Using Positron Emission Tomography and Carbon 11-Labeled Pittsburgh Compound B to Image Brain Fibrillar β-Amyloid in Adults With Down Syndrome Safety, Acceptability, and Feasibility

Objective: To investigate the safety, acceptability, and feasibility of positron emission tomography (PET) using carbon 11-labeled Pittsburgh Compound B ([C-11] PiB) to measure cerebral beta-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 non-randomly selected cohort of participants with DS (with or without AD) compared within group and with healthy controls without DS. All had dynamic [C-11] 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 [C-11] 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 [C-11] PiB binding in regions of interest usually associated with AD, whether or not they had clinical evidence of dementia. Conclusions: Dynamic [C-11] PiB PET can be used successfully to measure cerebral beta-amyloid deposition in DS. A clinical diagnosis of AD and age appear to be predictors of [C-11] PiB binding in regions of interest, but given the small numbers, we cannot generalize the results.