Shear wave velocity imaging using transient electrode perturbation: phantom and ex vivo validation

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Ultrasound Technology

Background:

• Radio-frequency and microwave ablation are critical medical procedures.
• Real-time monitoring of ablation zones is essential for effective treatment and patient safety.
• Current monitoring techniques may lack sufficient detail for precise ablation boundary delineation.

Purpose of the Study:

• To introduce and validate a new shear wave velocity imaging technique, electrode vibration elastography, for monitoring ablation procedures.
• To assess the feasibility and accuracy of electrode vibration elastography in various experimental settings.
• To compare electrode vibration elastography with electrode displacement elastography for complementary information.

Main Methods:

• Development of electrode vibration elastography using a piezoelectric actuator attached to an ablation needle to generate and track shear waves.
• Utilizing the time-to-peak algorithm for shear wave velocity and shear modulus reconstruction.
• Validation through finite element models, ultrasound simulations, tissue-mimicking phantoms (fully and partially ablated), and an ex vivo bovine liver ablation experiment.

Main Results:

• Feasibility demonstrated across simulations, phantoms, and ex vivo experiments.
• Good boundary delineation of ablated regions observed in phantom and ex vivo studies.
• Shear wave velocity estimates showed high accuracy in phantoms (within 7% and 17%) and comparable results in ex vivo liver tissue (within 20% for untreated tissue).

Conclusions:

• Electrode vibration elastography is a promising imaging modality for real-time ablation monitoring.
• The technique provides accurate boundary delineation and quantitative shear modulus information.
• Electrode vibration elastography offers complementary data compared to electrode displacement elastography, enhancing procedural guidance.