Anatomical constraints on visualization of the human hippocampus using echo-planar imaging

Area of Science:

• Neuroimaging
• Neuroscience
• Radiology

Background:

• Accurate visualization of the hippocampus is crucial for functional magnetic resonance imaging (fMRI) studies of memory function.
• Susceptibility artifacts, particularly near the skull base, frequently compromise hippocampal image quality in echo-planar imaging (EPI).
• Subject selection based on anatomical factors can mitigate these artifacts and improve imaging efficiency.

Purpose of the Study:

• To identify anatomical predictors of hippocampal image quality in EPI.
• To determine factors influencing susceptibility artifacts in the hippocampal region.
• To provide guidance for subject selection in fMRI studies focusing on memory function.

Main Methods:

• Acquired EPI data from 62 hippocampi of 31 healthy volunteers.
• Evaluated anatomical measurements potentially correlating with image quality.
• Utilized logistic regression analysis to identify significant predictive factors.

Main Results:

• Hippocampal head visualization was adequate in 65% of subjects (40/62).
• Vertical diameter of the internal acoustic meatus (DV-IAM) and sphenoid sinus pneumatization rate (RP-SS) significantly differed between good and poor quality images.
• Logistic regression identified DV-IAM, RP-SS, Dhippo-base (hippocampus to skull base distance), and Dhippo-IAM (hippocampus to IAM distance) as key factors influencing image quality.

Conclusions:

• Easily measurable anatomical parameters, including DV-IAM, RP-SS, Dhippo-IAM, and Dhippo-base, can predict hippocampal visualization quality in EPI.
• These parameters are valuable for optimizing subject selection in fMRI research on memory.
• Improved subject selection enhances the efficiency and reliability of hippocampal analysis in memory function studies.