Abstract
Purpose: The aim of the study was to examine the indices of the normal third ventricle of brain, its variation with age and discuss clinical application.
Methods: In a retrospective, cross-sectional, non-interventional study, the CT images of 60 patients (mean age 36.22+/-15.44 years) were subjected to morphometric analysis by dicom image software, and the 3rd ventricle indices, namely, third ventricle width (TVW), third ventricular sylvian fissure distance index (TSFI) and third ventricle ratio (TVR) were studied and correlated to age by finding Pearson correlation coefficient at 0.05 significance level.
Results: Mild positive non- significant correlation was observed between third ventricle widths with age. TSFI showed negative significant moderate correlation with age (r=-0.396, p= 0.0017) and TVW (r= - 0.340, p=0.007) whereas TVR showed no correlation with age. The distance between margin of third ventricle and respective sylvian fissure was more on left side with statistically non-significant difference.
Conclusion: The present study shows that TVW increases only mildly and TSFI decreases with age. TVR does not depend upon age.

Key words: Third ventricle indices, Third ventricle sylvian fissure distance index.