Gallichan, Daniel ![]() |
Abstract
Object This work seeks to examine practical aspects of in vivo imaging when spatial encoding is performed with three or more encoding channels for a 2D image. Materials and methods The recently developed 4-Dimensional Radial In/Out (4D-RIO) trajectory is compared in simulations to an alternative higher-order encoding scheme referred to as O-space imaging. Direct comparison of local k-space representations leads to the proposal of a modification to the O-space imaging trajectory based on a scheme of prephasing to improve the reconstructed image quality. Data were collected using a 4D-RIO acquisition in vivo in the human brain and several image reconstructions were compared, exploiting the property that the dense encoding matrix, after a 1D or 2D Fourier transform, can be approximated by a sparse matrix by discarding entries below a chosen magnitude. Results The proposed prephasing scheme for the O-space trajectory shows a marked improvement in quality in the simulated image reconstruction. In experiments, 4D-RIO data acquired in vivo in the human brain can be reconstructed to a reasonable quality using only 5 % of the encoding matrix—massively reducing computer memory requirements for a practical reconstruction. Conclusion Trajectory design and reconstruction techniques such as these may prove especially useful when extending generalized higher-order encoding methods to 3D images.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Cardiff University Brain Research Imaging Centre (CUBRIC) Engineering |
Subjects: | T Technology > TA Engineering (General). Civil engineering (General) |
Uncontrolled Keywords: | MRI Nonlinear spatial encoding Non-Fourier encoding PatLoc |
Publisher: | Springer |
ISSN: | 0968-5243 |
Last Modified: | 02 Nov 2022 10:21 |
URI: | https://orca.cardiff.ac.uk/id/eprint/98386 |
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