Evaluation of Multiband EPI Acquisitions for Resting State fMRI

Area of Science:

• Neuroimaging
• Systems Neuroscience
• Magnetic Resonance Imaging

Background:

• Resting-state functional magnetic resonance imaging (rs-fMRI) is crucial for studying brain networks.
• Echo planar imaging (EPI) is the standard fMRI technique, and improvements can enhance sensitivity.
• Multiband (MB) EPI offers reduced acquisition time by simultaneously acquiring multiple slices.

Purpose of the Study:

• To systematically investigate signal quality and resting-state brain network (RSN) sensitivity with increasing MB acceleration factors (M) in rs-fMRI.
• To evaluate the trade-offs between reduced scan time and data quality/sensitivity at higher acceleration.
• To determine optimal MB acceleration for reliable RSN detection.

Main Methods:

• Acquired rs-fMRI data from 20 healthy volunteers using MB-EPI.
• Systematically increased the MB acceleration factor (M=2-4), combined with an inplane SENSE acceleration factor (S=2), for a total acceleration up to 8 (S2xM4).
• Analyzed signal characteristics and sensitivity to detect common RSNs across different acceleration factors.

Main Results:

• An MB factor of 2 (total acceleration of 4) showed negligible signal-to-noise ratio (SNR) decrease while increasing RSN sensitivity and stability.
• Higher MB acceleration factors (M>2) introduced random artifacts, potentially affecting RSN interpretation.
• Moderate MB acceleration (total factor of 4) significantly reduced scanning time and improved RSN detection sensitivity.

Conclusions:

• MB-EPI with a total acceleration factor of 4 offers a promising balance between reduced scanning time and enhanced sensitivity for rs-fMRI.
• Moderate MB acceleration may represent a new standard for fMRI, improving the understanding of brain network dynamics.
• Careful consideration of acceleration factors is necessary to avoid artifacts and ensure reliable RSN analysis.