Improving Fetal Single-Voxel Magnetic Resonance Spectroscopy With Spectral Registration

Area of Science:

• Medical Imaging
• Neuroscience
• Biophysics

Background:

• Fetal brain magnetic resonance spectroscopy (MRS) is crucial for assessing neurodevelopment.
• Motion artifacts significantly degrade spectral quality and quantification reliability in fetal MRS.
• Developing robust post-processing techniques is essential for accurate fetal brain analysis.

Purpose of the Study:

• To evaluate the impact of spectral registration on spectral quality in fetal brain MRS.
• To assess whether spectral registration improves the reliability of metabolite quantification in fetal MRS.
• To determine the effectiveness of spectral registration as a retrospective processing step.

Main Methods:

• Acquired fourteen fetal PRESS (Proton Echo-Spin Spectroscopy) datasets at 3 Tesla with echo times (TE) of 35 ms and 135 ms.
• Processed raw data using eddy-current phase correction, coil combination, spectral registration, and outlier rejection.
• Compared corrected and uncorrected spectra using LCModel quality metrics (SNR, FWHM, CRLB), metabolite concentrations, and ratios.

Main Results:

• Spectral registration significantly improved spectral appearance, characterized by sharper peaks and reduced line broadening.
• Signal-to-noise ratio (SNR) increased, and full-width at half-maximum (FWHM) decreased significantly at both echo times.
• Cramér-Rao Lower Bound (CRLB) values decreased significantly at TE=35 ms, improving quantification reliability, with limited improvement at TE=135 ms.

Conclusions:

• Spectral registration effectively enhances fetal MRS spectral quality and modestly improves quantification reliability.
• The benefits of spectral registration are most pronounced at short echo times (TE=35 ms).
• Spectral registration is a practical retrospective processing method for motion-affected fetal MRS.