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Glutamate quantification by PRESS or MEGA-PRESS: Validation, repeatability, and concordance

Research output: Contribution to journalArticle

Tamar M. van Veenendaal, Walter H. Backes, Frank C.G. van Bussel, Richard A.E. Edden, Nicolaas A.J. Puts, Albert P. Aldenkamp, Jacobus F.A. Jansen

Original languageEnglish
Pages (from-to)107-114
Number of pages8
JournalMagnetic Resonance Imaging
Early online date3 Jan 2018
Publication statusPublished - May 2018

King's Authors


Purpose: While PRESS is often employed to measure glutamate concentrations, MEGA-PRESS enables simultaneous Glx (glutamate and glutamine) and GABA measurements. This study aimed to compare validation, repeatability, and concordance of different approaches for glutamate quantification at 3 T to aid future studies in their selection of the appropriate sequence and quantification method. Materials and methods: Nine phantoms with different glutamate and glutamine concentrations and five healthy participants were scanned twice to assess respectively the validation and repeatability of measurements with PRESS and MEGA-PRESS. To assess concordance between the different methods, results from 95 human participants were compared. PRESS, MEGA-PRESS (i.e. difference), and the MEGA-PRESS OFF spectra were analyzed with both LCModel and Gannet. Results: In vitro, excellent agreement was shown between actual and measured glutamate concentrations for all measurements (r > 0.98). In vivo CVs were better for PRESS (2.9%) than MEGA-PRESS (4.9%) and MEGA-PRESS OFF (4.2%). However, the concordance between the sequences was low (PRESS and MEGA-PRESS OFF, r = 0.3) to modest (MEGA-PRESS versus MEGA-PRESS OFF, r = 0.8). Conclusion: Both PRESS and MEGA-PRESS can be employed to measure in vivo glutamate concentrations, although PRESS shows a better repeatability. Comparisons between in vivo glutamate measures of different sequences however need to be interpreted cautiously.

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