Summed (10 to 60 min) images of [11
C]phenytoin in the rat brain. Before (second image) and 15 min after (third image) intravenous administration of tariquidar (15 mg·kg−1) in the rat. The brain is outlined in both images. Regions of interest used in the analysis are shown on an MR template image (left); the overlay image is shown on the right.