國家衛生研究院 NHRI:Item 3990099045/8073

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Title:	Temperature elevation by HIFU in ex vivo porcine muscle: MRI measurement and simulation study
Authors:	Solovchuk, MA;Hwang, SC;Chang, H;Thiriet, M;Sheu, TW
Contributors:	Division of Medical Engineering Research
Abstract:	PURPOSE: High-intensity focused ultrasound is a rapidly developing medical technology with a large number of potential clinical applications. Computational model can play a pivotal role in the planning and optimization of the treatment based on the patient's image. Nonlinear propagation effects can significantly affect the temperature elevation and should be taken into account. In order to investigate the importance of nonlinear propagation effects, nonlinear Westervelt equation was solved. Weak nonlinear propagation effects were studied. The purpose of this study was to investigate the correlation between the predicted and measured temperature elevations and lesion in a porcine muscle. METHODS: The investigated single-element transducer has a focal length of 12 cm, an aperture of 8 cm, and frequency of 1.08 MHz. Porcine muscle was heated for 30 s by focused ultrasound transducer with an acoustic power in the range of 24-56 W. The theoretical model consists of nonlinear Westervelt equation with relaxation effects being taken into account and Pennes bioheat equation. RESULTS: Excellent agreement between the measured and simulated temperature rises was found. For peak temperatures above 85-90 degrees C "preboiling" or cavitation activity appears and lesion distortion starts, causing small discrepancy between the measured and simulated temperature rises. From the measurements and simulations, it was shown that distortion of the lesion was caused by the "preboiling" activity. CONCLUSIONS: The present study demonstrated that for peak temperatures below 85-90 degrees C numerical simulation results are in excellent agreement with the experimental data in three dimensions. Both temperature rise and lesion size can be well predicted. Due to nonlinear effect the temperature in the focal region can be increased compared with the linear case. The current magnetic resonance imaging (MRI) resolution is not sufficient. Due to the inevitable averaging the measured temperature can be 10-30 degrees C lower than the peak temperature. Computational fluid dynamics can provide additional important information that is lost using a state of the art MRI device.
Date:	2014-05
Relation:	Medical Physics. 2014 May;41(5):Article number 052903.
Link to:	http://dx.doi.org/10.1118/1.4870965
JIF/Ranking 2023:	http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=NHRI&SrcApp=NHRI_IR&KeyISSN=0094-2405&DestApp=IC2JCR
Cited Times(WOS):	https://www.webofscience.com/wos/woscc/full-record/WOS:000336053100040
Cited Times(Scopus):	http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=84904865535
Appears in Collections:	[Hsu Chang(2004-2017)] Periodical Articles

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