Abstract: A method for ultrasonic harmonic imaging is disclosed, which uses microbubbles particularly selected for their properties of reradiating ultrasound energy at frequencies other than the exciting frequency.

Abstract: An ultrasonic imaging system generates a corrected Doppler energy signal as a function of both Doppler energy and Doppler velocity to correct for loss of sensitivity associated with the gradual roll off response characteristic of many clutter filters. Additionally, the corrected Doppler energy signal is generated as a function of Doppler variance to prevent enhancement of noisy samples.

Abstract: According to one embodiment, an apparatus for measuring rotational velocity includes a support member, a transducer, and a Doppler shift measurement module. The transducer, which is supported by the support member, emits a first wave and detects a corresponding second wave reflected by matter intercepted thereby as the support member rotates continuously about an axis of rotation. The Doppler shift measurement module measures frequency shifting between the first wave and the second wave as the support member rotates about the axis of rotation, the frequency shifting being indicative of a rotational velocity of the support member relative to the matter.

Abstract: Optical Doppler tomography permits imaging of fluid flow velocity in highly scattering media. The tomography system combines Doppler velocimetry with high spatial resolution of partially coherent optical interferometry to measure fluid flow velocity at discrete spatial locations. Noninvasive in vivo imaging of blood flow dynamics and tissue structures with high spatial resolutions of the order of 2 to 10 microns is achieved in biological systems. The backscattered interference signals derived from the interferometer may be analyzed either through power spectrum determination to obtain the position and velocity of each particle in the fluid flow sample at each pixel, or the interference spectral density may be analyzed at each frequency in the spectrum to obtain the positions and velocities of the particles in a cross-section to which the interference spectral density corresponds.

Abstract: A pulsed Doppler technique uses coded excitation on transmit and pulse compression on receive. Coded excitation allows a long transmit pulse to be compressed on receive such that most energy is concentrated in a short interval. In the case of a single coded transmit for each transmit focal position, the receive signals are compressed utilizing matched or mismatched filtering. In the case of a two or more coded transmits for each transmit focal position, the receive signals are compressed utilizing filtering coefficients which match the respective transmit codes during each firing. These techniques can be used to maximize Doppler sensitivity of a small but deep-lying sample volume. Alternatively, for a given transmit acoustic burst length and dosage, the sample volume can be reduced to achieve better spatial resolution without compromising sensitivity.

Abstract: The Doppler imaging of blood flow or slowly moving tissue at high frame rates of display is performed by oversampled acquisition of a Doppler ensemble from the body and display of Doppler information within a display range of Doppler values which is less than the range defined by said rate of oversampling. Preferably, Doppler information is acquired at the highest PRF for the depth of Doppler imaging. In one embodiment Doppler data is scaled in proportion to the ratio of the acquisition PRF to the display PRF. Alternatively, an embodiment of the present invention performs Doppler estimation by autocorrelation or spectral analysis which operates upon nonadjacent samples in the Doppler ensemble.

Abstract: A method and apparatus for generating three-dimensional (3D) images of flow structures and their flow lumen using ultrasound techniques. According to one aspect of the invention, a border between a flow region and a non-flow region is used to render a three-dimensional image of the flow lumen of the flow structure. The images may be viewed in real-time and/or stored on a machine-readable medium. In one embodiment, the three-dimensional images may be manipulated in a number of viewing directions/angles/distances/positions/styles. In one embodiment, a flow lumen may be displayed using a virtual angioscopic view.

Abstract: Continued bleeding into a pocket or hematoma in the cranium could exert pressure on the brain which would move it relative to the cranium to force the brain stem into the medulla oblongata to arrest breathing. Such brain micromovement is detected by projecting bursts of ultrasound into one or both of the temple areas of the cranium or into the medulla oblongata, and the readout of echoes received from different depths is displayed on a screen. The readout of the echoes indicates continued microshifts of the brain relative to the cranium. To differentiate microshifts of the brain relative to the cranium caused by continued intracranial bleeding as distinguished from pulsations of the brain relative to the cranium caused by supply of blood to the brain from the heart and return of blood from the brain to the heart, the timing of the bursts of ultrasound into the cranium is synchronized with the pulse indicated by a heart pulse monitor.

Abstract: The energy, power or amplitude of Doppler or time shift information signals is compared to a threshold in order to select a large or small weighting factor for temporal persistence. In the event of a "flash" signal or strong arterial flow signal, a small weighting factor is chosen to reduce the extent of temporal persistence via feedback of the averaged value for the prior frames so that the effect of the "flash" or strong flow signal would quickly dissipate in the imaging of subsequent frames and good temporal resolution preserved for the current frames, while low energy flow signals would cause a large weighting factor to be selected to improve the signal-to-noise ratio of low energy signals. Similar effects can be achieved by clipping the signals to not exceed a certain threshold.

Abstract: A method for measuring Doppler ultrasound information transmits a transmit beam having a frequency dependent focus in which low-frequency components of the transmit beam are focused at long ranges and progressively higher frequency components of the transmit beam are focused at progressively shorter ranges. Beamformed receive signals are generated in response to receive signals from the transducers, and these beamformed receive signals are applied to Doppler processors. The frequency dependent focus of the transmit beam provides a transmit beam that is more uniform in width and intensity, and the Doppler processors thereby provide an improved Doppler image signal.

Abstract: The method of the invention employs pulsed Doppler ultrasound signals to color image blood and tissue movement velocities in a body. The method initially images a movement with a transmitted ultrasound signal that manifests a current signal transmission frequency value and a current pulse repetition frequency (PRF) value. Those values exhibit a determined ratio R to each other. Thereafter, in response to an indication by the user that movement is to be imaged at a new depth, the method alters the current transmission frequency to a new frequency to provide improved signal back-scatter from movement at the new depth. Then, the current PRF is adjusted, automatically, to a new PRF value which, when compared to the new transmission frequency, manifests substantially the same determined ratio R that was present between the current transmission frequency and current PRF. The latter step assures that the mapping of movement velocity values to colors is maintained, notwithstanding use of a new transmission frequency.

Abstract: A wireless patient monitoring apparatus uses low frequency inductive coupling to couple signals from a transducer to monitoring and analysis instrumentation. Signals indicative of physiological functions are modulated onto a low frequency carrier and output from a self-contained portable transducer assembly via a transducer coil. A corresponding receiver coil receives the signals by electromagnetic induction. The received signals are demodulated and processed by instrumentation coupled to the receiver coil. A mattress pad containing the receiver coil is also disclosed. In a fetal monitor implementation, both wireless ultrasound and tocodynamometer transducers are provided.

Abstract: A method and apparatus for ultrasound imaging of Doppler energy-related parameters is described. An ultrasound imaging system includes a transducer for transmitting an ultrasound signal into a body and receiving a reflected ultrasound signal. The system determines the energy of the reflected signal from tissue within the body. Signal processing circuitry determines a Doppler intensity spectrum of the signal reflected from the tissue. The Doppler spectrum represents energy of the tissue-reflected signal as a function of Doppler frequency and time. Integration circuitry integrates the Doppler spectrum over Doppler frequency to determine the energy of the tissue-reflected signal as a function of time for display in strip mode. The system also determines an energy-velocity product.

Abstract: A wireless patient monitoring apparatus uses an optical signal to transmit information from a transducer to a photodetector of an optical receiver. The photodetector converts the optical signal to an electrical signal which is then provided to monitoring and analysis instrumentation. Signals which are indicative of physiological functions are modulated onto a carrier, and the resulting modulated signal is provided, in turn, to the optical source, which may be a light-emitting diode (LED) which emits in the infrared band. A self-contained portable transducer assembly which is strapped or otherwise secured to the patient may house the transducer, modulator and optical source, and is adapted for underwater use. Optionally, the optical source can be positioned remote from the assembly. In a fetal monitor implementation, both wireless ultrasound and tocodynamometer transducers are provided.

Abstract: A method and an apparatus for frame averaging ultrasound imaging data. A one-tap IIR filter is used to average the corresponding pixel data of two frames. The frame averaging is a function of a normalized difference between the pixel data of the two frames. This is achieved by taking the absolute difference between the signal levels of the current frame and the previous frame and dividing the result by the arithmetic (or geometric) mean of the two data. A multitude of look-up tables of output values are generated off-line. Each look-up table is designed to be used under a specific set of operating parameters. In response to the user's selection of these operating parameters, the system downloads a selected frame-averaging look-up table from system memory. During subsequent system operation, the downloaded look-up table outputs values which are a function of the normalized difference between the previous and current frame data used to address the look-up table.

Abstract: In order to enable quantitative and ready assessment of the kinetics of a tissue on the basis of motion information of the tissue resulting from analysis performed according to the Doppler method, and to enable ready observation of a temporal change in motion of the tissue, there is provided, as one aspect, a diagnostic ultrasound Doppler imaging system. The system comprises a unit for scanning an object with ultrasonic waves over a cross section of the object to produce an echo signal representing electrical quantities proportional to ultrasonic waves reflected from the object; a unit for extracting from the echo signal a Doppler signal emanating from a tissue in motion inside the object; and a unit for analyzing the frequency of the Doppler signal to obtain two-dimensional image data concerning the motion of the tissue on the cross section frame by frame.

Abstract: A method (280) and system (128) for selectively smoothing color flow images in a Doppler ultrasound system (100). A set of original digitized ultrasound signals is received for points (m, m-1, m-2) on a beamline (l-1), each point having associated with it a velocity signal (.phi..sub.j), a magnitude of autocorrelation signal (R.sub.i), and a power signal (P.sub.i). A point (X(1,1)) along a beamline is selected for processing. The set of digitized ultrasound signals is applied to a digital filter (152), and the digital filter computes a set of smoothed digitized ultrasound signals by computing an average velocity signal (.phi..sub.av), an average magnitude of autocorrelation signal (R.sub.av), and an average power signal (P.sub.av) of each point in the selected beamline and points in adjacent beamlines. For the selected point along the selected beamline, a selected velocity signal (.phi.(1,1)) is compared to a velocity threshold (V.sub.

Abstract: A system interrogates a region with ultrasound and then generates a vector field of values representing the velocity sensed at a plurality of image element positions. Spatial changes in the velocity vector field are then determined and displayed to the user, preferably in real time. The spatial changes include divergence and/or the rotation (also known as "curl") of the velocity vector field. In order to enable display of the vector spatial change information, either magnitude values, projected values, or color-coded vector information may be computed and displayed. In order to reduce the effect of noise on differentiation operations, the system preferably smooths the velocity vector field before, after or at the same time as it determines divergence or rotation.

Abstract: A servo system for directing the operation of an ultrasound beam is described. The system includes a rotor and stator combination that utilizes electromagnetic forces to move the ultrasound beam in translational and rotational directions. In an embodiment of the invention the rotor is a permanent magnet that may be levitated and moved using a plurality of stator coils. Sensors are used to determine the position of the rotor, which information is used by a controller to regulate the stator operation designed to effect movement of the rotor. The sensors are preferably hall effect sensors. The permanent magnet is optionally placed in a fluid having buoyancy characteristics that reduce the electromagnetic force required to levitate the rotor. The rotor may be located off center within a housing so as to conform to asymmetrical viewing requirements, such as in transcranial Doppler ultrasound measurements.

Abstract: A method for extracting anatomical M-Mode displays of tissue velocity information along arbitrary curved polygons that can track curved organs such as myocard is described. The generated images can display the temporal velocity variations in a curved organ such as myocard in a single view. Time delays between events can be measured from these images. Furthermore, the invention describes how the time delay of characteristic events in temporal velocity evolutions and information derived from these velocity evolutions can be integrated into spatial time delay images that show the spatial propagation of the selected phenomenon. The characteristic events include switch in velocity direction, peak velocity, peak acceleration and similar aspects of tissue thickening. These characteristic events will be almost angle independent even if the tissue velocity is estimated with a Doppler technique along the propagation direction of the ultrasound beam.

Abstract: An ultrasound beam is repeatedly transmitted and received to and from an object, so that an echo signal is repeatedly obtained. A velocity of each of a plurality of portions on the ultrasound beam is calculated based on the echo signal. A position of at least one specific portion of the plurality of portions is tracked in as it changes with the passage of time based on the velocity to obtain a path where the specific portion moves. Conventionally the change of brightness of the M-mode image was tracked to obtain the path. According to the present invention, since the path is obtained based on the velocity having high resolution, the accuracy of track can be improved.