Method and device for generating images from ultrasonic signals obtained by echography
First Claim
1. Method for generating images from source ultrasonic signals obtained by echography, wherein the echos signal is sampled and digitalized to form a succession of samples xi,jt as a echographical signal with a coded digital value of luminance X at an instant t, identified in the image by the row i of the horizontal column and the row j of the vertical column to which they belong, wherein said echographical signal is automatically processed to superimpose, on the image, a contour of the analyzed organ by the following steps:
- reducing the speckle present in said echographical signal through filtration by generating a prediction divergence signal which yields useful data by taking the difference between the digitalized signal xi,jt and a prediction signal calculated from a model of speckle, this step of reducing further providing a filtered digital signal Fi,jt and a binary signal Bi,jt deduced from the filtered signal produced by said filtration, at state 0 for the points of the filtered signal that have zero luminance and at state 1 for the other points;
processing said binary signal to extract from it the data corresponding to echos recognized as being non-characteristic of the contour, and outputting a signal Ii,jt ;
processing said signal Ii,jt by bridging to minimize discontinuities by eliminating isolated pixels, and outputting a bridged signal Ii,jt ;
processing said bridged signal Ii,jt to extract from it the characteristics parameters that can be used in a model of the contour of the organ examined, on the basis of a zone of maximum area, called a zero density zone, which comprises only zeros and corresponds to the interior of the organ analyzed;
calculating the pixels of the contour on the basis of said extracted characteristic parameters and the equation of the model of the organ;
replacing the digital signal, before filtration or when it is filtered, by an overlay signal for all the pixels of the contour;
displaying the result of said step of replacing the digital signal by said overlay signal.
1 Assignment
0 Petitions
Accused Products
Abstract
The method and the device provides for the automatic processing of digitalized signals in order to
remove speckle from the said signals by comparing the digitalized signal with a noise model obtained after learning its statistical properties,
extract, from the signals, echos not characteristic of the contour of the organ to be displayed,
extract the characteristic parameters of the contour from the said signals,
calculate the contour from these parameters by likening them to a pre-established model of variable parameters,
combine the digitalized signal, before or after eliminating noise, with the signal that is characteristic of the estimated position of the contour,
display the resultant signal in which the contour appears as an overlay.
50 Citations
14 Claims
-
1. Method for generating images from source ultrasonic signals obtained by echography, wherein the echos signal is sampled and digitalized to form a succession of samples xi,jt as a echographical signal with a coded digital value of luminance X at an instant t, identified in the image by the row i of the horizontal column and the row j of the vertical column to which they belong, wherein said echographical signal is automatically processed to superimpose, on the image, a contour of the analyzed organ by the following steps:
-
reducing the speckle present in said echographical signal through filtration by generating a prediction divergence signal which yields useful data by taking the difference between the digitalized signal xi,jt and a prediction signal calculated from a model of speckle, this step of reducing further providing a filtered digital signal Fi,jt and a binary signal Bi,jt deduced from the filtered signal produced by said filtration, at state 0 for the points of the filtered signal that have zero luminance and at state 1 for the other points; processing said binary signal to extract from it the data corresponding to echos recognized as being non-characteristic of the contour, and outputting a signal Ii,jt ; processing said signal Ii,jt by bridging to minimize discontinuities by eliminating isolated pixels, and outputting a bridged signal Ii,jt ; processing said bridged signal Ii,jt to extract from it the characteristics parameters that can be used in a model of the contour of the organ examined, on the basis of a zone of maximum area, called a zero density zone, which comprises only zeros and corresponds to the interior of the organ analyzed; calculating the pixels of the contour on the basis of said extracted characteristic parameters and the equation of the model of the organ; replacing the digital signal, before filtration or when it is filtered, by an overlay signal for all the pixels of the contour; displaying the result of said step of replacing the digital signal by said overlay signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. Device for generating images, using ultrasonic signals obtained by echography, comprising:
-
a memory input circuit a sequence of digitalized samples Xi,jt ; a speckle filtering circuit connected to said memory input circuit and providing an initial output to give a filtered digital signal of the speckle Fi,jt, and a second output to give an associated binary signal that has the logic 0 level for those points with a filtered value of zero and the logic 1 level for all the other points, a processing channel comprising, in series, a circuit for extracting data corresponding to echos not characteristic of the contour linked to the second output of the filtering circuit, bridging circuit to eliminate pixels detected as being isolated, a circuit for extracting the parameters of the contour and a circuit to calculate the contour, a single direct channel comprising a change-over switch, the inputs of which are linked to the output of the input circuit and to the first output of the filtering circuit, and the output of which transmits, to a delaying circuit, either the succession of digitalized samples Xi,jt or the filtered sequence Fi,jt, wherein the output of the direct channel after the delaying circuit and the output of the processing channel after the contour-calculating circuit is linked to the inputs of a circuit for overlaying the contour on the image, the output of this overlaying circuit being connected to a visual display screen. - View Dependent Claims (13, 14)
-
Specification