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The z-spectrum from human blood at 7T

Shah, Simon M.; Mougin, Olivier E.; Carradus, Andrew J.; Geades, Nicolas; Dury, Richard; Morley, William; Gowland, Penny A.

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Authors

Simon M. Shah

Andrew J. Carradus

Nicolas Geades

Richard Dury

William Morley



Abstract

Chemical Exchange Saturation Transfer (CEST) has been used to assess healthy and pathological tissue in both animals and humans. However, the CEST signal from blood has not been fully assessed. This paper presents the CEST and nuclear Overhauser enhancement (NOE) signals detected in human blood measured via z-spectrum analysis. We assessed the effects of blood oxygenation levels, haematocrit, cell structure and pH upon the z-spectrum in ex vivo human blood for different saturation powers at 7T. The data were analysed using Lorentzian difference (LD) model fitting and AREX (to compensate for changes in T1), which have been successfully used to study CEST effects in vivo. Full Bloch-McConnell fitting was also performed to provide an initial estimate of exchange rates and transverse relaxation rates of the various pools. CEST and NOE signals were observed at 3.5 ppm, -1.7ppm and -3.5 ppm and were found to originate primarily from the red blood cells (RBCs), although the amide proton transfer (APT) CEST effect, and NOEs showed no dependence upon oxygenation levels. Upon lysing, the APT and NOE signals fell significantly. Different pH levels in blood resulted in changes in both the APT and NOE (at -3.5ppm), which suggests that this NOE signal is in part an exchange relayed process. These results will be important for assessing in vivo z-spectra.

Citation

Shah, S. M., Mougin, O. E., Carradus, A. J., Geades, N., Dury, R., Morley, W., & Gowland, P. A. (2018). The z-spectrum from human blood at 7T. NeuroImage, 167, https://doi.org/10.1016/j.neuroimage.2017.10.053

Journal Article Type Article
Acceptance Date Oct 25, 2017
Online Publication Date Oct 27, 2017
Publication Date Feb 15, 2018
Deposit Date Oct 25, 2017
Publicly Available Date Oct 27, 2017
Journal NeuroImage
Print ISSN 1053-8119
Electronic ISSN 1095-9572
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 167
DOI https://doi.org/10.1016/j.neuroimage.2017.10.053
Keywords Chemical Exchange Saturation Transfer (CEST), Nuclear Overhauser Enhancement (NOE), z-spectrum, Magnetisation transfer, Blood relaxometry
Public URL https://nottingham-repository.worktribe.com/output/911958
Publisher URL http://www.sciencedirect.com/science/article/pii/S105381191730887X

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