ng/mL and carbon monoxide levels <11 ppm on the day of intake and day of scan. All women were required to have a negative pregnancy test during the screening process and prior to radiotracer injection on each study day. Plasma nicotine and cotinine levels were measured as previously described8. Urine cotinine levels were measured with either Accutest NicoMeter™ cotinine test strips (Jant Pharmacal, Encino, CA) or NicAlert™ cotinine test strips (Nymox Pharmaceutical, Hasbrouck Heights, NJ).
