Awake rodent fMRI: Gradient-echo echo planar imaging versus compressed-sensing fast low-angle shot

Area of Science:

• Neuroimaging
• Functional Magnetic Resonance Imaging (fMRI)
• Rodent Models

Background:

• Awake rodent fMRI is a valuable tool for studying neuronal activity at whole-brain and laminar scales.
• Optimization of acclimation, paradigms, and hardware is ongoing, but pulse sequence impact remains understudied.

Purpose of the Study:

• To compare gradient-echo echo planar imaging (GE-EPI) and compressed-sensing fast low-angle shot (CS-FLASH) pulse sequences for detecting hemodynamic activity in awake rodent fMRI.
• To evaluate sensitivity to brain activation using cerebral blood volume-weighted (CBVw) contrast enhancement in the olfactory bulb.

Main Methods:

• Comparison of GE-EPI and CS-FLASH pulse sequences in awake rodents.
• Utilized cerebral blood volume-weighted (CBVw) contrast enhancement.
• Investigated hemodynamic activity in the olfactory bulb.
• Analyzed motion parameters and image quality, including framewise displacement and spatial correlation censoring.

Main Results:

• CS-FLASH exhibited comparable motion parameters to GE-EPI but was more susceptible to motion-induced image corruption.
• GE-EPI demonstrated a consistently greater contrast-to-noise ratio (CNR) for odor activation than CS-FLASH.
• CS-FLASH produced sharper images and equivalent spatial activation patterns to GE-EPI, but with lower statistical strength and detection sensitivity.

Conclusions:

• GE-EPI is more sensitive for detecting hemodynamic brain activation in awake rodent fMRI compared to CS-FLASH.
• CS-FLASH offers sharper images but reduced CNR and statistical power for detecting activation.
• Pulse sequence choice significantly impacts the sensitivity and reliability of awake rodent fMRI studies.