Abstract: The invention provides a method and system for adaptive persistence processing in an ultrasound imaging system. Acoustic signals are temporally filtered using an adaptive persistence filter, having a recursive stage followed by a nonrecursive stage. A set of filtering coefficients for each stage are supplied by a look-up table in a memory, addressed or indexed in response to a plurality of input or output pixel values. The look-up table may therefore embody any selected function of its input variables. The input variables for the look-up table function are a current input pixel value X.sub.n and a previous intermediate pixel value W.sub.n-1, and the function embodied by the look-up table includes a relative first difference function for selecting a filter coefficient. A recursive filtering coefficient .alpha. is held constant over time, while a nonrecursive filtering coefficient .gamma.is adjusted dynamically in response to the current input pixel value X.sub.n and the previous intermediate pixel value W.sub.

Abstract: A user defines a line of study by two or more icons placed on a two-dimensional motion image. A velocity profile or the estimated spectra at each point along the line of study are displayed as a function of position along the line of study. The velocity and variance parameters displayed are computed in reference to velocity direction angles selected by the user. The information displayed is obtained from scan converted information to facilitate the process. One or more spectral strips may be displayed in addition at one or more range gate positions.

Abstract: An ultrasound imaging system of the type having a receive beamformer that acquires multiple receive beams from each respective transmit beam includes an azimuthal spatial filter which operates to correct for geometric distortions typically associated with such multi-beam imaging systems. This azimuthal spatial filter is responsive to input signals derived from the receive beams to generate a corrected signal output as a function of a selected set of receive beams and a set of filter weights. The filter weights are caused to vary in accordance with the azimuthal coordinates of the selected receive beams in order to improve performance.

Abstract: A transducer array control system for use with a transducer housing and a transducer array that includes a sensing mechanism that generates a sensor signal having a first state indicative of the use of the transducer array. A control mechanism generates a transducer disabling signal when the sensor signal fails to enter the first state within a selected time period. Methods for disabling a transducer array are also provided.

Abstract: According to the present invention, an ultrasonic probe for use with a remote ultrasonic imaging system is provided, having a multielement transducer with an upper surface and a lower surface. An ultrasonically attenuative backing material adjoins the lower surface of the multielement transducer. The attenuative backing material is disposed within a container. A circular track is mounted to the container, and a flexible assembly and a carrier band are attached to the container. The carrier band may be operable to rotate the multielement transducer about an axis defined by the circular track. Alternatively, the circular track may be operable to rotate the multielement transducer. Additionally, a method of forming near real-time images of an object in a plane that is oblique to the axis of rotation of the multielement transducer is provided.

Abstract: A method for making Doppler ultrasound measurements utilizes an ultrasound probe having two transducer arrays oriented at right angles to one another and spaced apart from one another. The first array is used to measure multiple apparent Doppler parameters such as velocity at respective regions within a cross section of a structure such as a blood vessel. The second array is used to measure second apparent Doppler parameters at one of these regions. The first and second apparent Doppler parameters for the same point are used to correct the first apparent Doppler parameters to more nearly equal true velocity or energy.

Abstract: There is provided a two-dimensional array for use in an acoustic imaging system which comprises a plurality of transducer segments each having a trace for exciting an electrode on each of the transducer segments, the trace and the electrode being formed of the same material. The two-dimensional array disclosed is capable of imaging deeper in the human body at higher frequencies and provides more reliable lead attachments to the respective segments forming the array. Methods of manufacturing the two-dimensional array are further provided.

Abstract: The invention disclosed relates to a novel method of mapping and presenting fluid pressure information within a living body utilizing changes in acoustic behavior of microbubbles situated in a bodily fluid such as blood. Differences in the returned acoustic spectra from the microbubbles are related by an algorithm to fluid pressure which is colorized and presented in a manner similar to Doppler imaging. In a further aspect of the invention, the work output of an organ such as the heart may computed from the blood pressure information in association with flow information obtained through Doppler related imaging, which then, is presented in a colorized fashion. In a still further aspect, an improved method of assessing the health of tissue is disclosed utilizing changes in the acoustic spectra of microbubbles infused in the tissue in response to palpitation.

Abstract: There is provided a transducer array with a plurality of piezoelectric elements having a minimum and maximum thickness. In one embodiment, the maximum thickness is less than or equal to 140 percent of the minimum thickness. In an alternate embodiment, the maximum thickness is greater than 140 percent of the minimum thickness and the transducer array is capable of simulating the excitation of a wider aperture two-dimensional transducer array. One or more matching layers may be used to further increase bandwidth performance. In addition, a two crystal transducer element as well as a composite transducer structure may be formed using the principles of this invention.

Abstract: A method for imaging a target including a nonlinear contrast agent includes the steps of transmitting ultrasonic energy at a fundamental frequency and receiving reflected ultrasonic energy at a harmonic of the fundamental frequency. The ultrasonic energy is transmitted in power bursts, each having a respective envelope shape, wherein the envelope shapes rise gradually to a respective maximum value and fall gradually from the respective maximum value. Ultrasonic energy in the transmit beam is focused in an elongated high power region, as for example by means of a line focus.

Abstract: An ultrasonic imaging system includes an ultrasonic transducer having multiple ultrasonic transducer elements which are movable between at least first and second configurations which differ in curvature. The transducer elements supply receive signals to a receive beamformer, and the receive beamformer supplies output signals to a scan converter, which is controlled by a scan converter controller. The scan converter controller generates a control signal indicative of the configuration of the transducer elements, and the scan converter responds to this control signal to reduce image distortion associated with movement of the transducer elements between the first and second configurations.

Abstract: To overcome the disadvantages of the prior art, the present invention provides a method and apparatus for distributed focus control with slope tracking. The invention operates in the context of an ultrasonic imaging system having an array of transducers. Each transducer converts received energy into an echo signal. A beamformer of the invention dynamically focuses the received energy. The beamformer includes delay computation circuitry for computing a delay function for the echo signal at a predetermined focal range. The delay of the echo signal with respect to range has a slope. Tracking circuitry varies the delay function to track the slope, thereby determining the delay function for a next focal range. The beamformer further comprises delay circuitry for compensating for the delay function of the echo signal. The delay function is an estimated relative delay with respect to a reference delay of an echo signal from a reference transducer.

Abstract: A user defines a line of study by two or more icons placed on a two-dimensional motion image. A velocity profile or the estimated spectra at each point along the line of study are displayed as a function of position along the line of study. The velocity and variance parameters displayed are computed in reference to velocity direction angles selected by the user. The information displayed is obtained from scan converted information to facilitate the process. One or more spectral strips may be displayed in addition at one or more range gate positions.

Abstract: A method and apparatus is provided for controlling rotation of an ultrasound transducer. In accordance with the method of the present invention, a user-operable actuator that is movable over a continuous range of positions and generates a first signal representing the position of the actuator is provided. The method includes the steps of transforming the first signal into a second signal representing a desired velocity. Preferably, the second signal is a nonlinear transform of the first signal. The method further provides for rotating the ultrasound transducer in accordance with the second signal. In accordance with the apparatus of the present invention, a probe having a control housing, an actuator that may be manually positioned within a range of positions, and a transducer housing coupled to the control housing, which transducer housing contains an ultrasound transducer that is rotatably mounted for scanning a plurality of planes in a body, is disclosed.

Abstract: A method and an apparatus are provided for storage and retrieval of measured aberration correction values used in adaptive focus ultrasound imaging. The aberration correction values, corresponding to an aberration region in an imaged subject, are measured at a transmit focal depth. The measured aberration correction values, typically delays, from a measurement depth are stored in a geometric aberration transform (GAT.TM.) table and transformed to aberration correction values at other focal depths for correcting the focus of both transmit and receive beamformers. The transformation is accomplished by using a geometric aberration transform (GAT.TM.) index table which retrieves one or more aberration correction values in the table for any desired depth.

Abstract: Color Doppler data is acquired only over a portion of the cardiac cycle, such as during diastole in order to increase the sensitivity of detection. Ultrasound system parameters such as clutter filter coefficience, temporal and spatial filter coefficients may be altered only for a portion of the cardiac cycle to increase detection sensitivity, to improve myocardial border estimation and to avoid the loss of color Doppler image at end-diastole.

Abstract: An ultrasound tissue imaging system having an acoustic transducer, B-mode imaging means to produce with said transducer an electronically scanned B-mode image of tissue under examination. Doppler imaging means that accepts and processes large amplitude, low frequency signals to produce with said transducer an electronically scanned acoustic image of moving tissue, and color display means for displaying the B-mode image as a two-dimensional image with echo intensities encoded using a first mapping function and for simultaneously displaying Doppler information from moving tissue as a two-dimensional image using a second and distinct mapping function that is spatially coordinated with and superimposed upon said B-mode image to augment the B-mode image.