MR findings in Murray Valley encephalitis

Abstract

Murray Valley encephalitis (MVE) is caused by a flavivirus related to West Nile and St. Louis encephalitis viruses. We report a case of MVE resulting in quadriplegia and respiratory failure. MR imaging demonstrated thalamic hyperintensity on T2-weighted images, with similar involvement of the red nucleus, substantia nigra, and cervical cord. These findings preceded serologic diagnosis and are similar to those of Japanese encephalitis. In the appropriate setting, thalamic T2 hyperintensity is suggestive of flavivirus infection.

Fig 1.

A, Axial spin-echo T1-weighted image (560/14 [TR/TE]) shows hypointensity of the thalami. B, Axial fast spin-echo T2-weighted image (3641/80) showing hyperintensity of the thalami. C, Coronal fast spin-echo T2-weighted image (3641/80) shows hyperintensity of both thalami, red nuclei, and substantia nigra. D, Axial spin-echo T1-weighted image (570/14) reveals subtle heterogeneous enhancement within the thalami. E and F, Single-shot spin-echo echo-planar axial diffusion-weighted image (E) with diffusion sensitivity of b = 1000 s/mm2 (4832/81) demonstrates bilateral thalamic high signal intensity. Corresponding apparent diffusion coefficient map (F) shows increased diffusion in the region of the thalami. This indicates that high signal intensity demonstrated on the diffusion-weighted images represents T2 shine-through rather than cytotoxic edema. G, Sagittal fast spin-echo T2-weighted (2654/100) image of the cervical spine show diffuse hyperintensity of the central cord. H, Axial gradient-echo T2-weighted (697/14; flip angle, 25°) image of cervical spine shows hyperintense gray matter within the cord.