title: Multiple sclerosis lesion formation and early evolution revisited: A weekly high-resolution magnetic resonance imaging study.
abstract: Several magnetic resonance imaging (MRI) studies investigated the evolution of multiple sclerosis (MS) lesions to understand the pathophysiological mechanisms leading to blood-brain barrier breakdown and lesion formation. Only a few assessed the early natural history of MS lesions using short-interval longitudinal MRI.
  
  
  
  The purpose of this study was to characterize MS lesion occurrence and early evolution on high-resolution MRI acquired at weekly intervals.
  
  
  
  Active lesions were characterized on 3D fluid attenuation inversion recovery (FLAIR) and gadolinium-enhanced 3D T1-weighted MRI performed weekly (seven weeks) on five untreated patients with relapsing-remitting MS (RRMS).
  
  
  
  Active lesions (n=212) were detected in all patients. All showed contrast-enhancement on at least one time-point. Most new lesions (83.5%) were visible on FLAIR and post-contrast T1-weighted images at first detection; 11.2% showed activity on FLAIR images, one or more weeks before the appearance of contrast-enhancement; 12.5% enhanced before being apparent on FLAIR.
  
  
  
  Blood brain barrier disruption is a constant step in the natural history of active MS lesions, but does not always constitute the initial event. These findings are consistent with the existence of a subpopulation of lesions with an 'inside-out' genesis, where neurodegenerative processes might precede microglial activation, and a subsequent adaptive immune response.
authors.affiliation: Center for Neurological Imaging, Brigham and Women's Hospital, USA.
authors.forename: Charles Rg
authors.initials: CR
authors.lastname: Guttmann
authors.affiliation: Service de Radiologie, Centre Hospitalier Lyon-Sud, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Rousset
authors.affiliation: Service de Radiologie, Centre Hospitalier Lyon-Sud, France/CREATIS, Université de Lyon, France.
authors.forename: Jean A
authors.initials: JA
authors.lastname: Roch
authors.affiliation: CREATIS, Université de Lyon, France.
authors.forename: Salem
authors.initials: S
authors.lastname: Hannoun
authors.affiliation: CREATIS, Université de Lyon, France/Service de Neurologie, Hospices Civils de Lyon, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Durand-Dubief
authors.affiliation: BioClinica SAS, France.
authors.forename: Boubakeur
authors.initials: B
authors.lastname: Belaroussi
authors.affiliation: Center for Neurological Imaging, Brigham and Women's Hospital, USA.
authors.forename: Michele
authors.initials: M
authors.lastname: Cavallari
authors.affiliation: Service de Biostatistique, Hospices Civils de Lyon, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Rabilloud
authors.affiliation: CREATIS, Université de Lyon, France/Département IRM, CERMEP-Imagerie du Vivant, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Sappey-Marinier
authors.affiliation: Service de Neurologie, Hospices Civils de Lyon, France.
authors.forename: Sandra
authors.initials: S
authors.lastname: Vukusic
authors.affiliation: Service de Radiologie, Centre Hospitalier Lyon-Sud, France/CREATIS, Université de Lyon, France francois.cotton@chu-lyon.fr.
authors.forename: François
authors.initials: F
authors.lastname: Cotton
mesh_terms: D000328:Adult; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000000981:diagnostic imaging*
keywords: Magnetic resonance imaging; T2 lesions; multiple sclerosis; relapsing–remitting