Purpose: To characterize the dynamic response of hippocampus blood flow to physostigmine infusion and to determine an infusion duration sufficiently long for robust detection of effects with arterial spin labeling (ASL) and sufficiently short to avoid peripheral side effects of physostigmine. Materials and Methods: Two female (49 ± 15 years) and nine male (53 ± 13 years) subjects were studied to determine the time course of the physostigmine effect on hippocampus blood flow with ASL perfusion imaging during 20 minutes of baseline, 30 minutes of physostigmine infusion at 1.0 mg/hr, and 70 minutes of recovery. Results: Hippocampus perfusion decreased steadily over the course of the infusion, with the reduction in flow becoming significant after 20 minutes of infusion, reaching lowest levels near the end of infusion, and remaining significantly low and stable in the 70-minute recovery period. Percentage changes of hippocampus perfusion were -13.3%, -13.4%, and -13.4% for left, right, and bilateral hippocampus, respectively, at the end of infusion. Conclusion: At a dose rate of 1.0 mg/hr it is feasible to use an infusion time as short as 20 minutes, performing perfusion imaging up to an hour after physostigmine infusion is discontinued, to minimize chances for adverse side effects.
- arterial spin labeling (ASL)
- regional cerebral blood flow (rCBF)