Monitoring of amyloid related imaging abnormalities: SWI vs T2*-GRE.

Amyloid-β-directed monoclonal antibody therapies may lead to amyloid-related imaging abnormalities (ARIA). Clinical trials that formed the basis for the ARIA radiographic severity grading scale adopted by the approved drugs' labels utilized T2* gradient recalled echo (T2*-GRE) images for ARIA-hemorrhagic (ARIA-H) assessment. Little is known about the application of susceptibility-weighted imaging (SWI) to ARIA-H assessment. We exploited comparative studies on the usage of SWI instead of 2D T2*-GRE and simulated the impact of SWI's higher sensitivity on the derived ARIA-H severity distribution for three approved drugs. The simulations indicated that the two sequences are not equivalent when grading ARIA-H severity and that the rate of therapy discontinuation would increase by more than 50% compared to the rates reported in the drugs' prescribing information. This should be taken into consideration whenever SWI is applied for ARIA safety monitoring. Appropriate imaging guidelines are needed to enhance management of amyloid-β-directed antibody therapies.