Annexin VSPECT imaging of phosphatidylserine expression in patients with dementia

Since its initial description, there have been no reports on the use of Tc-99m-HYNIC-annexin V, a marker of phosphatidylserine (PS) expression, for imaging patients with Alzheimer dementia (AD). (1) Annexin V is a ubiquitous 35-kDa endogenous intracellular protein that binds to the anionic membrane phospholipid, PS. (2) PS is selectively and massively expressed on cells immediately after caspase-3 activation during the early phases of apoptosis. Under conditions of mild ischemia/reperfusion related stress, however, low to intermediate levels of PS have been found which can be reversed with timely reperfusion and normal levels of oxygen. (3) In addition, Tc-99m-HYNIC-annexin V has been found to localize to sites of ischemic injury in animal models even in regions in which the blood-brain barrier is functionally intact. (4,5) In this study, we examined PS expression within the cerebrum of patients with AD as defined by Tc-99m-HYNIC-annexin V SPECT. We also studied patients with non-AD dementia and nondiseased healthy age-matched controls.