EP0205136A2
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EP
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Apparatus and method for measuring and imaging fluid flow
Assignee: General Electric Co
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Filing: 1986-06-07
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Granted: —
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Expires: 2006-06-07
Abstract
Abstract A time-of-flight magnetic resonance pulse sequence is used to detect arterial flow in an image of a slice of tissue. By timing the pulse sequence with the cardiac cycle and by holding the interpulse interval T, within time limits which ensure enhancement without significant change in flow velocity, arterial flow can be imaged. By triggering the pulse sequence from the QRS complex representative of the beginning of a body's cardiac cycle and delaying both excitation and detection pulses in the sequence by a time T A to ensure the pulses occur while flow is slow, MR signal data is generated which results in an image showing enhancement in the areas of arterial flow. in an extension of the foregoing, a second set of MR signal data is generated by adjusting the acquisition delay T A such that the excitation and detection pulses of a second sequence occurwhile arterial flow is fast. in the image formed from this second set of data, the increased arterial flow velocity decreases the enhanced image of the arteries. The images generated from the MR signals of the first and second sequences may be subtracted in orderto give a single high contrast image showing only arterial flow.
Inventors
- 👤 Felix Werner Wehrli
- 👤 Ann Shimakawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:05
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/03; G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/563; G01R33/56308; A61B5/02; A61B5/026; A61B5/0263; A61B5/72; A61B5/7271; A61B5/7285; G01F; G01F1/00; G01F1/704; G01F1/708; G01F1/716; G01R33/567; G01R33/5673; G01R33/5635
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
177 words
A non-invasive method employing MR for identifying flow within an artery of a living body, comprising the steps of: (a) positioning said body in a substantially homogeneous magnetic field; (b) sensing the cardiac cycle of said living body; (c) determining a region of said living body for MR imaging including said artery such that the direction of arterial flow is substantially transverse to the plane of said region; (d) determining the propagation delay from the start of a cardiac cycle, marked by a contraction of the heart, to the occurrence of fast arterial flow in the region to be imaged; (e) tagging a bolus of arterial flow within the region before the fast flow reaches the artery within the region; (f) waiting a predetermined time period then exciting a bolus of arterial flow in the region wherein the velocity of the flow throughout the time period remains substantially constant; and (g) detecting a first MR signal from said body responsive to the tagging and excitation in steps (e) and (f) which is enhanced by the arterial flow.
Claim 2
Dependent Claim
177 words
A non-invasive method employing MR for identifying flow within an artery of a living body, comprising the steps of: (a) positioning said body in a substantially homogeneous magnetic field; (b) sensing the cardiac cycle of said living body; (c) determining a region of said living body for MR imaging including said artery such that the direction of arterial flow is substantially transverse to the plane of said region; (d) determining the propagation delay from the start of a cardiac cycle, marked by a contraction of the heart, to the occurrence of fast arterial flow in the region to be imaged; (e) tagging a bolus of arterial flow within the region before the fast flow reaches the artery within the region; (f) waiting a predetermined time period then exciting a bolus of arterial flow in the region wherein the velocity of the flow throughout the time period remains substantially constant; and (g) detecting a first MR signal from said body responsive to the tagging and excitation in steps (e) and (f) which is enhanced by the arterial flow.
Claim 3
Dependent Claim
59 words
A non-invasive method as set forth in claim 1 including the steps of: (h) exciting a bolus of blood in said region during fast arterial flow through the region; and (i) detecting a second MR signal from said body responsive to said excitation in step (h) pulse sequence which is not enhanced by the arterial flow through the region.
Claim 4
Dependent Claim
49 words
A non-invasive method as set forth in claim 2, including the steps of: (j) repeating steps (e)-(i) to acquire sufficient first and second MR signals to construct first and second images, respectively; and (k) subtracting said first and second images to provide a single image of only arterial flow.
Claim 5
Dependent Claim
38 words
A non-invasive method as set forth in claim 1 wherein the delay between the sensing of the . cardiac cycle and the first tagging pulse is a constant percentage of the mean time period of the cardiac cycle.
Claim 6
Dependent Claim
47 words
A non-invasive method as set forth in anyone of claims 1 to 4 wherein the determining step includes determining a slice of said living body for MR imaging including said artery such that the direction of arterial flow is substantially perpendicular to the plane of said slice.
Claim 7
Independent Claim
156 words
An apparatus for enhancing arterial flow in an MR image of a portion of living tissue, said apparatus comprising: (1) means for generating a homogeneous magnetic field through said tissue; (2) means for determining the cycle of said arterial flow associated with said living tissue; (3) means responsive to means (2) for generating a first trigger signal at the end of a first time period which is a predetermined percentage of the mean time period for the flow cycle; (4) means responsive to the first trigger signal of means (3) for initiating a time-of-flight MR pulse sequence such that selected nuclei in said region are excited; (5) means associated with means (3) for adjusting said predetermined percentage such that any MR signal from the excited nuclei in said portion occurs during a time of slow arterial flow in the portion; and (6) means responsive to an MR signal from said living, tissue for providing imaging data.
Claim 8
Independent Claim
156 words
An apparatus for enhancing arterial flow in an MR image of a portion of living tissue, said apparatus comprising: (1) means for generating a homogeneous magnetic field through said tissue; (2) means for determining the cycle of said arterial flow associated with said living tissue; (3) means responsive to means (2) for generating a first trigger signal at the end of a first time period which is a predetermined percentage of the mean time period for the flow cycle; (4) means responsive to the first trigger signal of means (3) for initiating a time-of-flight MR pulse sequence such that selected nuclei in said region are excited; (5) means associated with means (3) for adjusting said predetermined percentage such that any MR signal from the excited nuclei in said portion occurs during a time of slow arterial flow in the portion; and (6) means responsive to an MR signal from said living, tissue for providing imaging data.
Claim 9
Dependent Claim
47 words
An apparatus as set forth in claim 6 wherein said means (3) includes a second trigger signal at the end of a second predetermined percentage of the mean time period for the flow cycle such that said trigger signal occurs at a time of fast arterial flow.
Claim 10
Dependent Claim
24 words
An apparatus as set forth in claim 7 wherein said means (5) adjusts said second predetermined percentage as well as said first predetermined percentage.
Claim 11
Dependent Claim
38 words
An apparatus as set forth in claim 8 wherein said means (4) is responsive to the second trigger signal of means (3) for initiating a time-of-flight MR pulse sequence such that selected nuclei in said portion are excited.
Claim 12
Dependent Claim
34 words
An apparatus as set forth in claim 8 including; (6) means for subtracting an image created from data taken during slow arterial flow from an image created from data taken during fast arterial flow.
Claim 13
Independent Claim
24 words
An apparatus as set forth in anyone of claims 6 to 10 wherein said portion of living tissue comprises a slice of living tissue.
Claim 14
Independent Claim
104 words
A method for enhancing the image of arterial flow in living tissue using time-of-flight MR methods wherein the portion of tissue to be imaged is composed of a number of small volume elements or voxels, said method comprising the steps of: a) identifying a time period of slow arterial flow; b) exciting the portion of voxels to produce an MR signal during slow arterial flow; c) sensing the MR signal; d) repeating steps (a) and (b) to provide a full set of data for all the voxels in a portion; and e) constructing an image of said portion from said full set of data.
Claim 15
Independent Claim
104 words
A method for enhancing the image of arterial flow in living tissue using time-of-flight MR methods wherein the portion of tissue to be imaged is composed of a number of small volume elements or voxels, said method comprising the steps of: a) identifying a time period of slow arterial flow; b) exciting the portion of voxels to produce an MR signal during slow arterial flow; c) sensing the MR signal; d) repeating steps (a) and (b) to provide a full set of data for all the voxels in a portion; and e) constructing an image of said portion from said full set of data.
Claim 16
Independent Claim
168 words
A method for providing a high contrast MR image of arterial flow in living tissue using time-of-flight MR methods wherein the portion of tissue to be imaged is composed of a number of small volume elements of voxels, said method comprising the sequential steps of: a) sensing the period of cyclic arterial flow velocity; b) generating a first MR signal at a first time location corresponding to a time of slow flow within a period of cyclic arterial flow velocity so as to enhance the MR signal; c) generating a second MR signal at a second time location corresponding to a time of fast flow within a period of cyclic arterial flow velocity so as not to enhance the MR signal; d) repeating steps (a), (b) and (c) to provide two full data sets for each voxel; e) forming a MR image from each of said data sets; and f) comparing said MR images to determine the arterial flow as represented by relatively enhanced areas in the images.
Claim 17
Independent Claim
168 words
A method for providing a high contrast MR image of arterial flow in living tissue using time-of-flight MR methods wherein the portion of tissue to be imaged is composed of a number of small volume elements of voxels, said method comprising the sequential steps of: a) sensing the period of cyclic arterial flow velocity; b) generating a first MR signal at a first time location corresponding to a time of slow flow within a period of cyclic arterial flow velocity so as to enhance the MR signal; c) generating a second MR signal at a second time location corresponding to a time of fast flow within a period of cyclic arterial flow velocity so as not to enhance the MR signal; d) repeating steps (a), (b) and (c) to provide two full data sets for each voxel; e) forming a MR image from each of said data sets; and f) comparing said MR images to determine the arterial flow as represented by relatively enhanced areas in the images.
Claim 18
Dependent Claim
49 words
A method as set forth in claim 13, including the step of: g) combining the image data of the two images to provide a single image wherein image data from stationary voxels and voxels of constant flow are cancelled, leaving only net image data for voxels representing arterial flow.
Claim 19
Independent Claim
30 words
A method as set forth in anyone of claims 12 to 14 wherein the portion of tissue to be imaged is comprised by a slice of tissue to be imaged.
References Cited (Backward Citations)
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