Siemens Medical Systems, Inc.

Matsushita Electrical Industrial Co., Ltd.

Jin H Kim

Zoran B Banjanin

Dong-Chyuan Liu

Lin X Yao

Steven R Marquis

Hisashi Hagiwara

Hiroshi Fukukita

Masami Kawabuchi

Ming Li

Robert N Phelps

Scott D Otterson

Jeffrey T Reeve

King-Yuen Wong

Chris Zobkiw

An ultrasound system produces composite color flow images of tissue samples. To reduce image flicker, the ultrasound system stores the data required to produce two sequential color flow images and computes a series of interpolated images that are displayed between the actual color flow images. A piece-wise interpolation function is used to create the interpolated images in order to prevent artificial smoothing of the image data. In addition, the ultrasound system quantizes the ultrasound data used to compute the interpolated images in order to reduce the amount of memory required to store the data for the sequential color flow images.

Method and apparatus for performing frame interpolation in an ultrasound

Ultrasound gray-scale image data and corresponding processed gray-scale image data are color-enhanced to generate an enhanced multi-color image. At one step, a color map look-up table is defined from the processed gray-scale image data to define a color palette of K colors, (e.g., K=4-16). Histogram analysis, nonlinear mapping or segmentation processing is used to map the gray-scale levels to the color palette. The processed gray-scale image data then is transposed into a transposed color image data set. Data interpolation then is performed in which each pixel of the original gray-scale image data is interpolated with a corresponding pixel among the transposed color image data set. Interpolation weighting is adjustable by the user to determine how much detail from the original gray scale image is preserved.

Method for enhancing ultrasound image

An ultrasonic Doppler flow (i.e. blood) imaging and/or measuring system capable of adaptively suppressing stationary or slowly-moving non-flow (i.e. tissue) signals having variable spectra from recovered ultrasonic echoes. In accordance with the invention, the tissue signals are suppressed using a tissue rejection filter having an attenuation characteristic which is controllably shaped based upon measured estimates of at least one spectral characteristic of the tissue signals to be removed, thereby maximizing the rejection of tissue movement signals and minimizing undesired attenuation of the blood flow signals. In accordance with one embodiment of the invention, the tissue rejection filter is embodied as a complex notch filter for filtering the baseband components of the recovered ultrasonic echoes, which filter has a variable notch shape and position as adaptively determined in response to changes in estimates of the spectral components of the tissue signal portion of the recovered echoes.

Ultrasonic doppler imager having an adaptive tissue rejection filter

An apparatus and method for removing noise from a signal S(x). The noise is removed by filtering S(x) through a low pass filter having an adjustable pass band. A control processor analyzes S(x) prior to S(x) being input to the low pass filter and adjusts the pass band in response to an estimate of the SNR or rate of change of S(x) such that the pass band is reduced when the estimated SNR decreases and the pass band is increased when the SNR increases. In embodiments in which the control processor utilizes the rate of change of S(x) to control the pass band, the pass band is reduced when the rate of change of S(x) increases and increased when the rate of change of S(x) decreases. In embodiments used in ultrasound applications, the estimate of the SNR can be obtained from x, the power in S(x), or the variance in the measured velocity. The estimate of the rate of change of S(x) may be computed from an estimate of the correlation distance in S(x).

Method and apparatus for adaptive spatial image filtering

An ultrasonic imaging system has a three-dimensional acoustic display. Beam-formed ultrasound scan signals are separated into channel signals and are then filtered using head-related transfer function (HRTF) filters. An HRTF is associated with each of several points in an interrogation region. A filter coefficient processor selects, for each channel signal, a set of HRTF filter parameters according to which sample volume the channel signal comes from. Each HRTF parameter set defines left-ear and right-ear response functions to a calibration sound generated at a calibration point in a calibration space; the calibration point itself corresponds to a predetermined position in the interrogation region. The HRTF-filtered channel signals are then combined into left and right audio output signals which drive left and right speakers that the user listens to while performing the ultrasound scan. The calibration points in the calibration space are mapped to respective reference sample volumes located in a predetermined ultrasonic interrogation region.

Acoustic display system and method for ultrasonic imaging

A spatial-temporal doppler velocity estimation method expands the detectable frequency range by extending the frequency boundary at which aliasing artifacts may occur. In various embodiments the detectable frequency range is extended beyond the Nyquist limit. To do so, multiple velocity estimation functions are defined. One function is the conventional function typically bound by the Nyquist limit. For additional functions, the (n-1)-th echo is spatially shifted with respect to the n-th echo, (i.e., temporal/spatial pulse-pairs are averaged). For example, in one embodiment a shift of +.DELTA. is inserted to define one additional estimation function, while a shift of -.DELTA. is inserted to define another additional estimation function. A power function then is calculated for each velocity estimation function. The estimation function having the highest power is selected for use in deriving the doppler shift frequency of a given sample point. By selecting a one of the K+1 velocity estimation functions with the highest power, the detectable frequency range, f, becomes: -(2.sup.K /2)f.sub.s &lt;f&lt;(2.sup.K /2)f.sub.s, where f.sub.s is the Doppler sampling frequency.

Doppler ultrasound velocity estimation

In accordance with the principles of the present invention, advantage is taken by the inventors of the fact that the speed of operation of the digital hardware in a digital beamformer can be reduced by providing, for example, multiple phases of the data signals and then processing the multi-phase data in N parallel summing paths. An interpolation-decimation filter receives the multi-phase data from the N parallel summing paths and provides at its output a signal having a reduced data rate (1/N). In accordance with this technique, the speed of operation of the individual digital circuits for forming the required beamforming delays is not increased as compared to conventional post-beamforming interpolation schemes, so that hereby the effective data rate is increased by a factor N and results in a decrease of the delay quantization error by a factor N. In accordance with the principles of the invention, the interpolation-decimation filter is incorporated into the beamformer at a most advantageous place. That is, it is incorporated into the beamformer processing after partial beamforming of a group of receive channels and before formation of the final beam. This approach allows the final beamforming to be simple and performed at a relatively low data rate and allows the higher rate signal processing to be confined to circuitry which may advantageously be on a single type of integrated circuit which is repetitively used in the beamformer. Further increase in the effective speed of operation is produced by providing timing circuitry that allows parallel processing of signals from a plurality of scanning beam lines.

Multi-beam digital beamforming method and apparatus

An ultrasonic Doppler flow (i.e. blood) imaging and/or measuring system capable of adaptively suppressing stationary or slowly-moving non-flow (i.e. blood) signals having variable spectra from the recovered ultrasonic echoes. In accordance with the invention, the tissue signals are suppressed using a tissue rejection filter arrangement having an attenuation characteristic which is controlled based upon measured estimates of at least one spectral characteristic of the tissue signals to be removed, thereby maximizing the rejection of tissue movement signals and minimizing undesired attenuation of the blood flow signals. In accordance with an embodiment of the invention, data representative of the tissue signal movement, e.g., the spectral estimates of the tissue signals, are spatially averaged before being used to control the tissue rejection filter arrangement. In accordance with an alternative embodiment of the invention, the spatial averaging algorithm itself is adaptively changed, for example, in response to changes in the value of the power estimate of the tissue movement signals. In accordance with an even further alternative embodiment of the invention, a plurality of parallel beamforming channels are used for developing multiple sets of color flow beamlines substantially simultaneously with one another which scan an area, and velocity estimates from at least two of the sets which are representative of movement in adjacent portions in the scanned area are averaged for developing a control signal which adaptively controls the tissue rejection filter.

Ultrasonic doppler imager having a spatially smoothed control signal for

Ultrasonic Doppler imager having an adaptive tissue rejection filter

Method for providing a quantitative color flow display of moving matter using an ultrasound imaging system, the display being formed of pixels on a display device, which method includes the steps of: (a) transmitting acoustic beams to a region of interest in the body, which region of interest includes the moving matter; (b) receiving echo beams from the region of interest; (c) obtaining, at each portion of the region of interest, which portion is referred to as a pixel, a measure of velocity of moving matter in the pixel and a measure of direction of the velocity of the moving matter in the pixel; (d) determining a maximum of the measure of velocity at each pixel in the region of interest over a predetermined period of time and the measure of direction of the maximum velocity; and (e) displaying the measures of velocity of the pixels for the predetermined period of time wherein the measures of velocity and the measure of direction of the velocity are displayed using a color indicator which is relative to the maximum measure of velocity at each pixel and to the measure of direction of the maximum velocity.

Quantitative color flow

An ultrasound pulsed Doppler system detects Doppler-shifted acoustic pulses reflected from moving material in a body and received by a transducer, and displays the velocity field of the material on a screen in a color flow format together with the black-and-white display of the ultrasound B-mode of the body. The system detects the average velocity of the material at a plurality of localized sample regions in the body by determining the complex correlation function for pairs of reflected signals from each sample region that are received by the transducer, where the complex phase of the correlation function is proportional to the velocity of the material, projected along the ray from the sample region to the transducer. The display constitutes an array of pixels, and the system determines a value at each pixel that represents the velocity for the material at the location imaged by the pixel. These velocity values are determined by selecting, for each pixel, a plurality of sample regions having images neighboring the pixel, and interpolating separately the real and imaginary parts of the complex correlation value from these sample regions. These interpolated complex correlation function values are used to determine the velocity value for the pixel. The interpolation is carried out using a 2.times.4 kernel, with 2-point interpolation along the dimension of the ray and 4-point interpolation along the perpendicular azimuthal dimension. In a further improvement, the system also displays the flow turbulence field in a color flow format by determining the average power in the reflected signals from each sample region, interpolating these values to obtain a pixel power value, and using this value and the magnitude of the complex correlation function value to obtain a turbulence estimate value.

Acoustic scan conversion method and apparatus for velocity flow

Apparatus for adaptive phase aberration correction of wave distortions caused by tissue inhomogeneities in ultrasound images. In accordance with the present invention, auto-correlation apparatus in multiple, parallel, color flow processors compute a cross-correlation which is used to correct distortions in real time.

Phase aberration corrections utilizing color flow processors

In accordance with the principles of the present invention, advantage is taken by the inventors of the fact that the speed of operation of the digital hardware in a digital beamformer can be reduced by providing, for example, multiple phases of the data signals and then processing the multi-phase data in N parallel summing paths. An interpolation-decimation filter receives the multi-phase data from the N parallel summing paths and provides at its output a signal having a reduced data rate (1/N). In accordance with this technique, the speed of operation of the individual digital circuits for forming the required beamforming delays is not increased as compared to conventional post-beamforming interpolation schemes, so that hereby the effective data rate is increased by a factor N and results in a decrease of the delay quantization error by a factor N. In accordance with the principles of the invention, the interpolation-decimation filter is incorporated into the beamformer at a most advantageous place. That is, it is incorporated into the beamformer processing after partial beamforming of a group of receive channels and before formation of the final beam. This approach allows the final beamforming to be simple and performed at a relatively low data rate and allows the higher rate signal processing to be confined to circuitry which may advantageously be on a single type of integrated circuit which is repetitively used in the beamformer.

Partial beamforming

In accordance with the principles of the present invention, advantage is taken by the inventors of the fact that the speed of operation of the digital hardware in a digital beamformer having a plurality of parallel receiving channels can be reduced by providing multiple phases for the data signals supplied by each receiving channel and then processing the multi-phase data in N parallel summing paths. An interpolation-decimation filter receives the multi-phase data from the N parallel summing paths and provides at its output a signal having a reduced data rate (1/N). In accordance with this technique, the speed of operation of the individual digital circuits for forming the required beamforming delays are not increased as compared to conventional post-beamforming interpolation schemes, so that hereby the effective data rate is increased by a factor N and the delay quantization error is reduced by a factor N.

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Issaquah, WA, United States of America

Jin H Kim