Background: Non-alcoholic fatty liver disease is rapidly emerging as the leading global cause of chronic liver disease. Efficient disease management requires low-cost, non-invasive techniques for diagnosing hepatic steatosis accurately. Here, we propose quantifying liver speed of sound (SoS) with computed ultrasound tomography in echo mode (CUTE), a recently developed ultrasound imaging modality adapted to clinical pulse-echo systems. CUTE reconstructs the spatial distribution of SoS by measuring local echo phase shifts when probing tissue at varying steering angles in transmission and reception.
Methods: In this first-in-human phase II diagnostic study, we evaluated the liver of 22 healthy volunteers and 22 steatotic patients. We used conventional B-mode ultrasound images and controlled attenuation parameter (CAP) to diagnose the presence (CAP≥ 280 dB/m) or absence (CAP < 248 dB/m) of steatosis in the liver. A fully integrated convex-probe CUTE implementation was developed on the ultrasound system to estimate liver SoS. We investigated its diagnostic value via the receiver operating characteristic (ROC) analysis and correlation to CAP measurements.
Results: We show that liver CUTE-SoS estimates correlate strongly (r = -0.84, p = 8.27 × 10-13) with CAP values and have 90.9% (95% confidence interval: 84-100%) sensitivity and 95.5% (81-100%) specificity for differentiating between normal and steatotic livers (area under the ROC curve: 0.93-1.0).
Conclusions: Our results demonstrate that liver CUTE-SoS is a promising quantitative biomarker for diagnosing liver steatosis. This is a necessary first step towards establishing CUTE as a new quantitative add-on to diagnostic ultrasound that can potentially be as versatile as conventional ultrasound imaging.
Non-alcoholic fatty liver disease (NAFLD), characterized by fat accumulation in the liver, is rapidly becoming the most common cause of chronic liver disease worldwide. Therefore, there is an urgent need to develop accurate diagnostic techniques that are inexpensive, non-invasive, and broadly available. Ultrasound imaging systems, which use sound waves to produce images of internal body structures, possess these qualities but cannot currently diagnose NAFLD accurately. Here, we propose to use a recently developed technique called computed ultrasound tomography in echo mode (CUTE). It measures the speed at which ultrasound waves propagate in tissues, a property that substantially varies with the fat content. We show that CUTE measurements allow us to accurately distinguish the livers of healthy people from those of individuals diagnosed with NAFLD. This promising finding encourages the integration of CUTE into standard ultrasound systems.
© 2023. The Author(s).