General Electric Company

Other

Larry Y Mo

Steven Charles Miller

Michael J Washburn

William Thomas Hatfield

Lihong Pan

Richard Yung Chiao

Boris Yamrom

Theodore Lauer Rhyne

Todd Michael Tillman

Mir Said Seyed-Bolorforosh

John E Mahony

David D Becker

Christopher J Gilling

Brian Peter Geiser

Vaishali Vilas Kamat

Shinichi Ishiguro

Masayoshi Honda

Kok-Hwee Ng

Kevin McCann

Stanley Siu-Chor Chim

Susan M Barnhart

A Doppler unit generates a Doppler signal from ultrasound backscattered signals. A logic unit performs a Fourier transform and compresses the resulting signals according to a compression curve determined in part by the noise level in the system. The peak values of the compressed signals also may be used to adjust the video gray mapping of the compressed signals in order to improve the appearance of a Doppler image on a display.

Doppler ultrasound automatic spectrum optimization

A method and an apparatus for displaying an ultrasound image comprising a region of interest (ROI) having an optimal image quality and a background region having a normal image quality. In the displayed image the background region lies outside the ROI. The optimal image quality within the ROI is achieved by using a set of imaging parameters which are different than the set of imaging parameters used to acquire the background image, including one or more of the following: different (e.g., shorter) transmit waveforms, an increased number of transmit focal zones per unit depth, different transmit and/or receive apertures, different center frequencies for the receive bandpass filter (primary and/or (sub)harmonics), and higher vector density (i.e., decreased vector spacing). Since the optimal imaging is restricted to a ROI, a high frame rate is still possible within the ROI depending on its size.

Ultrasound imaging with optimal image quality in region of interest

A method and an apparatus for automating the B-mode transmit waveform center frequency/length adjustment based on actual image data. The average SNR and the spatial correlation statistics in selected kernels of the image data are analyzed to test if high-quality signal is present. By placing one or more of the test kernels at relatively great depth (i.e., close to the bottom of the user-selected image depth range), the overall test results indicate the highest-resolution transmit waveform that can be used, while providing a sufficiently strong signal down to the desired depth.

Method and apparatus for automatic transmit waveform optimization in

A method and apparatus for calculating the inter-slice spacing in a data volume and registering the slices of that volume using SAD calculations. The resulting transformed data volume is then three-dimensionally reconstructed using a projection technique. If during scanning the probe is translated in the Z direction and at the same time is shifted in the X and/or Y direction, the SAD value will be artificially high. By translating two adjacent images with respect to each other in the X direction and then in the Y direction, and searching for the minimum SAD value, the amount of shift in the X and/or Y direction can be determined and that shift can then be removed. Also by rotating two slices with respect to each other and looking for a minimum SAD value, rotational motion of the probe during scanning can be removed.

Method and appartus for calculating distance between ultrasound images

A method and an apparatus for automating time-gain compensation (TGC) and lateral-gain compensation (LGC) based on the B-mode image data. The automatic gain adjustments are aimed at equalizing the mean signal intensities along the axial (for TGC) and/or lateral (for LGC) direction of the image, and suppressing any lateral band (for TGC) and/or sector (for LGC) that contains mostly noise. The automatic TGC/LGC adjustment method is implemented in software on a digital scanner and uses a noise model of the entire B-mode processing chain from the beamformer through the B-mode processor to the back-end video processor.

Method and apparatus for automatic time and/or lateral gain compensation

A method for automatic Doppler angle estimation based on the B-mode and color flow (if available) image. The method uses an algorithm for automatic vessel slope measurement which first finds an optimal initial point within the sample volume or range gate, and then searches for the most reliable pixel points (near or far walls) based on a combination of intensity-only and intensity-difference thresholds, before performing a slope estimation. B-mode intensity data and, optionally, color flow velocity or power data (before gray/color mapping) are used. The algorithm may also be applied to methods for automatic tracking of vessel diameter and flow rate calculations, although the primary objective is to achieve automatic Doppler angle estimation in an ultrasound scanner.

Method and apparatus for automatic Doppler angle estimation in

A method and an apparatus for enhancing the side-lobe performance of a sparse ultrasonic transducer array using harmonic imaging to reduce all beam sidelobe (including grating lobe) levels. Harmonic imaging consists of using the active transducer elements to transmit an ultrasound signal (wideband or narrowband) of center frequency f.sub.0 and receive at one or more harmonic frequencies nf.sub.0, where n.gtoreq.2.

Method and apparatus for improving sidelobe performance of sparse array

A method and an apparatus for tracking scan plane motion in free-hand three-dimensional ultrasound scanning using adaptive speckle correlation. The method employs a correlation index which adapts to different display dynamic range and post-processing filters. The method may include the following steps: choosing a kernel within each frame image for correlation calculations; rejecting duplicate image frames; measuring the degree of correlation between successive image frames; rejecting correlation estimates which may be associated with hand jitter and other artifacts; and computing the average frame-to-frame (i.e., interslice) spacing based on the average correlation estimate. This image-based motion tracking technique enables three-dimensional reconstruction with good geometric fidelity, without use of any external position-sensing device.

Method and apparatus for tracking scan plane motion in free-hand

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.

Method and apparatus for pulsed doppler imaging using coded excitation

A method and an apparatus for adaptively enhancing the B-mode image during post-detection image processing in an ultrasound imaging system. A low pass filter which smooths out speckle and a high pass filter which enhances edges are placed in parallel signal paths connected to the output of an envelope detector in a B-mode processor. The signals in the high pass filter path are logarithmically compressed before high pass filtering. The signals in the low pass filter path are logarithmically compressed after low pass filtering. Respective weighting factors are applied to the low- and high-pass-filtered signals by an adaptive weighting device, which may take the form of a processor or a look-up table. The weighted low- and high-pass-filtered signals are then summed and optionally input to an anti-aliasing low pass filter before decimation and scan conversion.

Method and apparatus for adaptive B-mode image enhancement

An analytical method for automatic tracing of a Doppler time-velocity waveform envelope. At the core of this algorithm is a maximum frequency detection mechanism which is based on searching for the highest frequency bin whose spectral amplitude exceeds a certain noise threshold. The method is based on a theoretical noise amplitude distribution in the video spectral domain. In particular, the method uses a precise model of the statistical distribution of the video spectral power of white noise to establish a threshold for maximum frequency detection. Input to the noise model is the average white noise level in the video spectral display, which can be computed using either of two analytical methods.

Method and apparatus for automatic tracing of Doppler time-velocity

A signal processing technique for improving the axial resolution and/or the sensitivity of an ultrasonic imaging system. This technique also improves the lateral resolution and the depth of field. The technique is based on combining two or more transmit wave functions in an optimal manner to achieve a synthetic waveform which has greater bandwidth and/or energy than the individual wave functions. This scheme operates on the imaging data before the data reaches the envelope detector, while the phase information is still maintained within the signal. Using a synthetic transmit wave design approach, the effective emitted pressure waveform would have a bandwidth which would be wider than the transducer bandwidth with high sensitivity. The synthetic transmit waveform design scheme consists of firing two or more relatively long transmit waveforms for each single A-line in a given focal zone. The frequency spectrum for each of these transmit pulses is centered at a slightly different frequency. The received signals from all of these transmit waveforms are added, while maintaining their phase information, to produce a synthetic waveform having an wider bandwidth than that of an impulse excitation.

Method, apparatus and applications for combining transmit wave functions

A method using a progressive sampling rate technique to maintain the sampling rate at the Nyquist frequency of the I/Q data through a tunable equalization bandpass filter in the front end of the imager and then increasing the sampling rate via axial interpolation to prevent aliasing during the nonlinear detection process. If an envelope detector is used, the bandwidth of the detector output should be approximately double that of the I/Q data. In this case, the sampling rate is doubled (or more) by axial interpolation before envelope detection. A 2-point linear interpolator can be used. Depending on the application, this axial interpolator can be turned on or off automatically by the system. After detection, the signal can be low-pass filtered to restrict the speckle bandwidth prior to log compression.

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Waukesha, WI, United States of America

Larry Y Mo