Abstract Background Early phase amyloid positron emission tomography (PET) imaging is known to correlated with glucose metabolism. However, studies on the optimal time frame and SUVR cut off for early‐phase amyloid PET have not been sufficiently progressed. In this study, the optimal time of early‐phase 18F‐FBB was determined and SUVR cut off was obtained. Method To determine the optimal time frame, the correlation between FBB and FDG SUVR of 67 subjects(34, Alzheimer’s disease(AD), 4 mild cognitive impairment(MCI), and 29 health control(HC)) was compared. In this method, 83 brain regions were treated as gray matter masks using an integrated brain map of PMOD 3.6. After obtaining the optimal time of FBB, which has a high correlation compared to FDG, a total of 225 subjects(188 AD, 37 HC) were targeted. SUVR cut off of dual‐phase 18F‐FBB PET of 11 brain regions was obtained. Calculate the composite mean SUVR and regional SUVR using MedCalc. Result The highest correlation between early‐phase 18F‐FBB and 18F‐FDG peaked at ‐.8747 at 270‐330s. Considering the minimum time and correlation between image noise and visual analysis, 90 to 330 seconds were set as the optimal time frame(r‐ratio ≥0.875). In the early‐phase FBB, cut off values in the order of HC>AD were valid. The classification accuracy of the composite mean SUVR was 72%(AD 69.15%, HC 86.49%), and the regional area accuracy was 85.78%(AD 93.62%, HC 45.95%). In the delay‐phase FBB, cut off vlaues in the order of AD>HC were valid. The classification accuracy of the composite mean SUVR was 77,33%(AD 72,87%, HC 100%), and the regional area accuracy was 84.89%(AD 86.17%, HC 78.38%). In the early and delay‐phase FBB, the classification accuracy of the composite mean SUVR was 90.67%(AD 92.02%, HC 86.49%), and the regional area accuracy was 88%(AD 98.4%, HC 37.84%). Conclusion In this study, it is possible to know the optimal time frame of the early‐phase 18F‐FBB showing a high correlation with 18F‐FDG. Composite mean SUVR and regional SUVR cut off of the dual‐phase 18F‐FBB are helpful for visually ambiguous analysis.