Neuroimaging in psychiatry — MEQ

(i) Purposes. Clinical neuroimaging in psychiatry is mainly for organic exclusion when pre-test probability of structural or other medical CNS disease is raised, and for selected specialised pathways (e.g. cognitive/neurology work-ups). Research uses include group structural meta-analyses, task and resting-state fMRI network models, and PET/SPECT occupancy studies that teach mechanisms. Research maps are not automatic clinical indications. ^[5][6]

(ii) Red flags and modality choice. Red flags: atypical age or tempo, focal neurology, seizures, fever, meningism, head trauma, fluctuating attention, rapid cognitive decline, immunodeficiency/cancer context, subacute psychosis with dysautonomia or movement disorder. Emergency trauma/stroke timing often starts with CT; elective organic work-up prefers MRI. Autoimmune/encephalitic phenotypes need imaging as part of a package with EEG/CSF as indicated — not imaging alone. ^[5][6]

(iii) BOLD and reverse inference. BOLD is a haemodynamic proxy related to local neural activity, not a direct spike count or photograph of thoughts. Reverse inference assumes that activation in a region uniquely identifies a mental state; this is invalid because regions support many functions. ^[3][4]

(iv) Landmark structural findings. CT-era work linked ventricular enlargement to chronic schizophrenia samples. MRI reviews/meta-analyses and ENIGMA-scale studies show group volumetric and subcortical differences. These support biological models at population level; effect sizes and overlap forbid individual diagnostic cut-offs. ^[1][2]

(v) Family counselling. Acknowledge the wish for certainty. Explain that diagnosis is clinical; MRI looks for medical problems we must not miss. A normal MRI does not mean the illness is imaginary or non-biological — brain systems for salience and thinking can be disrupted without a structural mass. Mention that research colour scans (fMRI) show group patterns, not personal proof. Outline next steps: treatment, early intervention supports, and when we would re-image if new neurological features appear. ^[5][6][4]