Validation of Volumetric Multifrequency Shear Wave Vibro-Elastography With Matrix Array Transducer for the In Vivo Liver

Abstract

Three-dimensional shear wave absolute vibro-elastography (S-WAVE) is a steady-state, volumetric elastography imaging technique similar to magnetic resonance elastography (MRE), with the additional advantage of multifrequency imaging and a significantly shorter examination time. We present a novel ultrasound matrix array implementation of S-WAVE for high-volume refresh rate acquisition. This new imaging setup is equipped with real-time shear wave monitoring for an improved data collection workflow and image quality. The image processing and elasticity reconstruction pipeline is tailored for high body mass index (BMI) subjects. We characterized this system with tissue phantoms and a human study cohort composed of 7 healthy volunteers and 25 patients with nonalcoholic fatty liver disease. The validation results show that S-WAVE can maintain a high agreement with the liver tissue stiffness measurements obtained with both the 2-D and 3-D MRE techniques, with an average cross correlation >93% and an average ${R} ^{{2}} =0.87$ , which outperforms the conventional transient elasticity technique. Our findings show that the matrix array-based 3-D S-WAVE is a suitable volumetric elastography imaging solution for delivering a similar assessment of liver fibrosis as MRE in a more accessible, flexible, and cost-effective way.