Abstract: A coherent imaging system includes a transmitter and a receive beamformer which are programmed with transmit and receive time delays, respectively, that take into account time-of-flight errors caused by an intervening mammography compression plate between the biological tissue being imaged and a phased array of ultrasonic transducer elements. A simple ray-tracing method is utilized to adjust the transmit and receive time delays according to compression plate thickness and speed of ultrasound propagation to mitigate spherical aberration due to the compression plate.

Abstract: A method and an apparatus for perfusion imaging using coded excitation. Bursting pulses are scanned over the region of interest in one or more frames followed by scanning one or more encoded imaging pulses in each subsequent frame. The bursting pulse is intended to break contrast micro-bubbles within a transmit focal zone and therefore should have high mechanical index and low frequency. The basic concept is to use a very low-amplitude encoded pulse train to image the contrast agents. The low amplitude prevents the contrast bubbles in the transmit focal zone from being destroyed while imaging, and the coded excitation provides the necessary signal-to-noise ratio. The imaging pulses are transmitted during refilling of the transmit focal zone with contrast agent subsequent to transmission of the bursting pulse into the transmit focal zone. On receive, the receive vectors are decoded to form a compressed pulse.

Abstract: A coherent imaging system includes a transmitter and a receive beamformer which are programmed with transmit and receive time delays, respectively, that take into account time-of-flight errors caused by an intervening mammography compression plate between the biological tissue being imaged and a phased array of ultrasonic transducer elements. A simple ray-tracing method is utilized to adjust the transmit and receive time delays according to compression plate thickness and speed of ultrasound propagation to mitigate spherical aberration due to the compression plate.

Abstract: In performing tissue-generated harmonic imaging using coded excitation, the transmit waveform for acquiring the N-th harmonic signal is biphase (1,−1) encoded using two code symbols of a code sequence, the portions (i.e., chips) of the transmit waveform encoded with the second code symbol each being phase-shifted by 180°/N relative to the chips encoded with the first code symbol. This is implemented by time shifting the portions (i.e., chips) of the transmit sequence which are encoded with the second code symbol by ½N fractional cycle at center frequency relative to the chips of the transmit sequence encoded with the first code symbol. During reception, the desired harmonic signal is isolated by a bandpass filter centered at twice the fundamental frequency and enhanced with decoding.

Abstract: A method and an apparatus for perfusion imaging using coded excitation. Bursting pulses are scanned over the region of interest in one or more frames followed by scanning one or more encoded imaging pulses in each subsequent frame. The bursting pulse is intended to break contrast micro-bubbles within a transmit focal zone and therefore should have high mechanical index and low frequency. The basic concept is to use a very low-amplitude encoded pulse train to image the contrast agents. The low amplitude prevents the contrast bubbles in the transmit focal zone from being destroyed while imaging, and the coded excitation provides the necessary signal-to-noise ratio. The imaging pulses are transmitted during refilling of the transmit focal zone with contrast agent subsequent to transmission of the bursting pulse into the transmit focal zone. On receive, the receive vectors are decoded to form a compressed pulse.

Abstract: A three-dimensional image of flowing fluid or moving tissue using velocity or power Doppler data is displayed by using an ultrasound scanner that collects velocity or power data in a cine memory to form a volume of pixel data. Average or median pixel values are projected on an image plane by casting rays through the data volume. As the ray passes through each scan plane, a data value is assigned to the ray at that point. At each scan plane, the assigned pixel data value is tested to see if it exceeds a noise threshold. For a given ray, pixel data values above the detection threshold are accumulated until a pixel data value falls below the detection threshold. A minimum number of pixel data values exceeding the threshold are required for each ray before the average of the accumulated values is processed and/or the median value is selected. When all pixels along a given ray have been tested, the projection is complete and the average or median projection is then displayed.

Abstract: A method and an apparatus for displaying three-dimensional images of ultrasound data having improved segmentation. This is accomplished by harmonic imaging. There are two types of harmonic imaging: (1) imaging of harmonics returned from contrast agents injected into the fluid; and (2) naturally occurring harmonics, generally referred to as "tissue harmonics". An ultrasound transducer array is controlled to transmit a beam formed by ultrasound pulses having a transmit center frequency and focused at a desired sample volume containing contrast agents. In the receive mode, the receiver forms the echoes returned at a multiple or sub-multiple of the transmit center frequency into a beam-summed receive signal. This process is repeated for each sample volume in each one of a multiplicity of scan planes. After filtering out the undesired frequencies in the receive signal, i.e.

Abstract: A method and apparatus for ultrasonically imaging flow directly in B mode employs a sequence of pulses transmitted to a transmit focal position, with the backscattered signals from this sequence being filtered to remove echoes from stationary or slow-moving reflectors along the transmit path. The resulting flow signals are superimposed on a conventional B-mode vector and displayed. A B-mode flow image is formed by repeating this procedure for multiple transmit focal positions across the region of interest. The filtering is performed in slow time (along transmit firings) using a high-pass "wall" filter (e.g., an FIR filter) with harmonic image feed-through and optionally B-mode (fundamental) feed-through. The resulting B-mode flow image has low clutter from stationary or slow-moving tissue or vessel walls, high resolution, high frame rate and flow sensitivity in all directions.

Abstract: Data for high-frame-rate high-resolution (i.e., low f-number) ultrasonic imaging are acquired by a technique that involves transmitting multiple physically separated beams simultaneously and acquiring imaging data for more than one scan line during receive. Spatial apodization is used to influence the transmit beamformation and to form two controlled and focused spatially separate beams with a single firing of the transducer array elements and without use of additional timing electronics.

Abstract: A method and an apparatus for selectively performing contrast harmonic imaging, tissue harmonic imaging and B-mode flow imaging with an ultrasound imaging system utilizes phase-coded excitation on transmit and selective firing-to-firing, i.e., "slow-time", filtering on receive. "Slow-time" filtering in combination with transmit phases which change over the set of transmit firings results in different effective "slow-time" filters corresponding to the different harmonic modes within the reflected signal. The transmit phases and the "slow-time" filter weightings are designed to selectively enhance the desired modes while substantially suppressing other modes.