Abstract: A method and apparatus for determining resistance and pulsatility indices of a flow of material, such as the flow of blood in the human body. This may be implemented, for example, in a color flow module in an ultrasonic imaging system for display of the pulsatility or resistance index in two dimensions and in different colors to allow discrimination between veins and arteries and detection of pathologic elevation of vascular resistance in a clinical survey mode of the system. The resistance index is determined from the ratio of a unipolar variation estimate of a velocity of the flow material divided by a peak velocity. The variation estimate may be one of the following: a difference between a peak velocity of the flow of material and a second minimum (if unipolar) or negative (if bipolar) velocity of the flow of material, a standard deviation .rho.

Abstract: A method and apparatus for displaying an image representing the flow of a substance in a scanned area. An Angio scanner scans a region of tissue and generates Ultrasound Angio data representing the flow of blood in the region of tissue. Relatively small blood flows are difficult to detect in images based solely on Angio data. To enhance the visibility of small blood flows, spatial derivative values are calculated from the Angio data. A fraction of the original Angio data plus a bias is summed with the spatial derivative values to generate composite values. An image of the scanned region is displayed with colors or grayscale shades based on the composite values. The resulting image depicts blood vessels in an edge-enhanced format, giving a three-dimensional appearance.

Abstract: A method and apparatus of processing signals in an ultrasonic imaging system for imaging a living subject. The ultrasonic imaging system including an ultrasonic emitter, receptor and display. N temporally-spaced signals from ultrasound produced by a plurality of temporally-spaced referenced pulses are obtained and the amplitude (power) of each of the N temporally-spaced signals is determined. In various embodiments, N is an odd integer, usually, 1, 3, 5 or 7, depending on a user-setting. A median temporal signal of the N amplitude signals is then obtained. In implemented embodiments, the median is obtained by sorting a list of the N amplitude signals until (N+1)/2 signals have been sorted. The median is temporally filtered with a previous signal displayed on the display of the ultrasonic imaging system, wherein the temporal filtering including a filtering coefficient having a magnitude approximating a cardiac cycle of the living subject.

Abstract: Method and apparatus for performing angiography of a subject under examination in an ultrasonic imaging apparatus. A set of ultrasonic reference pulses along each of a series of parallel vectors is emitted into the subject under examination, echoes are received, and a plurality of data samples are obtained. From each of the plurality of data samples a plurality of basis functions are removed to remove clutter and generate a plurality of processed samples. The processed samples are averaged and temporally filtered with signals displayed in a previous time period to generate a second averaged signals. The temporal filtering is performed using a filter coefficient which approximates a full cardiac cycle of the subject under examination.

Abstract: An apparatus for temporal filtering in an ultrasonic imaging system. The apparatus has a means for storing previous imaging information from a previous time period and a means for storing current imaging information from a current time period. Means for determining the larger of the current and previous imaging information is provided and a means is provided for generating an alpha value responsive to the larger information. The alpha value ranges between a minimum and maximum values and has the maximum value when the larger information has a large frequency and has the minimum value when the larger information has a small frequency. Means for generating output imaging information is provided, the output imaging information generated by multiplying the current imaging information by alpha and summing it with the product of the maximum value minus alpha and the previous imaging information.

Abstract: An apparatus and method for clutter elimination from signals which digitizes a signal to generate n samples of the signals. M basis functions (such as various levels of filters) are fit to the n samples. An i+1 basis function of the m basis functions is iteratively subtracted from each of the n samples, and the difference is stored in an i difference signal until the i+1 difference signal is less than a threshold. In various embodiments, the threshold may be an absolute noise floor (R.sub.O.sup.min) preset by a manufacturer or a user. In other embodiments, the threshold may be based upon an absolute or relative predictor error of the signal once the basis function (filter) has been removed. The i difference signal may be used for performing a frequency estimate of the signal.

Abstract: Signal processing apparatus and methods for elimination of undesirable clutter signals from desirable signals. This is performed without the use of filters by subtracting orthonormal basis functions from signal samples until the appropriate degree of clutter removal is achieved. Estimates of frequency information such as Doppler shifts due to fluid flow may thus be achieved with superior discrimination of true flow signals from sources of clutter or artifact, greater sensitivity to low flow rates, minimal computational effort and with fewer samples than the prior art.

Abstract: An apparatus and method for displaying ultrasonic data in real time reflected in a living organism. The apparatus comprises a plurality of analog-to-digital converters for digitizing reflected Doppler signals produced by reflecting a reference pulsed acoustic signal, each of the analog-to-digital converters capable of producing a plurality of digitized Doppler signals. The apparatus futher comprises a plurality of digital signal processors, each of the plurality of digital signal processors coupled to each of the plurality of analog-to-digital converters for processing digitized Doppler signals received from the analog-to-digital converters, each of the digital signal processors capable of producing a plurality of processed digital signals.