The z-spectrum from human blood at 7T

Shah, Simon M. and Mougin, Olivier E. and Carradus, Andrew J. and Geades, Nicolas and Dury, Richard and Morley, William and Gowland, Penny A. (2017) The z-spectrum from human blood at 7T. NeuroImage . ISSN 1095-9572

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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.

Item Type: Article
Keywords: Chemical Exchange Saturation Transfer (CEST), Nuclear Overhauser Enhancement (NOE), z-spectrum, Magnetisation transfer, Blood relaxometry
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: 10.1016/j.neuroimage.2017.10.053
Depositing User: Eprints, Support
Date Deposited: 25 Oct 2017 12:56
Last Modified: 16 Nov 2017 17:34
URI: http://eprints.nottingham.ac.uk/id/eprint/47563

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