Morphology of the adult midsagittal brainstem in relation to the reference systems MRI-based variability study.

RATIONALE AND OBJECTIVES: Anterior/posterior commissure reference system (AC/PC reference system) and the fastigium/ventricular floor plane reference system (FFL/VFL reference system) are two reference systems used in the stereotactic localization of the invisible nuclei of the brainstem in magnetic resonance (MR) images. This study investigated the variation of the midsagittal brainstem in relation to the AC/PC and VFL/FFL reference systems with respect to age and gender.

MATERIALS AND METHODS: High-resolution T1-weighted structural MR images were acquired from 64 adults (age range 21-60 years, 32 males and 32 females). The AC/PC and VFL/FFL reference systems were identified automatically. A set of landmarks of the midsagittal brainstem were defined and localized interactively.

RESULTS: Results illustrated that there was significant difference between the variance of the anteroposterior coordinate of the landmarks in relation to the AC/PC reference system and that in relation to the FFL/VFL reference system (P < .05), the former is larger than the latter. The positions of the landmarks in the females are more anterior than those in the males in relation to the AC/PC reference (P < .05); the difference in relation to the FFL/VFL reference system was not found.

CONCLUSION: Either the FFL/VFL reference system or the AC/PC reference system has its own advantage in the stereotactic localization of the structure in the brainstem.