Dual Time-Point [18F]Florbetaben PET Delivers Dual Biomarker Information in Mild Cognitive Impairment and Alzheimer's Disease.

Background: Current research diagnostic criteria for Alzheimer's disease (AD) and mild cognitive impairment (MCI) due to AD include biomarkers to supplement clinical testing. Recently, we demonstrated that dual time-point [18F]FBB PET is able to deliver both blood flow and amyloid-β (Aβ) load surrogates.

Objective: The aim of this study was to investigate whether these surrogates can be utilized as AD biomarkers.

Methods: 112 subjects (41 with MCI, 50 with probable/possible AD, 21 with other dementias) underwent dual time-point [18F]FBB PET. Data were visually and relative quantitatively (Herholz scores for the early and composite SUVRs for the late PET data) analyzed.

Results: In the early images AD-typical patterns were present in 42% /27% /33% of probable/possible AD/MCI/other dementia cases. In late [18F]FBB PET, 42% /29% /38% of probable/possible AD/ MCI/other dementia cases were Aβ-positive. 17% of the MCIs were categorized as "MCI due to AD-high likelihood", 44% of the probable ADs as "probable AD with high evidence of AD pathophysiological process" and 28% of the possible ADs as "possible AD with evidence of AD pathophysiological process". 27% of all subjects showed a positive diagnostic and progression biomarker. Herholz scores were lower (0.85±0.05 versus 0.88±0.04, p = 0.015) for probable/possible AD versus MCI. Composite late phase SUVRs were significantly higher (1.65±0.23 versus 1.15±0.17, p < 0.005) in Aβ-positive versus Aβ-negative patients. Herholz and MMSE scores were positively correlated (R = 0.30 p = 0.006).

Conclusion: Dual time-point [18F]FBB PET provides dual biomarker information which enables to categorize MCI and AD dementia patients according to established diagnostic criteria. Thus, dual time-point [18F]FBB PET has great potential to supplement diagnostic dementia workups.