Improved Activation and Hemodynamic Response Function of Olfactory fMRI Using Simultaneous Multislice with Reduced TR...

Area of Science:

• Neuroimaging
• Olfactory Neuroscience
• Magnetic Resonance Imaging

Background:

• Respiration can desynchronize odor stimulation and data acquisition in olfactory fMRI.
• This desynchronization degrades functional activation and hemodynamic response function (HRF) with conventional repetition times (TR).

Purpose of the Study:

• To evaluate if simultaneous multislice (SMS) technology with reduced TR can improve BOLD activation and HRF modeling in olfactory fMRI.
• To assess the impact of different TRs (3000ms, 1000ms, 500ms) on olfactory fMRI metrics.

Main Methods:

• Olfactory fMRI was performed on 16 healthy subjects using a 3T MRI scanner.
• Data were acquired with SMS acceleration at TRs of 3000ms, 1000ms, and 500ms.
• BOLD activation metrics and HRF parameters were analyzed in the amygdalae, hippocampi, and insulae.

Main Results:

• TRs of 500ms and 1000ms significantly improved BOLD activation (activated voxels, t-scores) in the amygdalae and insulae compared to 3000ms (P < 0.05).
• No significant differences in activation were found between 500ms and 1000ms TRs across regions of interest (ROIs).
• Faster TRs (500ms, 1000ms) resulted in higher HRF response height and shorter time to peak compared to 3000ms.

Conclusions:

• SMS technology with reduced TR significantly enhances functional activation and HRF in olfactory fMRI.
• This technique offers a promising approach to optimize olfactory fMRI studies by improving signal quality and temporal resolution.