DWI and FLAIR imaging in herpes simplex encephalitis: a comparative and topographical analysis
Dimitri Renard1, Elodie Nerrant2, Catherine Lechiche3
1Department of Neurology, CHU Nîmes, Hôpital Caremeau, Place du Pr Debré, 30029, Nîmes Cedex 4, France. dimitrirenard@hotmail.com.
Journal of Neurology
|June 21, 2015
Summary
Diffusion-weighted imaging (DWI) slightly outperforms FLAIR MRI in early herpes simplex virus encephalitis (HSE), except for thalamic involvement, which is better seen with FLAIR. Understanding MRI patterns aids in differentiating HSE from mimics.
Area of Science:
- Neuroradiology
- Infectious Diseases
Background:
- Herpes simplex virus encephalitis (HSE) is a severe neurological infection.
- Diffusion-weighted imaging (DWI) is often considered superior to FLAIR for early HSE detection.
- Detailed topographical analysis of MRI findings in HSE is limited.
Purpose of the Study:
- To compare the efficacy of DWI and FLAIR MRI sequences in detecting brain involvement in non-neonatal HSE.
- To perform a detailed topographical analysis of MRI findings in HSE.
- To identify characteristic patterns of HSE progression on MRI.
Main Methods:
- Retrospective analysis of 11 non-neonatal HSE patients with MRI within 60 days.
- Development of a 50-point radiological score for topographical analysis of each hemisphere.
- Comparison of DWI and FLAIR findings, particularly in early (<2 weeks) and late (>2 weeks) stages.
Main Results:
- DWI detected 11% more affected areas than FLAIR in early HSE (n=9).
- Thalamic involvement was frequently seen on early FLAIR (67%) and better visualized than on DWI.
- DWI showed more extensive cortical abnormalities (14%) in areas common to both sequences.
- Late-stage MRI (n=2) showed FLAIR superiority, with white matter involvement.
- Brain signal changes followed a centripetal gradient from the mesial temporal area.
- Contralateral hemisphere involvement occurred with a score of 8-9/25 in the initially affected hemisphere.
Conclusions:
- DWI is slightly superior to FLAIR in acute-subacute HSE, with FLAIR better visualizing early thalamic changes.
- Characteristic topographical MRI patterns in HSE can aid in differential diagnosis.
- Understanding these patterns is crucial for accurate and timely diagnosis of HSE.
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