Spatial relationships of neuroanatomic landmarks in schizophrenia

Two new morphometric techniques, landmark-based shape analysis and landmark-based image averaging, were applied to magnetic resonance images (MRIs) to investigate the sites and extent of structural neuropathology in schizophrenia. These analyses allow the identification of averaged anatomy through joint registration on multiple landmarks simultaneously. MRI scans obtained in the midsagittal plane were compared between 14 patients with schizophrenia and 14 normal subjects. The relation between averaged landmark configuration in the two groups was visualized as a deformation. There were no large-scale shape abnormalities noted, although the patients had significantly smaller brains. The data suggest that the neuroanatomic abnormality associated with schizophrenia, in the midsagittal plane, is circumscribed (focal), involving primarily the region of the posterior corpus callosum, upper brainstem, and quadrigeminal cistern. Also, the thickness of the corpus callosum is reduced all along its length. The findings are consistent with prior studies suggesting involvement in schizophrenia of the cerebellum, the corpus callosum and, possibly, the limbic structures contributing to the corpus callosum. The methods of image averaging and shape analysis used in this study complement the 'region of interest' method of investigating morphometric abnormalities by characterizing the precise locations and spatial relationships among relevant structural brain abnormalities in schizophrenia.