A dual K-space UNFOLD method for 3D functional brain imaging: A preliminary study.

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging (MRI)
• Biophysics

Background:

• High temporal resolution is crucial for 3D functional brain imaging.
• Existing methods like UNFOLD and excitation UNFOLD (XUNFOLD) have limitations in achieving desired temporal speeds.
• Investigating novel techniques to improve spatiotemporal resolution in neuroimaging is essential.

Purpose of the Study:

• To introduce and evaluate a novel dual k-space unaliasing method, DUNFOLD (dual k-space unaliasing by Fourier-encoding the overlaps using the temporal dimension).
• To assess the feasibility and performance of DUNFOLD for high temporal resolution 3D functional brain imaging.
• To compare DUNFOLD's capabilities against previous methods like XUNFOLD.

Main Methods:

• Developed DUNFOLD by merging excitation UNFOLD (XUNFOLD) and acquisition UNFOLD techniques.
• Validated DUNFOLD using phantom studies and direct comparison with XUNFOLD.
• Conducted 3D functional brain imaging focusing on microvascular response with temporal resolutions of 20s, 10s, and 5s at 0.6(3) mm³ spatial resolution.

Main Results:

• DUNFOLD achieved approximately four times greater temporal resolution compared to UNFOLD and XUNFOLD, with no discernible signal degradation.
• Successfully captured vascular responses in the visual cortex with high spatiotemporal resolution.
• Observed up to an 18% signal change in small vessels during visual stimulation.

Conclusions:

• The DUNFOLD method offers superior temporal resolution for 3D functional brain imaging compared to existing UNFOLD and XUNFOLD techniques.
• DUNFOLD is a promising advancement for functional imaging studies, particularly for investigating cerebral vascular responsiveness.
• The enhanced spatiotemporal resolution provided by DUNFOLD enables more detailed analysis of brain activity.