Large Field-Of-View Shear Wave Elasticity Imaging with Combined On- and Off-Axis Stiffness Estimation for High Frame Rate Hepatic HCC Screening

Heptaocellular carcinoma (HCC) is a commonly occurring cancer and is currently detected using B-mode ultrasound scans in at-risk patients. However, B-mode ultrasound has low sensitivity for HCC, particularly for early stage disease. Ultrasound elasticity imaging methods have been used to demonstrate a stiffness contrast between HCC lesions and the surrounding liver, but currently, these elasticity methods are limited to small fields of view (3x3 cm
²
), such that full liver elasticity screenings would be excessively time consuming. Previous work has simulated a large field-of-view shear wave elasticity imaging sequence with on-axis reconstruction techniques. This work demonstrates this sequence and reconstruction strategy in phantoms, including an experimentally developed lookup table for the on-axis reconstruction. Results are presented for both a homogeneous and lesion-containing phantom. In the homogeneous phantom, the experimentally derived lookuptable exhibits less bias in the on-axis reconstruction than when using a simulation-based lookup table. In the lesion phantom, three lesions are measured and found to have similar shear wave speed values and contrasts to the manufacturer quoted values. Overall, a field of view of 68 cm
²
is obtained using 3 overlapping SWEI reconstruction regions.