Approximate Analytical Solution for Tissue Temperature Distribution in High-Intensity Focused Ultrasound

2009 ◽  
Author(s):  
Dehui Li ◽  
Guofeng Shen ◽  
Jingfeng Bai ◽  
Yazhu Chen
Keyword(s):  
Temperature Distribution ◽  
Analytical Solution ◽  
High Intensity ◽  
Focused Ultrasound ◽  
Approximate Analytical Solution ◽  
High Intensity Focused Ultrasound ◽  
Tissue Temperature

Nonlinear Derating of High-Intensity Therapeutic Ultrasound Beams Using Gaussian Modal Sums

2013 ◽  
Author(s):  
Seyed Ahmad Reza Dibaji ◽  
Matthew R. Myers ◽  
Joshua E. Soneson ◽  
Rupak K. Banerjee
Keyword(s):  
High Intensity ◽  
Focused Ultrasound ◽  
High Intensity Focused Ultrasound ◽  
Nonlinear Propagation ◽  
Tissue Temperature ◽  
Medical Procedure ◽  
Pressure Amplitude ◽  
Pressure Trace ◽  
The Difference ◽  
Semi Empirical

High intensity focused ultrasound (HIFU) is a noninvasive medical procedure during which a large amount of energy is deposited in a short duration which causes sudden localized rise in tissue temperature, and ultimately, cell necrosis. In assessing the influence of HIFU on biological tissue, semi-empirical mathematical models can be useful for predicting thermal effects. These models require values of the pressure amplitude in the tissue of interest, which can be difficult to obtain experimentally. One common method for estimating the pressure amplitude in tissue is to operate the HIFU transducer in water, measure the pressure amplitude, then multiply by a scaling factor that accounts for the difference in attenuation between water and tissue. This procedure can be accurate when the ultrasound amplitude is low, and the pressure trace in tissue is proportional to that in water. Because of this proportionality, the procedure for reducing the amplitude from water to tissue is called linear derating. At higher intensities, however, harmonics of the fundamental frequency are generated due to nonlinear propagation effects. Higher harmonics are attenuated differently in water and tissue (Hamilton and Blackstock [1]), and the pressure waves in water and tissue are no longer proportional to one another. Techniques for nonlinearly transforming pressure amplitudes measured in water to values appropriate for tissue are therefore desirable when bioeffects of higher intensity procedures are being studied. These techniques are labeled “nonlinear derating”.

scholarly journals MR-Guided High Intensity Focused Ultrasound -- Temperature Measurement

2018 ◽  
Author(s):  
Dennis L Parker ◽  
Nick Todd ◽  
Yi Wang ◽  
Josh Coon
Keyword(s):  
Thermal Properties ◽  
Kalman Filter ◽  
Temperature Distribution ◽  
Simultaneous Measurement ◽  
High Intensity ◽  
Focused Ultrasound ◽  
High Intensity Focused Ultrasound ◽  
Current Estimate ◽  
Thermal Therapies ◽  
Predictive Filtering

Accurate, near-real-time temperature measurements are essential for effective monitoring of all types of thermal therapies. Current methods are too slow, subject to substantial errors from motion and fail in fat. We propose: 1) To develop a modification of the PRF technique to allow simultaneous measurement of proton longitudinal relaxation rate, T1. 2) To continue the implementation of model-based linear predictive techniques to utilize the best estimate of tissue thermal properties and linear predictive filtering (e.g., Kalman filter) to obtain the current estimate of the temperature distribution from the prior temperature distribution. Tissue thermal properties will be estimated based upon segmentation from multiple MRI contrasts.

DYNAMIC CHANGES IN THE ACOUSTO-MECHANICAL AND STATISTICAL PARAMETERS OF TISSUE DURING HIGH INTENSITY FOCUSED ULTRASOUND (HIFU) TREATMENT

2014 ◽  
Vol 26 (01) ◽  
pp. 1450009 ◽  
Author(s):  
Parisa Rangraz ◽  
Hamid Behnam ◽  
Pooya Sobhe Bidari ◽  
Naser Shakhssalim ◽  
Jahan Tavakkoli
Keyword(s):  
Ultrasound Imaging ◽  
High Intensity ◽  
Thermal Ablation ◽  
Focused Ultrasound ◽  
High Intensity Focused Ultrasound ◽  
Tissue Temperature ◽  
Hifu Treatment ◽  
Statistical Parameters ◽  
Dynamic Changes ◽  
Thermal Lesions

High intensity focused ultrasound (HIFU) induces focalized tissue coagulation by increasing the tissue temperature in a tight focal region and has been successfully used as a new technique of tumor treatment or to stop bleeding in clinical applications. The main challenges of this technique are: adjusting the location of HIFU thermal ablation exactly at the region of interest, and controlling the level of thermal ablation. Several imaging methods have been proposed to monitor HIFU-induced thermal lesions such as X-ray, MRI and ultrasound imaging. Currently, ultrasound imaging techniques that are clinically used for monitoring HIFU treatment are standard pulse-echo B-mode ultrasound imaging, ultrasound temperature estimation, and elastography-based methods. This study was carried on ex vivo animal tissue samples. Backscattered radio frequency (RF) signals were acquired in real-time including before, during and after HIFU treatment. In this study, first we estimate the dynamic changes in the acoustical, mechanical and statistical parameters of the tissue resulted from HIFU exposures with three different acoustic powers. Then, we use these parameters to detect the induced HIFU thermal lesions and monitor the treatment process. By estimating the standard deviation of the studied parameters along acquired RF data frames, we show that there are significant changes in the tissue properties during the HIFU treatment.

Temperature Dependent Tissue Properties and Ultrasonic Lesion Formation

1999 ◽  
Author(s):  
Michael C. Kolios ◽  
Michael D. Sherar ◽  
John W. Hunt
Keyword(s):  
Theoretical Model ◽  
High Intensity ◽  
Focused Ultrasound ◽  
High Intensity Focused Ultrasound ◽  
Bioheat Transfer ◽  
Tissue Temperature ◽  
Focal Region ◽  
Temperature Dependent ◽  
Size And Shape ◽  
Temperature Distributions

Abstract High intensity focused ultrasound has considerable potential for the noninvasive treatment of localised disease. A detailed understanding of the kinetics of tissue coagulation is required to optimise ultrasonic parameters. In this presentation a theoretical model was used to examine the effects of temperature dependent ultrasonic attenuation and absorption on the transient tissue temperature distributions and lesion dimensions. A finite difference algorithm was used to solve numerically the nonlinear form of the bioheat transfer equation in cylindrical coordinates. The lesion dimensions were calculated based on the time-temperature distributions in tissue by using a thermal dose threshold to define the lesion boundaries. The results were compared to published experimental data in which the the location of maximal energy deposition during short duration high intensity focused ultrasound irradiation of in vitro tissue was examined. It was found that the theoretical model did not predict the size and shape of the experimental lesions. To correctly predict lesion size and shape much higher values of attenuation and absorption were required than can be accounted for by thermal coagulation of the tissue alone. The values used suggest that for intensities greater than 3030 W/cm2 the effective local attenuation/absorption in the focal region increased by a factor of 10–20. It is finally shown that temperature dependent tissue changes should be incorporated in thermal models to avoid underestimation of the induced temperature distributions during high intensity focused ultrasound therapy.

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