title: Incidence of Radiologically Isolated Syndrome: A Population-Based Study.
abstract: Incidental MR imaging findings resembling MS in asymptomatic individuals, fulfilling the Okuda criteria, are termed "radiologically isolated syndrome." Those with radiologically isolated syndrome are at high risk of their condition converting to MS. The epidemiology of radiologically isolated syndrome remains largely unknown, and there are no population-based studies, to our knowledge. Our aim was to study the population-based incidence of radiologically isolated syndrome in a high-incidence region for MS and to evaluate the effect on radiologically isolated syndrome incidence when revising the original radiologically isolated syndrome criteria by using the latest radiologic classification for dissemination in space.
  
  
  
  All 2272 brain MR imaging scans in 1907 persons obtained during 2013 in the Swedish county of Västmanland, with a population of 259,000 inhabitants, were blindly evaluated by a senior radiologist and a senior neuroradiologist. The Okuda criteria for radiologically isolated syndrome were applied by using both the Barkhof and Swanton classifications for dissemination in space. Assessments of clinical data were performed by a radiology resident and a senior neurologist.
  
  
  
  The cumulative incidence of radiologically isolated syndrome was 2 patients (0.1%), equaling an incidence rate of 0.8 cases per 100,000 person-years, in a region with an incidence rate of MS of 10.2 cases per 100,000 person-years. There was no difference in the radiologically isolated syndrome incidence rate when applying a modified version of the Okuda criteria by using the newer Swanton classification for dissemination in space.
  
  
  
  Radiologically isolated syndrome is uncommon in a high-incidence region for MS. Adapting the Okuda criteria to use the dissemination in space-Swanton classification may be feasible. Future studies on radiologically isolated syndrome may benefit from a collaborative approach to ensure adequate numbers of participants.
authors: From the Departments of Clinical Science, Intervention and Technology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.) Radiology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.) Department of Radiology (Y.F., T.G., A.A.J.), Västmanland Hospital, Västerås, Sweden. yngve.forslin@ki.se.
authors: Y
authors: 0000-0001-7097-4765
authors: Y
authors: Forslin
authors: From the Departments of Clinical Science, Intervention and Technology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.) Radiology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.) Department of Radiology (Y.F., T.G., A.A.J.), Västmanland Hospital, Västerås, Sweden.
authors: T
authors: 0000-0001-6700-1022
authors: T
authors: Granberg
authors: Department of Radiology (Y.F., T.G., A.A.J.), Västmanland Hospital, Västerås, Sweden.
authors: A Antwan
authors: 0000-0001-8337-5614
authors: AA
authors: Jumah
authors: From the Departments of Clinical Science, Intervention and Technology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.) Radiology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.).
authors: S
authors: 0000-0002-5133-0224
authors: S
authors: Shams
authors: From the Departments of Clinical Science, Intervention and Technology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.) Radiology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.).
authors: P
authors: 0000-0001-6222-6855
authors: P
authors: Aspelin
authors: From the Departments of Clinical Science, Intervention and Technology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.) Radiology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.).
authors: M
authors: 0000-0001-6135-2999
authors: M
authors: Kristoffersen-Wiberg
authors: From the Departments of Clinical Science, Intervention and Technology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.) Radiology (Y.F., T.G., S.S., P.A., M.K.-W., J.M.).
authors: J
authors: 0000-0002-3212-9592
authors: J
authors: Martola
authors: Clinical Neuroscience (S.F.) Neurology (S.F.), Karolinska University Hospital, Stockholm, Sweden.
authors: S
authors: 0000-0002-8042-3286
authors: S
authors: Fredrikson
mesh_terms: D000328:Adult; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D033162:Incidental Findings; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009103:Multiple Sclerosis / Q000000981:diagnostic imaging / Q000453:epidemiology*; D013577:Syndrome