Quantification of liver fat content with ultrasonographic attenuation measurement function: Correlation with unenhanced multidimensional computerized tomography

Abstract

Purpose: To evaluate the efficacy of attenuation measurement function (ATT), a newly developed quantitative ultrasonography(US) method based on measurement of the attenuation coefficient, using unenhanced computerized tomography(CT) attenuation values as a reference standard, for the detection and measurement of hepatosteatosis.

Material and methods: A total of 98 patients were analyzed. The diagnostic ability of ATT was evaluated using receiver operating characteristic (ROC) curve analysis, and the correlation between liver attenuation index (LAI), the liver-to-spleen attenuation ratio (CT^L/S), liver attenuation value (CT^L), and ATT was determined.

Results: ATT is negatively correlated with LAI (r = -0.571, p < 0.001), CT^L/S (r = -0.532, p < 0.001), and mean CT^L (r = -0.50, p < 0.001). A significant difference was found between ATT values of patients with different grades of hepatosteatosis (p < 0.001). A significant difference was found between ATT values of patients with LAI < -10 and LAI > -10, CT^L < 40 and CT^L > 40, and CT^L/S < 1 and CT^L/S > 1 (p < 0.001). An ATT ≥ 0.665 showed a sensitivity of 100% and a specificity of 90% in diagnosing moderate-severe steatosis. The corresponding area under the ROC curve(AUROC) was 0.935. The intraclass correlation coefficient for the interobserver variability of ATT was 0.907 (95% CI, 0.85-0.95).

Conclusion: In conclusion, ATT values for evaluation of hepatosteatosis was closely correlated with the degree of hepatosteatosis and liver fat content. It can be used as a noninvasive method in the diagnosis and follow-up.

Keywords: Attenuation coefficient; Computerized tomography; Hepatic fat quantification; Hepatosteatosis; Ultrasound.