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Extracranial measurements of amide proton transfer using exchange‐modulated point‐resolved spectroscopy (EXPRESS)
Author(s) -
WalkerSamuel Simon,
Johnson S. Peter,
Pedley Barbara,
Lythgoe Mark F.,
Golay Xavier
Publication year - 2012
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1798
Subject(s) - nuclear magnetic resonance , spectroscopy , chemistry , saturation (graph theory) , analytical chemistry (journal) , spectral line , nuclear magnetic resonance spectroscopy , proton , physics , chromatography , mathematics , combinatorics , quantum mechanics , astronomy
Chemical exchange saturation transfer (CEST) imaging has been used experimentally in a large range of applications. However, full quantification of CEST effects in vivo using standard imaging sequences is time consuming as a large number of saturation frequency offsets, each followed by an imaging readout, are required to define a z spectrum. Furthermore, outside the brain, the presence of fat can confound the interpretation of z spectra. A novel acquisition and post‐processing technique is presented in this study, named exchange‐modulated point‐resolved spectroscopy (EXPRESS), which aims to address these limitations and to enable spatially localised, high signal‐to‐noise measurements of CEST effects in vivo . Using amide proton exchange (APT) measurements in tumours, it is demonstrated that the acquisition of two‐dimensional EXPRESS spectra composed of chemical shift and saturation frequency offset dimensions allows the correction of CEST data containing both fat and water signals, which is a common confounding property of tissues found outside the brain. Copyright © 2011 John Wiley & Sons, Ltd.