Matched filter for X-ray temporal subtraction

Claim 1

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the period during which contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images and means including a video camera are operative to produce data representative of the images, the method including the following steps: during said pre-contrast period, acquire an initial mask x-ray image and an additional sequence of pre-contrast images and take the differences between logarithmic data representative of the mask image data and logarithmic data representative of the respective additional images data and store the resulting sequence of pre-contrest difference image data, when the contrast medium arrives in the vessel, start to acquire an additional sequence of post-contrast and after-contrast images and take the differences between logarithmic data representative of the initial mask image and logarithmic data representative of the additional post-contrast and after-contrast images and store the resulting sequence of difference image data, multiply the sequence of pre-contrast, post-contrast and after-contrast difference image data by respective coefficients the coefficients by which the post-contrast difference image data are multiplied being proportional to the projected intensity, h, of the contrast medium bolus at times (t) and Substantially registered with the post-contrast difference images so that a selected one of the coefficients is applied to the corresponding post-contrast image containing maximum contrast medium, and the coefficients applied to the pre-contrast and after-contrast difference images are selected so that the summation of all coefficients equals substantially zero, and sum the results of the sequence of multiplications of coefficients and difference image data to produce a set of data representative of the contrast medium in the vessel.

Claim 2

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the period during which contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images and means including a video camera are operative to produce data representative of the images, the method including the following steps: during said pre-contrast period, acquire an initial mask x-ray image and an additional sequence of pre-contrast images and take the differences between logarithmic data representative of the mask image data and logarithmic data representative of the respective additional images data and store the resulting sequence of pre-contrest difference image data, when the contrast medium arrives in the vessel, start to acquire an additional sequence of post-contrast and after-contrast images and take the differences between logarithmic data representative of the initial mask image and logarithmic data representative of the additional post-contrast and after-contrast images and store the resulting sequence of difference image data, multiply the sequence of pre-contrast, post-contrast and after-contrast difference image data by respective coefficients the coefficients by which the post-contrast difference image data are multiplied being proportional to the projected intensity, h, of the contrast medium bolus at times (t) and Substantially registered with the post-contrast difference images so that a selected one of the coefficients is applied to the corresponding post-contrast image containing maximum contrast medium, and the coefficients applied to the pre-contrast and after-contrast difference images are selected so that the summation of all coefficients equals substantially zero, and sum the results of the sequence of multiplications of coefficients and difference image data to produce a set of data representative of the contrast medium in the vessel.

Claim 7

The method as in any of claims 1, 2, 3,4 or 5 wherein the energization factors of said x-ray source are an anode voltage in the range of 55 to 100 kilovolts and a current in the range of 5 to 20 milliamperes.

Claim 10

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the period during which the contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images, and means including a video camera are operative to produce data representative of the images, the method including the following steps: acquire a sequence of x-ray images starting at the beginning of the pre-contrast period and continuing through the post-contrast period, and convert the data representative of the images to logarithmic data, using the manner in which the projected intensity of the contrast medium at a point in an image of the vessel chances as a function, h, of time (t), multiply the data representative of the post-contrast images by respective coefficients that are proportional to the projected intensity of a contrast medium, h, at time (t), substantially registered with the post-contrast images so that a selected one of the coefficients such as the maximum coefficient is applied to the post-contrast image containing peak contrast, sum the results of the respective multiplications and store the resulting data, multiply data representative of the respective pre-contrast and after-contrast images, if any, by respective coefficients selected so that the difference between the sum of the coefficients applied to the pre-contrast and after-contrast images and the swn of the coefficients applied to the post-contrast images is substantially equal to zero, sum the results of the respective multiplications and store the resulting data, take the difference between the sum produced after said multiplying of the pre-contrast and after-contrast images data and the sum produced after said multiplying of the post-contrast images data to produce a set of data representative of an image of the contrast medium in the vessel.

Claim 11

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the period during which the contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images, and means including a video camera are operative to produce data representative of the images, the method including the following steps: acquire a sequence of x-ray images starting at the beginning of the pre-contrast period and continuing through the post-contrast period, and convert the data representative of the images to logarithmic data, using the manner in which the projected intensity of the contrast medium at a point in an image of the vessel chances as a function, h, of time (t), multiply the data representative of the post-contrast images by respective coefficients that are proportional to the projected intensity of a contrast medium, h, at time (t), substantially registered with the post-contrast images so that a selected one of the coefficients such as the maximum coefficient is applied to the post-contrast image containing peak contrast, sum the results of the respective multiplications and store the resulting data, multiply data representative of the respective pre-contrast and after-contrast images, if any, by respective coefficients selected so that the difference between the sum of the coefficients applied to the pre-contrast and after-contrast images and the swn of the coefficients applied to the post-contrast images is substantially equal to zero, sum the results of the respective multiplications and store the resulting data, take the difference between the sum produced after said multiplying of the pre-contrast and after-contrast images data and the sum produced after said multiplying of the post-contrast images data to produce a set of data representative of an image of the contrast medium in the vessel.

Claim 16

The method as in any of claims 9; 10, 11, 12 or 13 wherein the energization factors of said x-ray source are an anode voltage in the range O 55 to 100 kilovolts and a current in a range of 5 to 20 milliamperes.

Claim 19

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the period during which the contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images, and means including a video camera are operative to produce data representative of the images, the method including the following steps: acquire a sequence of x-ray image frames over the pre-contrast period and at least over the post-contrast period and convert the data representative of said image frames to corresponding logarithmic data representative of the sequence of images, respectively, using the manner in which the projected intensity of the contrast medium changes as a function h of time (t), multiply the data, respectively, representing the sequence of pre-contrast, post-contrast and after-contrast.images, if any, by a sequence of coefficients, the coefficients for multiplying the post-contrast images data being proportional to the projected intensity of the contrast medium h(t) substantially registered with the post-contrast image so that a selected one of the post-contrast images such as the maximum coefficient is applied to the post-contrast image data containing peak contrast, and the coefficients by which the pre-contrast and after-contrast image data are multiplied are selected so that the sum of all coefficients equals substantially zero, sum the results of the sequence of multiplications of coefficients and images data to produce a set of data representative of an image of the contrast medium in the vessel.

Claim 20

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the period during which the contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images, and means including a video camera are operative to produce data representative of the images, the method including the following steps: acquire a sequence of x-ray image frames over the pre-contrast period and at least over the post-contrast period and convert the data representative of said image frames to corresponding logarithmic data representative of the sequence of images, respectively, using the manner in which the projected intensity of the contrast medium changes as a function h of time (t), multiply the data, respectively, representing the sequence of pre-contrast, post-contrast and after-contrast.images, if any, by a sequence of coefficients, the coefficients for multiplying the post-contrast images data being proportional to the projected intensity of the contrast medium h(t) substantially registered with the post-contrast image so that a selected one of the post-contrast images such as the maximum coefficient is applied to the post-contrast image data containing peak contrast, and the coefficients by which the pre-contrast and after-contrast image data are multiplied are selected so that the sum of all coefficients equals substantially zero, sum the results of the sequence of multiplications of coefficients and images data to produce a set of data representative of an image of the contrast medium in the vessel.

Claim 28

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the period during which contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images and means including a video camera are operative to produce data representative of the images, the method including the following steps: during said pre-contrast period, acquire an initial mask x-ray image and an additional sequence of pre-contrast images and take the differences between logarithmic data representative of the mask image data and logarithmic data representative of the respective additional images data and store the resulting sequence of pre-contrast difference image data, when the contrast medium arrives in the vessel, start to acquire an additional sequence of post-contrast and after-contrast images and take the differences between lo g a-rithmic data representative of the initial mask image and logarithmic data representative of the additional post-contrast and after-contrast images and store the resulting sequence of difference image data, select a corresponding point in the successive post-contrast images obtained while said contrast medium was flowing in said vessel and determine the intensities, h, at said point in each of the images and convert said intensities, h, to coefficients that are proportional to h at successive times (t), multiply the sequence of pre-contrast, post-contrast and after-contrast difference images data by respective coefficients, the post-contrast difference images data being multiplied by the coefficients corresponding to the time (t) at which the post-contrast images were acquired, the coefficients by which the pre-contrast and after-contrast difference images data are multiplied being selected so that the summation of all coefficients equals substantially zero, and sum the results of the sequence of multiplications of coefficients and difference images data to produce a set of data representative of the contrast medium in the vessel.

Claim 29

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the period during which contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images and means including a video camera are operative to produce data representative of the images, the method including the following steps: during said pre-contrast period, acquire an initial mask x-ray image and an additional sequence of pre-contrast images and take the differences between logarithmic data representative of the mask image data and logarithmic data representative of the respective additional images data and store the resulting sequence of pre-contrast difference image data, when the contrast medium arrives in the vessel, start to acquire an additional sequence of post-contrast and after-contrast images and take the differences between lo g a-rithmic data representative of the initial mask image and logarithmic data representative of the additional post-contrast and after-contrast images and store the resulting sequence of difference image data, select a corresponding point in the successive post-contrast images obtained while said contrast medium was flowing in said vessel and determine the intensities, h, at said point in each of the images and convert said intensities, h, to coefficients that are proportional to h at successive times (t), multiply the sequence of pre-contrast, post-contrast and after-contrast difference images data by respective coefficients, the post-contrast difference images data being multiplied by the coefficients corresponding to the time (t) at which the post-contrast images were acquired, the coefficients by which the pre-contrast and after-contrast difference images data are multiplied being selected so that the summation of all coefficients equals substantially zero, and sum the results of the sequence of multiplications of coefficients and difference images data to produce a set of data representative of the contrast medium in the vessel.

Claim 30

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the period during which the contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images, and means including a video camera are operative to produce data representative cf the images, the method including the following steps: acquire a sequence of x-ray images starting at the beginning of the pre-contrast period and continuing through the post-contrast period, and convert the data representative. of the images to logarithmic data, select a corresponding point in the successive post-contrast images obtained while said contrast medium was flowing in said vessel and determine the intensities, h, at said point in each of the post-contrast images and convert said intensities to coefficients that are proportional to h at times (t), multiply the data representative of the post-contrast images by the coefficients respectively corresponding to the time (t), respectively, at which the post-contrast images were acquired, sum the results of the respective multiplications and store the resulting data, multiply data representative of the respective pre-contrast and after-contrast images; if any, by respective coefficients selected so that the difference between the sum of the coefficients applied to the pre-contrast and after-contrast images and the sum of the coefficients applied to the post-contrast images is substantially equal to zero, sum the results of the respective multiplications and store the resulting data, take the difference between the sum produced after multiplying of said pre-contrast and after-contrast images data and the sum produced after multiplying of said post-contrast images data to produce a set of data representative of the contrast medium in the vessel.

Claim 31

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the period during which the contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images, and means including a video camera are operative to produce data representative cf the images, the method including the following steps: acquire a sequence of x-ray images starting at the beginning of the pre-contrast period and continuing through the post-contrast period, and convert the data representative. of the images to logarithmic data, select a corresponding point in the successive post-contrast images obtained while said contrast medium was flowing in said vessel and determine the intensities, h, at said point in each of the post-contrast images and convert said intensities to coefficients that are proportional to h at times (t), multiply the data representative of the post-contrast images by the coefficients respectively corresponding to the time (t), respectively, at which the post-contrast images were acquired, sum the results of the respective multiplications and store the resulting data, multiply data representative of the respective pre-contrast and after-contrast images; if any, by respective coefficients selected so that the difference between the sum of the coefficients applied to the pre-contrast and after-contrast images and the sum of the coefficients applied to the post-contrast images is substantially equal to zero, sum the results of the respective multiplications and store the resulting data, take the difference between the sum produced after multiplying of said pre-contrast and after-contrast images data and the sum produced after multiplying of said post-contrast images data to produce a set of data representative of the contrast medium in the vessel.

Claim 32

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the- period during which the contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images, and means including a video camera are operative to produce data representative of the images, the method including the following steps: acquire a sequence of x-ray image frames over the pre-contrast period and at least over the post-contrast period and convert the data representative of said image frames to corresponding logarithmic data representative of the sequence of images, respectively, select a corresponding point in the successive post-contrast images obtained while said contrast medium was flowing in said vessel and determine the intensities, h, at said point in each of the post-contrast images and convert said intensities to coefficients that are proportional to h at times (t), multiply the data, respectively, representing the sequence of pre-contrast, post-contrast and after-contrast images, if any, by a sequence of coefficients, the sequence by which said post-contrast image being said coefficients that are proportional to h at times (t) corresponding substantially to the times at which said post-contrast images were acquired, and the coefficients by which the pre-contrast and after-contrast image data are multiplied are selected sc that the sum of all coefficients equals substantially zero, sum the results of the sequence of multiplications of coefficients and images data to produce a set of data representative of an image cf the contrast medium in the vessel.

Claim 33

A method of imaging a blood vessel in a body where the period before a bolus of x-ray contrast medium arrives in the vessel is designated the pre-contrast period, the- period during which the contrast medium is flowing in the vessel is designated the post-contrast period and the period following the latter when the medium has left the vessel is designated the after-contrast period, and where an x-ray source, when energized, projects a beam through a body to produce x-ray images, and means including a video camera are operative to produce data representative of the images, the method including the following steps: acquire a sequence of x-ray image frames over the pre-contrast period and at least over the post-contrast period and convert the data representative of said image frames to corresponding logarithmic data representative of the sequence of images, respectively, select a corresponding point in the successive post-contrast images obtained while said contrast medium was flowing in said vessel and determine the intensities, h, at said point in each of the post-contrast images and convert said intensities to coefficients that are proportional to h at times (t), multiply the data, respectively, representing the sequence of pre-contrast, post-contrast and after-contrast images, if any, by a sequence of coefficients, the sequence by which said post-contrast image being said coefficients that are proportional to h at times (t) corresponding substantially to the times at which said post-contrast images were acquired, and the coefficients by which the pre-contrast and after-contrast image data are multiplied are selected sc that the sum of all coefficients equals substantially zero, sum the results of the sequence of multiplications of coefficients and images data to produce a set of data representative of an image cf the contrast medium in the vessel.