Update on neuroimaging in infectious central nervous system disease.
OBJECTIVE
Neuroimaging constitutes an important component in the diagnosis of the underlying infectious agents in central nervous system infection. This review summarizes progress in the neuroimaging of infectious central nervous system disease since January 2003. It focuses on imaging of viral encephalitis, including that caused by exotic and emerging viruses, and on imaging in immunodeficient patients.


RESULTS
Diffusion-weighted imaging has been shown to be superior to conventional magnetic resonance imaging for the detection of early signal abnormalities in herpes simplex virus encephalitis but also in enterovirus 71 encephalitis and in West Nile encephalitis. Several studies defined the pattern of magnetic resonance imaging signal changes in endemic diseases such as West Nile encephalitis, Murray Valley encephalitis, enterovirus 71 encephalitis and Japanese encephalitis, but also in encephalitides due to ubiquitous viruses such as measles virus and Lyssavirus (rabies). In patients with HIV infection, apparent diffusion coefficient ratios obtained by diffusion-weighted imaging were significantly greater in lesions due to Toxoplasma encephalitis than in primary central nervous system lymphomas.


CONCLUSIONS
The diagnosis of unclear infectious central nervous system diseases remains a challenge. More recent magnetic resonance imaging techniques, such as diffusion-weighted imaging and magnetic resonance spectroscopy, provide additional helpful information. However, the mainstay of diagnosis remains the detection of viral DNA or serological markers of specific infectious agents within the cerebrospinal fluid.
Maschke
Matthias
M
Department of Neurology and Department of Radiology, University of Duisburg-Essen, Essen, Germany. Matthias.Maschke@uni-essen.de
Kastrup
Oliver
O
Forsting
Michael
M
Diener
Hans-Christoph
HC
D001921:Brain / Q000473:pathology* / Q000503:physiopathology / Q000821:virology; D002494:Central Nervous System Infections / Q000175:diagnosis* / Q000503:physiopathology / Q000821:virology; D004279:DNA, Viral / Q000134:cerebrospinal fluid; D003952:Diagnostic Imaging / Q000639:trends*; D038524:Diffusion Magnetic Resonance Imaging / Q000592:standards / Q000639:trends; D018792:Encephalitis, Viral / Q000175:diagnosis* / Q000503:physiopathology / Q000821:virology; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D009894:Opportunistic Infections / Q000175:diagnosis / Q000503:physiopathology / Q000821:virology; D014901:West Nile Fever / Q000175:diagnosis / Q000503:physiopathology / Q000821:virology
D004279:DNA, Viral