Improved functional mapping of the human amygdala using a standard functional magnetic resonance imaging sequence...

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Magnetic Resonance Imaging

Background:

• The amygdala plays a key role in emotional processing.
• Functional magnetic resonance imaging (fMRI) is a valuable tool for studying the amygdala.
• Susceptibility artifacts in fMRI can hinder accurate amygdala characterization.

Purpose of the Study:

• To evaluate the impact of simple acquisition parameter alterations on fMRI-amygdala imaging.
• To assess methods for reducing susceptibility artifacts in the amygdala region.
• To optimize fMRI acquisition for improved amygdala activation detection.

Main Methods:

• Evaluated standard gradient-echo echo-planar imaging at 3 T with varying echo times (27 and 36 ms) and section thicknesses (2 and 4 mm).
• Utilized an emotional stimulation paradigm to assess amygdala activation.
• Investigated the effects of spatial smoothing (4 and 8 mm) on functional data.

Main Results:

• A 2-mm section thickness minimized susceptibility artifacts in the anteromedial temporal lobe.
• Robust bilateral amygdala activation was observed with 2-mm sections.
• A longer echo time (36 ms) yielded larger amygdala activation volumes compared to 27 ms.
• Moderate spatial smoothing (4 mm) balanced sensitivity and specificity.

Conclusions:

• Increasing spatial resolution by reducing section thickness is sufficient to improve amygdala activation detectability in fMRI.
• Simple adjustments to acquisition parameters offer a practical approach to mitigate fMRI artifacts in the amygdala.
• Optimized fMRI parameters enhance the reliable characterization of amygdala function.