Abstract
Background: The ventricular system of brain can be visualized by using modern computerized x-ray tomography, an easy and safe available noninvasive technology and it can be used as a screening procedure for many pathological conditions. Cerebral ventricular enlargement has been associated with many neurological disorders. Whether this enlargement is primary or secondary to these pathological conditions remains controversial. To define such enlargement, one must have measurements in normal subjects (controls). Present article describes the third ventricle parameters correlated to cerebrum dimensions as part of PhD thesis work of 1st author under the supervision of 2nd, 3rd and 4th author.
Material and Methods: Fifty nine apparently normal axial non-contrast head CT scans of patients (32 males, 27 females) with age range between 5-70 years were subjected to morphometric measurements using dicom image software. Third ventricle width (TVW), third ventricle sylvian fissure distance index (TSFI), third ventricle ratio (TVR) were calculated. The data collected was statistically analyzed using student t- test to compare means in males and females and Spearman’s Rank correlation coefficient to find relationship with cerebrum dimensions taking level of significance as 0.05.
Results: Mean third ventricle width was found to be 6.86 +/- 2.74mm, Mean Third ventricle sylvian fissure distance index was found to be 0.55+/-0.06 and Third ventricle ratio was observed to be 0.07+/-0.02. The values were slightly higher in males. TVW and TVR showed weak positive significant correlation whereas TSFI showed negative weak non significant correlation to transverse diameter of cerebrum.
Conclusion: Measurements of all the three parameters in males and females of the apparently normal groups revealed no significant difference. However measurement of third ventricle at all the three levels provides comprehensive data especially in elderly which might help in distinguishing third ventricle enlargement in hydrocephalus and brain atrophy diseases.

Key words: third ventricle width (TVW), third ventricle sylvian fissure distance index (TSFI), third ventricle ratio (TVR).