High-resolution, 3D multi-TE ¹ H MRSI using fast spatiospectral encoding and subspace imaging

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging
• Spectroscopy

Background:

• Magnetic Resonance Spectroscopic Imaging (MRSI) is crucial for non-invasively assessing brain metabolites.
• Current MRSI techniques often face limitations in speed and spatial resolution, hindering clinical translation.
• Developing faster, higher-resolution methods is essential for advanced neuroscience and clinical diagnostics.

Purpose of the Study:

• To develop a novel method for rapid, high-resolution, 3D multi-echo ¹H-MRSI of the brain.
• To improve volumetric coverage and spatiospectral encoding efficiency.
• To enable detailed mapping of brain metabolites and their spectral changes.

Main Methods:

• A new multi-echo MRSI acquisition strategy was developed, integrating slab-selective excitation and adiabatic refocusing.
• Rapid spatiospectral encoding and sparse multi-echo sampling were employed.
• Interleaved water navigators were used for field mapping and calibration, alongside advanced data processing for signal interpolation and reconstruction.

Main Results:

• The proposed method achieves 3D multi-echo ¹H-MRSI data with a nominal spatial resolution of 3.4 × 3.4 × 5.3 mm³ in approximately 20 minutes.
• High signal-to-noise ratio (SNR) brain metabolite spatiospectral reconstructions were successfully obtained.
• Phantom and in vivo experiments demonstrated the method's capability for high-quality data acquisition.

Conclusions:

• High-resolution, 3D multi-echo ¹H-MRSI of the brain can be achieved within clinically feasible timeframes.
• The developed method holds potential for clinical applications and neuroscience research.
• Future optimizations could enable simultaneous mapping of metabolites, neurotransmitters, and TE-dependent spectral changes.