Usefulness of diffusion-weighted MRI in human herpesvirus-6 encephalitis

We report a patient with human herpesvirus-6 (HHV-6) encephalitis diagnosed by diffusion-weighted magneticresonance imaging (DW-MRI). A previously healthy 10-month-old girl developed acute encephalopathy. HHV-6 DNA was detected in her cerebrospinal fluid during the acute phase of the, disease by polymerase chain reaction. The patient demonstrated cortical diffusion abnormalities in I affected brain parenchyma, partially as the initial or most sensitive sign of encephalitis that could be detected not by conventional MRI but by DW-MRI. Serial imaging showed that the diffusion abnormality DW-MRI returned to normal after 45 days. Conclusion: DW-MRI may be a valuable tool for early detection and diagnosis of HHV-6 encephalitis and is more sensitive than conventional MRI to detect a subtle edematous change in the brain.