Angiography
Angiography is an x-ray examination of the arteries and veins to diagnose
obstructions and other blood vessel diseases. The test is performed
in a room called an angiography suite as pictured here.
The
test is performed by a radiologist, cardiologist, or vascular surgeon.
During the test, the doctor inserts a small tube known as a catheter
through a nick in the skin into an artery or vein. Using guidance from
an x-ray flouroscopy machine, the tube is directed into the part of
the body that requires study. The catheters come in various sizes and
configurations to best access the arteries in question.
One
such catheter is visualized at right and its tip is coiled. This is
referred to as a pigtail catheter for obvious reasons. After the catheter
has been threaded into the appropriate position, a substance called
contrast agent (also known as x-ray dye) is injected through the catheter
while x-ray pictures are made. These can be individual pictures or even
a movie of the injection. Below are two representative pictures made
during angiography. The one on the left is called aortography with bilateral
runoff. This means that dye is injected into the aorta. This dye show
up as white against a black background. The dye is allowed to "runoff"
or flow downstream into the arterial tree of both legs. The right picture
demonstrates carotid angiography in which contrat agent is injected
into a carotid artery going to the brain while pictures are taken. Note
that in this case the x-ray dye show up as black against a whitish background.
The pictures can be manipulated by computer to show up as black on white
and vice versa.
