摘要:
A time domain technique for implementing an adaptive wall filter improves imaging of low-velocity blood flow by removing signals associated with slowly moving tissue. Adaptive wall filtering is performed by estimating wall velocity and bandwidth, and then filtering the basebanded data with a complex time domain notch filter. The wall velocity estimate determines the center frequency of a wall signal while the wall variance estimate determines the wall signal bandwidth. The complex filter coefficients selected are those which will center the complex notch filter on the wall center frequency, and which will set the filter cutoff frequencies (measured from this center frequency) to match the wall signal bandwidth.
摘要:
An ultrasonic imaging system for displaying color flow images includes a receiver which demodulates ultrasonic echo signals received by a transducer array and dynamically focuses the baseband echo signals. A color flow processor includes a time domain adaptive wall filter which automatically adjusts to changes in frequency and bandwidth of the wall signal components in the focused baseband echo signals. The mean frequency of the resulting filtered baseband echo signals is used to indicate velocity of flowing reflectors and to control color in the displayed image.
摘要:
An ultrasonic imaging system for displaying color flow images includes a receiver which demodulates ultrasonic echo signals received by a transducer array and dynamically focuses the baseband echo signals. A color flow processor includes a frequency domain adaptive wall filter which automatically adjusts to changes in Doppler-shifted frequency and bandwidth of the wall signal components in the focused baseband echo signals after the echo signals have undergone Fourier transformation into the frequency domain. The mean Doppler-shifted frequency of the resulting filtered baseband echo signals is used to indicate velocity of moving scatterers and to control color in the displayed image.
摘要:
An ultrasound breast imaging assembly includes first and second compression plates angled with respect to one another, a breast compression area defined between the first and second compression plates, at least one pivot assembly, and an ultrasound probe. The pivot assembly allows relative motion between the first and second compression plates. The ultrasound probe, which is configured to translate over one of the first and second compression plates, includes an active matrix array (AMA) positioned on one of the first and second compression plates.
摘要:
A color flow processor has a fuzzy logic processor for determining when an adaptive wall filter can be turned off in response to the condition wherein flow signal will be treated as wall signal. The fuzzy logic processor uses details of wall velocity and power, as well as variance, to determine whether the measured echo signal component to be filtered truly represents the wall velocity only. The general rule applied by the fuzzy logic processor would be that if the wall velocity is LOW and the wall variance is LOW and the wall power is HIGH, than the adaptive filter is turned ON, where LOW and HIGH are fuzzy values. Use can be made of information from previous states, either temporally or spatially, allowing the system to adapt itself to each study or over time.
摘要:
In digital subtraction angiography a low X-ray energy temporal subtraction image is displayed on a video monitor. Regions in the temporal image frame that contain motion artifacts are outlined by using a cursor. The coordinates of the pixels in the defined outlined region are stored in a processor memory. The data for a related hybrid subtraction image are developed and stored. The processor then effects substitution of the hybrid subtraction image pixels, that fall within the same defined region, into the temporal subtraction image. The combined image data are transferred to a display controller memory which controls display of the combined image on a monitor. A method and means are provided for automatically determining the optimum value of the weighting coefficient applied to the high energy temporal subtraction image that results in the most complete cancellation of everything in the two images except the contrast medium filled blood vessel when the high and low energy temporal images are subtracted. A method and means are provided for altering the gain and offset of the hybrid image data in such manner as to match the hybrid image contrast and brightness with that of the temporal subtraction image.
摘要:
An ultrasonic imaging system for displaying color flow images includes a receiver which demodulates ultrasonic echo signals received by a transducer array and dynamically focuses the baseband echo signals. A color flow processor includes a plurality of logic units which perform different algorithms based on the type of examination being conducted.
摘要:
A multi-lag method for estimating both high and low velocities of blood flow from a single set of firings in situations where both high-velocity and low-velocity signals are of interest. A color flow processor uses multiple lags in the firing sequence. The normal lag of unity is used for high-velocity estimation; lags greater than unity are used for low-velocity estimation. A normal firing sequence is set up with a pulse repetition frequency that allows accurate velocity estimation of the highest flow velocity that the operator expects. This sequence yields data that is appropriately wall filtered, and a high-velocity estimate is made by correlation over adjacent firings, that is, firings 1 and 2, 2 and 3, 3 and 4, and so on, to the end of the packet, are respectively correlated. The same data is then used to provide a low-velocity estimate. The correlation is calculated between firings that are spaced by multiple units of the pulse repetition interval, e.g., by correlating firings 1 and 3, 2 and 4, 3 and 5, and so on.
摘要:
An ultrasound breast imaging assembly includes first and second compression plates angled with respect to one another, a breast compression area defined between the first and second compression plates, at least one pivot assembly, and an ultrasound probe. The pivot assembly allows relative motion between the first and second compression plates. The ultrasound probe, which is configured to translate over one of the first and second compression plates, includes an active matrix array (AMA) positioned on one of the first and second compression plates.
摘要:
An ultrasound system (1) acquires data using a gray scale mode of operation and a color flow mode of operation. A transducer (10) generates receive signals in response to echo ultrasound waves received from a subject (S) being studied. A gray scale receive channel (9G) generates gray scale data representing movement of portions of the subject, in particular that of blood flow or contrast agents in blood or tissue. A color flow receive channel (9C) generates color flow data (e.g., either power data or velocity data) also representing movement of portions of the subject. A processor (30) combines the gray scale flow data with the color flow data and displays the result on a display monitor (19) such that moving portions of the subject are displayed with a colored gray scale image.