GRACE-MORE: A Motion-Resolved Golden-Angle Radial CEST MRI Technique for Free-Breathing Abdominal Imaging

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Spectroscopy

Background:

• Chemical Exchange Saturation Transfer (CEST) MRI is valuable for abdominal imaging.
• Free-breathing abdominal CEST imaging is challenging due to motion artifacts.
• Current methods struggle with respiratory motion, impacting spectral reliability.

Purpose of the Study:

• To develop a novel framework for motion-resolved acquisition and reconstruction in abdominal CEST MRI.
• To achieve motion-robust and spectrally reliable CEST imaging under free-breathing conditions.
• To enhance the quality of abdominal CEST MRI by addressing respiratory motion.

Main Methods:

• Developed the Golden-angle RAdial CEST MRI with MOtion-REsolved reconstruction (GRACE-MORE) framework.
• Utilized interleaved steady-state saturation with golden-angle radial sampling for efficient k-space coverage.
• Implemented a self-gated strategy with advanced signal processing for respiratory-phase binning.
• Employed a deep unrolled network with low-rank and sparsity priors for reconstruction, incorporating a modified U-Net with channel attention.

Main Results:

• GRACE-MORE demonstrated over threefold improvement in respiratory-phase binning accuracy.
• The framework reduced reconstruction error and improved simulation metrics (structural similarity index, peak signal-to-noise ratio).
• In vivo results showed enhanced anatomical fidelity, effective motion suppression, and up to a fourfold increase in Z-spectral signal-to-noise ratio.

Conclusions:

• GRACE-MORE enables robust and spectrally reliable abdominal CEST imaging during free breathing.
• The developed framework significantly overcomes limitations posed by respiratory motion.
• This advancement holds promise for improved diagnostic capabilities in abdominal MRI.