Imaging and other key findings distinguishing between differential diagnoses
| Differential diagnosis | Imaging and laboratory findings |
| Rhomboencephalitis | Limited to the brainstem and cerebellum, ring-enhancing abscesses associated with Listeria; inflammatory CSF |
| Reversible cerebral vasoconstriction syndrome | Vasoconstriction on cerebral angiography |
| Demyelination | Postgadolinium enhancement with acute lesions; microhaemorrhages do not occur with demyelination; CSF evaluation especially for oligoclonal bands. |
| Paraneoplastic encephalitis | Inflammatory CSF, positive antineuronal antibodies. |
| CNS vasculitis | Circumferential arterial wall thickening and enhancement on vessel wall MRI, inflammatory CSF; serum vasculitis screen may be positive. |
| SMART syndrome | Prominent gyral enhancement with mild mass effect and cortical thickening (hyperintense on T2 and FLAIR) with or without diffusion restriction; typically, it is unilateral. |
| Acute hepatic encephalopathy | FLAIR hyperintensity and reduced diffusion in thalami, posterior limb of the internal capsules and periventricular white matter. Serum ammonia may be elevated. |
| Leucoencephalopathy | Symmetrical confluent T2 and FLAIR hyperintensities limited to the white matter; follow-up scans show persistent abnormalities. |
| Central pontine myelinolysis | Raised ADC and postgadolinium enhancement |
| Malignancy | Persistent abnormalities on follow-up scans commonly enlarging over time, asymmetrical and often focal |
| Gliomatosis cerebri | Isointense on T1 and hyperintense on T2, elevated choline/NAA peak |
| Acute stroke | Decreased ADC suggesting cytotoxic oedema |
| Cerebral venous sinus thrombosis | Abnormal signal in cerebral venous sinuses |
ADC, apparent diffusion coefficient; CNS, central nervous system; CSF, cerebrospinal fluid; FLAIR, fluid-attenuated inversion recovery; NAA, n-acetyl aspartate; SMART, stroke-like migraine attacks after radiation therapy.