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.