Estimation of Brain Volume from Physical Measurements
We discuss the possibility of estimating brain volume from certain head measurements (circumference, length, breadth and auricular height), based on findings in 83 male and 22 female Japanese cadavers ranging from 21-92 years of age. There was generally a low degree of correlation between brain volume and the other measurements with some exceptions. The head circumference in males and the head breadth in females were significantly correlated with the brain volume at the 1% level. By the least square method, all equations for estimating brain volume were obtained from each measurement, and a modulus of the sum and product of combinations of five measurements. According to Akaike's information criterion (AIC) in multiple regression analysis, the most useful variable for estimating the brain volume was the head circumference in males and the head breadth in females, followed by the stature in both sexes. From the standard error of regression (SE) and coefficient of correlation (r), it was found that a binomial equation based on the head circumference and stature (SE=99.0, r=0.41) was the most useful for estimating brain volume, followed by formulae from the sum of head circumference and auricular height (99.4, 0.39) and the head circumference alone (99.5, 0.39) in males. In females, the product of head circumference, head breadth and stature (74.2, 0.57) was the most useful, followed by the product of head circumference, head breadth, auricular height and stature (75.4, 0.57), or that of head breadth, auricular height and stature (76.5, 0.53). However, judging by standard error, it seems that a simple formula based on only the head circumference is sufficient to estimate the brain volume. The formulae should be used to compare populations not individuals.