Interferon β (IFN- β) has been proved as an effective treatment for relapsing-remitting type of multiple sclerosis (MS), however not all patients respond to this treatment. The aims of the present study were to assess the changes in number and volume of demyelinating plaques on magnetic resonance imaging (MRI) as surrogate markers for response to IFN-β treatment in patients with relapsing-remitting MS after one year of follow-up. Methods: 41 patients with relapsing-remitting MS were recruited

more »

... d IFN β-1-a treatment was started for them. Brain MRI were obtained at baseline and after one year of treatment. the number of plaques (NP) and volume of plaques (VP) were determined. The criterion for response to treatment on MRI was defined as 50% decrease in mean NP or VP. Findings: There was a significant decrease in the NP and VP after treatment (P < 0.001). The cut-off point defined for analyzing the data was 50% decrease in mean NP or VP.The specificity of NP and VP as two criteria was the same and equals to 100%. The sensitivity of the NP was 65.5% and that for VP was 90.6%. Furthermore, if the cut-off point for the NP is set at 10%, the sensitivity of NP as a criterion will be the same as that of VP (90.6%). Conclusion: These data suggest that both the NP and VP could be two reliable imaging criteria for the assessment of response to treatment on MRI. However, the VP was more accurate than the NP.