CT and MRI Diagnosis of Viral EncephalitisA Report of 48 Cases

Objective To make a further understanding of the manifestations of viral encephalitis on CT and MR images, and to improve its diagnostic accuracy.Materials and Methods The clinical and imaging data in 48 cases with viral encephalitis (26 male, 22 female, mean age 36 years) were analyzed retrospectively. The diagnosis was clinically and experimentally made in 47 cases, and was surgically and pathologically confirmed in one case. CT was performed in 23 cases, MRI in 14 cases, both CT and MRI in 11 cases, and enhanced CT or MR in 12 cases.Results Abnormalities were found in 47 cases, including multiple or single lesions located mainly in cortices, subcortical and periventricular white matter, basal ganglia and thalami. The lesions presented as low density on CT scan, and carried long T 1 and long T 2 on MRI. Of 11 cases underwent both CT and MRI, 5 showed normal on CT but demonstrated lesions on MRI. In 7 cases with HSV encephalitis, lesions were seen in temporal lobe, sub frontal lobe, insulate and the cingulate gyrus. Cerebellum was involved in 1 case. Hemorrhage was present in 1 case. One case appeared normal.Conclusion CT and MRI can provide important information for clinical diagnosis of viral encephalitis. MRI is superior to CT. Differential diagnosis from other diseases with similar CT and MRI findings should be based on clinical data.