Neuroimaging in Psychosis

Indications for Imaging

• The American College of Radiology recommends imaging in patients with new-onset psychosis when the clinical picture is unclear, the presentation is atypical, or there are abnormal findings on examination, including focal neurologic deficits, seizures, head trauma, headache, suspected stroke, or age ≥50 years 1
• Focal neurologic deficits present at any time warrant immediate non-contrast head CT as first-line imaging, according to the American College of Radiology 1, 2
• Suspected stroke requires referral to stroke-specific imaging protocols, as recommended by the American College of Radiology 1, 3
• Seizure activity necessitates imaging per epilepsy-specific guidelines, according to the American College of Radiology 1, 4
• Head trauma of any severity mandates imaging evaluation, as recommended by the American College of Radiology 1, 3
• Headache accompanying psychosis should trigger imaging workup, according to the American College of Radiology 1, 4
• Unclear clinical picture where the diagnosis remains uncertain after initial evaluation warrants consideration of imaging, as recommended by the American College of Radiology 1, 2
• Atypical presentation that deviates from classic psychotic symptomatology requires consideration of imaging, according to the American College of Radiology 1, 5
• Abnormal examination findings, including cognitive impairment beyond expected psychotic symptoms, warrant consideration of imaging, as recommended by the American College of Radiology 2, 6
• Known intracranial pathology from prior history requires imaging evaluation, according to the American College of Radiology 1, 5

Imaging Modality Selection

• Non-contrast head CT serves as the first-line test when neurologic deficits are present, offering rapid acquisition and safety in all patients, as recommended by the American College of Radiology 1, 6
• Brain MRI is the preferred modality according to the American Psychiatric Association when imaging is clinically indicated, particularly for atypical presentations 1, 2, 6
• MRI without IV contrast is appropriate as initial imaging when the clinical picture is unclear or presentation is atypical, as recommended by the American College of Radiology 1, 5
• MRI without and with IV contrast should be considered when autoimmune disorders are suspected or for definitive characterization of focal lesions, according to the American College of Radiology 7, 8, 9
• MRI has superior sensitivity for detecting small infarcts, encephalitis, and subtle subarachnoid hemorrhage compared to CT, as recommended by the American College of Radiology 6

Organic Causes to Consider

• Tumors or infarcts in temporal lobe regions should be evaluated, as recommended by the American College of Radiology 3
• Systemic lupus erythematosus with CNS involvement should be considered, according to the American College of Radiology 4
• Encephalitis should be evaluated, as recommended by the American College of Radiology 7
• Multiple sclerosis should be considered, according to the American College of Radiology 9
• Wilson disease should be evaluated, as recommended by the American College of Radiology 8
• Huntington disease should be considered, according to the American College of Radiology 7
• Metachromatic leukodystrophy should be evaluated, as recommended by the American College of Radiology 9

Critical Clinical Pitfalls

• Contrast-enhanced CT is generally not helpful for new-onset psychosis without focal neurologic deficits, as recommended by the American College of Radiology 1, 5, 3
• Do not defer imaging when focal neurologic signs are present, even if subtle, as this represents a fundamentally different clinical scenario requiring urgent evaluation, according to the American College of Radiology 1, 6
• The absence of neurologic deficits does not completely exclude organic pathology, but dramatically reduces pre-test probability, as recommended by the American College of Radiology 2, 3