An anaphylactic reaction is a generalized allergic effect (also called anaphylactic shock). Allergic or anaphylactoid reactions range from sneezing, urticaria and itching, bronchospasm, facial and laryngeal edema to life-threatening symptoms including cardiovascular collapse, shock and respiratory distress.
Iodinated contrast materials are safe and widely used. However, anaphylactoid reactions occur rarely after administration of x-ray contrast agents. Most hypersensitivity symptoms appear short time after the intravenous, oral, rectal or other application (e.g., retrograde pyelography), only few are delayed by hours.
Patients with a history of allergic, asthmatic or reactions to contrast agents are at increased risk of anaphylaxis. Pre-treatment with corticosteroids and antihistamines decreases the incidence of an adverse reaction.

An angiogram is an x-ray examination of the arteries (arteriogram) and veins (venogram) to detect blockage or narrowing of vessels.

See also Adventitia and Ischemia.

(Å* or A*) A unit used to measure the wavelength of x-rays.
Definition: 0.1 nanometer or 10^-10 meter or 100 picometer.

An anion is a negative charged ion; the atom has more electrons than protons. Anions are attracted from the positively charged anode. This is a basic part for producing radiation in the x-ray tube.

An arthrogram is an x-ray fluoroscopy of a joint performed with a sequential digital subtracted spot films after injection of a contrast agent.

See Arthrography.