METHODS FOR OPTIMAL GRADIENT DESIGN AND FAST GENERIC WAVEFORM SWITCHING
First Claim
1. A method for generating magnetic field gradients for use in magnetic resonance imaging (Mill), the method comprising:
- a) transforming, with the aid of a computer processor, a set of gradient parameters from a physical gradient space into a transformed space;
b) calculating, with the aid of a computer processor, a set of separable gradient waveforms that satisfy a set of gradient rate-of-change constraints in said transformed space;
c) repeating steps (a)-(b) until the gradient waveforms in said set of separable gradient waveforms are of substantially the same time length; and
d) transforming, with the aid of a computer processor, a resulting gradient set of waveforms of substantially the same time length back into said physical gradient space.
0 Assignments
0 Petitions
Accused Products
Abstract
This disclosure provides a computer-implemented method for sequencing magnetic resonance imaging waveforms using a multistage sequencing hardware. The method comprises creating, with the aid of a computer processor, an active memory region that includes waveforms and schedules being played, and creating one or more buffer memory regions that contain waveforms and schedules not currently being played. Next, the waveforms and schedules in the one or more buffer memory regions may be updated while waveforms may be played in the active memory region. Upon completion of the waveform playback in the active memory region, the active and buffer memory regions may be swapped so that the former buffer memory region becomes the active memory region, and the former active memory region becomes the buffer memory region. The method may be repeated as needed until the imaging process is completed or otherwise halted.
-
Citations
40 Claims
-
1. A method for generating magnetic field gradients for use in magnetic resonance imaging (Mill), the method comprising:
-
a) transforming, with the aid of a computer processor, a set of gradient parameters from a physical gradient space into a transformed space; b) calculating, with the aid of a computer processor, a set of separable gradient waveforms that satisfy a set of gradient rate-of-change constraints in said transformed space; c) repeating steps (a)-(b) until the gradient waveforms in said set of separable gradient waveforms are of substantially the same time length; and d) transforming, with the aid of a computer processor, a resulting gradient set of waveforms of substantially the same time length back into said physical gradient space. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A method for acquiring a volumetric scan from a heart of a subject, the method comprising:
-
(a) administering a precursor of a contrast agent to said subject, wherein the precursor of the contrast agent yields the contrast agent in the heart of the subject, and wherein the contrast agent is retained less in healthy myocardial tissue of the heart than in abnormal myocardial tissue of the heart; (b) applying an inversion radiofrequency (RF) pulse to the heart with the aid of an RF source of a magnetic resonance imaging (MRI) system, wherein said inversion RF pulse is applied between successive heartbeats of a cardiac cycle of said subject and within a single breath hold of said subject, and wherein said inversion RF pulse reduces or eliminates magnetic resonance (MR) signals from the healthy myocardial tissue of the heart where the contrast agent is less retained; (c) detecting magnetic resonance (MR) signals from the heart with the aid of a detector coil of said MRI system, wherein said MR signals are detected subsequent to a time delay upon applying said inversion RF pulse, and wherein said MR signals are detected between said successive heartbeats within said single breath hold; (d) storing said MR signals in a memory location as non-Cartesian data in k-space; (e) capturing an image of a slice of the heart, wherein the slice corresponds to an incomplete data set insufficient to generate a complete image of the heart; (f) repeating (b)-(e) within said single breath hold of said subject to capture a plurality of images of slices of the heart, wherein the plurality of the images of the slices correspond to a complete data set sufficient to generate the complete image of the heart; and (g) iteratively processing, with the aid of a computer processor, said non-Cartesian data corresponding to said plurality of images of slices of the heart, in a self-consistent and parallel manner, to reconstruct a three-dimensional volumetric scan, the three-dimensional volumetric scan comprising the complete image of the heart and showing enhanced contrast between the healthy and abnormal myocardial tissue. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
-
-
16. The method of claim 16, further comprising determining intensities of a given portion of said plurality of scans;
- generating a trajectory of said intensities with time based on the determined intensities; and
, wherein diagnosing said subject for said disease or adverse health condition based on the assessment comprises generating the assessment based on the generated trajectory, the trajectory indicating one or more of a rate of wash-out of the contrast agent from healthy myocardial tissue or a rate of wash-out of the contrast agent from abnormal myocardial tissue.
- generating a trajectory of said intensities with time based on the determined intensities; and
-
32. A method for characterizing myocardial tissue viability to determine a disease state of a heart of a subject, the method comprising:
-
(a) acquiring a plurality of two-dimensional (2D) magnetic resonance (MR) image sets of the heart over a plurality of breath-hold periods of the subject, each 2D MR image set being acquired from the heart during an individual breath-hold period of the plurality of breath-hold periods; (b) generating a plurality of three-dimensional (3D) MR images of the heart, each 3D image being generated from an individual 2D MR image set; (c) generating a time series of 3D MR images from the plurality of 3D MR images, the time series comprising MR intensities of a plurality of regions of the heart over the plurality of breath-hold periods; (d) determining washout rates of an MR contrast agent from the plurality of regions of the heart based on the MR intensities of the plurality of regions of the heart over the plurality of breath-hold periods; and (e) assessing viabilities of the plurality of regions of the heart based on their determined washout rates, wherein a lower washout rate indicates a lesser decrease of MR intensity over the plurality of breath-hold periods and injured tissue, and wherein a higher washout rate indicates a higher decrease of MR intensity over the plurality of breath-hold periods and normal tissue. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40)
-
Specification