Volumetric spectroscopic imaging with spiral-based k-space trajectories

Area of Science:

• Magnetic Resonance Imaging
• Spectroscopic Imaging
• Neuroimaging

Background:

• Spectroscopic imaging provides valuable chemical shift information for brain metabolite analysis.
• Low signal-to-noise ratio (SNR) of brain metabolites presents a challenge in imaging.
• Accurate spectral phasing and metabolite map reconstruction are crucial for reliable analysis.

Purpose of the Study:

• To develop and validate a spiral-based k-space trajectory for volumetric spectroscopic imaging of brain metabolites.
• To improve the speed and accuracy of metabolite mapping using rapid reference signal acquisition.
• To enhance spectral phasing and water suppression in the presence of radiofrequency field variations.

Main Methods:

• Utilized spiral k-space trajectories with time-varying readout gradients for data acquisition.
• Employed spectral-spatial pulses for excitation and water suppression, designed for radiofrequency field stability.
• Implemented a gridding algorithm for data resampling prior to fast Fourier transforms.
• Acquired high SNR water reference signals for automated spectral phasing and map reconstruction.

Main Results:

• Demonstrated in vivo imaging of brain metabolites at 1.5 T.
• Achieved a nominal voxel size of 1.1 cc with 10 slices.
• Acquisition times were 18 minutes for metabolite scans and 3 minutes for reference scans.
• Successfully phased spectra and aided metabolite map reconstruction.

Conclusions:

• Spiral k-space trajectories offer an efficient method for volumetric spectroscopic imaging of brain metabolites.
• The technique enhances SNR and accuracy in metabolite mapping.
• This approach holds promise for improved neuroimaging diagnostics and research.