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digital subtraction angiography

Digital Subtraction Angiography Procedure

To visualize clearly blood vessels that are surrounded by bones or dense soft tissues, medical specialists in interventional radiology use a fluoroscopy technique called Digital Subtraction Angiography or DSA.

The term “digital subtraction” refers to the digitalized images that are produced using a contrast medium, a kind of high density dye, which is injected into an arterial structure. The contrast material highlights the veins and arteries which can be seen by the X-ray. Then the X-ray images of the blood vessels are subtracted to produce a digital “pre-contrast image” that can be magnified and manipulated. Angiography refers to a similar medical imaging technique to visualize arteries, veins and organs from the inside using X-ray based radiology techniques.

Digital Subtraction Angiography Procedure

The digital subtraction angiography (DSA) usually takes between 30 minutes and several hours, depending on the condition to be diagnosed. During the test the patient is cared for by a team of health care professionals (nurses, consultants, radiographers, ECG technicians). The patient lies down comfortably on an X-ray couch and may feel some initial heaviness after local anesthetic is injected.

Then the contrast material is injected into the patient’s blood vessels and special X-ray images are taken from all angles of the highlighted veins and arteries. The computer produces real time X-ray images which can be magnified and then copied on a film.

Digital subtraction angiography procedure is not recommended for patients with renal insufficiency or diabetes because of the contrast agent, which is made of radiopaque iodine and injected intravenously.

The DSA procedure is primarily used to image blood vessels, in order to identify and treat certain vascular diseases:

  • Arterial stenosis
  • Ulcerated plaques
  • Arterial and venous occlusions, such as:
    • Cariotid artery stenosis
    • Pulmonary emolisms
    • Acute limb ischaemia
  • Cerebral aneurysms
  • Arterio-venous malformations

Due to the rise of computer tomography angiography (CTA), digital subtraction angiography procedure is disappearing from lab clinics and is being used less and less in imaging departments. CTA 3D image production is a less-invasive and less stressful procedure.