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ABSTRACT: This article presents a diagnostic ultrasound imaging technique that can be used in imaging protruding objects such as a human breast using two opposing array transducers. Because two B-mode images obtained from each of the two linear array transducers facing each other represent the same imaging area viewed in different directions, the image quality can be improved using a compounding technique. Using one array as a transmitter and the other as a receiver, the speed of sound distribution in a medium interposed between them is also reconstructed. In addition, because the spacing between the two arrays can be finely controlled, strain image can also be obtained. This new method can be used to produce a compound B-mode image, a speed of sound image, and a strain image of the same region-of-interest, making it possible to obtain more information leading to better diagnosis. Experimental results on a phantom containing a cylinder of different speed of sound and elasticity confirm that the proposed method is useful in obtaining compound and speed of sound images as well as strain images.
Ultrasound in medicine & biology 04/2010; 36(4):637-46. · 2.02 Impact Factor
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ABSTRACT: This paper presents a diagnostic ultrasound imaging technique that can be used in imaging protruding objects such as a human breast using two opposing array transducers. Images are obtained in both transmission and reflection modes using two opposing linear transducer arrays. In reflection mode, images are obtained from each of both transducer arrays, and are compounded to produce a B-mode image. Also, in transmission mode, speed of sound images are reconstructed. Experimental results with a phantom containing a cylinder of different speed of sound confirm that the proposed method is useful in obtaining compound as well as speed of sound images.
Ultrasonics Symposium, 2008. IUS 2008. IEEE; 12/2008
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ABSTRACT: A method to greatly simplify the high-frame-rate (HFR) imaging system using a rotation of coordinates in image reconstruction was developed. A theory of Fourier image reconstruction was also developed and both in vitro (on an ATS539 tissue-mimicking phantom) and in vivo (on a human heart) experiments were performed to verify the theory.
Ultrasonics Symposium, 2007. IEEE; 11/2007
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ABSTRACT: This paper proposes a method of imaging the stiffness of soft tissue to help diagnose cancers or tumors which have been difficult to detect with ultrasound B-mode imaging modality. To measure the soft tissue stiffness, sinusoidal vibrations are applied to it, and the magnitude of its mechanical vibration is determined by estimating the temporal variation of speckle pattern brightness in ultrasound B-mode images. It is verified by simulation and experiment that the proposed method can estimate the relative tissue stiffness from B-mode images with a modest amount of computation.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
05/2003;
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ABSTRACT: Applying vibration to a medium makes it vibrate. The resulting change in scatterer distribution inside the medium due to applied vibration changes the speckle pattern of ultrasound images. In this case, scatterers in a hard medium experience small displacements, and those in a soft medium experience large displacements. As a result, the amount of speckle pattern brightness change in ultrasound images is related to the tissue stiffness. Using this dependency, a two-dimensional profile of relative tissue stiffness can be constructed qualitatively at the display pixel resolution by determining at each pixel the standard deviation and/or the difference between minimum and maximum values over a certain number of consecutive B-mode images. Experiments with phantoms show that the softer the tissue, the larger the standard deviation. The proposed imaging modality is a simple yet practical method of resolving hard cysts surrounded by soft background in a phantom using B-mode frame data only.
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control 05/2003; 50(4):457-60. · 1.69 Impact Factor
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ABSTRACT: Orthogonal Golay codes feature perfect sidelobe cancellation properties, and are simple to implement because they have elements of +1 and -1 only. However, the frame rate is reduced by one half due to the requirement of two consecutive transmissions per scanline. This paper presents an ultrasonic B-mode imaging method using orthogonal complementary Golay codes without reducing the frame rate while achieving good SNR. In the method, the member codes applied to transducer elements are alternated from one transmission to another, with the focal points switched as well. The sidelobe and grating lobe levels from combining four consecutive transmit events are found to be as much as about 10 dB less than those from combining two transmit events.
Ultrasonics Symposium, 2002. Proceedings. 2002 IEEE; 11/2002
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ABSTRACT: The experimental results of two types of sidelobe reduction
filters are presented. These filters, named sidelobe filter and null
filter, improve the resolution by scaling the received signal according
to the ratio of the mainlobe and the sidelobe levels. In the sidelobe
filter, sidelobe echoes can be obtained in the sidelobe direction of
transmit beam by applying beam steering in receive focusing. Also some
echoes can be obtained in null directions of the transmit field
response, and this information, which can be obtained by taking Fourier
transform, can also be used for purposes of sidelobe reduction. We can
control each filter response by adjusting the filter order and scale
factor. Computer simulation results show that the two types of filters
can achieve more than 10 dB of the sidelobe level reduction, as well as
the mainlobe width narrowing, which helps overcome the diffraction
limited resolution of conventional focusing schemes. Experiments are
also performed using a prototype system based on a modified commercial
diagnostic ultrasound scanner (SA8800, Medison Co.). Experimental
results with phantom and in-vivo data demonstrate that the proposed
scheme is highly effective in enhancing the image resolution and
contrast
Ultrasonics Symposium, 2000 IEEE; 11/2000
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ABSTRACT: This paper presents a method of determining three intrinsic
mechanical parameters of an unknown object in the framework of
ultrasound inverse scattering tomography. Those parameters are the speed
of sound, density, and absorption whose values are given as the solution
of an inhomogeneous Helmholtz wave equation. Computer simulations are
carried out using the sinc basis moment method and Newton-Raphson method
in an measurement configuration where the object is insonified by an
incident plane wave over 360° and the scattered field is collected
by detectors arranged in a rectangular fashion around it. Two distinct
frequencies are used to separate each parameter of three Gaussian
objects that are either overlapped at the same location or separately
positioned from each other. The density turns out to be rather difficult
to reconstruct as compared with the other two parameters
Ultrasonics Symposium, 1998. Proceedings., 1998 IEEE; 02/1998
