Liver Fat Quantification With Ultrasound: The Influence of the Size of the Region of Interest on Attenuation Coefficient.

Abstract

Abstract: Noninvasive assessment of liver fat content is crucial due to the high global prevalence of nonalcoholic fatty liver disease. Algorithms based on ultrasound (US) attenuation coefficient (AC) for estimating liver fat content are commercially available, but a lack of consensus exists regarding the best estimation protocol. The aim of our study was to evaluate the influence of the size of the region of interest (ROI) on the US AC.A prospective study was conducted. An abdominal US was done for 86 outpatients. A sampling box was positioned within the liver parenchyma, approximately 2 cm beneath the liver capsule with a ROI, measuring about 2 × 4 cm and then 4 × 5 cm, precisely placed at the center of this sampling box. Five readings of the AC were captured, and the average of these measurements was employed to assess the severity of hepatic steatosisA statistically significant difference between AC with 2 different ROI sizes was shown (P < 0.001) with AC values with 2 × 4 cm ROI were higher than those obtained with 4 × 5 cm ROI (AC mean 0.668 VS 0.653). However, the agreement between AC values obtained with 2 different ROI sizes was excellent (correlation coefficient 0.941)An ROI size dependence is observed in the measurement of AC in the liver. A standardized acquisition protocol with a fixed size of the ROI needs to be developed to minimize differences in AC measurements and to assess changes in serial measurements reliably.