Measurement of vetricle volumes with cardiac MRI
First Claim
1. A method of generating outlines of ventricular volumes, the method comprising:
- non-invasively examining a region of a patient which includes at least one ventricle of a heart, the region being divided into an array of voxels, and generating a first image representation having an intensity value representing each voxel of the region;
storing the first image representation;
a time interval after generating the first image representation, non-invasively re-examining the region and generating a second image representation having an intensity value for each voxel of the region;
storing the second image representation;
subtracting the intensity values corresponding to common voxels of the first and second image representations to create difference intensity values of a difference image representation in which the difference intensity values corresponding to voxels containing substantially stationary tissue are substantially zero and the difference intensity values corresponding to voxels representing tissues which moved in the time interval between the first and second image representations are not zero, whereby the non-zero intensity values define an edge around the at least one ventricle of the heart.
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Abstract
A first image (20) and a second image (22) are taken through the patient'"'"'s heart region at small time displaced intervals. The first and second images are subtracted (24) to generate a difference image which is indicative of the tissue which has moved during the short time interval, i.e. the boundary of the ventricles. Voxels from regions outside the boundary are adjusted to remove lung tissue (40), and ventricle boundary or edge voxels (48) and analyzed to generate a non-blood tissue histogram (62). Voxels within the boundary are analyzed to generate a blood tissue histogram (60). The histograms are fit (66, 74) to smooth curves which represent the probability distribution or confidence that each voxel value represents blood or non-blood tissue. Contiguous voxels within the boundary are counted (96) and adjusted for voxel size (98) to create an indication of left and right ventricle volume (100l, 100r). In the preferred embodiment, the ventricle volume is determined by summing the confidence value that each voxel within the boundary represents blood.
79 Citations
28 Claims
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1. A method of generating outlines of ventricular volumes, the method comprising:
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non-invasively examining a region of a patient which includes at least one ventricle of a heart, the region being divided into an array of voxels, and generating a first image representation having an intensity value representing each voxel of the region; storing the first image representation; a time interval after generating the first image representation, non-invasively re-examining the region and generating a second image representation having an intensity value for each voxel of the region; storing the second image representation; subtracting the intensity values corresponding to common voxels of the first and second image representations to create difference intensity values of a difference image representation in which the difference intensity values corresponding to voxels containing substantially stationary tissue are substantially zero and the difference intensity values corresponding to voxels representing tissues which moved in the time interval between the first and second image representations are not zero, whereby the non-zero intensity values define an edge around the at least one ventricle of the heart.
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2. A method of generating outlines of ventricular volumes, the method comprising:
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non-invasively examining a region of a patient which includes at least one ventricle of a heart and generating (1) a first image representation representing the region and (2) a second image representation of the region using a black blood cine technique such that the first and second image representations depict blood tissue in black and non-blood tissue in lighter shades, the first and second image representations being displaced in time; subtracting the first and second image representations to create a difference image representation in which stationary tissue is depicted substantially in white and tissues which moved in the time between the first and second image representations are displayed in black, whereby the difference image representation depicts a ventricle defining edge in black against a substantially white background.
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3. A method of analyzing ventricular volumes, the method comprising:
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non-invasively examining a region of a patient which includes a heart and generating (1) a first image representation having intensity values representing voxels of the region and (2) a second image representation having intensity values representing voxels of the region, the first and second image representations being displaced in time; subtracting the intensity values of the first and second image representations corresponding to like voxels to create intensity values of a difference image representation in which the intensity values of voxels of the first and second image representations representing substantially stationary tissue cancel and the intensity values of the first and second image representations representing tissues which moved between the first and second image representations do not cancel, such that the non-canceling intensity values define an edge around at least one ventricle of the heart; and counting a number of voxels within the ventricle defining edge, the number of counted voxels being proportional to ventricular volume. - View Dependent Claims (4, 5, 6, 7)
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8. A method of analyzing ventricular volume comprising:
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non-invasively examining a region of a patient which includes at least one ventricle to generate values of voxels of a ventricle image representation; determining boundary indicative voxels of the ventricle image representation which are indicative of a peripheral boundary of the ventricle; determining a frequency of occurrence for voxel values of inside voxels disposed within the boundary indicative voxels; in accordance with the frequency of occurrence of each inside voxel value, determining a probability that each inside voxel value corresponds to blood tissue; counting the inside voxels and weighting each counted inside voxel in accordance with its determined probability to determine a sum which sum is proportional to the ventricular volume. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An apparatus for generating outlines of ventricular volumes, the apparatus comprising:
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a non-invasive examination means for non-invasively examining a region of a patient which includes ventricles of a heart, the region being divided into a rectangular array of voxels, and generating (1) a first image representation having an intensity value representing each voxel of the region and (2) a second image representation having an intensity value representing each voxel of the region, the first and second image representations being displaced in time; a subtracting means for subtracting the intensity values corresponding to common voxels of the first and second image representations to create difference intensity values of a difference image representation in which the difference intensity values corresponding to voxels containing substantially stationary tissue cancel and the difference intensity values corresponding to voxels that contain tissues which moved between the first and second image representations do not cancel, whereby the non-cancelling intensity values of the difference image representation represent an edge around ventricles of the heart; and a memory means for storing the difference intensity values of the difference image representation.
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19. An apparatus for analyzing ventricular volumes, the apparatus comprising:
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a non-invasive examination means for non-invasively examining a region of a patient which includes a heart and generating (1) a first image representation representing the region and (2) a second image representation of the region, the first and second image representations being displaced in time; a subtracting means for subtracting the first and second image representations to create a difference image representation in which voxel values of voxels of the first and second image representations representing substantially stationary tissue cancel and voxel values of like voxels representing tissues which moved between the first and second image representations do not cancel, whereby the difference image representation represents a surface of non-canceling voxel values around ventricles of the heart; a counting means for counting a number of voxels within the surface of non-canceling voxel values, the number of counted voxels being proportional to ventricular volume; and
,a display means for displaying the ventricular volume.
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20. An apparatus for analyzing ventricular volumes, the apparatus comprising:
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a non-invasive examination means for non-invasively examining a region of a patient which includes a heart and generating (1) a first image representation representing the region and (2) a second image representation of the region, the first and second image representations being displaced in time; a subtracting means for subtracting the first and second image representations to create a difference image representation in which voxel values of voxels of the first and second image representations representing substantially stationary tissue cancel and voxel values of like voxels representing tissues which moved between the first and second image representations do not cancel, whereby the difference image representation represents a ventricular edge. a probability determining means for determining a confidence value indicative of a probability that each voxel value within the ventricular edge defines blood; and a weighting means for weighting each counted voxel in accordance with the confidence value.
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21. An apparatus for analyzing ventricular volumes comprising:
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a non-invasive examination means for non-invasively examining a region of a patient which includes at least one ventricle to generate intensity values of voxels of a ventricle image representation; a means for determining which voxels of the ventricle image representation are indicative of a peripheral boundary of the ventricle; a histogram generating means for determining a frequency of occurrence of the intensity values of voxels surrounded by the ventricle boundary; a means for determining from the frequency of occurrence a probability that each of the intensity values corresponds to blood tissue; a counting means for counting voxels surrounded by the ventricle boundary and weighting each counted voxel in accordance with its determined probability to determine a sum which is proportional to the ventricular volume. - View Dependent Claims (22, 23)
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24. An apparatus for measuring ventricular volumes, the apparatus comprising:
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a non-invasive examination means for generating volume image representations of a patient region including its heart; a means for locating a subregion encompassing the heart; a means for determining a range of intensity values of voxels of the volume image representations, one of the volume image representations having a range of intensity values corresponding to blood tissue and a range of intensity values corresponding to non-blood tissue; a means for counting contiguous voxels with intensity values in the intensity value range corresponding to blood tissue, which voxel count is indicative of ventricular volume. - View Dependent Claims (25, 26, 27, 28)
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Specification