Table 3. Summary of magnetic resonance imaging findings in common flavivirus encephalitis.

Type	Sites of affection	Cranial MRI findings	Associated findings
Abbreviations: CVST, cerebral venous sinus thrombosis; FLAIR, fluid-attenuated inversion recovery; JE, Japanese encephalitis; MRI, magnetic resonance imaging.
Japanese encephalitis	- Thalami and substantia nigra are commonly involved - Basal ganglia, pons, cerebral cortex, and cerebellum are sometime involved	- T2 and FLAIR hyperintensities in the affected areas with diffusion restricted in early acute stage and facilitated diffusion in subacute stage - Rarely hemorrhage can be seen in JE	- Neurocysticercosis coinfection - Rarely dengue coinfection can occur - Rarely may associated with CVST
Dengue encephalitis	- Thalami and basal ganglia are commonly affected - Pons, medulla, cerebellum, corpus callosum, and cerebral cortex can be involved	- T2 and FLAIR hyperintensities with restricted diffusion - Parenchymal or extra-axial bleed can be seen and which is more common in dengue encephalitis than JE - Diffuse cerebral edema may be seen	- Cerebellitis is more common - Cortical laminar necrosis
West Nile encephalitis	- Brain stem, basal ganglia, and corona radiata commonly affected - Thalami, cerebral cortex, an white matters may be involved	- Isolated diffusion restrictions in posterior limb of internal capsule/corona radiata - T2 and FLAIR hyperintensities in brain stem, basal ganglia, thalami, etc. - Meningitis changes seen	- Enhancement of cauda equina and lumbosacral nerve roots - Spinal cord T2 hyperintensities can be seen
Tick-borne encephalitis	- Cerebellum commonly affected - Thalami, basal ganglia, and anterior horn cell of spinal cord may be affected	- Leptomeningitis along cerebellar folia and basal cisterns - T2 and FLAIR hyperintensities in thalami, basal ganglia, and cerebellum
Murray Valley encephalitis (Australian encephalitis)	- Thalami and brain stem commonly affected	- Bilateral symmetrical T2 and FLAIR hyperintensities in thalami and brain stem
St. Louis encephalitis	- Substantia nigra most commonly affected	- T2 hyperintensities in substantia nigra	-Myelitis can be seen rarely