Amyloid-related imaging abnormalities (ARIA)

Anti-amyloid treatments for Alzheimer's disease (AD) can lead to a side effect called Amyloid-Related Imaging Abnormalities (ARIA), which are detectable on brain MRI. ARIA is classified into two main types: ARIA-E (edema and effusion) and ARIA-H (microhemorrhages and hemosiderosis). These abnormalities are linked to the inflammatory response and increased vascular permeability caused by the anti-amyloid therapy

In the "ARIA: Train-the-Trainer Workshop", Dr. Mak introduced ARIA and illustrated how they can be detected in 3T MRI.

• What is ARIA?

  ARIA refers to specific MRI findings observed in patients receiving anti-amyloid therapies for AD. These findings include edema/effusion (ARIA-E) and microhemorrhages/hemosiderosis (ARIA-H). 

• Why does it happen?

  Anti-amyloid therapies target amyloid plaques in the brain. This process can trigger an inflammatory response and increased vascular permeability, leading to the leakage of fluid and blood products into the brain tissue, which are detected as ARIA on MRI. 

• ARIA-E vs. ARIA-H:

  ARIA-E is characterized by the presence of edema and effusion, indicating fluid accumulation in the brain. ARIA-H, on the other hand, is characterized by microhemorrhages and hemosiderosis, indicating the leakage of blood products into the brain. 

• Importance of monitoring:

  ARIA can be asymptomatic, but it's crucial to monitor patients for ARIA using MRI because it can be a serious side effect of anti-amyloid therapies. Early detection and proper management of ARIA are essential to ensure patient safety. 

• Risk factors:

  Cerebral amyloid angiopathy (CAA) is a major risk factor for ARIA. Other risk factors include the APOE-ε4 carrier status and pre-existing microhemorrhages. 

A close-up view of Dr. Mak's presentation.