Comparing the effect of multi-gradient echo and multi-band fMRI during a semantic task.

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Magnetic Resonance Imaging

Background:

• Blood oxygenation level dependent (BOLD) signal sensitivity in fMRI varies across brain regions due to magnetic susceptibility artifacts.
• Ventral anterior temporal lobes, crucial for semantic cognition, show reduced fMRI sensitivity with conventional protocols.
• Multi-echo fMRI enhances BOLD contrast-to-noise but can compromise sequence parameters.

Purpose of the Study:

• To investigate the independent and interactive effects of multi-echo and multi-band fMRI on sensitivity across the brain.
• To assess the impact of these techniques on univariate and multivariate analyses for detecting semantic activation and patterns.
• To evaluate the potential of combining multi-echo and multi-band fMRI for improved neuroimaging.

Main Methods:

• Factorial design manipulating the number of echoes and/or bands in fMRI acquisition.
• Assessment of activation detection precision (T-statistics) and magnitude.
• Evaluation of multi-voxel pattern detection and decoding performance.
• Application of independent component analysis (ICA)-denoising to multi-echo data.

Main Results:

• Multi-band protocols improved activation detection precision without signal leakage.
• Multi-echo protocols enhanced BOLD signal in susceptibility artifact-prone regions like temporal lobes.
• Both multi-banding and ICA-denoising improved multi-voxel decoding.
• Multi-echo protocols reduced signal magnitude in medial temporal lobes, potentially due to acceleration.

Conclusions:

• The combined multi-echo, multi-band fMRI protocol is a promising default for most brain regions, particularly those affected by susceptibility artifacts.
• This approach enhances sensitivity for both univariate and multivariate analyses.
• Future applications can leverage increased resolution and advanced denoising techniques for improved fMRI studies.