Morphometric Analysis of the Brainstem and Subarachnoid Cisterns Using Midsagittal MRI: A Retrospective Study

This study aimed to evaluate comprehensively the morphometric characteristics of the brainstem and posterior fossa cisterns using midsagittal magnetic resonance imaging (MRI) and to investigate sex-related differences. A total of 200 adult participants aged 18 years and older (100 males, 100 females) were retrospectively included. High-resolution midsagittal T2-weighted MRI sequences were analyzed to measure the tentorial angle, clivus length, foramen magnum diameter, anteroposterior and superoinferior dimensions of brainstem segments, and the anteroposterior distances of the cisterna interpeduncularis, cisterna prepontis, cisterna magna, and cisterna quadrigeminalis. Data were analyzed using SPSS 28.0 with Mann–Whitney U and Spearman correlation tests. Females demonstrated greater tentorial angle and cerebellar height, whereas males exhibited larger mesencephalic and pontine dimensions as well as a wider interpeduncular cistern. No significant sex-related differences were observed in the remaining parameters. Correlation analysis revealed that the tentorial angle was positively associated with cerebellar height but negatively correlated with the widths of the interpeduncular and magna cisterns. Additional positive correlations were identified among brainstem segments and between posterior fossa cisterns. This study provides normative morphometric data on the brainstem and posterior fossa cisterns, offering reliable reference values for clinical and radiological assessments. The findings may contribute to improving diagnostic accuracy, refining surgical safety margins, and aiding in the differential diagnosis of pathological conditions. Furthermore, the data are expected to facilitate a more comprehensive anthropological evaluation of cranial morphology.