US5167232A
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Magnetic resonance angiography by sequential multiple thin slab three dimensional acquisition
Assignee: BLATTER & PARKER LC
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Filing: 1990-08-07
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Granted: 1992-12-01
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Expires: 2010-08-07
Abstract
Abstract A method for acquiring image data for three dimensional magnetic resonance angiography using magnitude contrast, ("time-of-flight") imaging techniques allowing for the arbitrary offset of a slab or slabs in a sample, and allowing for the acquisition of multiple thin overlapping slabs using the steps of: selecting an image area on a sample as a one or more thin slabs; applying magnetic gradients to a sample in a logical x, y, and z coordinate system by use of a magetic resonance apparatus; applying radio frequency pulses to the image area within the sample; shifting the slab or slabs (overlapping the slab image area) by rotating the radio frequency pulse for the shifted (overlapping) slab or slabs.
Inventors
- 👤 Dennis L. Parker
- 👤 Duane D. Blatter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:05
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/563; G01R33/483; G01R33/4833; G01R33/4835; G01R33/56308; G01R33/56333
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
357 words
A method for obtaining measurements from which image data is obtained for providing a three-dimensional nuclear magnetic resonance (MR) magnitude contrast angiograph of fluid flowing in a preselected volume portion of a sample, within a logical x, y, and z axes coordinate system, comprising the steps of: (a) applying to said volume a main static magnetic field; (b) selecting a slab within said volume by (i) applying to said volume a magnetic field gradient in the logical z axis direction; and (ii) applying to said volume an RF pulse at a frequency band and of a strength to tip nuclear spins of material in said slab to create a nuclear magnetic signal; (c) applying to said volume a magnetic field gradient in the logical y axis direction for spatial phase encoding of said magnetic signal in the logical y axis dimension of said slab, wherein said magnetic field gradient in the logical y axis direction is a y axis phase encoding gradient; (d) applying to said volume a second magnetic field gradient in the logical z axis direction for spatial phase encoding of said magnetic signal in the logical z axis direction of said slab, wherein said magnetic field gradient in the logical z axis direction is a z axis phase encoding gradient; (e) applying to said volume a magnetic field gradient in the logical x axis direction for spatial encoding of said magnetic signal in the logical x axis direction, wherein said magnetic field gradient in the logical x axis direction is a readout gradient. (f) obtaining measurements of said nuclear magnetic signal while said readout gradient is being applied; and (g) repeating steps a through f multiple times to obtain a number of measurements to generate data from which a three dimensional image of said slab can be created; wherein said y axis and z axis phase encoding gradients are stepped through a combination of values requisite for the generation of a three dimensional image of said slab; and wherein the phase angle of said RF pulse is rotated by a desired phase angle to allow arbitrary slab position in the logical z axis direction.
Claim 2
Independent Claim
357 words
A method for obtaining measurements from which image data is obtained for providing a three-dimensional nuclear magnetic resonance (MR) magnitude contrast angiograph of fluid flowing in a preselected volume portion of a sample, within a logical x, y, and z axes coordinate system, comprising the steps of: (a) applying to said volume a main static magnetic field; (b) selecting a slab within said volume by (i) applying to said volume a magnetic field gradient in the logical z axis direction; and (ii) applying to said volume an RF pulse at a frequency band and of a strength to tip nuclear spins of material in said slab to create a nuclear magnetic signal; (c) applying to said volume a magnetic field gradient in the logical y axis direction for spatial phase encoding of said magnetic signal in the logical y axis dimension of said slab, wherein said magnetic field gradient in the logical y axis direction is a y axis phase encoding gradient; (d) applying to said volume a second magnetic field gradient in the logical z axis direction for spatial phase encoding of said magnetic signal in the logical z axis direction of said slab, wherein said magnetic field gradient in the logical z axis direction is a z axis phase encoding gradient; (e) applying to said volume a magnetic field gradient in the logical x axis direction for spatial encoding of said magnetic signal in the logical x axis direction, wherein said magnetic field gradient in the logical x axis direction is a readout gradient. (f) obtaining measurements of said nuclear magnetic signal while said readout gradient is being applied; and (g) repeating steps a through f multiple times to obtain a number of measurements to generate data from which a three dimensional image of said slab can be created; wherein said y axis and z axis phase encoding gradients are stepped through a combination of values requisite for the generation of a three dimensional image of said slab; and wherein the phase angle of said RF pulse is rotated by a desired phase angle to allow arbitrary slab position in the logical z axis direction.
Claim 3
Dependent Claim
32 words
A method as described in claim 1 further comprising a step of applying an additional magnetic gradient to spoil said magnetic signal after the step of obtaining measurements of said magnetic signal.
Claim 4
Dependent Claim
29 words
A method as described in claim 1 further comprising a step of reconstructing said magnetic signals into an image data set using a three dimensional magnetic resonance reconstruction algorithm.
Claim 5
Dependent Claim
23 words
A method as described in claim 1 further comprising a step of repeating steps a through g for additional slabs in said volume.
Claim 6
Dependent Claim
29 words
A method as described in claim 4 wherein said step of obtaining acquires said measurements of said nuclear magnetic signal in an alternating manner from a plurality of slabs.
Claim 7
Dependent Claim
31 words
A method as described in claim 4 wherein the phase angle of said RF pulse is further rotated to move a slowly varying error noise to any edge of said slab.
Claim 8
Dependent Claim
32 words
A method as described in claim 6 further comprising a step of applying an additional magnetic gradient to spoil said magnetic signal after the step of obtaining measurements of said magnetic signal.
Claim 9
Dependent Claim
31 words
A method as described in claim 1 wherein the phase angle of said RF pulse is further rotated to move a slowly varying error noise to any edge of said slab.
Claim 10
Dependent Claim
49 words
A method as described in claim 1 further comprising (h) a step of repeating steps a through g for additional slabs in said volume; and (i) a step of applying an additional magnetic gradient to spoil said magnetic signal after the step of obtaining measurements of said magnetic signal.
Claim 11
Dependent Claim
29 words
A method as described in claim 9 wherein said step of obtaining acquires said measurements of said nuclear magnetic signal in an alternating manner from a plurality of slabs.
Claim 12
Independent Claim
349 words
A method for obtaining measurements from which image data is obtained for providing a three-dimensional nuclear magnetic resonance (MR) magnitude contrast angiograph of fluid flowing in a preselected volume portion of a sample, within a logical x, y, and z axes coordinate system, comprising the steps of: (a) applying to said volume a main static magnetic field; (b) selecting a slab within said volume by (i) applying to said volume a magnetic field gradient in the logical z axis direction; and (ii) applying to said volume an RF pulse at a frequency band and of strength to tip nuclear spins of material in said slab to create a nuclear magnetic signal; (c) applying to said volume a magnetic field gradient in the logical y axis direction for spatial phase encoding of said magnetic signal in the logical y axis dimension of said slab, wherein said magnetic field gradient in the logical y axis direction is a y axis phase encoding gradient; (d) applying to said volume a second magnetic field gradient in the logical z axis direction for spatial phase encoding of said magnetic signal in the logical z axis direction of said slab, wherein said magnetic field gradient in the logical z axis direction is a z axis phase encoding gradient; (e) applying to said volume a magnetic field gradient in the logical x axis direction for spatial encoding of said magnetic signal in the logical x axis direction, wherein said magnetic field gradient in the logical x axis direction is a readout gradient. (f) obtaining measurements of said magnetic signal while said readout gradient is being applied; (g) repeating steps a through f multiple times to obtain a number of measurements to generate data from which a three dimensional image of said slab can be created; wherein said y axis and z axis phase encoding gradients are stepped through a combination of values requisite for the generation of a three dimensional image of said slab; and (h) repeating steps a through g for the imaging of a desired number of additional slabs, wherein said slabs are overlapped.
Claim 13
Independent Claim
349 words
A method for obtaining measurements from which image data is obtained for providing a three-dimensional nuclear magnetic resonance (MR) magnitude contrast angiograph of fluid flowing in a preselected volume portion of a sample, within a logical x, y, and z axes coordinate system, comprising the steps of: (a) applying to said volume a main static magnetic field; (b) selecting a slab within said volume by (i) applying to said volume a magnetic field gradient in the logical z axis direction; and (ii) applying to said volume an RF pulse at a frequency band and of strength to tip nuclear spins of material in said slab to create a nuclear magnetic signal; (c) applying to said volume a magnetic field gradient in the logical y axis direction for spatial phase encoding of said magnetic signal in the logical y axis dimension of said slab, wherein said magnetic field gradient in the logical y axis direction is a y axis phase encoding gradient; (d) applying to said volume a second magnetic field gradient in the logical z axis direction for spatial phase encoding of said magnetic signal in the logical z axis direction of said slab, wherein said magnetic field gradient in the logical z axis direction is a z axis phase encoding gradient; (e) applying to said volume a magnetic field gradient in the logical x axis direction for spatial encoding of said magnetic signal in the logical x axis direction, wherein said magnetic field gradient in the logical x axis direction is a readout gradient. (f) obtaining measurements of said magnetic signal while said readout gradient is being applied; (g) repeating steps a through f multiple times to obtain a number of measurements to generate data from which a three dimensional image of said slab can be created; wherein said y axis and z axis phase encoding gradients are stepped through a combination of values requisite for the generation of a three dimensional image of said slab; and (h) repeating steps a through g for the imaging of a desired number of additional slabs, wherein said slabs are overlapped.
Claim 14
Dependent Claim
33 words
A method as described in claim 11 further comprising a step of applying an additional magnetic gradient to spoil said magnetic signal after the step of obtaining measurements of said nuclear magnetic signal.
Claim 15
Dependent Claim
29 words
A method as described in claim 11 further comprising a step of reconstructing said magnetic signals into an image data set using a three dimensional magnetic resonance reconstruction algorithm.
Claim 16
Dependent Claim
23 words
A method as described in claim 11 further comprising a step of repeating steps a through g for additional slabs in said volume.
Claim 17
Dependent Claim
35 words
A method as described in claim 14, wherein the phase angle of said RF pulse is rotated by a desired phase angle to move a slowly varying error noise to any edge of said slab.
Claim 18
Dependent Claim
32 words
A method as described in claim 15 further comprising a step of applying an additional magnetic gradient to spoil said magnetic signal after the step of obtaining measurements of said magnetic signal.
Claim 19
Dependent Claim
35 words
A method as described in claim 11 wherein the phase angle of said RF pulse is rotated by a desired phase angle to move a slowly varying error noise to any edge of said slab.
Claim 20
Dependent Claim
29 words
A method as described in claim 11 wherein said step of obtaining acquires said measurements of said nuclear magnetic signal in an alternating manner from a plurality of slabs.
Claim 21
Dependent Claim
49 words
A method as described in claim 11 further comprising (i) a step of repeating steps a through g for additional slabs in said volume; and (j) a step of applying an additional magnetic gradient to spoil said magnetic signal after the step of obtaining measurements of said magnetic signal.
Claim 22
Dependent Claim
28 words
A method as described in claim 19 wherein said step of obtaining acquires said measurements of said magnetic signal in an alternating manner from a plurality of slabs.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-12-01 | 1996-06-01 | 1996-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-12-01 | 2000-06-01 | 2000-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-12-01 | 2004-06-01 | 2004-12-01 | $7700.00 | Window Closed / Lapsed |