Sensitivity to white matter FMRI activation increases with field strength

Area of Science:

• Neuroimaging
• Biophysics
• Magnetic Resonance Imaging

Background:

• Functional magnetic resonance imaging (fMRI) detection of white matter activation remains debated.
• Previous studies often employed high-field MRI systems, suggesting a potential role for field strength.

Purpose of the Study:

• To investigate the impact of magnetic field strength on fMRI sensitivity in white matter.
• To assess the temporal signal-to-noise ratio (tSNR) across tissue types at varying field strengths.

Main Methods:

• Acquired fMRI data during a finger-tapping motor task at 1.5 Tesla (T) and 4 T.
• Analyzed group and individual activation in sensorimotor cortex and posterior limb of the internal capsule.
• Evaluated tSNR as a function of field strength for different tissue types.

Main Results:

• Sensitivity increases with field strength were more pronounced in white matter compared to gray matter.
• White matter exhibited less susceptibility to physiological noise increases at higher field strengths.
• Higher field strengths (4 T) demonstrated greater potential for detecting white matter fMRI signals.

Conclusions:

• High-field MRI systems offer significant advantages for fMRI studies targeting white matter.
• Increased sensitivity and stable tSNR at high fields make them particularly beneficial for investigating both gray and white matter activation.
• Future research should leverage high-field MRI for enhanced exploration of white matter function.