A head ultrasound examination produces images of the brain and the cerebrospinal fluid that flows and is contained within its ventricles, the fluid filled cavities located in the deep portion of the brain.
Since ultrasound waves do not pass through bone easily, this exam is most commonly performed on infants, whose skulls have not completely formed.
The gaps between those skull bones provide a “window,” allowing the ultrasound beam to freely pass into and back from the brain. The ultrasound probe and some gel are placed on the outside of the head in one of those regions without bone.
In adults, head ultrasound is used to locate and evaluate tumor masses during brain surgery, facilitating their safe removal.