Real-time ablation monitoring and lesion quantification using harmonic motion imaging guided focused ultrasound (HMIgFUS)

Abstract

High-Intensity Focused Ultrasound (HIFU) monitoring is currently hindered by time- and cost-inefficient or inconclusive warranting, thus an imaging technique for efficient and reliable guidance. 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 also uses ultrasound imaging with parallel beamforming and estimates and maps the tissue dynamic motion in response to the oscillatory force at the same frequency based on consecutive RF frames. HMI has already been shown feasible in simulations, phantoms, ex vivo human and bovine tissues as well as animal tumor models in vivo. Using an FUS beam, HMI can also be seamlessly integrated with thermal ablation using HIFU, which leads to changes in the tumor stiffness. In this paper, an overview of HMI will be provided, including the capability of HMI to characterize and image the tumor prior to ablation, localize the beam for treatment planning, as well as monitor subsequent lesioning in real time. The findings demonstrate that HMI is capable of both detecting and characterizing the tumor prior to HIFU ablation as well as correctly depict and quantify the lesion during treatment. More importantly, HMI is shown capable of distinguishing the tumor margins from those of the thermal lesion in vivo in order to accurately determine treatment success. HMI thus constitutes an integrated, real-time method for efficient HIFU monitoring.