Abstract: A method and apparatus in an ultrasound imaging system is disclosed that enhances the contrast-to-tissue ratio and signal-to-noise ratio of contrast imaging using stepped-chirp waveforms. The first waveform component is employed with a first frequency optimized to initiate the bubble dynamics and the second waveform component is employed with a second frequency optimized to produce an enhanced bubble nonlinear response. The first waveform component and the at least a second waveform component are transmitted as a single stepped-chirp transmit pulse. At least one of a center frequency, an amplitude, a starting phase, and a bandwidth of the waveform components are adjusted to generate the single stepped-chirp transmit pulse. A relative phase, a switch time, and a time delay between the waveform components are also adjusted for maximal enhancement of bubble nonlinear response.

Abstract: Certain embodiments include a system and method for banding suppression in a B-mode ultrasound image. Banding occurs in a diagnostic image when two or more focal regions having different waveforms and/or frequencies, for example, are combined. The resulting difference in intensity between the focal regions produces banding in the final image. For purposes of illustration only, the method below will be described with two focal zones. Certain embodiments of the present invention reduce banding in a diagnostic image including a plurality of focal zones by processing the first focal zone, determining intensity around the border or “stitch line” between the two focal regions, and adjusting the second focal region based on the difference in intensity. Preferably, processing is done in real time as image frames are updated.

Abstract: Certain embodiments include a system and method for banding suppression in a B-mode ultrasound image. Banding occurs in a diagnostic image when two or more focal regions having different waveforms and/or frequencies, for example, are combined. The resulting difference in intensity between the focal regions produces banding in the final image. For purposes of illustration only, the method below will be described with two focal zones. Certain embodiments of the present invention reduce banding in a diagnostic image including a plurality of focal zones by processing the first focal zone, determining intensity around the border or “stitch line” between the two focal regions, and adjusting the second focal region based on the difference in intensity. Preferably, processing is done in real time as image frames are updated.

Abstract: A method and apparatus in an ultrasound imaging system is disclosed that enhances the contrast-to-tissue ratio and signal-to-noise ratio of contrast imaging using stepped-chirp waveforms. The first waveform component is employed with a first frequency optimized to initiate the bubble dynamics and the second waveform component is employed with a second frequency optimized to produce an enhanced bubble nonlinear response. The first waveform component and the at least a second waveform component are transmitted as a single stepped-chirp transmit pulse. At least one of a center frequency, an amplitude, a starting phase, and a bandwidth of the waveform components are adjusted to generate the single stepped-chirp transmit pulse. A relative phase, a switch time, and a time delay between the waveform components are also adjusted for maximal enhancement of bubble nonlinear response.

Abstract: A method and apparatus for performing harmonic imaging. Each transmit focal zone in the near-field is interrogated by two or more transmit firings of different phase, while each transmit focal zone in the far-field is interrogated by a single transmit firing. On receive, the respective near-field vectors are summed, thereby substantially canceling the fundamental signal components while isolating the (sub)-harmonic signal components. In the far-field, the single transmit firing has a fundamental frequency .function..sub.0. A filter isolates the signal component having a passband centered at a (sub)harmonic frequency, e.g., 2.function..sub.0. The near-field and far-field receive vectors at each scan angle are then stitched together to form a composite vector.

Abstract: A method and an apparatus for improving the signal-to-noise ratio (SNR) and/or resolution in color flow ultrasound imaging by using complementary-coded excitation of the transducer array. The SNR is improved by transmitting a pair of Golay-coded pulse sequences in alternating sequence at the same transmit focal position over multiple firings and then partly decoding the beamsummed data. The partly decoded data is then vector summed and high pass filtered. The summed and high-pass-filtered data is optionally decimated by a factor of two. The decimated or undecimated data is then input to the parameter estimator, which provides imaging signals representing the flow in a scan plane. Those imaging signals are then displayed as color information on a display monitor.

Abstract: A method and an apparatus for imaging the nonlinear components of an ultrasound signal returned from ultrasound scatterers in tissue or contrast agents in blood. The method employs a code-modulated wavelet for transmission combined with correlation filtering on reception. Coding methods are used to simultaneously manipulate the linear and nonlinear terms. The manipulations affect the magnitude and temporal arrangement of the resulting decoded waveforms. Among the simultaneous manipulations of linear and harmonic decoded signals are: orthogonal linear terms, finite linear terms, minimum sidelobe with optimal peak harmonic terms and optimally compressed harmonic terms.

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: A method and an apparatus for imaging the nonlinear components of an ultrasound signal returned from ultrasound scatterers in tissue or contrast agents in blood. The method employs a code-modulated wavelet for transmission combined with correlation filtering on reception. Transmit codes are used to modulate the phases of wavelets for successive transmit firings focused at the same transmit focal position. For example, for a first transmit firing a first transmit code is used to modulate a base wavelet to form a first coded wavelet and for a second transmit firing a second transmit code is used to modulate the same base wavelet to form a second coded wavelet. On reception, the receive signals resulting from the first and second transmit firings are decoded by correlating the receive signals with first and second receive codes respectively.

Abstract: A color flow imaging 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. Multiple transmit firings of the same coded pulse sequence are focused at the same transmit focal position with the same transmit characteristics. The receive signals are compressed utilizing matched or mismatched filtering. These techniques can be used to maximize color flow sensitivity in deep-lying regions. Alternatively, for a given transmit acoustic burst length and dosage, the spatial resolution can be improved without compromising sensitivity.

Abstract: A method and an apparatus for three-dimensional imaging of ultrasound data by constructing projections of data from a volume of interest. An ultrasound scanner collects B-mode or color flow images in a cine memory, i.e., for a multiplicity of slices. A multi-row transducer array having a uniform elevation beamwidth is used to provide reduced slice thickness. In particular, the multi-row transducer array has a central row made up of elements having an area smaller than the combined area of the paired elements of two outermost rows The data from a respective region of interest for each of a multiplicity of stored slices is sent to a master controller, such data forming a volume of interest. The master controller performs an algorithm that projects the data in the volume of interest onto a plurality of rotated image planes using a ray-casting technique. The data for each projection is stored in a separate frame in the cine memory. These reconstructed frames are then displayed selectively by the system operator.

Abstract: A method and circuit for improved digitization of waveforms having a large dynamic range, including selecting a signal threshold value which partitions the dynamic range of the waveform into a small signal region and a large signal region; sampling the waveform to obtain a sampled signal therefrom at a given sampling frequency; for each sampled signal, comparing the sampled signal with the signal threshold value to determine whether the sampled signal is within the small signal region or the large signal region; and directly digitizing the sampled signal if the sampled signal is within the small signal region or differentially digitizing the sampled signal if the sampled signal is within the large signal region, wherein differentially digitizing the sampled signal includes digitizing a value representing the difference between the sampled signal at a present sampling instant and a previous sampling instant.

Abstract: The present invention discloses a system and a method for ultrasonically detecting ply wrinkling in a laminated composite. The composite is ultrasonically scanned with sound wave energy generated from transducer(s) operating in an oblique incidence pulse echo mode. Echo signals reflected from the plies of the composite are then detected with the transducer(s). Each set of reflected echo signals represents a three-dimensional waveform data set u(x,y,t) having spatial dimensions (x,y) and a temporal dimension (t) mapping directly to a third spatial dimension (z) orthogonal to the surface of the composite. The three dimensional waveform data set u (x,y,t) corresponds to a three-dimensional volumetric region in the composite. The three-dimensional waveform data set u(x,y,t) is then processed into a rectified data set w(x,y,t). Ply noise in the three-dimensional data set w(x,y,t) is then filtered. The filtered three-dimensional data set is then converted into wrinkle severity C-scan and a wrinkle depth C-scan.

Abstract: A method for detecting and characterizing flaws in an object having an arbitrary-shaped geometry. The present invention uses a synthetic aperture focusing technique (SAFT) which enables maximum aperture imaging. Maximum aperture imaging is attained by determining whether a plurality of reconstruction points within an object are in the width of a transmitted ultrasonic sound wave.

Abstract: A method of suppressing grain noise resulting from ultrasonic inspection of an object, including ultrasonically scanning an object and detecting waveform signals therefrom, determining, from the signals, data values which define a 3D waveform data set U(x,y,t) having both spatial (x,y) and temporal (t) ultrasonic data values from the scanned object, converting the 3D waveform data set into a 3D filtered waveform data set V(x,y,t) by performing a 3D filtering operation thereon, wherein for each data value in the 3D waveform data set U(x,y,t), a filtered data value is obtained by taking into account data values which are adjacent thereto both spatially and temporally, thereby reducing grain noise relative to flaw signals to enable a high probability of flaw detection and a low probability of false flaw indications.