Time course of [18F]nifene in the blood. A: Rate of metabolism of [18F]nifene in plasma. Parent [18F]nifene and radiolabeled metabolites are expressed as a percentage of total radioactivity present in the plasma. B: Time-activity curve of [18F]nifene parent in arterial plasma. Values are normalized by injected dose and multiplied by subject weight (kBq/cc/i.d.×kg).