This study investigated MRI results on clinically-stable patients treated with natalizumab. Its purpose was to determine the frequency of asymptomatic lesions and whether clinicians changed DMT based on these results.

A retrospective chart review was conducted of all MRIs ordered in absence of new symptoms and the resultant changes to their treatment by 7 clinicians.

246 patients, 78 of whom were JCV Ab negative, were identified.   870 brain MRIs and 193 spine MRIs of the spine were ordered. New T2-hyperinstense lesions were found in 50 brain MRIs and 17 spinal MRIs. 226 MRIs (154 brain and 72 spine) were done in the JCV Ab negative cohort. Of these, 17 brain MRIs and 9 spinal MRIs showed new T2-hyperintense lesions. Clinicians changed a patient’s DMT in only 1 JCV Ab positive and 1 JCV Ab negative case based on MRI findings. No PML cases were found.  

Though MRIs revealed new lesions in some natalizumab-treated patients, in all but two cases clinicians continued natalizumab. As clinicians are counseled to avoid tests that will not impact clinical decision making, this study questions the value of routine, surveillance MRIs in stable patients on a high-efficacy DMT such as natalizumab, especially those who are negative for the JC virus antibody and have a low-risk for PML. Further study is needed to elucidate the clinical utility of MRI in patients on natalizumab.