Angiography (angio) is the procedure by which blood vessels of the body are visualised by injecting contrast or otherwise. Most popular contrast media are iodinated dyes which cast shadows of the vessels on x-ray imaging. When the imaging is done by continuous filming it is known as cine-angiography. Now a days most of the angiograms are cine angiograms. Cut film angiograms which used to be done earlier have become obsolete with the advent of good cine technology. Even films have almost disappeared, being replaced by digital recording in compact discs (CD) or digital versatile disks (DVD). Visualisation of the vessels in the retina (light sensitive layer of the eye which processes vision) is done by injecting a fluorescent dye known as fluorescein. Hence this form of angiography is known as fluorescein angio. Dyeless angio is possible with magnetic resonance imaging where the signals from the moving hydrogen particles in blood give the image. This is known as magnetic resonance angio.
Conventional angio using x-ray equipment is used for imaging the blood vessels of the heart and is known as coronary angio. Imaging of peripheral vessels of the limbs is known as peripheral angiography. Imaging vessels of the kidney is known as renal angiography. Cerebral angiography is done to visualise the blood supply of the brain. Pulmonary angiography visualises the vessels of the lung. Intestinal blood supply is seen by mesenteric angiography.
Contrast injected for angiography can cause some problems rarely. There are various types of iodinated contrasts: non-ionic and ionic; hyperosmolar and iso-osmolar etc. Non-ionic contrast is costlier, by produces less of adverse effects like fall in blood pressure and nausea. Rarely the individual can be allergic to the contrast dye. In an individual with compromised or borderline kidney function, the dye can precipitate renal failure.