Objective To investigate the safety, acceptability, and feasibility of positron emission tomography (PET) using carbon 11–labeled Pittsburgh Compound B ([11C]PiB) to measure cerebral β-amyloid in adults with Down syndrome (DS) and to explore if the technique differentiates between participants with and without Alzheimer disease (AD).
Design Proof-of-principle case-controlled study of a nonrandomly selected cohort of participants with DS (with or without AD) compared within group and with healthy controls without DS. All had dynamic [11C]PiB PET and magnetic resonance imaging. Carbon 11–labeled PiB binding in the regions of interest associated with AD was quantitatively analyzed.
Setting Wolfson Brain Imaging Centre, Cambridge, England.
Participants Nine with DS (aged 25-64 years), of whom 5 had a diagnosis of AD, and 14 healthy controls without DS (aged 33-69 years).
Main Outcome Measure Positive [11C]PiB binding in regions of interest.
Results The scanning process was feasible and acceptable with no adverse events or safety concerns. Maps and regional values of nondisplaceable binding potential were produced using the reference tissue–input Logan plot, with the cerebellum used as the reference tissue. When compared with the healthy control group without DS, only participants with DS older than 45 years had significant [11C]PiB binding in regions of interest usually associated with AD, whether or not they had clinical evidence of dementia.
Conclusions Dynamic [11C]PiB PET can be used successfully to measure cerebral β-amyloid deposition in DS. A clinical diagnosis of AD and age appear to be predictors of [11C]PiB binding in regions of interest, but given the small numbers, we cannot generalize the results.