Image-Guided Measurement of Radiation Force Induced by Focused Ultrasound Beams.

The radiation force balance (RFB) is a widely used method for measuring acoustic power output of ultrasonic transducers. The reflecting cone target is attractive due to its simplicity and long-term stability, at a reasonable cost. However, accurate measurements using this method depend on the alignment between the ultrasound beam and cone axes, especially for highly focused beams utilized in therapeutic applications.

Safety and feasibility study of non-invasive robot-assisted high-intensity focused ultrasound therapy for the treatment of atherosclerotic plaques in the femoral artery: protocol for a pilot study.

Introduction: Peripheral arterial disease (PAD) is an atherosclerotic disease leading to stenosis and/or occlusion of the arterial circulation of the lower extremities. The currently available revascularisation methods have an acceptable initial success rate, but the long-term patency is limited, while surgical revascularisation is associated with a relatively high perioperative risk. This urges the need for development of less invasive and more effective treatment modalities.

Spatio-Spectral Ultrasound Characterization of Reflection and Transmission Through Bone With Temperature Dependence.

Transcranial focused ultrasound (tFUS) is a promising approach for the treatment of neurological disorders. It has proven useful in several clinical applications, with promising outcomes reported in the recent literature. Furthermore, it is currently being investigated in a range of neuromodulation (NM) and ablative applications, including epilepsy.

Precision Targeted Ablation of Fine Neurovascular Structures In Vivo Using Dual-mode Ultrasound Arrays.

Carotid bodies (CBs) are chemoreceptors that monitor and register changes in the blood, including the levels of oxygen, carbon dioxide, and pH, and regulate breathing. Enhanced activity of CBs was shown to correlate with a significant elevation in the blood pressure of patients with hypertension. CB removal or denervation were previously shown to reduce hypertension.

The Optimization of Transcostal Phased Array Refocusing Using the Semidefinite Relaxation Method.

Tumors in organs partially obscured by the rib cage represent a challenge for high-intensity focused ultrasound (HIFU) therapy. The ribs distort the HIFU beams in a manner that reduces the focusing gain at the target, which could result in treatment-limiting collateral damage. In fact, skin burns are a common complication during the ablation of hepatic tumors.

Reversible neuroinhibition by focused ultrasound is mediated by a thermal mechanism.

Background: Transcranial focused ultrasound (tFUS) at low intensities has been reported to directly evoke responses and reversibly inhibit function in the central nervous system. While some doubt has been cast on the ability of ultrasound to directly evoke neuronal responses, spatially-restricted transcranial ultrasound has demonstrated consistent, inhibitory effects, but the underlying mechanism of reversible suppression in the central nervous system is not well understood.

Objective/hypothesis: In this study, we sought to characterize the effect of transcranial, low-intensity, focused ultrasound on the thalamus during somatosensory evoked potentials (SSEP) and investigate the mechanism by modulating the parameters of ultrasound.

Nonlinear Imaging of Microbubble Contrast Agent Using the Volterra Filter: In Vivo Results.

A nonlinear filtering approach to imaging the dynamics of microbubble ultrasound contrast agents (UCAs) in microvessels is presented. The approach is based on the adaptive third-order Volterra filter (TVF), which separates the linear, quadratic, and cubic components from beamformed pulse-echo ultrasound data. The TVF captures polynomial nonlinearities utilizing the full spectral components of the echo data and not from prespecified bands, e.

In Vivo application and localization of transcranial focused ultrasound using dual-mode ultrasound arrays.

Focused ultrasound (FUS) has been proposed for a variety of transcranial applications, including neuromodulation, tumor ablation, and blood-brain barrier opening. A flurry of activity in recent years has generated encouraging results demonstrating its feasibility in these and other applications. To date, monitoring of FUS beams has been primarily accomplished using MR guidance, where both MR thermography and elastography have been used.

Anatomical-based model for simulation of HIFU-induced lesions in atherosclerotic plaques.

Purpose: The aim of this study was to simulate the effect of high intensity focused ultrasound (HIFU) in non-homogenous medium for targeting atherosclerotic plaques in vivo.

Materials And Methods: A finite-difference time-domain heterogeneous model for acoustic and thermal tissue response in the treatment region was derived from ultrasound images of the treatment region. A 3.

Ultrasound-guided therapeutic focused ultrasound: current status and future directions.

This paper reviews ultrasound imaging methods for the guidance of therapeutic focused ultrasound (USgFUS), with emphasis on real-time preclinical methods. Guidance is interpreted in the broadest sense to include pretreatment planning, siting of the FUS focus, real-time monitoring of FUS-tissue interactions, and real-time control of exposure and damage assessment. The paper begins with an overview and brief historical background of the early methods used for monitoring FUS-tissue interactions.

In vivo ultrasound thermography in presence of temperature heterogeneity and natural motions.

Real-time ultrasound thermography has been recently demonstrated on commercially available diagnostic imaging probes. In vitro experimental results demonstrate high sensitivity to small, localized temperature changes induced by subtherapeutic focused ultrasound. Most of the published results, however, are based on a thermally induced echo strain model that assumes infinitesimal change in temperature between imaging frames.

High-intensity focused ultrasound for potential treatment of polycystic ovary syndrome: toward a noninvasive surgery.

Objective: To investigate the feasibility of using high-intensity focused ultrasound (HIFU), under dual-mode ultrasound arrays (DMUAs) guidance, to induce localized thermal damage inside ovaries without damage to the ovarian surface.

Design: Laboratory feasibility study.

Setting: University-based laboratory.

Feasibility of targeting atherosclerotic plaques by high-intensity-focused ultrasound: an in vivo study.

Purpose: To investigate the feasibility and acute safety of targeting atherosclerotic plaques by high-intensity-focused ultrasound (US) in vivo through a noninvasive extracorporeal approach.

Materials And Methods: Four swine were included in this prospective study, three of which were familial hypercholesterolemic swine. The procedure was done under general anesthesia.

Real-time implementation of a dual-mode ultrasound array system: in vivo results.

A real-time dual-mode ultrasound array (DMUA) system for imaging and therapy is described. The system utilizes a concave (40-mm radius of curvature) 3.5 MHz, 32 element array, and modular multichannel transmitter/receiver.

Realtime control of multiple-focus phased array heating patterns based on noninvasive ultrasound thermography.

A system for the realtime generation and control of multiple-focus ultrasound phased-array heating patterns is presented. The system employs a 1-MHz, 64-element array and driving electronics capable of fine spatial and temporal control of the heating pattern. The driver is integrated with a realtime 2-D temperature imaging system implemented on a commercial scanner.

Monitoring and guidance of HIFU beams with dual-mode ultrasound arrays.

We present experimental results illustrating the unique advantages of dual-mode array (DMUA) systems in monitoring and guidance of high intensity focused ultrasound (HIFU) lesion formation. DMUAs offer a unique paradigm in image-guided surgery; one in which images obtained using the same therapeutic transducer provide feedback for: 1) refocusing the array in the presence of strongly scattering objects, e.g.

Real-time two-dimensional temperature imaging using ultrasound.

We present a system for real-time 2D imaging of temperature change in tissue media using pulse-echo ultrasound. The frontend of the system is a SonixRP ultrasound scanner with a research interface giving us the capability of controlling the beam sequence and accessing radio frequency (RF) data in real-time. The beamformed RF data is streamlined to the backend of the system, where the data is processed using a two-dimensional temperature estimation algorithm running in the graphics processing unit (GPU).

A 2D post-beamforming filter for contrast restoration in medical ultrasound: in vivo results.

We have recently developed a robust 2D post-beamforming filter for contrast restoration in ultrasound imaging systems using coarsely-sampled array apertures, e.g. high frequency ultrasound (HFUS).

Monitoring and guidance of minimally-invasive thermal therapy using diagnostic ultrasound.

We present specialized ultrasound imaging modes for monitoring and guidance of noninvasive and minimally-invasive thermal therapy. One mode is based on two-dimensional imaging of temperature change using diagnostic ultrasound. We have validated this method both in vivo and in vitro in monitoring the heating patterns produced by noninvasive HIFU source and minimally-invasive RF ablation device, respectively.

Real-time 2-D temperature imaging using ultrasound.

We have previously introduced methods for noninvasive estimation of temperature change using diagnostic ultrasound. The basic principle was validated both in vitro and in vivo by several groups worldwide. Some limitations remain, however, that have prevented these methods from being adopted in monitoring and guidance of minimally invasive thermal therapies, e.

A post-beamforming 2-D pseudoinverse filter for coarsely sampled ultrasound arrays.

Beamforming artifacts due to coarse discretization of imaging apertures represent a significant barrier against the use of array probes in high-frequency applications. Nyquist sampling of array apertures dictates center-to-center spacing of lambda/2 for elimination of grating lobes in the array pattern. However, this requirement is hard to achieve using current transducer technologies, even at the lower end of high-frequency ultrasonic imaging (in the range 25-35 MHz).