Multi-slice passband bSSFP for human and rodent fMRI at ultra-high field

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging
• Biophysics

Background:

• Gradient-echo (GE) Echo-Planar Imaging (EPI) for BOLD fMRI suffers from distortions and signal drop-outs at ultra-high fields.
• Existing 3D bSSFP methods have limitations in human (suboptimal localization, motion sensitivity) and animal (low temporal resolution, insufficient coverage) neuroimaging.

Purpose of the Study:

• To implement and validate a multi-slice bSSFP acquisition with Cartesian read-out for non-distorted BOLD fMRI at ultra-high fields.
• To evaluate its performance in human and rat brains for both task- and resting-state fMRI.

Main Methods:

• Development of a multi-slice bSSFP sequence with a novel pseudo-steady-state for preserved signal characteristics.
• Acquisition of BOLD fMRI data in the human brain at 7 Tesla and the rat brain at 14 Tesla.
• Comparison of multi-slice bSSFP with 3D bSSFP and GE-EPI in terms of image quality, temporal signal-to-noise ratio (SNR), and sensitivity.

Main Results:

• The multi-slice bSSFP sequence successfully produced non-distorted BOLD fMRI activation maps in both human and rat brains.
• In humans (7 T), multi-slice bSSFP achieved temporal SNR comparable to 3D bSSFP for task and resting-state fMRI.
• In rats (14 T), multi-slice bSSFP demonstrated similar sensitivity to GE-EPI for task fMRI, with significantly reduced distortions and signal drop-outs.

Conclusions:

• Multi-slice bSSFP with Cartesian read-out is a viable alternative to GE-EPI and 3D bSSFP for ultra-high field BOLD fMRI.
• This method offers improved image quality by minimizing distortions and signal drop-outs, particularly beneficial for pre-clinical research.
• The technique shows promise for enhanced neuroimaging applications in both human and animal models.