Arch Development Corporation

The University of Chicago

Heber MacMahon

Samuel G Armato, Iii

Maryellen L Giger

Kunio Doi

Xin-Wei Xu

Kenneth R Hoffmann

Samuel Armato

Samuel G Armato Iii

Roger Engelmann

Geoffrey R Oxnard

An apparatus, method and computer program product for performing computer aided diagnosis on temporal subtraction images of objects. A mode of a gray-level histogram is identified, and a gray-level threshold is established at a predefined fraction of this modal value. All pixels with gray levels below this threshold that lie within the lung regions of the temporal subtraction image remain 'on,' while all other pixels are set to zero. Area and circularity requirements are imposed to eliminate false-positive regions. Areas of pathologic change identified in this manner may be presented as outlines in the subtraction image or as highlighted regions in the original radiographic image so that, in effect, temporal subtraction becomes a 'background' process for computer-aided diagnosis. The present invention is also directed to method, apparatus, and computer program product for performing temporal subtraction on energy subtraction images, with or without subsequent computer aided diagnosis, of objects.

Automated method and system for the evaluation of disease and registration accuracy in the subtraction of temporally sequential medical images

A method, system and computer readable medium for automated detection of lung nodules in computed tomography (CT) image scans, including generating two-dimensional segmented lung images by segmenting a plurality of two-dimensional CT image sections derived from the CT image scans; generating three-dimensional segmented lung volume images by combining the two-dimensional segmented lung images; determining three-dimensional lung nodule candidates from the three-dimensional segmented lung volume images, including, identifying structures within the three-dimensional segmented lung volume images that meet a volume criterion; deriving features from the lung nodule candidates; and detecting lung nodules by analyzing the features to eliminate false-positive nodule candidates from the nodule candidates.

Method, system and computer readable medium for the two-dimensional and three-dimensional detection of lesions in computed tomography scans

A method, system, and computer program product for automated and semi-automated measurements of pleural space and/or pleural thickening in thoracic CT images to identify the presence and quantify the extent of pleura-based disease, including obtaining a CT image including the pleural space and/or the pleural thickening, segmenting lungs in the obtained image, obtaining an initial endpoint on a chest wall or a mediastinum boundar; determining a terminal endpoint on a boundary of the at least one segmented lung; and determining a distance between said initial endpoint and said the terminal endpoint as the extent of the pleural space and/or the pleural thickening. Exemplary embodiments include determining the extent of pleural space and/or pleural thickening based on linear distance, area, and volume of the space between the lung boundary and at least one of the chest wall and the mediastinum boundary. These pleural determinations may be used to quantify the extent of disease in a particular case as additional information to be incorporated into a radiologist's decision-making process, or as part of a computer-aided diagnostic scheme that alerts radiologists of the potential for pleural disease in the case.

Automated method and system for the delineation of the chest wall in computed tomography scans for the assessment of pleural disease

A method, system, and computer product for the automated segmentation of the lung fields and costophrenic angle (CP) regions in posteroanterior (PA) chest radiographs, wherein image segmentation based on gray-level threshold analysis is performed by applying an iterative global gray-level thresholding method to a chest image based on the features of a global gray-level histogram. Features of the regions in a binary image constructed at each iteration are identified and analyzed to exclude regions external to the lung fields. The initial lung contours that result from this global process are used to facilitate a local gray-level thresholding method. Individual regions-of-interest (ROIs) are placed along the initial contour. A procedure is implemented to determine the gray-level thresholds to be applied to the pixels within the individual ROIs. The result is a binary image, from which final contours are constructed. Smoothing processes are applied, including a unique adaptation of a rolling ball method. CP angles are identified and delineated by using the lung segmentation contours as a means of placing ROIs that capture the CP angle regions. Contrast-based information is employed on a column-by-column basis to identify initial diaphragm points, and maximum gray-level information is used on a row-by-row basis to identify initial costal points. Analysis of initial diaphragm and costal points allows for appropriate adjustment of CP angle ROI positioning. Polynomial curve-fitting is used to combine the diaphragm and costal points into a continuous, smooth CP angle delineation. This delineation is then spliced into the final lung segmentation contours. In addition, quantitative information derived from the CP angle delineations is used to assess the presence of abnormal CP angles.

Method and system for the automated delineation of lung regions and costophrenic angles in chest radiographs

A method, system, and computer program product for automated measurements of pleural space and/or pleural thickening in thoracic CT images to identify the presence and quantify the extent of pleura-based disease, including obtaining a CT image including the pleural space and/or the pleural thickening, segmenting lungs in the obtained image, constructing a chest wall image from the obtained image using a lung boundary obtained in the segmenting step, identifying ribs in the chest wall image, mapping a location of the identified ribs back into the obtained image, and determining in the obtained image the extent of the pleural space and/or the pleural thickening between the identified ribs mapped back into the obtained CT image and at least one segmented lung. Exemplary embodiments include determining the extent of pleural space and/or pleural thickening based on linear distance, area, and volume of the space between the ribs and the lung boundary. These pleural determinations may be used to quantify the extent of disease in a particular case as additional information to be incorporated into a radiologist's decision-making process, or as part of a computer-aided diagnostic scheme that alerts radiologists of the potential for pleural disease in the case.

Detecting costophrenic angles in chest radiographs

A system and method for digital imaging. A digital radiological image of a subject is obtained having at least one low density region. The image is processed using first weighting factors in the at least one low density region of the digital image and second weighting factors smaller than the first weighting factors in regions of the digital image other than the at least one low density region. A processed digital image is obtained and a representation of the processed digital image is produced. In the processing of the image, unsharp mask filtering is employed using a processing curve having maximum unsharp mask filtering in the at least one low density region of the digital image and a constant amount of unsharp mask filtering less than the maximum unsharp mask filtering in the regions of the image other than the low density regions.

Method and system for digital radiography

A method and system for the automated segmentation of the lung regions in lateral chest radiographs. This is achieved according to the invention by providing an improved computerized, automated method for image segmentation based on gray-level threshold analysis. A unique method for identifying an approximate outer bounds on the extent of the lung fields in the image is performed to restrict the region further analyzed. An iterative global gray-level thresholding method is applied based on the features of a global gray-level histogram. Features of the regions in a binary image constructed at each iteration are identified and subjected to a modified analysis to exclude regions external to the lung field. The initial lung region contour that results from this global process is used to facilitate a novel adaptive local gray level thresholding method. Individual regions-of-interest (ROIs) are placed along the initial contour. The dimensions of the several ROIs are based upon the patient anatomy enclosed therein. A unique procedure is implemented to determine the single gray-level threshold to be applied to the pixels within the individual ROIs. A composite binary image results, and a final contour is constructed to enclose &ldquo;on&rdquo; regions thereof. Smoothing processes are applied, including a unique adaptation of a rolling ball method, and fitted polynomial curves are spliced into the final contour.

Method and system for the segmentation of lung regions in lateral chest radiographs

A method, system, and computer product for the automated segmentation of the lung fields and costophrenic angle (CP) regions in posteroanterior (PA) chest radiographs wherein image segmentation based on gray-level threshold analysis is performed by applying an iterative global gray-level thresholding method to a chest image based on the features of a global gray-level histogram. Features of the regions in a binary image constructed at each iteration are identified and analyzed to exclude regions external to the lung fields. The initial lung contours that result from this global process are used to facilitate a local gray-level thresholding method. Individual regions-of-interest (ROIs) are placed along the initial contour. A procedure is implemented to determine the gray-level thresholds to be applied to the pixels within the individual ROIs. The result is a binary image, from which final contours are constructed. Smoothing processes are applied, including a unique adaptation of a rolling ball method. CP angles are identified and delineated by using the lung segmentation contours as a means of placing ROIs that capture the CP angle regions. Contrast-based information is employed on a column-by-column basis to identify initial diaphragm points, and maximum gray-level information is used on a row-by-row basis to identify initial costal points. Analysis of initial diaphragm and costal points allows for appropriate adjustment of CP angle ROI positioning. Polynomial curve-fitting is used to combine the diaphragm and costal points into a continuous, smooth CP angle delineation. This delineation is then spliced into the final lung segmentation contours. In addition, quantitative information derived from the CP angle delineations is used to assess the presence of abnormal CP angles.

A method, system and computer readable medium configured for computerized detection of lung abnormalities, including obtaining a standard digital chest image and a soft-tissue digital chest image; generating a first difference image from the standard digital chest image and a second difference image from the soft-tissue digital chest image; identifying candidate abnormalities in the first and second difference images; extracting from the standard digital chest image and the first difference image predetermined first features of each of the candidate abnormalities identified in the first difference image; extracting from the soft-tissue digital chest image and the second difference images predetermined second features of each of the candidate abnormalities identified in the second difference image; analyzing the extracted first features and the extracted second features to identify and eliminate false positive candidate abnormalities respectively corresponding thereto; applying extracted features from remaining candidate abnormalities derived respectively from the first and second difference images and remaining after the elimination of the false positive candidate abnormalities to respective artificial neural networks to eliminate further false positive candidate abnormalities; performing a logical OR operation of the candidate abnormalities derived respectively from the first and second difference images and remaining after the elimination of the false positive candidate abnormalities; and outputting a signal indicative of a result of performing the logical OR operation. The logical OR combination, of locations of the candidate abnormalities detected in the first difference image and the second difference image, yields an improved detection sensitivity (over 90%) and only slightly increased false positives rate (3.2 false positives per chest image).

Computerized detection of lung nodules using energy-subtracted soft-tissue and standard chest images

A method and system for displaying medical images and computer output from various CAD schemes on the images. Images are loaded into the display system and displayed in a main viewing area. The system can display various CAD schemes, such as the automated detection of lung nodules, interstitial infiltrates, and heart size, in the case of a chest image, on the image. The method and system also display interval change (temporal subtraction) between images. Individual abnormality from CAD schemes can be viewed by clicking buttons with minified (postage stamp size) images with CAD annotation rendered into them. The images and results are then shown on a high-speed monitor. Interval change between the current and a previous image can also be chosen by clicking buttons containing minified images. Interval change between any other pair of images for a patient can be selected by choosing from minified subtraction images presented in a two-dimensional array format. A previewer next to the array permits rapid inspection of subtraction images before a subtraction set is chosen for detailed study.

Method and system for displaying medical images

A method for the automated detection of gross abnormalities and asymmetries in chest images, including generating image data from radiographic images of the thorax. The image data are then analyzed in order to produce the boundaries of the aerated lung regions in the thorax. This analysis comprises location of the mediastinum and lung apices, iterative global thresholding with centroid testing of contours, local thresholding on regions along initial contours of the aerated lung, correction for regions near the costo- and cardiophrenic angles in the chest, analysis of the areas and density distribution within the aerated lung regions in the chest and determination of the likelihood of the presence of a gross abnormality or asymmetry. Final output could be the computer determined contours of the lungs or the likelihood for abnormality.

Automated method and system for the detection of gross abnormalities and

An alignment method and system for aligning an anti-scatter grid with an x-ray source of a radiographic apparatus, to facilitate accurate alignment of the central x-ray beam of the x-ray source of the radiographic apparatus with a focused grid. The present invention uses a first light projector that is substantially fixed relative to the x-ray source, which produces a first alignment image that is substantially fixed relative to the grid. Also included is a second light projector that is substantially fixed relative to the grid, and that produces a second alignment image that is substantially fixed relative to the x-ray source. The first light projector is preferably the collimator light included within the collimator housing of the x-ray apparatus, and the second light projector is preferably a laser light source, that is attachable to a grid cassette holding the grid.

Alignment method for radiography and radiography apparatus incorporating

An optical alignment system for aligning a film cassette carrying grid cassette with an x-ray source of a portable x-ray apparatus. To facilitate accurate alignment of the central x-ray beam of the x-ray source of a portable x-ray apparatus with a focused grid in a clinical setting, the present invention uses a light projector and a reflector device. The light projector is substantially fixed relative to the x-ray source and projects a spot or line of light on the surface of the grid cassette. The reflector device, which can be temporarily or permanently fixed to the grid cassette, includes a reflector surface and an image surface. Images of the incident light spot or line and of the reflected light spot or line are formed on the image surface, and the distance between the images indicates the magnitude of angulation alignment error between the grid cassette and the x-ray source. When beam alignment is accurate, the incident light spot or line and reflected light spot or line will be substantially superimposed, producing a single image on the reflector element. In addition, an opaque line on the transparent front surface of the collimator housing of the x-ray apparatus appears as a dark shadow within the field projected by the collimation light. Coincidence between the incident light spot or line and the shadow produced by the opaque line on the collimator serves as a distance indicator facilitating the placement of the grid cassette at the proper focal distance from the x-ray source. Further aspects of the invention include radiopaque markers which are located on front and rear surfaces of the grid cassette, and which produce images on an x-ray film when exposed. The relative positions between the images of the markers on the exposed radiographs are indicative of the amount of angulation alignment error between the grid cassette and the x-ray source. Yet another aspect of the present invention is the capability of the grid cassette to accommodate a standard x-ray film cassette in either a horizontal or vertical orientation, without reorienting the grid cassette itself.

Optical grid alignment system for portable radiography and portable

An alignment device for use in mobile radiography. In contrast to prior practice in which a film cassette is placed on one side of the patient, an x-ray source on the other, and it is left to the skill of the technician to approximate the necessary alignment, the present invention assures consistent alignment much more precise than is typically achieved. The precise alignment allows regular use of a grid in mobile radiography which helps to prevent image deterioration caused by scattered radiation. The precise alignment is achieved by providing an adaptable physical connection which when in the deployed condition, accurately establishes both the distance between the focal spot and the film plane and the alignment of the grid with respect to the central ray.

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Chicago, IL, United States of America

Heber MacMahon