A radiological technique that enhances X-ray images, most commonly of blood vessels (see angiography). A digitized image is taken before the contrast medium (a ‘mask’) is added, and this is subtracted by computer from the images taken after contrast injection. Only the outline of the blood vessel or other structure containing contrast medium remains on the image. The technique enables blood-vessel anatomy and blood supply to an organ to be demonstrated more clearly. The quality of the image is very dependent on the patient remaining still, since movement causes severe loss of image (movement artifact). The technique can also be used in nuclear medicine using two different tracers to look for parathyroid gland tumours.
Subjects: Medicine and Health.