MRI protocols and sequences for amyloid-related imaging abnormalities monitoring in Alzheimer's disease patients treated with monoclonal antibodies.

Purpose of review: This review provides an updated overview of amyloid-related imaging abnormalities (ARIA) associated with antiamyloid monoclonal antibodies (mAbs) in Alzheimer's disease (AD). Following regulatory approvals for both lecanemab and donanemab in the United States, and pending decisions in Europe, standardized understanding of ARIA definitions, risk factors, and optimal MRI surveillance is increasingly important to guide treatment and ensure safety.

Recent findings: ARIA, including vasogenic edema (ARIA-E) and microhemorrhages/siderosis (ARIA-H), are a frequent adverse event in patients receiving antiamyloid mAbs, particularly among APOE ε4 homozygotes. Incidence varies by agent and trial design. While often asymptomatic and self-limiting, ARIA can occasionally present with symptoms or recur. MRI, especially FLAIR and susceptibility-sensitive imaging, is essential for baseline risk stratification and monitoring. Key imaging biomarkers include microbleeds and superficial siderosis. Recent guidelines support genotyping and risk-adapted MRI protocols before and during therapy.

Summary: ARIA reflect vascular vulnerability during amyloid clearance in AD. Their management requires close collaboration between neurologists and neuroradiologists, with harmonized MRI protocols and risk mitigation strategies critical for safe and effective use of disease-modifying therapies.