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

Battiston, Marco, Grussu, Francesco, Ianus, Andrada, Schneider, Torben, Prados, Ferran, Fairney, James, Ourselin, Sebastien, Alexander, Daniel C, Cercignani, Mara, Wheeler-Kingshott, Claudia A M Gandini and Samson, Rebecca S (2017) An optimized framework for quantitative magnetization transfer imaging of the cervical spinal cord in vivo. Magnetic Resonance in Medicine. ISSN 1522-2594 (Accepted)

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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 [ math formula, math formula], 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), math formula = 46.5(±1.6) ms, math formula = 11.0(±0.2) µs, and kFB = 1.95(±0.06) Hz. Protocol optimization has a beneficial effect on reproducibility, especially for math formula and kFB.

Conclusion

The framework developed enables robust characterization of spinal cord microstructure in vivo using qMT. Magn Reson Med, 2017. © 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
Schools and Departments: Brighton and Sussex Medical School > Neuroscience
Subjects: R Medicine > R Medicine (General)
R Medicine > R Medicine (General) > R895 Medical physics. Medical radiology. Nuclear medicine
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Depositing User: Patricia Butler
Date Deposited: 02 Oct 2017 13:00
Last Modified: 02 Oct 2017 13:00
URI: http://sro.sussex.ac.uk/id/eprint/70392

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