[Magnetic resonance imaging of central nervous system inflammation]

[Is MRI monitoring useful in clinical practice in patients with multiple sclerosis? Yes]

The place of magnetic resonance imaging (MRI) in the monitoring of patients with multiple sclerosis (MS) is not codified except during the diagnostic phase. Several studies in the literature have shown that lesion load measured on an MRI done at the beginning of the disease or its increase during the first years had a predictive value, although moderate, on the occurrence of long-term disability as measured by the EDSS. Early worsening of brain atrophy during the early stages of the disease is predictive of worsening cognitive impairment in the following years. Perform an MRI is not required when setting up a first-line disease-modifying therapy (DMT) such as an immunomodulatory treatment but it is useful because it can be used as a reference scan in case of treatment failure. The indications of second-line DMTs, whether prescribed in naive patients with an active disease or after failure of a first-line DMT, are based on combined criteria incorporating MRI data acquired in the previous 3 months compared with a recent MRI. Thus the practical criteria for failure of first-line DMTs are partly based on MRI. During interferon therapy, identification of disease activity on an MRI conducted 1 year after the start of the treatment can predict treatment failure in combination with clinical criteria, such as relapses occurring during the first year. Finally, MRI is essential to the safety monitoring of patients on natalizumab to detect progressive multifocal leukoencephalopathies (PML). In patients at high risk for PML, tested positive for JC virus antibodies and having received natalizumab for more than 2 years, it could be proposed to do a short MRI with FLAIR and diffusion weighted imaging sequences every 3 months to detect preclinical PML.