Combining chemical exchange saturation transfer and 1 H magnetic resonance spectroscopy for simultaneous determination of metabolite concentrations and effects of magnetization exchange.

Hoefemann, Maike; Döring, André; Fichtner, Nicole Damara; Kreis, Roland (2021). Combining chemical exchange saturation transfer and 1 H magnetic resonance spectroscopy for simultaneous determination of metabolite concentrations and effects of magnetization exchange. Magnetic resonance in medicine, 85(4), pp. 1766-1782. Wiley-Liss 10.1002/mrm.28574

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PURPOSE

A new sequence combining chemical-exchange saturation-transfer (CEST) with traditional MRS is used to simultaneously determine metabolite content and effects of magnetization exchange.

METHODS

A CEST saturation block consisting of a train of RF-pulses is placed before a metabolite-cycled semi-LASER single-voxel spectroscopy sequence. The saturation parameters are adjustable to allow optimization of the saturation for a specific target. Data were collected in brain from 20 subjects in experiments with different B1 -settings (0.4-2.0 µT) on a 3T MR scanner. CEST Z-spectra were calculated from water intensities and fitted with a multi-pool Lorentzian model. Interrelated metabolite spectra were fitted in fitting tool for arrays of interrelated datasets (FiTAID).

RESULTS

Evaluation of traditional Z-spectra from water revealed exchange effects from amides, amines, and hydroxyls as well as an upfield nuclear Overhauser effect. The magnetization transfer effect was evaluated on metabolites and macromolecules for the whole spectral range and for the different B1 levels. A correction scheme for direct saturation on metabolites is proposed. Both magnetization-transfer and direct saturation proved to differ for individual metabolites.

CONCLUSION

Using non-water-suppressed spectroscopy offers time-saving simultaneous recording of the traditional CEST Z-spectrum from water and the metabolite spectrum under frequency-selective saturation. In addition, exchange and magnetization-transfer effects on metabolites and macromolecules can be detected, which might offer additional possibilities for quantification or give further insight into the composition of the traditional CEST Z-spectrum. Apparent magnetization-transfer effects on macromolecular signals in the 1 H-MR spectrum have been found. Detailed knowledge of magnetization-transfer effects is also relevant for judging the influence of water-suppression on the quantification of metabolite signals.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic, Interventional and Paediatric Radiology > DCR Magnetic Resonance Spectroscopy and Methodology (AMSM)
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > Forschungsbereich Pavillon 52 > Abt. Magnetresonanz-Spektroskopie und Methodologie, AMSM
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR)

Graduate School:

Graduate School for Cellular and Biomedical Sciences (GCB)

UniBE Contributor:

Höfemann, Maike Svenja; Döring, André; Fichtner, Nicole Damara and Kreis, Roland

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0740-3194

Publisher:

Wiley-Liss

Language:

English

Submitter:

Maria de Fatima Henriques Bernardo

Date Deposited:

04 Dec 2020 12:19

Last Modified:

04 Jan 2021 01:33

Publisher DOI:

10.1002/mrm.28574

PubMed ID:

33151011

Uncontrolled Keywords:

chemical exchange macromolecules magnetization transfer metabolites modeling saturation

BORIS DOI:

10.7892/boris.147861

URI:

https://boris.unibe.ch/id/eprint/147861

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