Off-Target 18F-AV-1451 Binding in the Basal Ganglia Correlates with Age-Related Iron Accumulation

Off-target binding in the basal ganglia is commonly observed in the 18F-AV-1451 PET studies of the elderly. We sought to investigate the relationship between this phenomenon in the basal ganglia and iron accumulation using iron-sensitive R2* MRI. Methods: Fifty-nine healthy controls and 61 patients with Alzheimer disease and mild cognitive impairment underwent 18F-AV-1451 PET and R2* MRI studies. A correlation analysis was performed for age, 18F-AV-1451 binding, and R2* values. Results: There was an age-related increase in both 18F-AV-1451 binding in the basal ganglia and R2* values in the putamen in both the controls and the Alzheimer disease/mild cognitive impairment patients. 18F-AV-1451 binding in the basal ganglia increased with R2* values. Conclusion: Off-target 18F-AV-1451 binding in the basal ganglia is associated with the age-related increases in iron accumulation. Postmortem studies are required to further investigate the nature of this association.