Amyloid PET in patients with carotid occlusive disease: Preliminary results of the AMYCODE study

Abstract Background Carotid occlusive disease (COD) is a risk factor for cognitive decline. One of the proposed underlying mechanisms is that cerebral hypoperfusion may result in accelerated accumulation of amyloid‐β in the brain. We hypothesized that patients with longstanding, unilateral COD have an asymmetrical burden of cerebral amyloid‐β, with more amyloid‐β in the hemisphere ipsilateral to the COD than in the contralateral hemisphere. Method The AMYCODE study is a cross‐sectional observational study. Inclusion criterion is a unilateral occlusion of the internal carotid artery. Exclusion criteria are: a contralateral stenosis of > 70% and a history of vascular reconstructive surgery. All patients underwent a neuropsychological assessment, MRI‐scan and dynamic 18 F Florbetaben positron emission tomography scan (PET). Global relative perfusion (R 1 ) and binding potential (BP ND ) were determined from the PET‐images using PMOD and a simplified reference tissue model with the cerebellar grey matter as reference region. Distribution Volume ratio (DVR) was calculated as BP ND + 1. We performed Wilcoxon signed‐rank tests to examine differences between hemispheres within subjects. Result To date, we included eight participants (seven males, age 66.1±7.3 years, MMSE score 28.1±2.0; inclusion ongoing, target n = 20). Mean global DVR was 1.03±0.03 in the ipsilateral hemisphere (i.e. side of the occlusion) and 1.04±0.02 in the contralateral hemisphere (p = 0.064). Mean global R1 was 0.89±0.06 in the ipsilateral hemisphere and 0.91±0.05 in the contralateral hemisphere (p = 0.033). Conclusion Preliminary analyses suggest that patients with unilateral COD had similar amyloid‐β distribution, despite lower cerebral perfusion in the hemisphere ipsilateral to the COD than in the contralateral hemisphere.