Amyloid imaging for Alzheimer's disease.

INTRODUCTION Biomarkers for Alzheimer's disease (AD) may facilitate early and accurate diagnosis and offer a way to track the effectiveness of new therapies. Amyloid imaging offers an unrivaled ability to visualize the presence and anatomical distribution of fibrillar beta-amyloid (Aβ) pathology non-invasively in living humans. New diagnostic criteria for AD incorporate the use of such biomarkers as amyloid imaging, highlighting the importance of this technology going forward. AREAS COVERED Here, the author reviews individual amyloid tracers, including the (11)C-labeled tracer Pittsburgh compound B and the (18)F-labeled tracers nearing FDA approval. While these tracers are reliable at detecting fibrillar Aβ pathology, there is a weaker connection with true AD pathology, reflecting the complex relationship between Aβ and AD. The author discusses apolipoprotein E genotyping and spinal fluid Aβ levels in relation to amyloid imaging, and considers the possible uses of amyloid imaging as a diagnostic instrument in the clinic, or as a clinical trials tool for selecting patients or monitoring outcomes. Selected literature retrieved by Medline searches for 'amyloid imaging' and related terms from 2001 to present is discussed. EXPERT OPINION Amyloid imaging accurately portrays the presence of fibrillar Aβ pathology in the brain. However, fundamental questions about the role of Aβ in AD must be answered before the full potential of amyloid imaging can be realized.