Magnetic resonance and diffusion-weighted imaging findings of herpes simplex encephalitis.

Herpes simplex encephalitis (HSE) is a rare, life-threatening disease. This paper draws attention to the role of imaging in early HSE diagnosis. Five consecutive patients diagnosed with HSE (type 1) between June 2005 and June 2006 (three males, two females, mean age 44 [range 16-68] years) were included in this retrospective study. Computed tomography, conventional magnetic resonance imaging (MRI) sequences and diffusion-weighted imaging (DWI) were obtained for each patient. Apparent diffusion coefficient values were calculated in diseased and normal tissue. Therefore, we propose that MRI scan with DWI should be performed when HSE is suspected, although in disease follow-up DWI is not superior to conventional sequences. There is no need for contrast media to be administered at any disease stage. Fluid-attenuated inversion recovery is superior to T2 sequencing in showing cortical lesions at all disease stages.