Anatomical and functional brain imaging using high-resolution echo-planar spectroscopic imaging at 1.5 Tesla

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging
• Spectroscopy

Background:

• Accurate anatomical and functional brain imaging is crucial for understanding neurological function and disease.
• Existing magnetic resonance imaging (MRI) techniques face limitations in resolving fine details and susceptibility effects.

Purpose of the Study:

• To introduce and evaluate high-resolution echo-planar spectroscopic imaging (EPSI) for simultaneous anatomical and functional brain imaging at 1.5 Tesla.
• To investigate the utility of water resonance imaging for detecting susceptibility-related effects and improving BOLD contrast.

Main Methods:

• Acquisition of high-resolution water spectra using EPSI in small voxels (1.7 x 1.7 x 3 mm3) without water suppression.
• Analysis of spectral lineshape (Lorentzian vs. non-Lorentzian) and T2* values in relation to anatomical structures and functional activation.
• Generation of high-resolution T2* maps from EPSI data to assess brain activation during a motor task.

Main Results:

• High-resolution water spectra were obtained with 2.6 Hz resolution and 333 Hz bandwidth.
• Non-Lorentzian broadening of water resonance was observed in voxels containing blood vessels.
• Robust activation in motor cortices was detected using T2* maps, with observed shifts in water resonance frequency during neuronal activation.
• Excluding voxels with elevated T2* and non-Lorentzian lineshapes during activation improved the localization of activation areas.

Conclusions:

• High-resolution EPSI is a promising tool for brain imaging, providing both anatomical and functional information.
• The technique effectively visualizes susceptibility-related effects, contributing to improved BOLD contrast.
• EPSI demonstrates potential for more localized and accurate functional brain imaging by analyzing water resonance characteristics.