Anterior commissure--posterior commissure revisited

Area of Science:

• Neuroimaging
• Radiology
• Human Anatomy

Background:

• Conventional MRI systems (e.g., 1.5T) have limitations in visualizing the anterior commissure (AC) and posterior commissure (PC).
• Advances in ultra-high resolution MRI, specifically 7.0T MRI, allow for direct and detailed examination of these brain structures.

Purpose of the Study:

• To standardize the shape and size of the AC and PC using 7.0T MRI.
• To propose a novel brain reference line, the central intercommissural line (CIL), for improved anatomical standardization.

Main Methods:

• Thirty-four healthy volunteers underwent 7.0T MRI scans.
• The centers of the AC and PC were identified, and the central intercommissural line (CIL) was defined by connecting these centers.
• The CIL was compared with established reference lines (tangential intercommissural line, canthomeatal line) by measuring angular differences.

Main Results:

• The CIL demonstrated reproducible angular differences from the horizontal line (8.7° males, 17.4° females).
• Angular differences between the CIL and the canthomeatal line were consistent (10.1°) across sexes.
• No significant sex-based differences were observed in the angles between the CIL and the tangential intercommissural line.

Conclusions:

• 7.0T MRI provides a robust method for quantitative definition of the AC and PC.
• The central intercommissural line (CIL) is a reproducible reference line.
• The CIL can serve as a standardized reference for axial brain imaging.