Because vein of Galen malformations are usually diagnosed in young infants, we like to avoid the use of x-rays. For that reason, magnetic resonance imaging (MRI) is the main imaging technique we use to visualize the malformations, understand their structure and assess the status of the surrounding arteries and the overall condition of the brain. MRI is noninvasive and uses a strong magnetic field, radio waves and advanced computer processing to produce 2- and 3-dimensional images of the head, neck and brain. Read more about MRI.
However, a variety of other techniques may be useful in particular cases. Specific tests may include:
Cerebral angiography, sometimes called cerebral arteriography or catheter angiography, produces the most detailed images of the arteries and veins of the neck, head and brain, using live x-rays. We rarely perform angiography purely as a test, but instead use it to guide treatment of the malformation through embolization.
- The neuroradiologist or neurointerventionalist inserts a small needle into the femoral artery in the groin and introduces a soft, thin wire that guides a catheter up to the arteries near the brain area to be imaged.
- A special dye (known as contrast) is injected through the catheter, allowing the radiologist to more clearly see the malformation and the surrounding arteries and veins. The catheter also can be used to deliver treatments from within the vessels.
- Cerebral angiography can take 30 minutes to several hours and is usually done under general anesthesia. After the angiogram, patients must lie flat for four hours in the recovery room, but can sleep, watch TV or use a handheld device, with parents close by.
- We ask patients not to do vigorous exercise for several days after angiography, but they can return to school as soon as they feel ready. Read more about angiograms.
CT Angiography (CTA)
CT angiography (CTA) uses the technology of a conventional CT scan, along with an injected dye, to generate images of the blood vessels of the upper chest, neck and brain.
- CTA generates images somewhat similar to those seen with cerebral angiography, but since the dye is injected into a vein through a standard IV, rather than into an artery, CTA is less invasive.
- During this test, the child lies still on a table that slides slowly through a donut-shaped device. A computer constructs 3D images of the blood vessels from the CTA images.
- Young children may need sedation to keep them still.
Magnetic resonanc angiography (MRA)
Magnetic resonance angiography (MRA) is a group of imaging techniques based on MRI technology, used to evaluate blood vessels in the brain, head and neck. Unlike CT angiography, many MRA scans do not rely on contrast injected into the veins to generate images of the vessels, although contrast injections are sometimes used. Like conventional MRI, MRA avoids the use of x-rays.