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Joint B0 and image estimation integrated with model based reconstruction for field map update and distortion correction in prostate diffusion MRI

Usman, M; Kakkar, L; Matakos, A; KIRKHAM, A; Arridge, S; Atkinson, D; (2020) Joint B0 and image estimation integrated with model based reconstruction for field map update and distortion correction in prostate diffusion MRI. Magnetic Resonance Imaging , 65 pp. 90-99. 10.1016/j.mri.2019.09.008. Green open access

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Abstract

In prostate Diffusion Weighted MRI, differences in susceptibility values exist at the interface between the prostate and rectal-air. This can result in off-resonance magnetic field leading to geometric distortions including signal stretching and signal pile-up in the reconstructed images. Using a set of EPI data acquired with blip-up and blip-down phase encoding gradient directions, model based reconstruction has recently been proposed that can correct these distortions by using a B0 field estimated from a separate B0 scan. However, change in the size of the rectal air region across time can occur that can result in a mismatch of the B0 field to the EPI scan. Also, the measured B0 field itself can be erroneous in regions of low Signal to Noise ratio around the prostate rectal air interface. In this work, using a set of single shot EPI data acquired with blip-up and blip-down phase encoding gradient directions, a novel joint model based reconstruction is proposed that can account for changes in the off resonance effects between the B0 and EPI scans. For ten prostate patients, using a measured B0 field as an initial B0 estimate, on a 5-point scale (1-5) image quality scores evaluated by an experienced radiologist, the proposed framework achieved scores of 3.50+/-0.85 and 3.40+/-0.51 for bvalues of 0 and 500 s/mm2, respectively compared to 3.40+/-0.70 and 3.30+/-0.67 for model based reconstruction. The proposed framework is also capable of estimating a distortion corrected EPI image even without an initial B0 field estimate in situations where a separate B0 scan cannot be obtained due to time constraint.

Type: Article
Title: Joint B0 and image estimation integrated with model based reconstruction for field map update and distortion correction in prostate diffusion MRI
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.mri.2019.09.008
Publisher version: https://doi.org/10.1016/j.mri.2019.09.008
Language: English
Additional information: Copyright © 2019 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/).
Keywords: Geometric distortion, Diffusion, Prostate MRI, B0 mapping
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine > Department of Imaging
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Computer Science
URI: https://discovery.ucl.ac.uk/id/eprint/10082126
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