MR Imaging Features of Amyloid-Related Imaging Abnormalities

ARIA-E (edema and effusion); parenchymal and sulcal FLAIR hyperintensity. FLAIR sequences at baseline (A), week 19 (B), and week 32 (C). By week 19 (6 weeks after the second dose of bapineuzumab), a zone of cortical swelling, sulcal effacement, and parenchymal hyperintensity has developed in the right temporal-occipital lobe. A small sulcal effusion and faint overlying linear leptomeningeal hyperintensity (arrows) help define the area of abnormality. By week 32, these findings have largely resolved. As is typically the case with bapineuzumab-related ARIA, the patient remained asymptomatic throughout all imaging time points.

ARIA-E (edema); week 19 parenchymal FLAIR hyperintensity. Week 19 FLAIR (A) and corresponding DWI (B) and week 19 gadolinium (C). On the surveillance scan for week 19 (A), several large regions of parenchymal edema develop, principally in the bifrontal and left temporal regions, which resolve on follow-up (not shown). Week 19 DWI reveals minimal T2 shinethrough (B), but no ADC abnormality (not shown). With gadolinium, there is no frank enhancement with only mild prominence of overlying cortical vasculature, in keeping with nonspecific cerebral swelling (C).

ARIA-E (edema) with incident ARIA-H (microhemorrhages). FLAIR and corresponding gradient recalled-echo/T2* sequences of the same patient, at baseline (A and B) and week 19 (C and D). By week 19 (6 weeks after the second dose of bapineuzumab), significant right-hemispheric edema has developed. As is characteristic of ARIA-E, despite the extensive parenchymal changes, DWI and ADC findings remained normal (not shown), confirming these findings as reflecting vasogenic as opposed to cytotoxic edema. On the corresponding gradient recalled-echo/T2* images, there is concomitant development of several punctate microhemorrhages in the right parietal region (circle). On subsequent imaging, the cerebral edema resolved while the microhemorrhages remained stable (not shown). In general, the severity of ARIA changes was associated with both Apolipoprotein ε4 allele status and drug dosage. As such, this patient was an Apolipoprotein ε4 homozygote and in the highest drug-dose arm.