We studied the possibility of making an objective diagnosis of dementia based on radiological findings by evaluating cerebral and hippocampal atrophy and the corpus callosum shape on MRI images in patients with Alzheimer-type dementia, compared with healthy elderly individuals. There was a statistically significant difference in the hippocampus area index, the ventricle area index, and the area ratio for the second, forth, and fifth parts of corpus callosum. Discriminant analysis using these three parameters demonstrated the sensitivity of 88.5% and the specificity of 85.7%, suggesting a highly positive diagnostic rate. These results indicate that quantitative MRI measurements could be used for differentiating Alzheimer-type dementia from similar diseases.