Phase-adjusted echo time (PATE)-averaging 1 H MRS: application for improved glutamine quantification at 2.89 T

Area of Science:

• Neuroscience
• Biochemistry
• Medical Imaging

Background:

• Proton magnetic resonance spectroscopy (MRS) is vital for studying brain metabolism in psychiatric disorders.
• Accurate quantification of glutamate and glutamine is challenging at clinical magnetic field strengths due to overlapping signals.

Purpose of the Study:

• To develop and validate a novel post-processing method for retrieving glutamine signals from echo time (TE)-averaged (1)H MRS data.
• To improve the accuracy and reliability of glutamine quantification in vivo.

Main Methods:

• Phase-adjusted echo time (PATE) averaging: a novel post-processing technique.
• Spectral simulation to derive optimal TE-specific phase terms.
• In vivo (1)H MRS data acquisition from the human frontal lobe at 2.89 T.
• Metabolite normalization schemes for test-retest reliability assessment.

Main Results:

• PATE averaging successfully retrieves glutamine signals from TE-averaged (1)H MRS data.
• Test-retest reliability for glutamine measurement showed comparable within-subject (9-14%) and inter-subject (14-20%) variability.
• Glutamine quantification is achievable in approximately 10 minutes.

Conclusions:

• PATE averaging offers a robust method for glutamine quantification using (1)H MRS.
• The technique can be applied retrospectively to existing TE-averaged datasets.
• Improved glutamine and glutamate measurements can advance psychiatric disorder research.