F]FDOPA-PET images of rats and radiochromatograms of rat plasma samples after the administration of [18
F]FDOPA. (a) Representative [18F]FDOPA-PET image of a sham-operated control rat coregistered with MRI template at 7 weeks after sham operation. PET image was reconstructed using FBP and summated from 11 to 90 min after the tracer injection. Blue broken lines in both panels and red lines in right panel indicate ROIs (striatum and cerebellum, respectively). L = left striatum; R = right striatum. (b) Effect of carbidopa (C) and entacapone (E) on striatal accumulation of [18F]FDOPA in 6-OHDA-lesioned rats. PET images were summated from 11 to 90 min after tracer injection. One rat from the 6-OHDA 28 μg group was scanned in the presence of both inhibitors (left panel, "C + E"), and after 2 weeks the same rat was scanned in the presence of carbidopa (right panel, "C"). L = left striatum; R = right striatum. (c) Radiochromatograms of authentic [18F]FDOPA and plasma obtained from each rat in (b) after PET scan completion. [18F]FDOPA (peak at 3.8 min) was detected in the plasma from the rat pretreated with carbidopa and entacapone (C + E), whereas it was low and the other metabolite, may be 3-O-methyl-FDOPA, existed mainly (peak at 6.0 min) in the plasma from the rat pretreated with carbidopa only (C).