Age and Gender Related Morphometric Analysis of the Fourth Ventricle Using MRI in Healthy Adults: A Cross-Sectional Study

Objective: To analyze age- and gender-related differences in the length and width of the fourth ventricle using MRI in healthy adults in two different age groups. Methodology: This cross-sectional study was conducted in the Department of Anatomy and Radiology of Jinnah Postgraduate Medical Centre, Karachi, from November 2019 to December 2021. The study was carried out on 206 healthy subjects. divided into two age groups: Group A (20–40 years) and Group B (41-60 years). Both groups included male and female participants with no clinical symptoms or metallic implants. Images were acquired using a thin-slice (1 mm) 3D brain MRI protocol on a 1.5-Tesla scanner (T1-weighted, T2-weighted, and FLAIR sequences). Fourth-ventricle dimensions were measured on axial images using MicroDicom: length was measured craniocaudally at the midline (roof-to-floor), and width was measured transversely at the level of the lateral recesses. Results: The fourth ventricle was slightly larger in males than in females in both age groups. In Group A (20–40 years), males had a mean length of 14.3 ± 1.16 and width of 13.6 ± 1.36, compared to females (length 13.8 ± 0.91, width 12.9 ± 1.35; p = 0.007). In Group B (41–60 years), males were slightly larger (length 14.7 ± 1.19, width 13.9 ± 1.19) than females (length 14.5 ± 1.02, width 13.6 ± 1.21), without statistical significance. Age-related comparison showed a significant increase in females’ length (p = 0.001) and width (p = 0.005), while males showed no significant change (all values in mm). Conclusion: The study provides MRI-based normative reference values for fourth-ventricle dimensions in healthy Pakistani adults, demonstrating modest gender differences and age-related enlargement, particularly in females. These population-specific measurements serve as an important baseline for distinguishing normal anatomical variation from pathological ventricular dilation in clinical practice.