Anisotropic FOVs for Radial Imaging
Peder Larson and Paul Gurney
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| 2D PR Point Spread Functions |
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| PROPELLER sampling patterns and point spread functions |
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Introduction
We have developed new methods for design of
acquisition schemes in radial imaging, used in both Computed
Tomography (CT) and Magnetic Resonance Imaging (MRI), that will support a desired
imaging shape, or field-of-view (FOV). The projection spacing is
varied so any desired, convex FOV shape can be supported.
This allows for FOVs that are tailored to
non-circular objects or regions-of-interest in 2D and 3D imaging.
Tailoring the FOV allows for scan time reductions without introducing
aliasing artifacts and/or reduction of these artifacts.
On this page is MATLAB code for designing 2D and
3D imaging trajectories, including the PROPELLER trajectory.
Also shown are movies demonstrating how the
algorithms work.
These movies illustrate the evolution of the point spread function (PSF),
which defines the FOV and resolution for a given trajectory.
- Please see the following references for more information:
- Larson PEZ, Gurney PT, Nishimura DG. "Anisotropic Field-of-Views in Radial Imaging." IEEE Transactions on Medical Imaging 2008; 27(1): 47-57.
PDF
- Larson PEZ, Nishimura DG. "Anisotropic Field-of-Views for PROPELLER MRI". Proceedings of the 15th Annual Meeting of the ISMRM, Berlin, Germany, 1726 (2007). PDF
MATLAB
- radial_fovs package: download ZIP
- This MATLAB package provides design functions as well as some
simple FOV shapes. Use help radial_fovs in MATLAB, and
view the README file for more information.
Please send any bug reports/comments/suggestions regarding the MATLAB package
to peder AT mrsrl DOT stanford DOT edu.
Movies
The following movies show how the PSF, which is
proportional to the FOV, evolves as the anisotropic FOV algorithm
progresses.
2D PR
The left side in the movies show the gridded projections,
while the right side shows the computed PSF for that
set of projections. The movies show how the variable angular spacing
defines the perpendicular FOV, and how varying this spacing varies the FOV.
NOTE: these mpg-files are approximately 2-5 MB.
3D PR
In these movies, the bottom-left corner shows a top-down view
of the sampling pattern, while the other three images are views of
the PSF. They show planes at x=0, y=0, and z=0, illustrating how the
PSF evolves in the different sampling directions as the projections
are designed.
NOTE: these files are approximately 4-5 MB.
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Peder Larson (peder AT mrsrl DOT stanford DOT edu)
Last Updated January 23, 2008
