title: MR imaging of human herpesvirus-6 encephalopathy after hematopoietic stem cell transplantation in adults.
abstract: OBJECTIVE
  Human herpesvirus-6 (HHV-6)-associated encephalopathy tends to develop in immunocompromised patients. Neurologic symptoms, such as disorientation, short-term memory loss, convulsion, coma, and hypopnea could occur, but they may be nonspecific. We retrospectively reviewed MR images of 6 adults with HHV-6-associated encephalopathy to study characteristic imaging findings that could be useful in making the diagnosis.
  
  
  METHODS
  Between 2003 and 2005, we encountered 6 cases of HHV-6-associated encephalopathy (3 men and 3 women; age range, 36-55 years) in 3 hospitals. The diagnosis was made clinically according to the neurologic symptoms accompanied by high-level copies of HHV-6 DNA in CSF or peripheral blood by quantitative polymerase chain reaction without the detection of any other infectious pathogen.
  
  
  RESULTS
  All 6 patients had abnormal hippocampus/amygdala findings on presentation, and no other regions were involved. In the early period (0-2 days from onset), abnormal high signal intensity on fluid-attenuated inversion recovery (FLAIR) imaging (2 of 3, 67%) and on diffusion-weighted images accompanied by apparent diffusion coefficient (ADC) reduction (2 of 2, 100%) were observed. In the middle period (3-30 days), abnormal low signal intensity on T1-weighted images (5 of 6, 83%) and abnormal high signal intensity on T2-weighted images (4 of 6, 67%) and FLAIR (5 of 6, 83%) were confirmed. In the late period (> 30 days), we saw the resolution of signal intensity abnormalities and the appearance of atrophic change (4 of 4, 100%) of the affected regions.
  
  
  CONCLUSIONS
  HHV-6-associated encephalopathy in adults tends to affect the mesial temporal lobe. MR imaging is useful for detecting HHV-6 encephalopathy and distinguishing it from the other diseases of the central nervous system in immunocompromised patients.
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Noguchi
authors.forename: F
authors.initials: F
authors.lastname: Mihara
authors.forename: T
authors.initials: T
authors.lastname: Yoshiura
authors.forename: O
authors.initials: O
authors.lastname: Togao
authors.forename: K
authors.initials: K
authors.lastname: Atsumi
authors.forename: T
authors.initials: T
authors.lastname: Matsuura
authors.forename: T
authors.initials: T
authors.lastname: Kuroiwa
authors.forename: H
authors.initials: H
authors.lastname: Honda
mesh_terms: D000328:Adult; D018792:Encephalitis, Viral / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation / Q000009:adverse effects*; D015654:Herpesvirus 6, Human; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D019349:Roseolovirus Infections / Q000175:diagnosis* / Q000209:etiology