Resting state BOLD functional connectivity at 3T: spin echo versus gradient echo EPI.

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging (MRI)
• Brain Connectivity

Background:

• Spin-echo (SE) BOLD signals offer improved linearity and promptness compared to gradient-echo (GE) acquisitions, even at low fields.
• SE fMRI's potential benefits for spontaneous brain activity investigation are suggested but underexplored for connectivity studies.
• No prior studies have investigated spin-echo fMRI for resting-state functional connectivity at low magnetic field strengths.

Purpose of the Study:

• To compare resting-state functional connectivity using GE and SE Echo-Planar Imaging (EPI) sequences at 3 Tesla.
• To evaluate the sensitivity, inter-subject variability, and regional performance of SE versus GE fMRI for connectivity analysis.

Main Methods:

• Comparison of resting-state functional connectivity between GE and SE EPI sequences at 3T.
• Analysis of within-subject sensitivity and inter-subject variability for both acquisition methods.
• Assessment of performance in specific brain regions, particularly the ventral default mode network.

Main Results:

• GE fMRI demonstrated higher sensitivity than SE fMRI within subjects, though the difference was less pronounced than in activation studies.
• Reduced sensitivity of SE fMRI was offset by lower inter-subject variability, leading to comparable group connectivity maps.
• SE fMRI outperformed GE fMRI in the ventral default mode network, an area prone to signal dropout with GE acquisition.

Conclusions:

• SE fMRI provides comparable group-level resting-state functional connectivity maps to GE fMRI at 3T.
• SE fMRI's reduced inter-subject variability and improved performance in signal dropout regions present potential advantages.
• Further research is needed to determine SE fMRI's utility in detecting subtle connectivity variations in specific populations or treatments, especially when vascular confounds are present.