Looping Star fMRI in Cognitive Tasks and Resting State

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging (MRI)

Background:

• Conventional T2*-weighted functional MRI (fMRI) using echo-planar imaging (EPI) generates significant acoustic noise, potentially impacting auditory cortex activation and other fMRI experiments.
• This noise interference is a critical limitation in both resting-state and task-based fMRI studies.

Purpose of the Study:

• To assess the feasibility of a novel, quiet T2*-weighted whole-brain blood oxygenation level-dependent (BOLD)-fMRI method, Looping Star.
• To compare the performance of Looping Star against conventional multislice gradient-echo EPI.

Main Methods:

• The study prospectively compared the Looping Star fMRI sequence with gradient echo (GE)-EPI at 3.0T.
• Both resting-state (RS) and working memory (WM) tasks were conducted in a phantom and 10 healthy volunteers.
• Temporal stability, acoustic noise levels, functional maps, and activation accuracy were assessed for both methods.

Main Results:

• Looping Star demonstrated a 98% reduction in sound pressure compared to GE-EPI, operating at only 0.5 dB above ambient noise.
• While exhibiting stable temporal stability, Looping Star showed a 15.9% reduction in temporal signal-to-noise ratio (tSNR).
• Consistent activations were observed for RS and WM tasks, with increased activation correlating with task difficulty, though activation accuracy was 4-8% lower than GE-EPI.

Conclusions:

• Looping Star offers a promising, quiet approach for whole-brain fMRI with adequate spatiotemporal resolution and BOLD sensitivity.
• Further development is recommended to enhance sensitivity and spatial specificity for both resting-state and task-based fMRI applications.