title: Quantitative Measurement of tissue damage and recovery within new T2w lesions in pediatric- and adult-onset multiple sclerosis.
abstract: BACKGROUND
  Children and adolescents with relapsing-remitting multiple sclerosis (RRMS) have a similar T2 lesion burden as adults matched for disease duration. However, it is unknown whether the degree of tissue destruction within lesions is also similar. Persistent reduced T1-weighted signal intensity within lesions indicates loss of tissue integrity.
  
  
  OBJECTIVE
  We aimed to compare change over a 2-year period in T1 intensity within new T2 lesions, from pre-lesion levels to chronic post-lesion levels, between pediatric and adult-onset MS.
  
  
  METHODS
  A two-point intensity-normalization method was used to generate normalized T1-weighted (NT1) images from T1-weighted data in 29 pediatric MS patients (age(mean±SD, years), disease duration (years)=15.7±2.4, 3.9±2.6) and 24 adult MS patients (36.7±8.9, 6.9±4.8). Subjects were imaged at three consecutive timepoints, 1 year apart. For each subject, a 'new-T2' lesion mask was created and the NT1 intensities 'pre-lesion', 'peri-lesion' and 'post-lesion' were determined. A longitudinal model was used to capture NT1 changes.
  
  
  RESULTS
  The NT1 in both groups failed to recover to pre-lesion values by 1 year post-lesion (p=0.0002), with children showing significantly better recovery than adults (p=0.0089).
  
  
  CONCLUSIONS
  Both groups showed a significant chronic reduction of T1 intensity within new T2 lesions. However, children showed a significantly greater recovery of T1 intensity, suggesting that MS lesions in the pediatric MS population are less destructive, or that pediatric patients have greater reparative capacity.
authors.affiliation: Montreal Neurological Institute, McGill University, Montreal, QC, Canada.
authors.forename: Rezwan
authors.initials: R
authors.lastname: Ghassemi
authors.affiliation: Montreal Neurological Institute, McGill University, Montreal, QC, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Brown
authors.affiliation: The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada; The Children's Hospital of Philadelphia, Philadelphia, USA.
authors.forename: Brenda
authors.initials: B
authors.lastname: Banwell
authors.affiliation: Montreal Neurological Institute, McGill University, Montreal, QC, Canada.
authors.forename: Sridar
authors.initials: S
authors.lastname: Narayanan
authors.affiliation: Montreal Neurological Institute, McGill University, Montreal, QC, Canada douglas.arnold@mcgill.ca.
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Arnold
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000473:pathology*
keywords: Axonal loss; MRI; T2 lesions; demyelination; multiple sclerosis; relapsing/remitting