Ultrasound Elastography for Biomedical Applications and Medicine

18 Harmonic Motion Imaging

Elisa Konofagou

Department of Biomedical Engineering, Columbia University, New York, NY, USA

18.1 Introduction

Harmonic motion imaging (HMI) uses a focused ultrasound (FUS) beam to generate an oscillatory acoustic radiation force for an internal, non‐contact palpation to internally estimate relative tissue hardness. HMI estimates and maps the tissue dynamic motion in response to the oscillatory force at the same frequency, and has been shown to be feasible in simulations, phantoms, ex vivo human and bovine tissues, as well as animals in vivo. Using an FUS beam, HMI can also be used in an ideal integration setting with thermal ablation using high‐intensity focused ultrasound (HIFU), which leads to an alteration in the tumor stiffness. In this chapter, the capability of HMI to localize and target the tumor as well as monitor its subsequent ablation is assessed. The findings presented here demonstrate that HMI is capable of both detecting and characterizing the tumor as well as efficiently detecting the onset of ablation. More importantly, HMI is shown to be capable of distinguishing the tumor margins from the margins of the thermal lesion in vivo in order to assess the treatment success. HMI may thus constitute an integrated, real‐time method for efficient HIFU monitoring.

18.2 Background

18.2.1 Ultrasound‐guided HIFU

In ultrasound‐guided methods, the HIFU lesion can only be detected when cavitation or boiling occurs due to the high ...