Abstract: An ultrasonic diagnostic system for measuring fluid flow velocities through Doppler techniques is provided which eliminates the effects of tissue motion from fluid flow velocity information. In a preferred embodiment Doppler information signal are discriminated to determine the presence of signal components resulting from moving tissue, which signal components are located at frequencies of a Doppler spectrum other than the predetermined frequency location of stationary tissue signals. The tissue motion signal components present are shifted to the predetermined frequency location and removed by high pass filtering the Doppler signals. The remaining signals are then shifted back to their original frequency location and transmitted to a Doppler velocity estimator for further processing of the fluid flow velocity information and ultimate display of the information.

Abstract: An ultrasonic imaging system for guiding a user in the placement of a medical instrument within the body is described. As the medical instrument approaches the image plane of an imaging transducer, ultrasonic wave energy is received by a transducer located on the medical instrument. The level of received energy is detected and used to develop a control signal which varies as a function of the quantum of received energy. The control signal is used to modulate an audible indicator, which provides an audible indiction of proximity of the medical instrument to the image plane as the instrument approaches and intersects the plane. A visual marker is produced on an image display which represent the location of the instrument within the body. As the instrument approaches and intersects the image plane the visual marker is also modulated.

Abstract: An ultrasonic diagnostic imaging system is provided for scanning with a linear transducer array and displaying an image area which is truncated with respect to a conventional triangular image sector to take the form of a trapezoid. Uniformity of image resolution and ease of signal processing enhancement is provided by transmitting adjacent ultrasonic beams at equal angular increments over the sector area. The ultrasonic beams transmitted are focused around predetermined transmit focal points and the transmit aperture employed for each transmission is determined by a transducer sensitivity criterion applied to the focal point. Means are provided for delaying signal components received from the beam directions so that the sum of the components will form a coherent echo signal.

Abstract: A technique for increasing the display frame rate of a medical ultrasound imaging system. The system receives trigger signals, each based upon the occurrence of a predetermined event in a subject's cardiac cycle, such as an R-wave. In one technique, in response to each trigger signal, the ultrasound system acquires a series of frames, each frame comprising data representing an image of a portion of the subject's body at an associated acquisition time. A frame time is determined for each frame, each frame time being the time from the preceding trigger signal to the acquisition time for the frame. Two or more frame series are then played back in order of increasing frame times, thereby producing a display frame rate higher than the acquisition frame rate.

Abstract: A system for imaging a biopsy needle with ultrasound is shown in which the needle tip elicits a Doppler response through controlled reciprocation of the needle tip. In a preferred embodiment the biopsy needle includes a hollow cannula which carries a removable stylet. Means for reciprocating the stylet is coupled to the proximal end of the stylet, and the distal tip of the stylet is reciprocated at the distal end of the cannula. This motion is detected through Doppler interrogation of the body region at which the biopsy is to be performed, and the Doppler response of the needle tip in the image of the body region allows the needle tip to be monitored as it approaches the tissue to be biopsied.

Abstract: An ultrasonic transesophageal scanhead is provided which enables a physician to easily and quickly change the orientation of the image plane during a scanning procedure without disrupting control of the scanhead. Means are provided on the external control unit of the scanhead for unambiguously selecting the orientation of the plane which is imaged by the transducers at the end of the probe of the scanhead. In one embodiment of the present invention, a rocker switch is provided on the underside of the control unit, and a lighted indicator is provided on top of the control unit. When the physician desires to change the image plane, the rocker switch is rolled forward to select the transducer elements of the probe which are configured for scanning in the desired image plane. As the rocker switch is moved, the lighted indicator on the top of the control unit provides a visual display pattern aligned either longitudinally or transversely with respect to the axis of the probe.

Abstract: A method and apparatus for producing the Doppler audio output in a medical ultrasound system. The system includes a transmitter for transmitting ultrasound into a body, a receiver for receiving and processing echoes to produce a Doppler signal, and a Doppler signal processor for converting the Doppler signals into an audio signal that in turn is converted into audible sound. The system alternates between first time intervals during which the Doppler samples are produced, and second time intervals when imaging is performed. The improvement of the invention involves producing at least one actual spectrum of the Doppler signal, based upon Doppler samples produced during one of the first time intervals. A synthetic spectrum is then produced for an adjacent second time interval, based upon the actual spectrum. The synthetic spectrum is then converted into a corresponding time domain data set, and the audio signal for the second time interval is then produced based upon the time domain data set.

Abstract: An improved temporal compounding technique for a medical ultrasound imaging system. The imaging system produces a plurality of pixel signals, such that each pixel signal comprises a time series of pixel values X(k), each pixel value being a function of the magnitude of the echo received from a particular sample volume. Each pixel signal is filtered to produce a filtered signal comprising a time series of filtered values Y(k). For each pixel signal, the characteristic of the filter varies as the magnitude of the pixel signal varies. In one embodiment, each filtered value Y(k) is equal to A.multidot.X(k)+(1-A).multidot.Y(k-1), with A being a monotonically increasing function of X(k). Embodiments are also disclosed in which the filter characteristic is a function of the absolute value of the difference between X(k) and Y(k-1).

Abstract: The present invention is a biopsy guide for use with a medical ultrasound scanhead of the type used for intravaginal scans and ultrasound guided biopsies. The guide fits over an intravaginal scanhead, and it includes a slot for guiding a biopsy needle. The guide also includes a unique needle cover which is slidably attached to the guide and which encloses a biopsy needle until actual flesh penetration is desired, thereby preventing unnecessary injury to a patient in the course of the examination.

Abstract: A Doppler blood velocity measuring device is described which includes anti-aliasing circuitry. The anti-aliasing circuitry is based upon the use of a multigate Doppler unit which receives Doppler shift frequency information from various depth ranges. Thereafter, the Doppler frequencies received are corrected by adding a correction frequency to the perceived Doppler frequency with the correction frequency selected based on the assumption that blood flow velocity cannot change drastically between adjacent depths.

Abstract: A method of manufacturing a phased array ultrasound transducer, and the transducer manufactured by the inventive method are described. In the method, a piezoelectric crystal is soldered to the edges of a pair of double sided printed circuit boards, each of which has traces on either side. Then, a backing material is poured to secure the crystal and boards, and a saw is used to define the elements of the transducer.

Abstract: The present invention is a method and structure which produces extremely thin, electrically conductive epoxy bonds between two substrates. Copper microspheres, having an average diameter of about 2 microns are bound in an epoxy layer which bonds two substrates together. The microspheres make electrical contact between the substrates while providing intersphere gaps which are filled with the epoxy which actually bonds the substrates together.

Abstract: The present invention is a multiline beamformer for use in a medical ultrasound scanner using a phased array transducer. Lines of ultrasound energy are generated having a pressure at the array aperture corresponding to sin (.pi.x)/.pi.x, where x is the normalized distance of the array element measured from the center of the array. This transmitted energy creates a flat field in space which can then be received in multiple receive lines, using bundled, parallel time delays.

Abstract: A circuit for controlling a patient exposure timer used to measure the time which a patient has been exposed to ultrasound energy is disclosed. The circuit operates by measuring a signal representative of whether an ultrasound transducer is coupled to air or to a patient. If the transducer is coupled to a patient, then the exposure timer is turned on. In the case of a mechanical scanhead, such as an oscillating scanhead or a rotating scanhead, the exposure timer control circuit can also be used to control the mechanical movement of the scanhead itself.

Abstract: The present invention relates to a seal for a rotatable therapeutic catheter, such as a motor driven therapeutic catheter. The seal is made of a drive shaft which extends through an elongated bushing. The combined drive shaft and bushing form a low-friction axle/bearing combination such that there is little friction between them. In addition, the long restrictive path between the drive shaft and the bushing serves to prevent leakage between them.