| FDG-PET | Amyloid PET | Tau PET |
---|---|---|---|
Patient Preparation | 4 to 6Â h fasting Abstain from heavy exercise for 24Â h prior to injection Following injection sit quietly in dimly lit room with eyes open | No special preparation | No special preparation |
Administered activity MBq (mCi) | 185–740 (5–20) | F-18-Florbetapir 370 (10) F-18-Florbetaben 300 (8) F-18-Flutemetamol 185 (5) | F-18-Flortaucipir 370 (10) |
Effective dose | 0.019 mSv/MBq | ~ 6–7 mSv | ~ 8–9 mSv |
Uptake period (minutes) | 30–60 | F-18-Florbetapir 30–50 F-18-Florbetaben 45–130 F-18-Flutemetamol 90 *Note dynamic imaging immediately following bolus can also be performed to estimate cerebral blood flow | F-18-Flortaucipir 80 |
Acquisition time (minutes) |  | F-18-Florbetapir 10 F-18-Florbetaben 15–20 F-18-Flutemetamol 20 | F-18-Flortaucipir 20 |
Normal study | Uptake within the cerebral cortex and deep gray nuclei greater than cerebellum | Uptake within the cerebral white matter | Absence of neocortical uptake. Note there can be significant off-target binding in the striatum, choroid plexus, and brainstem nuclei which is considered normal |
Abnormal study | Regions within the cerebral cortex and deep gray nuclei with decreased metabolic activity compared to cerebellum (with the exception of Parkinson plus syndromes which lead to cerebellar hypometabolism) | Uptake in the cerebral white matter with blurring of the corticomedullary junction, with various named signs (tree in summer, kissing hemispheres, etc.) | Increased contiguous neocortical activity, generally involving greater than one area |