Method and apparatus for anatomically tailored k-space sampling and recessed elliptical view ordering for bolus-enhanced 3D MR angiography
First Claim
1. A method of MR imaging a region of interest in a body containing arterial features comprising:
- a) applying a static magnetic field to the region of interest;
b) applying a magnetic gradient along at least first and second dimensions to produce a spatially distributed magnetic response of varying frequency and varying magnitude;
c) sampling the magnetic response at a spacing interval corresponding to a sampling rate which is less than a Nyquist rate;
d) performing a Fourier transform on the result of step (c) to provide a first imaging result;
e) providing a duplicate of image information of the first imaging result to provide a second imaging result; and
f) combining the first and second imaging results to isolate arterial features in the region of interest.
3 Assignments
0 Petitions
Accused Products
Abstract
Current bolus chase magnetic resonance angiography is limited by the imaging time for each station. Tailoring the density of k-space sampling along the anterior-posterior direction of the coronal station allows a substantial decrease in scan time that leads to greater contrast bolus sharing among stations and consequently a significant improvement in image quality. Fast arterial-venous transit in the carotid arteries requires accurate, reliable timing of the acquisition to the bolus transit to maximize arterial signal and minimize venous artifacts. The rising edge of the bolus is not utilized in conventional elliptical-centric view ordering because the critical k-space center must be acquired with full arterial enhancement. The invention provides a recessed elliptical-centric view ordering scheme is introduced in which the k-space center is acquired a few seconds following scan initiation. The recessed view ordering is shown to be more robust to timing errors in a patient studies.
25 Citations
40 Claims
-
1. A method of MR imaging a region of interest in a body containing arterial features comprising:
-
a) applying a static magnetic field to the region of interest;
b) applying a magnetic gradient along at least first and second dimensions to produce a spatially distributed magnetic response of varying frequency and varying magnitude;
c) sampling the magnetic response at a spacing interval corresponding to a sampling rate which is less than a Nyquist rate;
d) performing a Fourier transform on the result of step (c) to provide a first imaging result;
e) providing a duplicate of image information of the first imaging result to provide a second imaging result; and
f) combining the first and second imaging results to isolate arterial features in the region of interest. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 12, 19, 20, 21)
-
-
10. A method of MR imaging a region of interest in a body containing arterial features comprising:
-
a) applying a static magnetic field to the region of interest;
b) applying a magnetic gradient along at least first and second dimensions to produce a spatially distributed magnetic response of varying frequency and varying magnitude;
c) sampling the magnetic response at a spacing interval which corresponds to a sampling rate which is less than a Nyquist rate, but taking a number of samples that corresponds to the Nyquist rate, thereby expanding a sampling range of the frequency;
d) performing a Fourier transform on the result of step (c) to provide a first imaging result;
e) providing a duplicate of image information of the first imaging result to provide a second imaging result; and
f) combining the first and second imaging results to isolate arterial features in the region of interest.
-
-
11. An MR imaging apparatus for imaging a region of interest in a body containing arterial features, comprising:
-
a) a static magnetic field generator to apply a magnetic field to the region of interest;
b) a magnetic gradient generator to generate a gradient along at least first and second dimensions to produce a spatially distributed magnetic response of varying frequency and varying magnitude;
c) a computer readable medium for sampling the magnetic response at a spacing interval corresponding to a sampling rate which is less than a Nyquist rate;
d) a computer readable medium for performing an inverse Fourier transform on the output result of the computer readable medium of element (c) to provide a first imaging result during a first sampling of the region of interest and a computer readable medium for providing a second imaging result including a duplicate of information of the first imaging result; and
e) computer readable medium for combining the first imaging result and the second imaging result to isolate arterial features in said region of interest.
-
-
13. A computer readable medium for isolating a feature from a magnetic resonance image of a region of interest, said magnetic resonance image formed by applying a magnetic field to the region of interest and generating a gradient along at least first and second dimensions to produce a spatially distributed magnetic response of varying frequency and varying magnitude, said computer readable medium comprising:
-
a) a computer readable medium for sampling the magnetic response at a spacing interval corresponding to a sampling rate which is less than a Nyquist rate;
b) a computer readable medium for performing an inverse Fourier transform on the output result of the computer readable medium of element (a) to provide a first imaging result during a first sampling of the region of interest and a computer readable medium for providing a second imaging result including a duplicate of information of the first imaging result; and
c) computer readable medium for combining the first imaging result and the second imaging result to isolate arterial features in said region of interest.
-
-
14. A method of accelerating volumetric MR imaging of arteries or other structures comprising the following:
-
a) an image volume having x, y and z orthogonal coordinates and a thickness along z=Tv;
b) for every x, y location within the volume the structures to be imaged have a thickness Ts<
Tvc) three-dimensional k space sampling is accelerated by a factor F≦
Tv/Ts by increasing the spacing of k space sampling along kz by a factor of F while maintaining the sampling spatial frequency ranges unchanged.d) reconstruct with 3-D Fourier Transformation utilizing a field of view in the z direction which is equal to Tv/F d) create 1/F duplicate copies of the reconstructed volumetric data and stacked together adjacent to each other in the z direction e) post-process the combined multiple copies of volumetric data to select a subset of the total combined volume containing a single complete data set of the structures of interest. - View Dependent Claims (15, 17, 18, 22)
-
-
16. A method of increasing the resolution of volumetric MR imaging of arteries or other structures comprising the following:
-
a) an image volume having x, y and z orthogonal coordinates and a thickness along z=Tv b) for every x, y location within the volume the structures to be imaged have a thickness Ts<
Tvc) increase the maximum spatial frequency sampled by a factor F≦
Tv/Ts by increasing the spacing of k space sampling along kz by a factor of F while maintaining the same total acquisition timed) reconstruct with 3-D Fourier Transformation utilizing a field of view in the z direction which is equal to Tv/F e) create 1/F duplicate copies of the reconstructed volumetric data and stacked together adjacent to each other in the z direction f) post-process the combined multiple copies of volumetric data to select a subset of the total combined volume containing a single complete data set of the structures of interest.
-
-
23. A method of MR imaging a region of interest comprising:
-
administering a contrast agent to the region of interest;
applying a static magnetic field to the region of interest;
applying a magnetic gradient along at least one of first and second dimensions to produce a distributed magnetic response having a spatial distribution in k-space;
sampling the magnetic response, wherein sampling is performed such that sampling of a center of the k-space is delayed from a start of sampling of the magnetic response, such that sampling of the center of the k-space is timed to coincide with a substantial peak of the contrast agent passing through the region of interest. - View Dependent Claims (24, 25, 26, 27, 28, 37, 39)
-
-
29. A method of MR imaging a region of interest comprising:
-
a) administering a contrast agent to the region of interest;
b) applying a static magnetic field to the region of interest;
c) applying a magnetic gradient along at least one of first and second dimensions to produce a distributed magnetic response having a spatial distribution in k-space including a low spatial frequency, an intermediate spatial frequency and a high spatial frequency;
d) sampling the magnetic response in order of the intermediate frequency, the low spatial frequency and the high spatial frequency, said high spatial frequency corresponding to a maximum radius value of the magnetic response in the k-space for said region of interest. - View Dependent Claims (30, 31, 32, 33, 38, 40)
-
-
34. An MR imaging apparatus for imaging a region of interest comprising:
-
a static magnetic field generator to apply a magnetic field to the region of interest;
a magnetic gradient generator to generate a gradient along at least first and second dimensions to produce a spatially distributed magnetic response having a spatial distribution in a k-space;
a computer readable medium to control sampling of the magnetic response such that sampling of a center of the k-space is delayed from a start of sampling of the magnetic response, such that sampling of the center of the k-space is timed to coincide with a substantial peak of the contrast agent passing through the region of interest. - View Dependent Claims (35, 36)
-
Specification