MR Imaging Spectrum of Japanese B Encephalitis in Pediatric Age Group

Abstract

BACKGROUND: Japanese B encephalitis is an important public health problem, mainly in the districts of upper Assam. MRI Brain with its conventional T2/FLAIR sequences as well as DWI & ADC mapping can clearly depict the site & extent of involvement of different parts of the brain along with any associated coinfections. Especially DWI sequence shows findings that closely follows the pathological changes of the encephalitic process. OBJECTIVE: To evaluate Japanese B encephalitis in pediatric age group with MRI Brain. METHODS: It is a retrospective descriptive observational study carried out on AES cases referred to our department from Pediatric department for MRI Brain during January-September 2015. All cases were evaluated as per following protocol. Axial T1-weighted (T1-W) & T2-weighted (T2-W), axial & coronal fluid-attenuated inversion recovery pulse image (FLAIR), axial GRE/SWI and axial Diffusion-weighted imaging (DWI) with ADC (Apparent diffusion coefficient) sequences were taken. In cases where contrast study was indicated, post contrast T1-W fat saturated (T1FS) sequence in axial, coronal and saggital planes were taken. Serological tests, i.e., MAC ELISA and VNT, for the diagnosis of JE were done by using paired blood & CSF samples. RESULTS: Out of the 24 cases referred for MRI evaluation, JE was confirmed serologically in 21 patients. Most of the cases showed symmetrical T2/FLAIR hyperintensity in bilateral Thalami & Substantia nigra. CONCLUSION: Japanese B Encephalitis is the most common & important cause of AES in this region of Upper Assam, especially in pediatric age group mainly in the rainy season. MRI could detect the disease process as efficiently as that of serological and CSF studies along with its coinfections.