Ex Vivo Demonstration of a Novel Dual-Frequency Ultrasound Method for Quantitative Measurements of Liver Fat Content

Objective: The rise in metabolic dysfunction-associated steatotic liver disease prevalence, closely linked with metabolic syndromes and obesity, demands accurate, cost-effective diagnostic methods for early-stage fat quantification in the liver. Here we demonstrate a novel dual-frequency ultrasound method that enables the quantitative measurement of liver fat fraction ex vivo and its correlation with actual fat content. Methods: A total of 24 Wistar rats were divided into four different groups, where three groups were given a highfat diet for 2, 4, and 6 wk, and the last group was given a control diet for 6 wk. Livers were imaged with ultrasound ex vivo in a water bath with a dual-frequency ultrasound transducer and experimental imaging protocol implemented on the Verasonics Vantage research ultrasound scanner. Ultrasound data were post-processed to estimate the non-linear bulk elasticity parameter and the liver samples were analyzed with respect to fat fraction and triglycerides. Results: Rats given a high-fat diet had increased mean levels of liver fat compared with the control group. More importantly, correlation between the ultrasound-based estimation of the non-linear bulk elasticity parameter and fat fraction and triglycerides on an individual level was found to be strong (R2 = 0.81, p = 5.8 x 10-9 and R2 = 0.72, p = 3.6 x 10-7, respectively). Conclusion: This study demonstrates the potential of the novel dual-frequency ultrasound method for the quantitative measurement of liver fat fraction in excised rat livers, showing great promise for this method to become clinically relevant in the diagnosis and follow-up of patients with fatty liver disease.