Extracranial measurements of amide proton transfer using exchange-modulated point-resolved spectroscopy (EXPRESS)

Simon Walker-Samuel, S. Peter Johnson, Barbara Pedley, Mark F. Lythgoe, Xavier Golay

Research output: Contribution to journalArticlepeer-review


Chemical exchange saturation transfer (CEST) imaging has been used experimentally in a large range of applications. However, full quantification of CEST effects invivo 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 invivo. 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.

Original languageEnglish (US)
Pages (from-to)829-834
Number of pages6
JournalNMR in biomedicine
Issue number6
StatePublished - Jun 2012
Externally publishedYes


  • Amide proton transfer (APT)
  • Chemical exchange saturation transfer (CEST)
  • Extracranial
  • Fat
  • MRI
  • Protein concentration
  • Tumour
  • Xenograft

ASJC Scopus subject areas

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Spectroscopy


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