Should frequent MRI monitoring be performed in natalizumab-treated MS patients? A contribution to a recent debate

• Published in: Multiple sclerosis p. 1352458519854162
• Main Authors: Scarpazza, Cristina, Signori, Alessio, Cosottini, Mirco, Sormani, Maria Pia, Gerevini, Simonetta, Capra, Ruggero
• Format: Journal Article
• Language: English
• Published: England 01.09.2020
• Subjects: Natalizumab; lesion volume; progressive multifocal leukoencephalopathy; high frequency MRI
• ISSN: 1477-0970
• DOI: 10.1177/1352458519854162

Brain magnetic resonance imaging (MRI) is the most effective surveillance tool for the detection of asymptomatic progressive multifocal leukoencephalopathy (PML). However, the optimal frequency for routine MRI surveillance is under-investigated. To understand whether, upon their first MRI appearance, PML lesions present a difference in volume when comparing patients who frequently underwent MRI surveillance (3/4 months) with those who were assessed at longer intervals (6/12 months) and to understand the impact of the volume of lesions on clinical outcome. The data of patients included in the Italian PML cohort were retrospectively analysed. Patients who had all the pre-diagnostic MRI scans available ( n = 37) were included. The volume of PML lesion was calculated by manually outlining the PML lesion. Compared with patients who underwent MRI examination at least every 4 months, patients who were assessed less frequently had a lesion of significantly higher volume (median: 2567 (883-3583) vs. 664 mm (392-963) p = 0.006) and suffered a higher rate of disability (median: 2.25 expanded disability status scale points (-2.5 to 8) vs. 0.5 (-1 to 2.5) p = 0.004). The positive clinical outcome of patients undergoing frequent MRI surveillance and the small volume of the PML lesion upon first appearance justify a frequent surveillance using MRI in patients at high risk of PML.