Improving thermal ablation delineation with electrode vibration elastography using a bidirectional wave propagation assumption

Thermal ablation procedures are commonly used to treat hepatic and renal cancers, and accurate ablation representation on shear wave velocity images is crucial to ensure complete treatment of the malignant mass. Electrode vibration elastography is a shear wave imaging technique recently developed to monitor thermal ablation extent during treatment procedures. Previous work has shown good lateral boundary delineation of ablated volumes, but axial delineation was more ambiguous, which may be a result of the assumption of lateral shear wave propagation. In this work, we assume both lateral and a complex wave propagation along the axial direction and compare shear wave velocity images to those obtained assuming only lateral shear wave propagation in finite element simulations, tissue mimicking phantoms, and bovine liver tissue. Our results show that assuming bidirectional wave propagation minimizes artifacts above and below ablated volumes, yielding a more accurate representation of the ablated region on shear wave velocity images. Area overestimation was reduced from 13.4% to 3.6% in a stiff inclusion embedded in a tissue mimicking phantom and from 9.1% to 0.8% in a radiofrequency ablation created in bovine liver tissue. More accurate ablation representation during ablation procedures increases the likelihood of complete treatment of the malignant mass, lowering tumor recurrence.