scholarly journals Estimating dynamic changes of tissue attenuation coefficient during high-intensity focused ultrasound treatment

2021 ◽  
Author(s):  
Siavash Rahimian ◽  
Jahan Tavakkoli
Keyword(s):  
Attenuation Coefficient ◽  
High Intensity ◽  
Exposure Duration ◽  
Focused Ultrasound ◽  
Thermal Damage ◽  
Ex Vivo ◽  
High Intensity Focused Ultrasound ◽  
Hifu Treatment ◽  
Dynamic Changes ◽  
Bubble Clouds

Background This study investigated the dynamic changes of tissue attenuation coefficients before, during, and after high-intensity focused ultrasound (HIFU) treatment at different total acoustic powers (TAP) in ex vivo porcine muscle tissue. It further assessed the reliability of employing changes in tissue attenuation coefficient parameters as potential indicators of tissue thermal damage. Methods Two-dimensional pulse-echo radio frequency (RF) data were acquired before, during, and after HIFU exposure to estimate changes in least squares attenuation coefficient slope (Δβ) and attenuation coefficient intercept (Δα0). Using the acquired RF data, Δβ and Δα0 images, along with conventional B-mode ultrasound images, were constructed. The dynamic changes of Δβ and Δα0, averaged in the region of interest, were correlated with B-mode images obtained during the HIFU treatment process. Results At a HIFU exposure duration of 40 s and various HIFU intensities (737–1,068 W/cm2), Δβ and Δα0 increased rapidly to values in the ranges 1.5–2.5 dB/(MHz.cm) and 4–5 dB/cm, respectively. This rapid increase was accompanied with the appearance of bubble clouds in the B-mode images. Bubble activities appeared as strong hyperechoic regions in the B-mode images and caused fluctuations in the estimated Δβ and Δα0 values. After the treatment, Δβ and Δα0 values gradually decreased, accompanied by fade-out of hyperechoic spots in the B-mode images. At 10 min after the treatment, they reached values in ranges 0.75–1 dB/(MHz.cm) and 1–1.5 dB/cm, respectively, and remained stable within those ranges. At a long HIFU exposure duration of around 10 min and low HIFU intensity (117 W/cm2), Δβ and Δα0 gradually increased to values of 2.2 dB/(MHz.cm) and 2.2 dB/cm, respectively. This increase was not accompanied with the appearance of bubble clouds in the B-mode images. After HIFU treatment, Δβ and Δα0 gradually decreased to values of 1.8 dB/(MHz.cm) and 1.5 dB/cm, respectively, and remained stable at those values. Conclusions Δβ and Δα0 estimations were both potentially reliable indicators of tissue thermal damage. In addition, Δβ and Δα0 images both had significantly higher contrast-to-speckle ratios compared to the conventional B-mode images and outperformed the B-mode images in detecting HIFU thermal lesions at all investigated TAPs and exposure durations.

scholarly journals Estimating dynamic changes of tissue attenuation coefficient during high-intensity focused ultrasound treatment

2021 ◽  
Author(s):  
Siavash Rahimian ◽  
Jahan Tavakkoli
Keyword(s):  
Attenuation Coefficient ◽  
High Intensity ◽  
Exposure Duration ◽  
Focused Ultrasound ◽  
Thermal Damage ◽  
Ex Vivo ◽  
High Intensity Focused Ultrasound ◽  
Hifu Treatment ◽  
Dynamic Changes ◽  
Bubble Clouds

Background This study investigated the dynamic changes of tissue attenuation coefficients before, during, and after high-intensity focused ultrasound (HIFU) treatment at different total acoustic powers (TAP) in ex vivo porcine muscle tissue. It further assessed the reliability of employing changes in tissue attenuation coefficient parameters as potential indicators of tissue thermal damage. Methods Two-dimensional pulse-echo radio frequency (RF) data were acquired before, during, and after HIFU exposure to estimate changes in least squares attenuation coefficient slope (Δβ) and attenuation coefficient intercept (Δα0). Using the acquired RF data, Δβ and Δα0 images, along with conventional B-mode ultrasound images, were constructed. The dynamic changes of Δβ and Δα0, averaged in the region of interest, were correlated with B-mode images obtained during the HIFU treatment process. Results At a HIFU exposure duration of 40 s and various HIFU intensities (737–1,068 W/cm2), Δβ and Δα0 increased rapidly to values in the ranges 1.5–2.5 dB/(MHz.cm) and 4–5 dB/cm, respectively. This rapid increase was accompanied with the appearance of bubble clouds in the B-mode images. Bubble activities appeared as strong hyperechoic regions in the B-mode images and caused fluctuations in the estimated Δβ and Δα0 values. After the treatment, Δβ and Δα0 values gradually decreased, accompanied by fade-out of hyperechoic spots in the B-mode images. At 10 min after the treatment, they reached values in ranges 0.75–1 dB/(MHz.cm) and 1–1.5 dB/cm, respectively, and remained stable within those ranges. At a long HIFU exposure duration of around 10 min and low HIFU intensity (117 W/cm2), Δβ and Δα0 gradually increased to values of 2.2 dB/(MHz.cm) and 2.2 dB/cm, respectively. This increase was not accompanied with the appearance of bubble clouds in the B-mode images. After HIFU treatment, Δβ and Δα0 gradually decreased to values of 1.8 dB/(MHz.cm) and 1.5 dB/cm, respectively, and remained stable at those values. Conclusions Δβ and Δα0 estimations were both potentially reliable indicators of tissue thermal damage. In addition, Δβ and Δα0 images both had significantly higher contrast-to-speckle ratios compared to the conventional B-mode images and outperformed the B-mode images in detecting HIFU thermal lesions at all investigated TAPs and exposure durations.

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.

scholarly journals Characterization and Ex Vivo evaluation of an extracorporeal high‐intensity focused ultrasound (HIFU) system

2021 ◽  
Author(s):  
Yufeng Zhou ◽  
Bryan W. Cunitz ◽  
Barbrina Dunmire ◽  
Yak‐Nam Wang ◽  
Steven G. Karl ◽  
...  
Keyword(s):  
High Intensity ◽  
Focused Ultrasound ◽  
Ex Vivo ◽  
High Intensity Focused Ultrasound

scholarly journals The feasibility of a noise elimination method using continuous wave response of therapeutic ultrasound signals for ultrasonic monitoring of high-intensity focused ultrasound treatment

2021 ◽  
Author(s):  
Ryo Takagi ◽  
Toshikatsu Washio ◽  
Yoshihiko Koseki
Keyword(s):  
Noise Reduction ◽  
High Intensity ◽  
Focused Ultrasound ◽  
Continuous Wave ◽  
High Intensity Focused Ultrasound ◽  
Hifu Treatment ◽  
Noise Elimination ◽  
Tissue Samples ◽  
Wave Response ◽  
Failure Conditions

Abstract Purpose In this study, the robustness and feasibility of a noise elimination method using continuous wave response of therapeutic ultrasound signals were investigated when tissue samples were moved to simulate the respiration-induced movements of the different organs during actual high-intensity focused ultrasound (HIFU) treatment. In addition to that, the failure conditions of the proposed algorithm were also investigated. Methods The proposed method was applied to cases where tissue samples were moved along both the lateral and axial directions of the HIFU transducer to simulate respiration-induced motions during HIFU treatment, and the noise reduction level was investigated. In this experiment, the speed of movement was increased from 10 to 40 mm/s to simulate the actual movement of the tissue during HIFU exposure, with the intensity and driving frequency of HIFU set to 1.0–5.0 kW/cm2 and 1.67 MHz, respectively. To investigate the failure conditions of the proposed algorithm, the proposed method was applied with the HIFU focus located at the boundary between the phantom and water to easily cause cavitation bubbles. The intensity of HIFU was set to 10 kW/cm2. Results Almost all HIFU noise was constantly able to be eliminated using the proposed method when the phantom was moved along the lateral and axial directions during HIFU exposure. The noise reduction level (PRL in this study) at an intensity of 1.0, 3.0, and 5.0 kW/cm2 was in the range of 28–32, 38–40, and 42–45 dB, respectively. On the other hand, HIFU noise was not basically eliminated during HIFU exposure after applying the proposed method in the case of cavitation generation at the HIFU focus. Conclusions The proposed method can be applicable even if homogeneous tissues or organs move axially or laterally to the direction of HIFU exposure because of breathing. A condition under which the proposed algorithm failed was when instantaneous tissue changes such as cavitation bubble generation occurred in the tissue, at which time the reflected continuous wave response became less steady.

scholarly journals High-Intensity Focused Ultrasound Treatment for Advanced Pancreatic Cancer

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Yufeng Zhou
Keyword(s):  
Pancreatic Cancer ◽  
High Intensity ◽  
Focused Ultrasound ◽  
Advanced Pancreatic Cancer ◽  
High Intensity Focused Ultrasound ◽  
Treatment Modalities ◽  
Karnofsky Performance Scale ◽  
Great Success ◽  
Hifu Treatment ◽  
Performance Scale

Pancreatic cancer is under high mortality but has few effective treatment modalities. High-intensity focused ultrasound (HIFU) is becoming an emerging approach of noninvasively ablating solid tumor in clinics. A variety of solid tumors have been tried on thousands of patients in the last fifteen years with great success. The principle, mechanism, and clinical outcome of HIFU were introduced first. All 3022 clinical cases of HIFU treatment for the advanced pancreatic cancer alone or in combination with chemotherapy or radiotherapy in 241 published papers were reviewed and summarized for its efficacy, pain relief, clinical benefit rate, survival, Karnofsky performance scale (KPS) score, changes in tumor size, occurrence of echogenicity, serum level, diagnostic assessment of outcome, and associated complications. Immune response induced by HIFU ablation may become an effective way of cancer treatment. Comments for a better outcome and current challenges of HIFU technology are also covered.

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