Diffusion-weighted magnetic resonance spectroscopy boosted by simultaneously acquired water reference signals

Area of Science:

• Magnetic Resonance Imaging
• Neuroscience
• Biophysics

Background:

• Diffusion-weighted 1H-MR spectroscopy (MRS) is crucial for assessing metabolite apparent diffusion coefficients (ADCs).
• Motion artifacts and signal loss can compromise ADC accuracy in MRS.
• Existing methods often struggle with low signal-to-noise ratios for certain metabolites.

Purpose of the Study:

• To integrate metabolite-cycling with diffusion-weighted 1H-MRS for enhanced ADC estimation.
• To utilize the inherent water signal for motion-related signal loss compensation.
• To improve the accuracy and reliability of metabolite ADC measurements.

Main Methods:

• Simultaneous acquisition of diffusion-weighted spectra for water and metabolites at 3 Tesla using metabolite-cycling.
• Employing the water signal for correction of phase, frequency, eddy currents, and motion-induced signal loss.
• Utilizing 2D simultaneous fitting for ADC estimation and in vitro quality assessment.

Main Results:

• Metabolite-cycled diffusion 1H-MRS successfully measured simultaneous metabolite and water ADCs.
• The water reference effectively restored signal amplitude and compensated for motion artifacts.
• 2D fitting improved ADC estimation for low signal-to-noise metabolites, reducing uncertainties and variance.

Conclusions:

• Simultaneous water referencing in diffusion-weighted 1H-MRS significantly enhances metabolite ADC estimation by compensating for fluctuations and motion.
• The combined approach of metabolite-cycling, water referencing, and 2D fitting provides access to diffusion properties of low signal-to-noise metabolites.
• This integrated technique improves the specificity and sensitivity of metabolite ADC measurements in cohort studies.