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Background: Magnetic resonance imaging (MRI) enhanced with gadolinium-based contrast agents (GBCAs) is an essential tool in the diagnosis and management of many neurologic diseases, including multiple sclerosis, brain tumors, and infections. The clinical utility of GBCAs is evidenced by their widespread use. GBCAs are produced in macrocyclic and linear forms. Since 2014, evidence has suggested that repeated administration of GBCAs can lead to gadolinium deposition in the brain. Methods: We review the literature on gadolinium deposition, including both animal and human studies, as well as the literature on GBCA-associated health outcomes. Additionally, we summarize and discuss the updated medical society recommendations and perspectives on GBCA use in clinical practice. Results: The first publication reporting gadolinium deposition in the human brain was published in 2014. Since that seminal report, multiple studies have demonstrated that exposure to linear GBCAs is associated with gadolinium deposition in the dentate nucleus and globus pallidus as seen on brain MRI. Macrocyclic GBCA exposure has not convincingly been associated with gadolinium deposition evident on brain MRI. Conclusion: Clear evidence demonstrates that GBCAs lead to gadolinium deposition in the brain in a dose-dependent manner; however, only linear GBCAs have been associated with gadolinium deposition visualized on MRI. To date, no evidence links gadolinium deposition with any adverse health outcome. Updated medical society guidelines emphasize the importance of an individualized risk-benefit analysis with each administration of GBCAs.

Purpose of Review The newer, higher-efficacy disease-modifying therapies (DMTs) for multiple sclerosis (MS)-orals and monoclonals-have more profound immunomodulatory and immunosuppressive properties than the older, injectable therapies and require risk mitigation strategies to reduce the risk of serious infections. This review will provide a systematic framework for infectious risk mitigation strategies relevant to these therapies. Recent Findings We classify risk mitigation strategies according to the following framework: (1) screening and patient selection, (2) vaccinations, (3) antibiotic prophylaxis, (4) laboratory and MRI monitoring, (5) adjusting dose and frequency of DMT, and (6) behavioral modifications to limit the risk of infection. We systematically apply this framework to the infections for which risk mitigations are available: hepatitis B, herpetic infections, progressive multifocal leukoencephalopathy, and tuberculosis. We also discuss up-to-date recommendations regarding COVID-19 vaccinations for patients on DMTs. Summary We offer a practical, comprehensive, DMT-specific framework of derisking strategies designed to minimize the risk of infections associated with the newer MS therapies.