Magnetic resonance angiography by sequential multiple thin slab three dimensional acquisition
AssigneeIHC Hospitals, Inc.
InventorsDennis L. Parker, Duane D. Blatter
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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.
Claims20
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.
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.
Dependencies are inferred from the claim text.