ABSTRACTINTRODUCTIONImmunotherapeutic agents against amyloid beta (Aβ) are associated with adverse events, including amyloid‐related imaging abnormalities with edema and effusion (ARIA‐E). Recently, a magnetic resonance imaging (MRI) rating scale was developed for ARIA‐E detection and classification. The aim of this study was to validate the use of this rating scale in a larger patient group with multiple raters.METHODSMRI scans of 75 patients (29 with known ARIA‐E and 46 control subjects) were analyzed by five neuroradiologists with different degrees of expertise, according to the ARIA‐E rating scale. For each patient, we included a baseline and a follow‐up fluid‐attenuated inversion recovery image. Interrater agreement was calculated using intraclass correlation coefficient (ICC).RESULTSOn average, 4.1% of the ARIA‐E cases were missed. We observed a high interrater agreement for scores of sulcal hyperintensity (SH; ICC = .915; 95% CI 85–95) and for the combined scores of the 2 ARIA‐E findings, parenchymal hyperintensity (PH) and SH (ICC = .878; 95% CI 79–93). A slightly lower agreement for PH (ICC = .678; 95% CI 51–81) was noted.CONCLUSIONThe ARIA‐E rating scale is a simple tool to evaluate the extent of ARIA‐E in patients recruited into Aβ‐lowering therapeutic trials. It shows high interrater agreement among raters with different degrees of expertise.