Arteriovenous Malformation (cont.)
How are AVMs and other vascular lesions detected?
Physicians now use an array of traditional and new imaging technologies to
uncover the presence of AVMs. Angiography provides the most accurate
pictures of blood vessel structure in AVMs. The technique requires injecting a
special water-soluble dye, called a contrast agent, into an artery. The dye
highlights the structure of blood vessels so that it can be recorded on
conventional X-rays. Although angiography can record fine details of vascular
lesions, the procedure is somewhat invasive and carries a slight risk of causing
a stroke. Its safety, however, has recently been improved through the
development of more precise techniques for delivering dye to the site of an AVM.
Superselective angiography involves inserting a thin, flexible tube
called a catheter into an artery; a physician guides the tip of the catheter to
the site of the lesion and then releases a small amount of contrast agent
directly into the lesion.
Two of the most frequently employed noninvasive imaging
technologies used to detect AVMs are
computed axial
tomography (CT) and magnetic
resonance imaging (MRI) scans. CT scans use X-rays to create a
series of cross-sectional images of the head, brain, or spinal cord and are
especially useful in revealing the presence of hemorrhage. MRI imaging, however,
offers superior diagnostic information by using magnetic fields to detect subtle
changes in neurological tissues. A recently developed application of MRI
technology-magnetic resonance angiography(MRA)-can record the pattern
and velocity of blood flow through vascular lesions as well as the flow of
cerebrospinal fluid throughout the brain and spinal cord. CT, MRI, and MRA can
provide three-dimensional representations of AVMs by taking images from multiple
angles.
Next: How can arteriovenous malformations and other vascular lesions be treated? »
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