Is a computed tomography (CT) scan of the brain part of the initial workup for first-episode psychosis?

From the Guidelines

A computed tomography (CT) scan of the brain is not routinely recommended as part of the initial workup for first-episode psychosis in patients without neurologic deficits or other specific risk factors. This recommendation is based on the low yield of CT scans in detecting pathology responsible for psychotic symptoms in such patients, ranging from 0% to 1.5% as reported in the literature search 1. The American College of Emergency Physicians Clinical Policies Subcommittee on the Adult Psychiatric Patient also found inadequate literature on the usefulness of neuroimaging for new onset psychosis without a neurologic deficit in the ED setting, suggesting individual assessment of risk factors to guide the decision for neuroimaging 1.

Key Considerations

• The decision to obtain a CT scan should be individualized based on the patient's clinical presentation, age, and presence of atypical features such as late onset, neurological signs, or rapid progression of symptoms.
• Patients with suspected stroke, focal neurologic deficit, seizure, head trauma, or headache should be referred to the respective ACR Appropriateness Criteria for further guidance 1.
• Other important components of the workup include comprehensive history taking, physical and neurological examination, laboratory tests (including toxicology), and possibly EEG if seizure disorders are suspected.
• In some settings, MRI may be preferred over CT as it provides better resolution of brain tissue and can detect subtle abnormalities, though CT is often more readily available and sufficient for initial screening 1.

Rationale

The rationale behind not routinely recommending a CT scan for first-episode psychosis without specific risk factors is to avoid unnecessary radiation exposure and costs associated with the scan, given the low likelihood of detecting a significant abnormality that would change the clinical management 1. However, in patients with new onset psychosis and suspected organic causes such as tumors, infarcts, or other lesions, neuroimaging, including CT or MRI, is crucial for diagnosis and guiding treatment 1.

From the Research

Computed Tomography (CT) Scan in First-Episode Psychosis

• A CT scan of the brain is not typically part of the initial workup for first-episode psychosis, as studies have shown that it is unlikely to reveal disease leading to a significant change in management 2, 3, 4, 5.
• The evidence suggests that routine CT scans in first-episode psychotic patients have limited clinical consequences, with potentially causal brain abnormalities found in only 0.8% of cases 2.
• Studies have also shown that MRI scans are comparable to CT scans in terms of diagnosis of both pathological and incidental cerebral lesions, and that routine brain structural imaging of first-episode psychosis in patients without focal neurology may not be routinely required 3.
• Incidental brain findings not causally related to the psychosis, such as brain atrophy, arachnoid cyst, and asymmetric lateral ventricles, are more common, but do not typically require further medical referral 4, 5.
• The diagnostic yield of CT scans in first-episode psychosis is low, with no focal brain lesion potentially responsible for the psychosis or focal lesion requiring surgical intervention identified in several studies 2, 3, 4, 5.