Blind Source Separation-Based Displacement Tracking Improves Quantitative, On-Axis Shear Elastic Modulus Estimation from DoPIo Ultrasound

While SWEI methods require shear wave propagation to be sampled across a measurement kernel, the recently-introduced double-profile intersection (DoPIo) ultrasound can estimate shear moduli locally and on-axis by exploiting ARF-induced displacement underestimation caused by scatterer shearing under a tracking PSF. We herein perform a systematic comparison of DoPIo to MTL/STL-SWEI to identify the benefits and limitations of using multiple tracking F-numbers. We further compare DoPIo performance achieved using conventional normalized cross-correlation (NCC) to that using a blind source separation (BSS) estimator by assessing its impact of mechanical feature resolution and measurements via automatic segmentation. DoPIo shear modulus estimates in a simulated elastic phantom using BSS resulted in a contrast transfer efficiency comparable to STL-SWEI (0.81 for a 12.0 kPa feature within an 8.0 kPa background using BSS-DoPIo, compared to 0.77 for NCC, 0.76 for MTL-SWEI, and 0.81 for STL-SWEI). We also demonstrate DoPIo measurements in a calibrated phantomm using a clinical ultrasound scanner system. In doing so, we present DoPIo as a method to ultrasonically measure the shear modulus of tissue that may be performed on-axis independently of ARF amplitudes.