Computed Tomography in Patients with Psychiatric Illnesses: Advantage of a "Rule-In" Approach

Abstract

Computed tomography (CT) is used commonly to "rule-out" disease. In 123 consecutive patients with psychiatric diseases in three institutions, 105 CT scans (85.4%) interpreted as normal or normal except for atrophy did not influence management, only reassured clinicians and patients. Incidental and false positive findings were more numerous than true positive findings. All six true positive findings occurred in patients with focal findings on neurologic examination; four led to management changes. The lower 954% confidence limit of the cost of case finding by CT only was estimated to be $2931 for all patients; $603 for patients with focal findings; and at least $7083 for patients without focal findings. Computed tomography is a sensitive diagnostic method that may detect more false and incidental positive findings when used somewhat unselectively to "rule-out" disease. In these patients, a examination suggesting structural intracranial abnormalities would have been less expensive and more effective.

An observational study of CT scanning in psychiatric patients

“…No previous study has reported such a high percentage of abnormal brain scans as found in our study, which could be due to the inclusion of a higher percentage of elderly patients (average age 70 years) compared with earlier studies, 3,5 as with advanced age, more CT brain abnormalities can be expected. The majority of patients in our study had dementia, which is a common condition in the elderly population.…”

“…In the literature, a study reported that abnormal scans correlated with focal findings on neurological examination. 3 Another study showed that when a history of neurological disorder or neurological/organic mental signs was absent then brain scans were normal in 75 per cent of cases but when both were positive scans were abnormal in 74 per cent of cases and when both history/examination and electroencephalography (EEG) was abnormal the scan were abnormal in 92 per cent of cases. 5 In our study not all patients had had an EEG, hence we could not compare these results.…”

“…The frequency of abnormal brain scans found in psychiatric patients reported in previous studies has been highly variable, ranging from 6.8 per cent to 53 per cent. 3,5,8,10 Such a wide variation in the frequency of abnormal brain scans among psychiatric patients in different studies has been attributed to a variety of reasons, such as variable selection of patients referred by psychiatrists, differences in interpretation of scans by radiologists, different patient populations studied, eg inpatient vs outpatient, varying duration of illnesses and different age groups.…”

“…The frequency of abnormal brain scans found in psychiatric patients reported in previous studies has been highly variable, ranging from 6.8 per cent to 53 per cent. 3,5,8,10 Such a wide variation in the frequency of abnormal brain scans among psychiatric patients in different studies has been attributed to a variety of reasons, such as variable selection of patients referred by psychiatrists, differences in interpretation of scans by radiologists, different patient populations studied, eg inpatient vs outpatient, varying duration of illnesses and different age groups.No previous study has reported such a high percentage of abnormal brain scans as found in our study, which could be due to the inclusion of a higher percentage of elderly patients (average age 70 years) compared with earlier studies, 3,5 as with advanced age, more CT brain abnormalities can be expected. The majority of patients in our study had dementia, which is a common condition in the elderly population.…”

“…A number of published studies have addressed the issue of proper use of brain computerised tomography (CT) imaging in psychiatry. [2][3][4][5][6][7][8][9] The recommendations of these studies varied, from advocating imaging scans as a screening procedure for all patients, risking low yield, to restricting the recommendation to scan only those patients with clear focal neurological abnormalities on examination, accepting the risk of missing a rare diagnosis. Hence, there is a wide divergence of opinion about the proper utilisation of brain scans in psychiatric conditions.…”