AIMS To determine whether simple linear measurements can be used as an accurate and reproducible replacement of the volumetric ones. METHODS We measured the cella media distance (CM1) and the distance between the right and left human brain surfaces (CM2)--measured along the CM1 line--in the groups of women (F) and men (M) who were divided according to diagnoses into three subgroups (F1-3 and M1-3). Examinations were carried out under standardized conditions: axial serial CT (Computed Tomography) images, in 4 mm layers (333 patients). Measured values were detected by Osiris Software. Recorded values were statistically analysed. RESULTS We found very highly significant (subgroups M1, M3), and significant (subgroups F1, F2, F3, M2) associations between the cella media distance and the decade of age. There were only non-significant differences in CM1 distances between men and women and between the diagnoses groups as well. Correlation between cella media distance and volume of lateral ventricles was greater in men in both, subgroup M1 (r = 0.659, P < 0.0001) and in a mixed group where all the three male subgroups M1-3 were combined into one group (r = 0.675, P < 0.0001). Among women the correlation was lower, however still significant (r = 0.357, P < 0.0001 for F1 and r = 0.465, P < 0.0001 for F1-3). CONCLUSIONS The cella media distance is much better predictor of brain lateral ventricular volume in men than in women.