Fig. 1. Scanning protocol for positron emission tomography imaging. Tx is a transmission scan. The first positron emission tomography scan is acquired in the awake state. Then, the anesthetic conditions are changed (or not if a control study), and a second transmission and [F-18]FECNT scan are collected. Table 1 describes the different conditions used. Bk is a 10-min background scan that immediately precedes the second injection. The timing between scans was the same for all subjects. The scanning is complete, and recovery from anesthesia begins at 250 min.