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Your search keyword '"ultrasound surgery"' showing total 4 results
Start Over Descriptor "ultrasound surgery" Topic cavitation
4 results on '"ultrasound surgery"'

1. Histotripsy for Pediatric Cardiac Applications: In Vivo Neonatal Pig Model.

Author

Miller, Ryan M., Owens, Gabe, Ensing, Gregory, Ludomirsky, Achiau, Cain, Charles, and Xu, Zhen

Subjects
*HEART ventricles, *HEART septum, *HOLES, *TISSUES, *DIAGNOSTIC imaging
Abstract

This study investigated the in vivo feasibility of using histotripsy to non-invasively create a flow channel between the ventricles by generating a perforation of the ventricular septum, clinically referred to as a ventricular septum defect (VSD). The overall goal is to develop a non-invasive procedure to aid in the treatment of neonatal patients with complex congenital heart diseases such as Hypoplastic Left Heart Syndrome (HLHS). Histotripsy is a therapeutic ultrasound technique that produces mechanical fractionation of soft tissue through controlled cavitation. The study was conducted in a live and intact neonatal pig model. The ventricular septum in the neonatal pig heart was treated with histotripsy delivered by a spherically focused 1 MHz transducer positioned outside the chest wall. Histotripsy treatment was applied using 5-cycle ultrasound pulses at 1 kHz pulse repetition frequency with 12–18 MPa peak negative pressure. The treatment was guided and monitored with ultrasound imaging. In all nine subjects treated, a bubble cloud was generated on the ventricular septum using histotripsy, and visualized with ultrasound imaging. Within 20 seconds to 4 minutes following the initiation of a bubble cloud, a VSD was created in all nine pigs and confirmed by the detection of blood flow through the ventricular septum with color Doppler ultrasound. Gross morphology and histology on all hearts showed a demarcated perforation in the ventricular septum. This study shows that a VSD can be created in an intact neonatal animal using extracorporeal histotripsy under real-time ultrasound guidance. [ABSTRACT FROM AUTHOR]

Published
2010
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2. Cardiovascular cavitation

Author

Brujan, Emil-Alexandru

Subjects
*CAVITATION, *FLUID dynamics of heart valve prosthesis, *LASER surgery, *ULTRASONICS in surgery, *THERAPEUTIC embolization, *MEDICAL lasers, *EXTRACORPOREAL shock wave therapy, *CARDIOVASCULAR disease treatment
Abstract

Abstract: This article reviews the role of cavitation in the therapeutic applications of ultrasound and laser surgery, and the cavitation effects in mechanical heart valves. Whenever laser pulses are used to ablate or disrupt tissue in a liquid environment, cavitation bubbles are produced which interact with the tissue. The interaction between cavitation bubbles and tissue during pulsed laser surgery may cause collateral damage to sensitive tissue structures in the vicinity of the laser focus, and it may also contribute in several ways to ablation and cutting. Cavitation is also one of the most exploited bioeffects of ultrasound for therapeutic advantage. In both cases, the violent implosion of cavitation bubbles can lead to the generation of shock waves, high-velocity liquid jets, free radical species, and strong shear forces that can damage the nearby tissue. Knowledge of these physical mechanisms is therefore of vital importance and would provide a framework wherein novel and improved surgical techniques can be developed. [Copyright &y& Elsevier]

Published
2009
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3. Experimental evaluation of lesion prediction modelling in the presence of cavitation bubbles: intended for high-intensity focused ultrasound prostate treatment.

Author

Curiel, L., Chavrier, F., Gignoux, B., Pichardo, S., Chesnais, S., and Chapelon, J. Y.

Subjects
*MEDICAL imaging systems, *PRECANCEROUS conditions, *PROSTATE cancer, *TRANSDUCERS, *HEAT transfer, *CAVITATION, *PROSTATE tumors treatment, *ANIMAL experimentation, *BIOLOGICAL models, *COMPARATIVE studies, *LIVER, *RESEARCH methodology, *MEDICAL cooperation, *RESEARCH, *SOUND, *SWINE, *EVALUATION research, *ULTRASONIC therapy, *EQUIPMENT & supplies
Abstract

The accuracy of high-intensity focused ultrasound (HIFU) lesion prediction modelling was evaluated for a truncated spherical transducer designed for prostate cancer treatment. The modelling adapted the bio heat transfer equation (BHTE) to take into account the activity of cavitation bubbles generated during HIFU exposure. This modelling was used to predict the lesions produced by three different transducer geometries: fixed-focus, concentric-ring and 1.5D phased-array. Lesions were predicted for different ultrasound exposure conditions close to those used in prostate cancer treatment. Twenty-one in vitro and nine in vitro experiments were performed on pig liver to validate the accuracy of the predictions. A good match was found between the predicted and experimental lesion shapes. Lesion dimensions (maximum depth and length, area at the centre of the lesion or central surface area) were measured on experimental and predicted lesions. The central surface area was predicted by the model with a range of error of O. 15-6.5% for in vitro tests and 0.97-9% in vivo. For comparison, BHTE without bubbles had a range of error of 0.4-55.5% (in vitro) and 9-25.5% (in vivo). The model should be accurate enough to predict HIFU lesions under ultrasound exposure conditions used in prostate cancer treatment. [ABSTRACT FROM AUTHOR]

Published
2004
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4. Histotripsy: Non-invasive ultrasound surgery.

Author

Hall, Timothy L.

Subjects
Cavitation, Histotripsy, Non, Noninvasive Surgery, Phased Arrays, Ultrasound Surgery
Abstract

Histotripsy is a method of ultrasonic surgical intervention using tissue disrupting effects of cavitating microbubbles in an intense sound field. Targets for this form of therapy include removal of malignant and benign growths in many parts of the body. While thermal methods of ultrasound tissue ablation have been in development for more than 50 years, recent availability of reliable, extremely high power transducers has made histotripsy methods practical. The dissertation work presented here is in three chapters. Chapter 2 presents designs of transducers and electronic systems specific for histotripsy. Included are some of the most powerful therapeutic ultrasound systems in the world and the first 512 channel phased-array therapy system. Chapter 3 presents experiments to analyze in detail the histotripsy process and construct models for ablation. Proper control of cavitation using low duty cycles to avoid bulk tissue heating is shown to produce very precise tissue ablation with sharp treatment margins. Avoidance of heating is shown to be aided by using an electronic scanning phased-array transducer system. Chapter 4 presents work on various non-invasive imaging feedback methods to verify targeting, monitor histotripsy treatment, and to assess treatment outcome. Ultrasound imaging is demonstrated for in-vivo and ex-vivo ablation guidance permitting real-time monitoring of treatment. Ultrasound imaging and magnetic resonance imaging are demonstrated to produce useful contrast between disrupted and surrounding tissue allowing non-invasive assessment of treatment effects. Results suggest that with additional optimization of treatment methods, clinical trials for histotripsy surgery should be possible. Chapter 5 presents some initial clinical targets for histotripsy with along with specific considerations for each.

Published
2007

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