Using pneumoencephalography and computerized axial tomography (EMI scanning) Polaroid® pictures, the relationship between ventricular size and cerebral size was investigated in 35 patients. Evans' index was used for pneumoencephalograms, and planimetric measurement of the ventricular and cerebral cross-sectional areas was used for EMI scanning. The percentage ratio for the latter technique is termed VBR. The correlation coefficient between the two methods was 0.9510 (p < 0.001).