Siemens Medical Solutions Usa, Inc.

Acuson Corporation

Rickard C Loftman

Kutay F Ustuner

Ismayil M Guracar

Tommaso Mansi

Ankur Kapoor

Patrick J Phillips

Charles E Bradley

Bhaskar S Ramamurthy

Randall L Schlesinger

John I Jackson

Helene C Houle

Constantine Simopoulos

Anming He Cai

Seshadri Srinivasan

William Robert Dreschel

James E Chomas

Liang Zhai

Zoran B Banjanin

Karen Elizabeth Morgan

Douglas B Dull

Erkan Mumcuoglu

Zafer Zamboglu

Lex J Garbini

For quantification of blood flow by an ultrasound system, B-mode images generated with a multi-transmit, coherent image formation produce swirling or other speckle patterns in the blood regions. These patterns, as represented in specially formed B-mode images, are tracked over time to indicate two or three-dimensional velocity vectors of the blood at a B-mode resolution. Various visualizations may be provided at the same resolution, including the velocity flow field, flow direction, vorticity, vortex size, vortex shape, and/or divergence.

Quantification of blood flow with ultrasound B-mode imaging

For intraluminal ultrasound probes, two long-thin arrays (e.g., 1D arrays) are provided in the intraluminal ultrasound probe for bi-plane imaging. The arrays are rotatable relative to each other so that during insertion the arrays align to be long and thin, allowing the shaft of the probe to be narrow. For bi-plane imaging after insertion, one array is rotated relative to the other array, defining two non-parallel imaging planes.

Ultrasound catheter with adjustable apertures for multi-plane imaging

Coherent combination of ultrasound data for collinear receive beams adapts to the ultrasound data. Beam-to-beam coherence metrics, such as correlation coefficient and/or phase change or functions of these parameters, are used to adapt weighting of the ultrasound data for the receive beams prior to combination or to adapt the results of the combination.

Adaptive post beamformation synthetic aperture for ultrasound imaging

Using parallel receive beamformation, sets of data representing locations in at least a common field of view are obtained, each set in response to a transmit with a spatially distinct phase front. The common field of view receive data are time aligned and amplitude weighted for retrospective transmit focusing and retrospective transmit apodization, respectively. A time offset is applied to the receive data for retrospective transmit focusing. The offset is selected to emulate shifting the transmit delay profile to be tangentially intersecting with the dynamic receive delay profile for each location which is the desired transmit delay profile. A weight is applied to the receive data for retrospective transmit apodization. The offset and weighted data representing a same location from different transmit events is coherently combined. The number of sets of data offset, weighted and combined may vary as a function of depth for dynamic transmit beamformation.

Coherent image formation for dynamic transmit beamformation

Retrospective dynamic transmit beamformation is provided in medical ultrasound imaging. Using parallel receive beamformation, sets of data representing locations in at least a common field of view are obtained, each set in response to a transmit with a spatially distinct phase front. The common field of view receive data are time aligned and amplitude weighted for retrospective transmit focusing and retrospective transmit apodization, respectively. A time offset, such as of a cycle or more in some cases, is applied to the receive data for retrospective transmit focusing. The offset is selected to emulate shifting the transmit delay profile to be tangentially intersecting with the dynamic receive delay profile for each location which is the desired transmit delay profile. A weight is applied to the receive data for retrospective transmit apodization. The weight is selected based on the desired transmit apodization profile. The offset and weighted data representing a same location from different transmit events is coherently combined. The number of sets of data offset, weighted and combined may vary as a function of depth for dynamic transmit beamformation.

Velocity scale is automatically determined for ultrasound imaging. Receive signals corresponding to different pulse repetition intervals are used to estimate velocities. The different velocities are used to determine the velocity scale. For example, the different pulse repetition intervals are obtained by selecting different sets of signals from a group of signals for a scan line. As another example, the different pulse repetition intervals are obtained by transmitting for a scan line with changing, such as increasing, pulse repetition intervals. The lower pulse repetition interval of a pair of intervals associated with a sign change in the phase is used for the velocity scale. In yet another example, at least two demodulation frequencies are used for a broadband transmit in at least two sets, each set with a different pulse repetition interval. Velocities are estimated for a greater number of pulse repetition intervals than transmitted using the broadband pulses.

Automatic velocity scale identification for medical diagnostic ultrasound

Methods are provided for automatic setting of parameters for contrast agent quantification. Various processes may improve quantification. For example, for consistency in contrast agent quantification, a gain or other setting of an ultrasound system is automatically determined in response to destruction of the contrast agent or at the initiation of the contrast agent quantification procedure. Automatic setting of an adaptive gain provides equalized image intensity for each repetition of a contrast agent quantification procedure based on a same triggering event, the destruction of contrast agent. By synchronizing the adaptive setting algorithms with contrast agent destruction, similar base line information is provided for each iteration of a contrast agent quantification procedure. As another example, the contrast agent gain setting treats acoustic signals representing tissue or other non-contrast agent structure as noise, mapping the tissue values to a substantially constant low value within the dynamic range. As yet another example, by segmenting out blood pools or other areas of contrast agent likely to have contrast agents even after destruction, the resulting gain is more likely sensitive to the detection of perfused contrast agents.

Methods for adaptively varying gain during ultrasound agent quantification

Transmit based axial whitening is provided. Ultrasonic waveforms to be transmitted are designed to provide for wideband imaging characteristics prior to detection. Rather than transmitting a waveform having a spectral magnitude as white or flat as possible, waveforms with adjusted spectral content, such as spectrally bi-modal waveforms are generated in order to compensate for subsequent effects. Prior to detection, a more wideband or whiter signal response is provided in response to the transmitted waveform. Any of various alterations of the transmit waveform, such as asymmetric, spectrally bi-modal or other characteristics in anticipation of a system transfer function or physical phenomena through which the signal passes electronically or acoustically to result in a wideband or white spectral magnitude and generally linear spectral phase is used. The transmit waveform is altered to improve the imaging characteristics of the downstream processing.

Transmit based axial whitening

An image formed from compounded frames of ultrasound data acquired with different steering angles is displayed. Each component frame is associated with a scan of the entire displayed region. A majority of scan lines for each component frame are pointed in one direction or the same relative direction, and a minority of the scan lines are steered at different angles within each component frame to scan the rest of the display region, but with a different steering angle for the majority of scan lines of each of the component frames. As a result, the benefits of spatial compounding component frames associated with different steering angles are provided without having to apply filtering to reduce line artifacts.

Overlapped scanning for multi-directional compounding of ultrasound images

The gain for multiple mode imaging and/or contrast agent imaging is automatically adjusted. The gain algorithm separately determines gain parameters for two different types of imaging, such as tissue and contrast agent imaging. The gain based on the contrast agent image may be optimized to provide maximum sensitivity, such as by mapping noise values measured prior to injection of contrast agent to low values within the dynamic range or somewhat below the display dynamic range. The automatic gain based on the contrast agent image may be free of variance calculations. One of the two gain parameters is selected as the system gain, or the two gain parameters are combined to form the system gain. The presence of contrast agents within the image may be determined, and different gain parameters used based on the presence or absence of contrast agents. Various ones or combinations of the gain adjustments summarized above may be used.

Automatic gain compensation for multiple mode or contrast agent imaging

The preferred embodiments described herein provide a medical diagnostic ultrasound catheter with a tip portion carrying an ultrasound transducer. The tip portion comprises a first portion that is in the acoustic path of the ultrasound transducer, and a second portion that is outside the acoustic path of the ultrasound transducer. The first and second portions comprise different acoustic and mechanical properties. For example, the mechanical properties of the second portion can give the catheter tip sufficient durability to withstand normal use without bowing, while the acoustic properties of the first portion can give the catheter tip desired acoustic properties. This may be especially important for small diameter catheters (e.g., maximum cross-sectional dimensions less than or equal to about 10 French or 8 French) where the stiffness of the catheter tip is reduced.

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Menlo Park, CA, United States of America

Rickard C Loftman