Morphological brain abnormalities in schizophrenia determined by computed tomography: a problem of measurement?

The size of the cerebral ventricles was estimated from computed tomographic (CT) scans of 14 young patients with schizophrenia and 12 medical controls. The subjects were a representative subsample from a larger sample studied by Boronow et al. (1985). Although no CT abnormalities were detected in the psychiatric patients using traditional measures (mechanical planimetry for the lateral ventricles and a linear measure for the third ventricle), a volumetric analysis of the same 26 scans revealed enlargement of the lateral and third ventricles in the schizophrenics. The effect revealed by volumetric measures of the lateral ventricles was 58% greater than that obtained with digital planimetry and 96% greater than the effect found using mechanical planimetry. No differences were found between volumetric and digital planimetric measures of the third ventricle, but the effect revealed by the latter measure was 114% greater than that obtained by a linear index. It is suggested that volumetric measures of lateral ventricles based on information from several CT slices may be more sensitive to group differences in ventricular size than planimetry. Likewise, area measures of the third ventricle may be more sensitive to group differences than linear measures.