English: Sequence of 123-iodide total-body scintiscans of a woman after intravenous injection of 123-iodide (half-life: 13 hours); (from left) respectively at 30 minutes, and at 6, 20 and 48 hours. High and rapid concentration of radio-iodide (in white) in extra-thyroidal organs is evident in gastric mucosa of the stomach, epidermis, salivary glands, periencephalic and cerebro-spinal fluid, choroid plexus and oral mucosa. In gastric mucosa 131-iodide (half-life: 8 days) persists in scintiscans for more than 72 hours. In the thyroid, iodide-concentration is more progressive, as in a reservoir [from 1% (after 30 minutes) to 5.8 % (after 48 hours) of the total injected dose]. High iodide-concentration by the mammary gland is evident only in pregnancy and lactation. High excretion of radio-iodide is observed in the urine.