Improved BOLD detection in the medial temporal region using parallel imaging and voxel volume reduction

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging (MRI)

Background:

• Gradient-echo echo-planar imaging (GE-EPI) often suffers from signal dropout in susceptible regions like the anterior medial temporal lobe (MTL).
• This dropout, caused by macroscopic off-resonance effects, hinders blood-oxygen-level-dependent (BOLD) signal change detection, crucial for functional brain studies.

Purpose of the Study:

• To investigate methods for improving BOLD signal detection in the anterior MTL.
• To assess the impact of high-resolution imaging and multi-channel receiver technology on mitigating susceptibility artifacts and enhancing signal-to-noise ratio (SNR).

Main Methods:

• Utilized a 16-element surface coil array with a multi-channel MRI receiver at 3 Tesla.
• Acquired high-resolution images, comparing 2 mm and 4 mm thick slices with identical in-plane resolution.
• Evaluated the effects of reduced voxel size and array coil SNR gains on temporal signal-to-noise ratio (TSNR) and contrast-to-noise ratio (CNR).

Main Results:

• High-resolution imaging significantly reduced susceptibility artifacts.
• The 16-channel array coil improved image SNR, compensating for signal loss from smaller voxels.
• Thinner slices (2 mm) demonstrated enhanced TSNR and CNR in ventral-medial temporal lobe regions, particularly anterior MTL.
• Combining adjacent 2 mm slices further improved results.

Conclusions:

• Decreasing voxel size, in conjunction with the SNR benefits of a 16-channel head coil, enhances BOLD investigation of anterior MTL function.
• This optimized MRI approach is vital for accurate functional neuroimaging of the anterior MTL.