Conventional Ultrasound Systems Research Articles

Apparatus and method for locating an interventional medical device with an ultrasonic color imaging system

A VIBER vibrating mechanism is coupled to a cannula or needle and operates to provide flexural vibrations to move the needle and to enable detection of the position of a needle within a body of interest by a color ultrasound imaging system. The VIBER mechanism exhibits multiple modes of oscillation when energized. The VIBER mechanism is excited to exhibit predetermined oscillations at a given frequency in the X plane, a predetermined oscillation at another frequency in the Y plane and still another frequency of oscillation in the Z plane. In this manner, the VIBER mechanism device exhibits motion in all three planes, which motion is detectable by a conventional color ultrasound imaging system. The frequency of oscillation is a function of the entire system, namely the VIBER mechanism, the needle or cannula which is attached to the VIBER mechanism and the tissue. The resonant frequency is preferred as it provides larger vibrational amplitudes. In this manner, a resonant frequency is controlled by means of a feedback control loop, whereby the frequency applied to the VIBER mechanism is monitored to determine resonance and is held at the resonant frequency as the VIBER mechanism or needle is moved. The vibration in the representative planes causes a typical conventional color ultrasound imaging system to display the vibration or movement by means of a color variation. By viewing the display, a system operator, such as a physician can visualize the location of the needle because of the color indication provided by the display.

Development of the bi-directional ultrasound system for base of tongue imaging

The use of conventional ultrasound systems to image the upper airway has been limited because ultrasound energy is attenuated by the air column. In an attempt to study upper airway geometry, we developed a computer controlled bi-directional ultrasound system which combines two conventional ultrasound devices with computer image processing to yield images of upper airway structures. Human studies and cadaver studies were performed to evaluate the system. Images acquired by the bi-directional ultrasound system were comparable to images from 3D volume rendered CT scans. This system may provide valuable data in the study of upper airway physiology and pathology.

On-line assessment of ventricular function by automatic boundary detection and ultrasonic backscatter imaging

To provide an approach suitable for on-line analysis of ventricular function, a conventional two-dimensional ultrasound imaging system was modified to detect and track blood-tissue interfaces in real time based on their quantitative acoustic properties. This modification permitted on-line display of the left ventricular cavity area, fractional area change, volumes and ejection fraction on a beat by beat basis.Images were obtained from 54 patients and 12 normal subjects with broad ranges of ventricular dimensions and systolic function. On-line measurements of cavity areas were compared with off-line measurements of cavity areas (analysis of videotaped conventional images). Left ventricular cavity areas measured on-line from short-axis views correlated closely with off-line views as did areas from apical views. On-line fractional area change correlated well with ejection fraction calculated off-line.More than 70% of patients could be studied adequately with the approach developed. Thus, automatic boundary detection based on quantitative assessment of tissue acoustic properties permits on-line quantitation of ventricular cavity areas and indexes of function.

Method and apparatus for stone localization using ultrasound imaging

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Theory of ultrasound Doppler-spectra velocimetry for arbitrary beam and flow configurations

In conventional ultrasound Doppler systems, the velocity component along the beam axis is derived from the observed frequency shift. Recently, it was verified that by using a pulsed-Doppler system with the beam transversely oriented with respect to the flow, the velocity component transverse to the beam can be derived from the edges of the spectrum. These results are generalized to take into account arbitrary angles of incidence, effects of velocity gradients, arbitrary apertures, and arbitrary source pulses. For uniform apertures and transverse flow, it has been previously shown that the Doppler output spectrum is symmetrical about zero frequency, with its width depending on the Doppler effect due to the transverse velocity and the geometry of the problem. For a beam direction oblique to the velocity, it is shown that the spectrum is now shifted, and is centered about the classical Doppler frequency. For velocity gradients and transverse flows the spectrum remains symmetrical, with the edges corresponding to the maximal velocity; however, the profile becomes peaked at the center. For oblique incidence, an asymmetrical spectrum is obtained and its edges are related to the maximal and minimal velocities within the sampling volume. >