An ultrasound is a medical imaging technique that uses high-frequency sound waves to create live pictures from inside the body. This procedure allows healthcare providers to visualize soft tissues and organs that X-rays might not clearly show. A head ultrasound specifically focuses on imaging structures within the head, without using ionizing radiation.
Understanding Head Ultrasounds
A head ultrasound, also known as a cranial ultrasound, is primarily performed on infants. Infants have soft spots on their heads, called fontanelles, where the skull bones have not yet fused. These soft spots act as “acoustic windows,” allowing sound waves to pass through to the brain and create detailed images.
The scan uses a small, handheld probe called a transducer. This transducer emits high-frequency sound waves into the head. As these sound waves encounter different internal structures, they bounce back to the transducer, which sends the information to a computer to form images of the brain and its fluid-filled cavities, called ventricles.
Why a Head Ultrasound is Performed
Head ultrasounds are performed on infants with neurological concerns, particularly in premature babies. These infants often undergo routine head ultrasounds to screen for conditions linked to their early birth, such as bleeding in the brain, known as intraventricular hemorrhage (IVH), or damage to the white matter of the brain, called periventricular leukomalacia (PVL).
Head ultrasounds also investigate other neurological issues in infants, such as an unusual increase in head size or a bulging fontanel, which could indicate hydrocephalus (excess fluid in the brain). The scan can detect congenital abnormalities of the brain. It can also evaluate for suspected infections, such as meningitis, or monitor known conditions and the effectiveness of ongoing treatments.
What to Expect During a Head Ultrasound
Preparation for a head ultrasound requires little special preparation. Parents might be advised to feed their infant before the procedure to encourage sleep or stillness, as a calm baby helps ensure clear images. The infant will lie comfortably on their back on an exam table.
A clear, water-based gel is applied to the soft spots on the infant’s head. This gel eliminates air pockets between the transducer and the skin, allowing sound waves to transmit effectively into the brain. A sonographer or radiologist will gently move the small transducer over the fontanelles to capture images of the brain’s structures. The procedure is quick, taking about 15 to 30 minutes, and is considered painless and non-invasive.
Safety and Important Considerations
Ultrasound imaging uses sound waves and does not involve ionizing radiation, which is used in X-rays or CT scans. This characteristic makes head ultrasounds generally considered safe for infants. However, some research has explored potential thermal and mechanical effects of ultrasound, suggesting possible temperature elevations in neural tissue.
A limitation of head ultrasounds is their effectiveness once an infant’s fontanelles close and the skull bones fuse, typically by 18 to 24 months of age. Once the skull bones harden, they block the passage of ultrasound waves, making it difficult to obtain clear images of the brain. For older children and adults, other imaging techniques, such as Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans, are preferred for visualizing brain structures. A radiologist interprets the images and communicates the findings to the referring physician for discussion with parents or guardians.