Evaluation of the ECAT EXACT HR+ 3D PET scanner in 15O-water brain activation studies

We evaluated the performance of the ECAT EXACT HR⁺ 3D whole body PET scanner when employed to measure brain function using ¹⁵O-water-bolus activation protocols in single data acquisition sessions. Using vibrotactile and auditory stimuli as independent activation tasks, we studied the scanner´s performance under different imaging conditions in four healthy volunteers. Cerebral blood flow images were acquired from each volunteer using ¹⁵O-water-bolus injections of activity varying from 5 to 20 mCi. Performance characteristics. The scanner´s dead time grew linearly with injected dose from 10% to 25%. Random events varied from 30% to 50% of the detected events. Scattered events were efficiently corrected at all doses. Noise-effective-count curves plateau about 15 mCi. One-session 12-injection bolus PET activation protocol. Using an acquisition protocol that accounts for the scanner´s performance and the practical aspects of imaging volunteers and patients in one session, we assessed the correlation between the statistical significance of activation foci and the dose per injection used. The one-session protocol employs 12 bolus injections per subject. We present evidence suggesting that 15-20 mCi is the optimal dose per injection to he used routinely in one-time scanning sessions