Inertial Cavitation Behaviors Induced by Nonlinear Focused Ultrasound Pulses.

Inertial cavitation induced by pulsed high-intensity focused ultrasound (pHIFU) has previously been shown to successfully permeabilize tumor tissue and enhance chemotherapeutic drug uptake. In addition to HIFU frequency, peak rarefactional pressure ( p ), and pulse duration, the threshold for cavitation-induced bioeffects has recently been correlated with asymmetric distortion caused by nonlinear propagation, diffraction and formation of shocks in the focal waveform, and therefore with the transducer F -number. To connect previously observed bioeffects with bubble dynamics and their attendant physical mechanisms, the dependence of inertial cavitation behavior on shock formation was investigated in transparent agarose gel phantoms using high-speed photography and passive cavitation detection (PCD).

Comparison of Imaging Changes and Pain Responses in Patients with Intra- or Extraosseous Bone Metastases Treated Palliatively with Magnetic Resonance-Guided High-Intensity-Focused Ultrasound.

Purpose: This study compared changes in imaging and in pain relief between patients with intraosseous, as opposed to extraosseous bone metastases. Both groups were treated palliatively with magnetic resonance-guided high-intensity-focused ultrasound (MRgHIFU).

Materials And Methods: A total of 21 patients were treated prospectively with MRgHIFU at 3 centers.

MR guided high intensity focused ultrasound (MRgHIFU) for treating recurrent gynaecological tumours: a pilot feasibility study.

Objective: To assess the feasibility of targeting recurrent gynaecological tumours with MR guided high intensity focused ultrasound (MRgHIFU).

Methods: 20 patients with recurrent gynaecological tumours were prospectively scanned on a Philips/Profound 3 T Achieva MR/ Sonalleve HIFU system. Gross tumour volume (GTV) and planning target volume (PTV) were delineated on W and diffusion-weighted imaging (DWI).

Value of diffusion-weighted imaging for monitoring tissue change during magnetic resonance-guided high-intensity focused ultrasound therapy in bone applications: an study.

Background: Magnetic resonance (MR)-guided high-intensity focused ultrasound (HIFU) can palliate metastatic bone pain by periosteal neurolysis. We investigated the value of diffusion-weighted imaging (DWI) for monitoring soft tissue changes adjacent to bone during MR-guided HIFU. We evaluated the repeatability of the apparent diffusion coefficient (ADC) measurement, the temporal evolution of ADC change after sonication, and its relationship with thermal parameters.

Development of a hybrid magnetic resonance and ultrasound imaging system.

A system which allows magnetic resonance (MR) and ultrasound (US) image data to be acquired simultaneously has been developed. B-mode and Doppler US were performed inside the bore of a clinical 1.5 T MRI scanner using a clinical 1-4 MHz US transducer with an 8-metre cable.

Design and development of a prototype endocavitary probe for high-intensity focused ultrasound delivery with integrated magnetic resonance imaging.

Purpose: To integrate a high intensity focused ultrasound (HIFU) transducer with an MR receiver coil for endocavitary MR-guided thermal ablation of localized pelvic lesions.

Materials And Methods: A hollow semicylindrical probe (diameter 3.2 cm) with a rectangular upper surface (7.

Spatial and acoustic pressure dependence of microbubble-mediated gene delivery targeted using focused ultrasound.

Background: Ultrasound/microbubble-mediated gene delivery has the potential to be targeted to tissue deep in the body by directing the ultrasound beam following vector administration. Application of this technology would be minimally invasive and benefit from the widespread clinical experience of using ultrasound and microbubble contrast agents. In this study we evaluate the targeting ability and spatial distribution of gene delivery using focused ultrasound.

Physical parameters affecting ultrasound/microbubble-mediated gene delivery efficiency in vitro.

Ultrasound (US)/microbubble-mediated gene delivery is a technology with many potential advantages suited to clinical application. Previous studies have demonstrated transfection but many are unsatisfactory in respect to the exposure apparatus, lack of definition of the US field or the limitations on parameters that can be explored using clinical diagnostic US machines. We investigated individual exposure parameters using a system minimising experimental artefacts and allowing control of many parameters of the US field.

Contrast-enhanced ultrasound assessment of tissue response to high-intensity focused ultrasound.

We report the use of contrast-enhanced ultrasonography as an immediate means of assessing the clinical response to high-intensity focused ultrasound (US) or HIFU treatment of liver tumours. HIFU is a noninvasive transcutaneous technique for the ablation of tumours that has been shown to destroy tumour vasculature, as well as to cause coagulative necrosis of tumour cells. As a dynamic indicator of tissue perfusion, microbubble contrast agents have already been reported to increase the diagnostic sensitivity of ultrasonography in the detection of liver tumours.

Imaging of temperature-induced echo strain: preliminary in vitro study to assess feasibility for guiding focused ultrasound surgery.

Ultrasonic estimation of heat-induced echo strain has been suggested as a noninvasive technique for guiding focused ultrasound (US) surgery (FUS), that is, for predicting the location of the thermal lesion before it is formed. The proposed strategy is to run the FUS system at a nonablative intensity and to use a diagnostic transducer to image the heat-induced echo strain, which, over a sufficiently small temperature range, is proportional to the temperature rise. The principal aim of this in vitro study was to determine if temperature-induced strain imaging is likely to be able to visualise the small (< 0.