Method for computer-aided detection of clustered microcalcifications from digital mammograms
First Claim
1. A method of computerized detection of clustered microcalcifications in a digital mammogram derived from an original radiographic image, comprising:
- producing a multi-pixel difference image of said digital mammogram to remove low-frequency structured anatomic background;
performing a global gray-level thresholding of said difference image to produce a global thresholded image, includingproducing a histogram of the difference image,setting a global threshold based on a pre-selected percentage of pixels at the high end of the histogram,retaining unchanged in said difference image those pixels having a value above said global threshold, andsetting to a predetermined constant the values of those pixels in the difference image which have a value below said global threshold;
performing area filtering by means of morphological erosion on the image data resulting after global thresholding thereby to produce an area filtered image in which small signals are selectively removed; and
processing said area filtered image in which small signals are selectively removed to identify microcalcifications;
wherein said step of performing area filtering comprises;
defining plural structuring elements each having a size of at least two pixels,sequentially defining each pixel in the image after global thresholding as an operating pixel and sequentially overlaying each operating pixel with each structuring element;
determining, for each operating pixel sequentially overlaid by each structuring element, the minimum pixel value of the pixels overlaid by each structuring element in relation to the same operating pixel;
determining the maximum of the minimum pixel values determined in relation to the same operating pixel; and
setting the value of each pixel in the output area-filtered image corresponding to the position of the operating pixel in the global thresholded image to the respective maximum of said minimum values determined in the preceding step.
2 Assignments
0 Petitions
Accused Products
Abstract
A method of computerized detection of clustered microcalcifications in digital mammograms, including obtaining a digitized mammogram, deriving a difference image signal from the digitized mammogram, performing global grey-level thresholding, area filtering, and local grey-level thresholding on the difference image, in that order, performing a texture discrimination of the signal extracted from the previous step, performing a cluster filtering technique on the texture discriminated signals to identify locations in the digitized mammogram corresponding to candidate clustered microcalcifications, performing a feature extraction step in which the area, contrast and background pixel values of signals corresponding to the candidate clustered microcalcifications in the original image are extracted, performing thresholding tests based on the extracted features to eliminate from the candidate clustered microcalcifications particular candidate clustered microcalcification identified as corresponding to false-positive identifications, cluster filtering the remaining candidate clustered microcalcifications to eliminate further candidate clustered microcalcifications which are not sufficiently clustered, and outputting to a radiologist an image indicating, by use of arrows, the positions of the remaining clustered microcalcifications.
-
Citations
26 Claims
-
1. A method of computerized detection of clustered microcalcifications in a digital mammogram derived from an original radiographic image, comprising:
-
producing a multi-pixel difference image of said digital mammogram to remove low-frequency structured anatomic background; performing a global gray-level thresholding of said difference image to produce a global thresholded image, including producing a histogram of the difference image, setting a global threshold based on a pre-selected percentage of pixels at the high end of the histogram, retaining unchanged in said difference image those pixels having a value above said global threshold, and setting to a predetermined constant the values of those pixels in the difference image which have a value below said global threshold; performing area filtering by means of morphological erosion on the image data resulting after global thresholding thereby to produce an area filtered image in which small signals are selectively removed; and processing said area filtered image in which small signals are selectively removed to identify microcalcifications; wherein said step of performing area filtering comprises; defining plural structuring elements each having a size of at least two pixels, sequentially defining each pixel in the image after global thresholding as an operating pixel and sequentially overlaying each operating pixel with each structuring element; determining, for each operating pixel sequentially overlaid by each structuring element, the minimum pixel value of the pixels overlaid by each structuring element in relation to the same operating pixel; determining the maximum of the minimum pixel values determined in relation to the same operating pixel; and setting the value of each pixel in the output area-filtered image corresponding to the position of the operating pixel in the global thresholded image to the respective maximum of said minimum values determined in the preceding step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A method of computerized detection of clustered microcalcifications in a digital mammogram derived from an original radiographic image, comprising:
-
filtering said digital mammogram to produce a filtered image from which signals meeting predetermined criteria are removed; performing a first cluster filtering on said filtered image to produce a cluster image of single-pixel signals identifying locations of prospective problematic microcalcifications; extracting predetermined features from signals at locations in the digital mammogram identified by the single-pixel signals in said cluster image; performing at least one predetermined thresholding test based on the extracted features and based on said predetermined thresholding test, determining whether the signals from which the features were extracted correspond to a false-positive microcalcification cluster; eliminating from said cluster image those single-pixel signals corresponding to locations of false-positive microcalcification clusters; performing a second cluster filtering on the cluster image remaining after said eliminating step and outputting a further cluster image comprised of single-pixel values; and indicating in said original radiographic image locations of clustered microcalcifications based on the locations of pixels having a predetermined value in said further cluster image. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
-
Specification