Motion correction and lipid suppression for 1H magnetic resonance spectroscopy

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Spectroscopy
• Medical Physics

Background:

• Lipid suppression is crucial for accurate in vivo magnetic resonance spectroscopy (MRS) of aqueous metabolites.
• Motion artifacts significantly degrade MRS data quality, necessitating robust correction strategies.
• Existing PRESS-based sequences often struggle with complete lipid suppression and motion correction.

Purpose of the Study:

• To develop and validate a PRESS-based MRS sequence with enhanced lipid suppression and motion correction capabilities.
• To assess the performance of the novel sequence in phantoms and human subjects.
• To evaluate the utility of the sequence for analyzing metabolites in the liver, kidney, and breast.

Main Methods:

• Incorporation of spectral/spatial spin-echo pulses with asymmetric excitation profiles into a PRESS sequence.
• Acquisition of 1H MRS data at 1.5 Tesla from a motion phantom and in vivo (liver, kidney, breast).
• Implementation of a regularization algorithm for phasing residual water signal to correct motion-induced phase variations.

Main Results:

• Complete suppression of lipids in the chemical shift stopband was achieved.
• Full metabolite signal intensity was maintained post-processing.
• Identified resonances in liver/kidney spectra attributed to trimethylammonium moieties (betaine plus choline) and potentially glycogen.
• Observed significantly elevated choline signal in breast cancer tissue compared to normal tissue.

Conclusions:

• The developed MRS technique effectively suppresses lipids and corrects for motion artifacts.
• The method preserves metabolite signal intensity, enabling reliable in vivo spectral acquisition.
• The technique shows promise for clinical applications, particularly in detecting metabolic changes like elevated choline in breast cancer.