Cranial ultrasounds are imaging tests that use sound waves to make pictures of the brain. There are two types: head ultrasounds and the transcranial Doppler.
During this test, a machine sends sound waves into the head, and a computer records the images they make. The black-and-white pictures show the inside structures of the brain and the fluid that flows within the hollow spaces deep inside the brain, called ventricles.
Doctors use head ultrasounds most often on infants younger than 6 months old. In older children and adults, the bones of the skull block sound waves. But infants have a soft spot on top of their heads where the skull hasn't yet grown together. The gap between the bones lets the ultrasound through.
Doctors may also do this test on adults during brain surgery.
What Is a Head Ultrasound Used For?
- Bleeding in the brain, called an intraventricular hemorrhage (IVH)
- Injury to the tissue around the ventricles, called periventricular leukomalacia (PVL)
It can also help doctors diagnose other brain problems, such as:
- Too much fluid in the brain or ventricles, called hydrocephalus
- Tumors, cysts, or others masses
Doctors may also order the test for a baby with:
- A head that’s larger than normal
- A bulge in the head’s soft spot
- Any symptoms of brain or nerve problems
Adults may need a head ultrasound during brain surgery to find a mass or tumor.
Transcranial Doppler is also an ultrasound. Doctors use it to check how blood moves through the brain. It can help them check on conditions that can affect blood flow there, such as stenosis and vasospasm, which can narrow blood vessels that affect the brain. It can also check on the risk of stroke in adults and children with sickle cell disease.
Is It Safe?
An ultrasound doesn’t use radiation. The sound waves that make the images are safe and painless.
What Happens During the Test?
Your child can have a head ultrasound in the radiology department of the hospital or in the neonatal intensive care unit (NICU). The technician will bring a portable machine to your baby’s bedside.
Your baby will lay face up in the bed. You can stay with them during the test or hold them if you need to. The room will be dark so the technician can see the images on the computer screen more clearly.
The technician will put a clear gel on a small wand, called a probe or transducer, and on the top of your baby’s head. The technician moves the probe gently over the area. Sound waves go from the probe, through the gel, and into the head. The computer changes the sound waves into images. The test usually takes 15 to 30 minutes.
If an adult gets a head ultrasound during brain surgery, the surgeon will remove part of the skull and use the probe to help find a tumor or mass in the brain.
The Doppler procedure also uses a wand and ultrasound machine, but the process is different. The gel goes on your neck and up to your cheek, to check on blood flow from that angle. It can take up to 35 minutes. Your doctor may also leave a headgear on the patient for continuous monitoring for 30 minutes to look for "hits" or high intensity signals.
A specially trained doctor called a radiologist will look over the images and report the results to your doctor. Your doctor should explain the findings to you and talk with you about what to do next.