamaguchi score ( = 0.08,  = 0.478). However, there was a positive correlation between UDFF and the Hamaguchi score ( = 0.71,  < 0.001). Multivariate analysis indicated a significant correlation between UDFF and WD hepatic steatosis, with a regression coefficient of 1.243, OR of 3.465, and 95% CI of 1.617–10.51 ( = 0.008). ROC curve analysis demonstrated that the optimal cutoff value of UDFF for diagnosing WD hepatic steatosis was 4.5%, with an AUROC of 0.80 (95% CI: 71 − 90%), sensitivity of 90%, and specificity of 80%.

CONCLUSION

The clinical operation of UDFF exhibits high repeatability. In patients with WD, there may be a paradoxical phenomenon where those with low or normal BMI co-exist with hepatic steatosis. UDFF can serve as a valuable tool for the quantitative assessment of WD hepatic steatosis. Our study broadens the clinical applications of UDFF.