Midsagittal MRI Morphometric Reference Values for the Anterior Frontal Lobe and Central Region in Native Tibetan...

Midsagittal magnetic resonance imaging (MRI) provides reproducible landmarks for assessing the anterior frontal lobe and central region, but population-specific reference data for native Tibetan adults are limited. This study established normative midsagittal MRI morphometric values and examined sex- and age-related differences.

This cross-sectional MRI-based morphometric study included 186 native Tibetan adults aged 18 to 76 years (mean age, 36.0±13.1 y), comprising 74 men and 112 women. Measurements were obtained from midsagittal T1-weighted images using predefined anatomic landmarks. Key landmarks relevant to the findings reported here included the frontal pole (FP), anterior commissure (AC), posterior commissure (PC), anterior-most point of the outer surface of the genu of the corpus callosum (AGCC), inner surface of the genu of the corpus callosum (IGCC), frontal cortical surface (FCS), cortical surface at the level of the coronal suture (CCS), central sulcus (CS), and marginal sulcus (MS). Linear measurements included FP-IGCC, FP-AGCC, FCS-AGCC, AC-PC, CCS-CS, and CS-MS, and angle α was defined using lines from PC to CS and from PC to MS. Sex differences were evaluated using age-adjusted linear regression, and age associations were assessed using sex-adjusted linear regression. Benjamini-Hochberg false discovery rate correction was applied, and false discovery rate-adjusted P values (FDR- P ) were reported.

Men had larger age-adjusted values for several anterior frontal and central-region measurements, including FP-IGCC ( B =1.77 mm; 95% CI: 0.88-2.66; FDR- P <0.001) and CCS-CS ( B =4.89 mm; 95% CI: 2.82-6.95; FDR- P <0.001). Women had larger CS-MS distance ( B =-1.86 mm; 95% CI: -2.73 to -0.99; FDR- P <0.001) and angle α ( B =-1.59 degrees; 95% CI: -2.30 to -0.87; FDR- P <0.001). After sex adjustment and FDR correction, age was associated with FP-AGCC, FP-IGCC, FCS-AGCC, and AC-PC (all FDR- P <0.05).

Native Tibetan adults showed measurable sex-related differences in midsagittal anterior frontal and central-region MRI morphometry, whereas age-related associations were smaller and limited to selected measurements. These data provide population-specific reference values for anatomic assessment and preoperative orientation.