Suppression of physiological eye movement artifacts in functional MRI using slab presaturation

Area of Science:

• Neuroimaging
• Biophysics

Background:

• Functional magnetic resonance imaging (fMRI) studies require minimizing signal fluctuations and imaging artifacts for accurate results.
• While artifacts from respiration, cardiac pulsation, and head motion are well-studied, those from eye movements remain less understood.
• Eye movements can introduce substantial signal fluctuations, particularly in the phase-encoding direction, impacting fMRI mapping.

Purpose of the Study:

• To investigate the impact of involuntary eye movements on fMRI signal fluctuations during resting conditions.
• To develop and evaluate a novel technique for suppressing eye movement-induced artifacts in fMRI.
• To assess the effectiveness of the proposed technique in improving fMRI reliability for brain activation mapping.

Main Methods:

• An oblique slab presaturation technique was designed to target and saturate the magnetization of ocular tissues.
• This technique was applied during resting-state fMRI acquisition using a fast echo-planar imaging sequence.
• Signal fluctuations and artifact levels were quantified and compared before and after applying the presaturation technique.

Main Results:

• Involuntary eye movements were shown to induce significant signal fluctuations in the phase-encoding direction, even with fast imaging sequences.
• The oblique slab presaturation technique effectively reduced these eye movement-induced signal fluctuations.
• The proposed method minimized signal loss in other brain tissues while suppressing ocular artifacts.

Conclusions:

• Involuntary eye movements represent a significant source of artifact in fMRI data.
• The developed oblique slab presaturation technique offers an effective solution for suppressing eye movement artifacts.
• This method enhances the reliability of fMRI for mapping functional brain activation.