PET amyloid imaging as a tool for early diagnosis and identifying patients at risk for progression to Alzheimer's disease

Current theory suggests that β-amyloid accumulation may be an early step in the cascade that leads to cognitive impairment in Alzheimer's disease. β-Amyloid targeted positron emission tomography (PET) imaging potentially provides a direct, relatively noninvasive estimate of brain β-amyloid burden. This has recently been supported by demonstration that amyloid plaque binding on PET was strongly correlated with brain β-amyloid burden at autopsy. Additionally, there is growing consensus that PET imaging can identify subjects with elevated β-amyloid burden, even at early stages of disease. Finally, preliminary evidence suggests that abnormal β-amyloid accumulation, as evidenced by PET imaging, has implications for both present nd future cognitive performance. Although large longitudinal studies like the ongoing ADNI trial will be required for definitive evaluation, present data suggest that PET amyloid imaging has the potential to promote earlier and more specific diagnosis of dementia.