Clinical impact of 11C‐Pittsburgh compound‐B positron emission tomography carried out in addition to magnetic resonance imaging and single‐photon emission computed tomography on the diagnosis of Alzheimer's disease in patients with dementia and mild cognitive impairment

Aims The purpose of this study was to evaluate the clinical impact of addition of [11C]Pittsburgh compound-B positron emission tomography (11C-PiB PET) on routine clinical diagnosis of Alzheimer's disease (AD) dementia and mild cognitive impairment (MCI), and to assess diagnostic agreement between clinical criteria and research criteria of the National Institute on Aging–Alzheimer's Association. Methods The diagnosis in 85 patients was made according to clinical criteria. Imaging examinations, including both magnetic resonance imaging and single-photon emission computed tomography/computed tomography to identify neuronal injury (NI), and 11C-PiB PET to identify amyloid were performed, and all subjects were re-categorized according to the research criteria. Results Among 40 patients with probable AD dementia (ProAD), 37 were NI-positive, 29 were 11C-PiB-positive, and 27 who were both NI- and 11C-PiB-positive were categorized as having ‘ProAD dementia with a high level of evidence of the AD pathophysiological process’. Among 20 patients with possible AD dementia (PosAD), 17 were NI-positive, and six who were both NI- and 11C-PiB-positive were categorized as having ‘PosAD with evidence of the AD pathophysiological process’. Among 25 patients with MCI, 18 were NI-positive, 13 were 11C-PiB-positive, and 10 who were both NI- and 11C-PiB-positive were categorized as having ‘MCI due to AD-high likelihood’. Conclusions Diagnostic concordance between clinical criteria and research criteria may not be high in this study. 11C-PiB PET may be of value in making the diagnosis of dementia and MCI in cases with high diagnostic uncertainty.