Application of angle between canthomeatal line and anterior commissure-posterior commissure line in sagittal plane projection assisted by MRI

Abstract

Objective To explore the significance and application of the angle between the canthomeatal line （CML） and the anterior commissure-posterior commissure （AC-PC） line in the sagittal plane projection in stereotactic neurosurgery. Methods Quantitative MRI was performed in a crosssectional analysis of 120 normal volunteers from south China; the angle between the canthomeatal line and the AC-PC line in the sagittal plane projection, the length of the intercommissure line, and the vertical distance from external auditory canal midpoint to the AC-PC plane were measured and matched for age and gender. Results The average angle between the CML and the AC-PC line in the sagittal plane projection of all South China adult brains is （12.03± 1.11）° , which is （12.17± 1.06）° in male and （11.89±1.14）° in female. The average length of AC-PC line is （23.74±0.95）° mm, which is （24.35±0.64）° mm in male and （23.14±0.95）° mm in female. The average length of the vertical distance from external auditory canal midpoint to the AC-PC plane of all is （48.69±4.03） mm, which is （49.57±3.10） mm in male and （47.82±4.61） mm in female. Clinical validation showed that the deviation angle to the actual AC-PC plane was （1.56±0.63） . Conclusion The angle formed by CML and the AC-PC plane is stable in adults of different gender and ages; taking CML as a baseline, the surface projection of AC-PC line can be drew with the angle and the vertical distance, and then, the AC-PC plane by adjusting the directional headstock can be obtained with high accuracy, repeatability and maneuverability; therefore, these datacan be used as a valuable reference of adult brain structure of Han nationality in South China. Key words: Functional stereotaxis; Anterior commissure; Posterior commissure; Canthomeatal line; Nuclear magnetic resonance