title: Focal multiple sclerosis lesions abound in 'normal appearing white matter'.
abstract: BACKGROUND
  The 'normal appearing white matter' (NAWM) in multiple sclerosis (MS) is known to be abnormal using quantitative magnetic resonance (MR) techniques. The aetiology of the changes in NAWM remains debatable.
  
  
  OBJECTIVE
  To investigate whether high-field and ultra high-field T(1)-weighted magnetization prepared rapid acquisition gradient echo (MPRAGE) MRI enables detection of MS white matter lesions in areas defined as NAWM using high-field T(2)-weighted fluid attenuation inversion recovery (FLAIR) MRI; that is, to ascertain whether undetected lesions are likely contributors to the burden of abnormality in similarly defined NAWM.
  
  
  METHODS
  Fourteen MS patients underwent MRI scans using 3T FLAIR and MPRAGE and 7 Tesla (7T) MPRAGE sequences. Independent observers identified lesions on 3T FLAIR and (7T and 3T) MPRAGE images. The detection of every individual lesion was then compared for each image type.
  
  
  RESULTS
  We identified a total of 812 white matter lesions on 3T FLAIR. Using 3T MPRAGE, 186 additional lesions were detected that were not detected using 3T FLAIR. Using 7T MPRAGE, 231 additional lesions were detected that were not detected using 3T FLAIR.
  
  
  CONCLUSIONS
  MRI with 3T and 7T MPRAGE enables detection of MS lesions in areas defined as NAWM using 3T FLAIR. Focal MS lesions contribute to the abnormalities known to exist in the NAWM.
authors.affiliation: Division of Clinical Neurology, University of Nottingham, Queen's Medical Centre, UK.
authors.forename: Niraj
authors.initials: N
authors.lastname: Mistry
authors.forename: Emma C
authors.initials: EC
authors.lastname: Tallantyre
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Dixon
authors.forename: Nicolas
authors.initials: N
authors.lastname: Galazis
authors.forename: Tim
authors.initials: T
authors.lastname: Jaspan
authors.forename: Paul S
authors.initials: PS
authors.lastname: Morgan
authors.forename: Peter
authors.initials: P
authors.lastname: Morris
authors.forename: Nikos
authors.initials: N
authors.lastname: Evangelou
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology*; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004739:England; D006801:Humans; D008875:Middle Aged; D020528:Multiple Sclerosis, Chronic Progressive / Q000473:pathology*; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000473:pathology*; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D055815:Young Adult