Iron accumulation and MRI iron contrast are not driven by amyloid plaques in posterior cortical atrophy

We combined ultra-high resolution quantitative MRI, X-ray fluorescence, and biophysical modeling to study iron-induced MRI contrast in the visual cortex of patients with Alzheimer’s disease (AD) and its variant posterior cortical atrophy (PCA). The iron content of amyloid plaques in patients with PCA and AD exceeded the iron concentration in the surrounding tissue by less than 15%, constituting only a minor contribution to the intracortical T2* contrast. The elevated levels of brain iron detected by iron-sensitive MRI contrasts are not indicative of plaques but may reflect other processes, such as inflammation or leakage in the blood-brain barrier.