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Updated: Jun 12, 2026
Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
Published on: February 19, 2021
MRI only conversion to multiple sclerosis following a clinically isolated syndrome
D T Chard1, C M Dalton, J Swanton
1Department of Neuroinflammation, UCL Institute of Neurology, University College London, Queen Square, London, UK. d.chard@ion.ucl.ac.uk
Objectives:
Using current diagnostic criteria, patients who present with a clinically isolated syndrome (CIS) may develop multiple sclerosis (MS) by subsequently exhibiting dissemination in space and time on clinical (clinically definite (CD) MS) or radiological (MRI) grounds. This study investigated the frequency of radiological without clinical conversion to MS after long term follow-up as this has not previously been defined.
Methods:
Two cohorts who underwent serial clinical and MRI studies from presentation with a CIS and who were followed-up over a mean of 6 and 20 years were investigated. The distribution and formation of lesions visible on brain MRI were assessed using the revised McDonald criteria (2005). Radiologically defined (RD) MS was determined by fulfilment of the MRI but not the CDMS criteria.
Results:
105 people were followed-up for 6 years after a CIS, of whom 51% developed CDMS, 15% RDMS and the remainder were classified as still having had a CIS. 70 people were followed-up at 20 years, of whom 61% and 11% had developed CDMS and RDMS, respectively.
Conclusion:
About 10-15% of CIS patients may develop MS on MRI criteria only, without further clinical events for up to two decades.
Insights
Approximately 10-15% of patients with a clinically isolated syndrome (CIS) may develop multiple sclerosis (MS) based on MRI criteria alone, without experiencing new clinical symptoms for up to 20 years.
Area of Science:
- Neurology
- Radiology
- Clinical Medicine
Background:
- Clinically isolated syndrome (CIS) is an initial presentation that may precede multiple sclerosis (MS).
- Current criteria define MS conversion based on clinical events (clinically definite MS) or radiological findings (dissemination in space and time on MRI).
- The long-term frequency of developing MS solely on radiological criteria without clinical events has been underexplored.
Purpose of the Study:
- To determine the frequency of radiological conversion to MS in patients with CIS over extended follow-up periods.
- To define the rate of radiologically defined (RD) MS without clinically definite MS (CDMS) conversion.
Main Methods:
- Analysis of two patient cohorts presenting with CIS, followed clinically and with serial brain MRI.
- Assessment of lesion distribution and formation using the revised McDonald criteria (2005).
- Definition of RDMS as fulfilling MRI criteria for MS but not CDMS criteria.
Main Results:
- After 6 years, 51% of 105 CIS patients developed CDMS and 15% developed RDMS.
- After 20 years, 61% of 70 CIS patients developed CDMS and 11% developed RDMS.
- A significant proportion of CIS patients convert to MS based on MRI criteria alone, without clinical relapse.
Conclusions:
- Around 10-15% of CIS patients may develop MS based on MRI criteria only.
- This radiological conversion can occur without subsequent clinical events for up to two decades.
- Findings highlight the importance of MRI monitoring in CIS patients for early MS detection.
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