Real-time 3D image-guided HIFU therapy.
ABSTRACT Real-time three-dimensional ultrasound imaging (4D US) was utilized to monitor the treatment site during high-intensity focused ultrasound (HIFU) treatment. To obtain real-time monitoring during HIFU sonication, a 4D US imaging system and HIFU were synchronized and interference on the US image adjusted so that the region of interest was visible during treatment. The system was tested using tissue mimicking phantom gels and chicken breast tissue. The 4D US showed hyperechoic spots at the focal region of the HIFU transducer which then slowly faded after HIFU treatment. The hyperechoic regions were used as an indication of coagulative necrosis which occurs at temperatures higher than 60 degrees C. Different intensities of HIFU were applied to observe the difference in lesion formation and to determine the threshold intensity that produced hyperechoic regions due to the thermal and mechanical effects of focused ultrasound waves. The position, orientation, and shape of various lesions were examined in the three dimensional ultrasound images, and the volume of the lesions was measured. These volumes were compared to the volume measurements obtained from dissection of the tissue and phantom gels.
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ABSTRACT: The problem studied in this paper is ultrasound image reconstruction from frequency-domain measurements of the scattered field from an object with contrast in attenuation and sound speed. The case where the object has uniform but unknown contrast in these properties relative to the background is considered. Background clutter is taken into account in a physically realistic manner by considering an exact scattering model for randomly located small scatterers that vary in sound speed. The resulting statistical characteristics of the interference is incorporated into the imaging solution, which includes applying a total-variation minimization based approach where the relative effect of perturbation in sound speed to attenuation is included as a parameter. Convex optimization methods provide the basis for the reconstruction algorithm. Numerical data for inversion examples are generated by solving the discretized Lippman-Schwinger equation for the object and speckle-forming scatterers in the background. A statistical model based on the Born approximation is used for reconstruction of the object profile. Results are presented for a two dimensional problem in terms of classification performance and compared to minimum-l2-norm reconstruction. Classification using the proposed method is shown to be robust down to a signal-to-clutter ratio of less than 1 dB.03/2011;
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ABSTRACT: The aim of this work is to understand how the variations in grayscale values of B-mode ultrasound (US) images can be used as an approach for non-invasive temperature estimation. In order to obtain real-time monitoring of HIFU treatment, an US imaging system and HIFU were synchronized. Images were acquired using an electronic convex imaging probe. An 8% BSA tissue-mimicking polyacrylamide gel was used for the experiments. First, the HIFU power was set to 10 W. The application of HIFU resulted in the appearance of hyperechoic regions that were used to place a thermocouple tip at the focal spot by means of US imaging. Afterwards, the power was gradually increased up to 40 W for 4 min. The temperature sampling rate was set to 5 Hz. For each temperature sample the synchronization system captured one frame. The region of interest (ROI) was manually selected and a set of morphological operations were implemented in order to obtain the shape and size of the thermal lesion. From here, the average grayscale (AGS) and area of the thermal lesion were calculated to assess temperature quantification. The AGS parameter showed a maximum correlation coefficient of 0.6626 as a function of temperature whereas the thermal lesion appeared. In contrast, area values showed a greater correlation coefficient of 0.9122. In conclusion, temperature shows a non-linear behavior with respect to the parameters estimated due to the nature of the thermal lesion formation by HIFU exposure.Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2010; 2010:5983-6.
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ABSTRACT: Image-guided high-intensity focused ultrasound (HIFU) has been used for more than ten years, primarily in the treatment of liver and prostate cancers. HIFU has the advantages of precise cancer ablation and excellent protection of healthy tissue. Breast cancer is one of the most common cancers in women. HIFU, in combination with other therapies, has the potential to improve both oncological and cosmetic outcomes for breast cancer patients by providing a curative therapy that conserves mammary shape. Unfortunately, HIFU therapy is not frequently used in breast cancer treatment currently, and efforts to increase HIFU treatment availability must be made. In this article, we compare different image-guided models for HIFU and review the status, drawbacks and potential of HIFU therapy for breast cancer treatment.Chinese journal of cancer 12/2012;