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Image reconstruction for MRI with a rotating RF coil

Phair, AR ORCID: 0000-0003-3527-0724 2020 , 'Image reconstruction for MRI with a rotating RF coil', PhD thesis, University of Tasmania.

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A novel data acquisition method in Magnetic Resonance Imaging (MRI) utilising a Rotating Radio-Frequency Coil (RRFC) has recently been developed as an alternative to a single volume coil or a surface coil array. Herein, we explore the problem of image reconstruction from data acquired using an RRFC with radial k-space trajectories and develop two distinct reconstruction approaches.
The first method we introduce is WARF (a weighted-sum approach to radial MRI image reconstruction with a rotating RF coil), which is built on the assumption that each image pixel may be considered as a weighted sum of all acquired k-space data, as is implicitly the case in several established methods. The problem is thus posed as one of solving for the weights directly. WARF is applied to both simulated and experimental data sets, where it is shown to produce good quality reconstructions and an improved robustness to both variation in the rotational coil velocity and deviations in the k-space trajectory.
Although WARF is developed for radial RRFC data, neither the radial trajectory nor the rotating coil is explicitly incorporated into the theory. As such, we also utilise simulations to consider the efficacy of WARF when applied to a range of acquisition schemes, including data acquired with spiral and PROPELLER trajectories, radial data acquired with a stationary parallel array and data acquired from accelerated RRFC acquisitions.
The second method we present utilises Hankel transforms to reconstruct data from radial k-space to a Cartesian image, avoiding the interpolation in image-space that has been present in previous Hankel transform-based methods. A SPIRiT-like approach is developed to synthesise missing radial data for undersampled radial trajectories acquired with either an RRFC or a parallel array, yielding fully-sampled radial k-spaces to which our Hankel transform technique can be readily applied. Finally, the method is validated using simulated data sets.

Item Type: Thesis - PhD
Authors/Creators:Phair, AR
Keywords: MRI, image reconstruction, rotating coil, WARF, Hankel transform
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Copyright 2020 the author

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