Shinichiro Ueno

Ultrasound pulse reflection mode measurement of nonlinearity parameter B/A and attenuation coefficient

A new method for obtaining depth distribution of the nonlinearity parameter B/A and the frequency‐dependent attenuation coefficient is outlined. In this method, the higher frequency probe pulse wave, superposed coaxially on the lower frequency pump pulse wave, is modulated nonlinearly due to their propagation, and is received as an echo signal. The relationship between these acoustic parameters and the modulation characteristics of the probe pulse wave is derived by the division of the spectra of modulated echo signals with each other. The possibility of canceling out of error factors, such as the frequency‐dependent acoustic reflection coefficient of random scattering medium, in the above division process is discussed. A preliminary evaluation of this method is made by using an experimental system. B/A values are obtained for various kinds of sponge test targets immersed in water, n‐propyl alcohol, isopropyl alcohol, ethylene glycol, or diethylene glycol; and for agar graphite phantom.

Ultrasonic tomographic with alternate image scaling

An ultrasonic tomographic diagnosis apparatus suitable for skin disease displays a first ultrasonic tomographic image (12) of an object of a fairly broad area, wherein sizes in depthwise direction (X in FIG. 1) displayed in an enlarged scale in relation to sizes in a direction (Y in FIG. 1) on the skin surface, and further a second ultrasonic tomographic image (13) of an object wherein sizes in depthwise direction and sizes in the direction on the skin surface are displayed in substantially proportional to actual size relations, for a selected part marked by a marker (14) on the first tomographic image (12). While specific embodiments of the invention have been illustrated and described herein, it is realized that modifications and changes will occur to those skilled in the art. It is therefore to be understood that the appended claims are intended to cover all modifications and changes as fall within the true spirit and scope of the invention.

Application of Nonlinear Ultrasonic Pulse Reflection Method –Measurement of Acoustic Parameters–

The method for measuring the distribution of the attenuation coefficient and the nonlinearity characteristic, using the nonlinear effect in superposed probe and pump pulse waves, is described. The relationship between these acoustic parameters, the measured crossing frequency (ωx) and the slope of the depth dependence of ωx is also described. The experimental result of using a pig liver as a lossy medium is reported.

Application of Nonlinear Effect to Ultrasonic Pulse Reflection Method –Modulation Characteristics of Received Pulse–

An application of nonlinear effect to ultrasonic pulse reflection method is described. With this method, higher frequency probe pulse wave and lower frequency large pressure amplitude pump pulse wave are transmitted along the axis of a coaxially arranged probe transducer and a pump transducer, and are superposed in the propagation medium by precisely controlling the relative phase of these pulses. Frequency characteristics of a nonlinearly modulated probe pulse wave are analyzed, and center frequency shift and change in group delay are obtained. These experimental values are evaluated by a simple analytical method.

A Simulation Model for B-Mode Imaging

Ultrasonic B-mode images, as the output of diagnostic ultrasonic imaging systems, are the results caused by acoustic properties inside the human body and a number of acoustic or electrical processings by equipment. In order to estimate a B-mode image and extract useful information for diagnosis, research in the new methods is necessary so that B-mode images can be analyzed quantitatively. For the first step in the development of such new techniques, a simulation model for B-mode imaging was developed. This paper describes the structure of the simulation model studied, and presents some calculated B-mode images.

Application of Nonlinear Effect to the Ultrasonic Pulse Reflection Method –Influence of a Probe Pulse with Finite Applitude and Duration–

The modulation characteristics of a high frequency probe pulse, superposed on a large amplitude low frequency pump pulse, are analyzed in a medium modeled with a frequency dependent attenuation coefficient. The influence of a probe pulse with finite amplitude and duration on these modulation characteristics is simulated by numerical computation. An algorithm estimating the local distribution of acoustic parameters in a random scattering medium is derived.