title: Evolution of lesions in Susac syndrome at serial MR imaging with diffusion-weighted imaging and apparent diffusion coefficient values.
abstract: OBJECTIVE
  Susac syndrome is a rare disorder consisting of encephalopathy, hearing loss, and retinal arteriolar occlusions. The purpose of this study was to evaluate the evolution of lesions in this disease by using serial MR imaging with diffusion-weighted imaging (DWI) and apparent diffusion coefficients (ADCs). Abnormalities in the nonlesional white matter (NLWM) were also analyzed.
  
  
  METHODS
  Serial MR and DWI findings in two patients with Susac syndrome were reviewed retrospectively. ADCs of the lesions and the NLWM were compared with values of the corresponding anatomical regions in 16 control subjects.
  
  
  RESULTS
  T2-weighted images, DWIs, and fluid-attenuated inversion-recovery (FLAIR) images demonstrated diffuse small hyperintense lesions predominantly involving the corpus callosum, white matter, cerebral cortex, and deep gray structures. During the whole course in the two patients, 437, 295, and 113 lesions were depicted on FLAIR images, T2-weighted images, and DWIs, respectively. With the aggravation and mitigation of the clinical symptoms, the size and number of the lesions changed over time. Of 65 lesions with measured ADCs, six had restricted ADCs (5.29-6.91 x 10(-4) mm(2)/s), and 29 had elevated ADCs (8.02-13.5 x 10(-4) mm(2)/s). With disease progression, ADCs in the NLWM changed from normal to elevated; this corresponded to the diffuse signal-intensity change seen in the white matter.
  
  
  CONCLUSIONS
  FLAIR imaging is the most sensitive sequence for detecting lesions of Susac syndrome. DWI is useful in demonstrating the heterogeneous nature of lesions, depicting occult abnormalities in the white matter, elucidating underlying pathologic processes, and conducting patient follow-up.
authors.affiliation: Department of Radiology, University of Iowa College of Medicine, Iowa City, 52242, USA.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: White
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wendy R K
authors.initials: WR
authors.lastname: Smoker
mesh_terms: D000208:Acute Disease; D000328:Adult; D001927:Brain Diseases / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000473:pathology*; D006801:Humans; D008875:Middle Aged; D015356:Retinal Artery Occlusion / Q000473:pathology*; D012189:Retrospective Studies; D013577:Syndrome