MRI plays a pivotal role in the diagnosis of multiple sclerosis (MS) in children, as it does in adults. The presence of multiple lesions in CNS locations commonly affected by MS, along with the presence of both enhancing and nonenhancing lesions, can facilitate a diagnosis of MS at the time of a first attack, whereas the accrual of serial lesions or new clinical attacks over time confirms the diagnosis in patients not meeting such criteria at onset. T2 and enhancing lesion accrual could serve as a primary outcome metric for pediatric MS clinical trials of selected therapies with anti-inflammatory activity in order to facilitate feasible trial size numbers. More-advanced MRI techniques reveal the impact of MS on tissue integrity within both T2-bright and T1-hypointense lesions and regions of normal-appearing tissue. Volumetric MRI analyses quantify the impact of MS on age-expected brain growth, and fMRI reveals activation and resting-state functional connectivity patterns in patients with pediatric MS that differ from those seen in healthy age-matched youth. Such studies are of critical importance because MS onset during childhood may profoundly influence maturing and actively myelinating neural networks. Highfield MRI visualizes MS pathology at a near-microscopic level and has the potential to more fully explain mechanisms for cognitive impairment, fatigue, and disability in patients with pediatric MS. Multiple sclerosis (MS) in childhood and adolescence is characterized by both clinical and MRI evidence of highly active inflammation. Although many aspects of relapsing-remitting MS (RRMS) are similar in both pediatric-and adult-onset disease, very young pediatric patients have certain unique features. Disorders to consider in the differential diagnosis of MS include non-MS inflammatory diseases, CNS involvement in systemic inflammatory disorders, and genetic and metabolic disorders of white matter, some of which have an associated inflammatory response. MRI forms a key component in evaluation. Pediatric-onset MS also provides a window into understanding the earliest biological aspects of MS. The disease has a great impact on brain integrity, as evidenced by MRI metrics that quantify disruption of tissue microstructure as well as loss of age-expected brain volume. The present article focuses on recent advances in neuroimaging in pediatric MS, with practical considerations for the use of MRI in diagnosis, monitoring of clinical course, and response to therapy. Potential advanced imaging techniques to further understand the impact of the disease on the ongoing maturing CNS are discussed, as is the utility of MRI as an outcome measure for clinical trials in pediatric MS.
ROLE OF MRI IN MS DIAGNOSISConsiderable recent effort has focused on the contributions of MRI for distinguishing children with MS from children with monophasic demyelination. Other articles in this supplement provide details regarding the clinical features of incident demyelination, including acute disseminated From The Children's