title: Midsagittal corpus callosum area and conversion to multiple sclerosis after clinically isolated syndrome: A multicentre Australian cohort study.
abstract: BACKGROUND
  Patients presenting with clinically isolated syndrome (CIS) may proceed to clinically definite multiple sclerosis (CDMS). Midsagittal corpus callosum area (CCA) is a surrogate marker for callosal atrophy, and can be obtained from a standard MRI study. This study explores the relationship between CCA measured at CIS presentation (baseline) and at 5 years post presentation, with conversion from CIS to CDMS. The association between CCA and markers of disability progression is explored.
  
  
  METHODS
  Corpus callosum area was measured on MRI scans at presentation and 5-year review following diagnosis of a first demyelinating event, or evidence of progressive MS, in 143 participants in the Ausimmune/AusLong Study. Relationships between CCA (at baseline and follow-up) and clinical outcomes were assessed.
  
  
  RESULTS
  Mean CCA at baseline study was 6.63 cm2(SD 1.01). Patients who converted to MS by 5-year review (n = 100) had a significantly smaller mean CCA at follow-up (6.22 vs. 6.74, P = 0.007). Greater CCA reduction was associated with higher annualized relapse rate over follow-up.
  
  
  CONCLUSIONS
  Baseline CCA obtained from standard MRI protocols may be compared with subsequent MRI examinations as a surrogate for neurodegeneration and cerebral atrophy in patients with MS. This study demonstrates an association between CCA and disability in individuals presenting with CIS who convert to MS.
authors.affiliation: Department of Medical Imaging, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.|School of Medicine, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Cara
authors.initials: C
authors.lastname: Odenthal
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Steve
authors.initials: S
authors.lastname: Simpson
authors.affiliation: Department of Medical Imaging, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.|School of Medicine, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Justin
authors.identifier: http://orcid.org/0000-0001-7296-9783
authors.initials: J
authors.lastname: Oughton
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Ingrid
authors.initials: I
authors.lastname: van der Mei
authors.affiliation: School of Medicine, The University of Queensland, Brisbane, Queensland, Australia.|ICT - Australian e-Health Research Centre, Brisbane, Queensland, Australia.
authors.forename: Stephen
authors.initials: S
authors.lastname: Rose
authors.affiliation: ICT - Australian e-Health Research Centre, Brisbane, Queensland, Australia.
authors.forename: Jurgen
authors.initials: J
authors.lastname: Fripp
authors.affiliation: National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: Robyn
authors.initials: R
authors.lastname: Lucas
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Bruce
authors.initials: B
authors.lastname: Taylor
authors.affiliation: Duke Kunshan University, Kunshan, China.
authors.forename: Keith
authors.initials: K
authors.lastname: Dear
authors.affiliation: Murdoch Children's Research Institute, Royal Children's Hospital, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Anne-Louise
authors.initials: AL
authors.lastname: Ponsonby
authors.affiliation: Department of Medical Imaging, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.|School of Medicine, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Alan
authors.identifier: http://orcid.org/0000-0003-1110-9207
authors.initials: A
authors.lastname: Coulthard
mesh_terms: D000328:Adult; D001315:Australia; D003337:Corpus Callosum / Q000000981:diagnostic imaging* / Q000473:pathology*; D003711:Demyelinating Diseases / Q000000981:diagnostic imaging* / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D009103:Multiple Sclerosis / Q000000981:diagnostic imaging* / Q000473:pathology*; D012307:Risk Factors
keywords: atrophy; clinically isolated syndrome; corpus callosum; magnetic resonance imaging; multiple sclerosis