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

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control ferroelectrics, and frequency control, 2012-01, Vol.59 (1), p.168-173
• Main Authors: Dewall, R. J., Varghese, T.
• Format: Article
• Language: English
• Subjects: Ablation; Acoustic signal processing; Acoustics; Animals; Biological and medical sciences; Cattle; Computer Simulation; Delineation; Elasticity Imaging Techniques - instrumentation; Elasticity Imaging Techniques - methods; Electrodes; Exact sciences and technology; Finite Element Analysis; Finite element methods; Fundamental areas of phenomenology (including applications); Image Processing, Computer-Assisted; Investigative techniques, diagnostic techniques (general aspects); Laser Therapy - methods; Liver - diagnostic imaging; Liver - surgery; Medical sciences; Miscellaneous. Technology; Pathology; Phantoms; Phantoms, Imaging; Physics; Propagation; Radio frequency; Representations; Signal Processing, Computer-Assisted; Sound waves; Studies; Surgery, Computer-Assisted - methods; Transduction; acoustical devices for the generation and reproduction of sound; Ultrasonic investigative techniques; Vibration; Vibrations; Wave propagation
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2012.2169

Thermal ablation procedures are commonly used to treat hepatic cancers and accurate ablation representation on shear wave velocity images is crucial to ensure complete treatment of the malignant target. 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 have resulted from the assumption of lateral shear wave propagation. In this work, we assume both lateral and axial wave propagation and compare wave velocity images to those 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 tissue-mimicking phantom and from 9.1% to 0.8% in a radio-frequency ablation in bovine liver tissue. More accurate ablation representation during ablation procedures increases the likelihood of complete treatment of the malignant target, decreasing tumor recurrence.