Clinical use of CT and MR scans in psychiatric patients.

During a three-year period, 337 CT or MR scans were ordered for psychiatric patients in a teaching hospital. Scans were normal in 185 instances, equivocal in 34, and abnormal in 118 instances. When a history of neurologic disorder and/or the presence of abnormal neurologic/organic mental signs was positive, scans were abnormal in 74% of cases; when these indicators were negative, scans were normal in 72% of cases. In all, only 4 new diagnoses were made. Two patients, both with markedly abnormal neurological findings, were shown to have brain tumors, which changed their management. Two others showed abnormalities which would have been missed, both of which were of no clinical consequence. The following are suggested as sound indications for ordering CT or MR brain imaging among psychiatric patients: 1) positive history of head injury, stroke or other neurologic disease, as well as suspected Alzheimer disease or multi-infarct dementia; 2) presence of abnormal neurologic signs or organic mental signs, such as confusion or cognitive decline; and, 3) a first psychotic break or personality change after the age of 50 years.