Magnetic resonance imaging concepts
First Claim
1. A method of acquiring magnetization prepared steady-state magnetic resonance imaging data from a tissue, comprising the steps of:
- defining a plane within k-space;
dividing said plane within k-space into a plurality of pairs of radial wedges, wherein each pair of radial wedges has a common vertex at the center of k-space, further wherein each pair of radial wedges reside on opposite sides of the center of k-space, and further wherein said plurality of pairs of radial wedges represent all of said plane within k-space;
collecting a series of images from said tissue by following a trajectory in k-space, wherein said trajectory comprises a first sequence of steps, wherein said first sequence comprisesa first collection step across the width of the first of said first pair of radial wedges; and
a second collection step along the border of said first of said first pair of radial wedges, wherein the second collection step is oriented towards the center of k-space;
further wherein said first and second collection steps are repeated until said trajectory reaches the center of k-space,wherein said trajectory further comprises a second sequence of steps wherein said second sequence comprisesa first collection step across the width of the second of said first pair of radial wedges; and
a second collection step along the border of said second of said first pair of radial wedges, wherein the second collection step is oriented away from the center of k-space;
further wherein said trajectory comprises a third sequence of steps wherein said third sequence comprisesa third collection step across the width of said second of said first pair of radial wedges and further across the first of a second pair of radial wedges, wherein said second pair of radial wedges is adjacent to said first pair of radial wedges; and
a fourth collection step along the border of said second of said first pair of radial wedges or along the border of said first of said second pair of radial wedges, wherein the second collection step is oriented away from the center of k-space.
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Abstract
Methods of acquiring magnetic resonance imaging (MRI) data for angiography. The present invention includes novel magnetization preparation schemes where the navigator and fat saturation pulses are executed in steady state after the preparatory pulses in order to minimize the delay between the magnetization preparation and the image echoes. The present invention also provides for improved methods of contrast-enhanced MRI where data are collected along non-linear trajectories through k-space and may also involve novel view ordering. In addition, the present methods employ novel motion corrections that minimize motion artifacts. The present invention further provides novel methods of self-calibrated sensitivity-encoded parallel imaging that allow for accurate and rapid scanning of subjects.
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Citations
22 Claims
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1. A method of acquiring magnetization prepared steady-state magnetic resonance imaging data from a tissue, comprising the steps of:
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defining a plane within k-space; dividing said plane within k-space into a plurality of pairs of radial wedges, wherein each pair of radial wedges has a common vertex at the center of k-space, further wherein each pair of radial wedges reside on opposite sides of the center of k-space, and further wherein said plurality of pairs of radial wedges represent all of said plane within k-space; collecting a series of images from said tissue by following a trajectory in k-space, wherein said trajectory comprises a first sequence of steps, wherein said first sequence comprises a first collection step across the width of the first of said first pair of radial wedges; and a second collection step along the border of said first of said first pair of radial wedges, wherein the second collection step is oriented towards the center of k-space; further wherein said first and second collection steps are repeated until said trajectory reaches the center of k-space, wherein said trajectory further comprises a second sequence of steps wherein said second sequence comprises a first collection step across the width of the second of said first pair of radial wedges; and a second collection step along the border of said second of said first pair of radial wedges, wherein the second collection step is oriented away from the center of k-space; further wherein said trajectory comprises a third sequence of steps wherein said third sequence comprises a third collection step across the width of said second of said first pair of radial wedges and further across the first of a second pair of radial wedges, wherein said second pair of radial wedges is adjacent to said first pair of radial wedges; and a fourth collection step along the border of said second of said first pair of radial wedges or along the border of said first of said second pair of radial wedges, wherein the second collection step is oriented away from the center of k-space. - View Dependent Claims (2)
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3. A method of acquiring magnetization prepared steady-state magnetic resonance imaging data from a tissue, comprising the steps of:
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(a) for each of a plurality of segments into which k-space has been segmented; (1) enhancing contrast in the tissue; and (2) acquiring image data from the tissue using a segmented steady state free precession sequence along a trajectory comprising points in k-space, wherein; the points of the trajectory are; confined to the segment of k-space or to the segment of k-space and an adjacent segment of k-space; and include points in k-space center and k-space periphery; image data is acquired at all points in the trajectory before any image data is acquired along another trajectory; and points nearest the k-space center are acquired at a time corresponding to a maximal contrast enhancement; and (b) compiling the acquired image data into a magnetic resonance image; wherein acquisition of a first segment commences at a point intermediate between k-space center and an extreme of k-space periphery, and wherein the point intermediate between k-space center and the extreme of k-space periphery is selected such that the trajectory traverses the k-space center at a time corresponding to a background nulling point. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification