An optimized framework for quantitative magnetization transfer imaging of the cervical spinal cord in vivo

Battiston, Marco, Gurssu, Francesco, Ianus, Andrada, Schneider, Torben, Prados, Ferran, Fairney, James, Ourselin, Sebastien, Alexander, Daniel C., Cercignani, Mara ORCID: https://orcid.org/0000-0002-4550-2456, Wheeler‐Kingshott, Claudia A.M. Gandini and Samson, Rebecca S. 2018. An optimized framework for quantitative magnetization transfer imaging of the cervical spinal cord in vivo. Magnetic Resonance in Medicine 79 (5) , pp. 2576-2588. 10.1002/mrm.26909

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Abstract

Purpose To develop a framework to fully characterize quantitative magnetization transfer indices in the human cervical cord in vivo within a clinically feasible time. Methods A dedicated spinal cord imaging protocol for quantitative magnetization transfer was developed using a reduced field‐of‐view approach with echo planar imaging (EPI) readout. Sequence parameters were optimized based in the Cramer‐Rao‐lower bound. Quantitative model parameters (i.e., bound pool fraction, free and bound pool transverse relaxation times [ urn:x-wiley:07403194:media:mrm26909:mrm26909-math-0014, urn:x-wiley:07403194:media:mrm26909:mrm26909-math-0015], and forward exchange rate [kFB]) were estimated implementing a numerical model capable of dealing with the novelties of the sequence adopted. The framework was tested on five healthy subjects. Results Cramer‐Rao‐lower bound minimization produces optimal sampling schemes without requiring the establishment of a steady‐state MT effect. The proposed framework allows quantitative voxel‐wise estimation of model parameters at the resolution typically used for spinal cord imaging (i.e. 0.75 × 0.75 × 5 mm3), with a protocol duration of ∼35 min. Quantitative magnetization transfer parametric maps agree with literature values. Whole‐cord mean values are: bound pool fraction = 0.11(±0.01), urn:x-wiley:07403194:media:mrm26909:mrm26909-math-0016 = 46.5(±1.6) ms, urn:x-wiley:07403194:media:mrm26909:mrm26909-math-0017 = 11.0(±0.2) µs, and kFB = 1.95(±0.06) Hz. Protocol optimization has a beneficial effect on reproducibility, especially for urn:x-wiley:07403194:media:mrm26909:mrm26909-math-0018 and kFB. Conclusion The framework developed enables robust characterization of spinal cord microstructure in vivo using qMT. Magn Reson Med 79:2576–2588, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Psychology Cardiff University Brain Research Imaging Centre (CUBRIC)
Publisher:	Wiley
ISSN:	0740-3194
Date of First Compliant Deposit:	18 March 2021
Date of Acceptance:	16 August 2017
Last Modified:	05 May 2023 15:23
URI:	https://orca.cardiff.ac.uk/id/eprint/139550

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