Digital subtraction angiography

Digital subtraction angiography

DSA is a way of taking images of arteries, veins and organs of the body  using complex computerised x-ray equipment.    This usually requires an injection of a special ‘dye’ to highlight the blood supply to the legs, heart or other organ.  The ‘dye’ is a clear liquid which shows on x-rays due to its high density.  This 'dye' is harmless and will pass out of your body in your urine over the hours following your test.

What is subtraction

Its simply a technique by which bone structures images are subtracted or canceled out from a fim of bones plus opacified vessels, leaving an unobstructed image of the vessels

Block diagram of Digital subtraction angiography

Principle

Blood vessels are not normally seen in an x-ray image because of low contrast. Dense fluid with high atomic numbers increases the contrast. e.g. Iodine. Iodine absorbs photons more than blood and tissue. The first contrast media used for intravascular injection were called high-osmolar contrast media (HOCM).

Some of the more common examinations carried out in the DSA Suite are listed below:

Angioplasty – This is a treatment to open narrowings or blockages of arteries using a small balloon.  It would normally be used in the legs or heart, but can be used in any artery of the body.

Arterial Stent – This is a treatment to open blockages of arteries using an expanding metal mesh which remains in place to hold the artery open.  This is used in the heart, pelvis and abdomen.

Biliary Procedures - This is treatment to relieve a blockage of the bile duct draining the liver.

Coronary Angiogram – This is an x-ray of the arteries that supply blood to the heart. 

Femoral Angiogram - This is an x-ray of the arteries which supply blood to the legs

Nephrostomy – This is a treatment to relieve pain from a blocked kidney.  A tube is inserted into the kidney to allow it to drain properly. 

Pacemaker – This is a small battery powered box that is implanted under the skin on the chest wall with wires leading to the heart to help it to beat properly.