Ultrasound devices emit sound waves and then create images by calculating the angle of the waves as they bounce back.
For their experiments, the Duke team studied 17 healthy people. After injecting them with a contrast dye to enhance the images, the researchers aimed ultrasound wands, or transducers, into the brain from three vantage points the temples on each side of the head and upwards from the base of the neck. The temple locations were chosen because the skull is thinnest at these points.
Ivancevich took this approach one step further to compensate for the thickness and unevenness of the skull in one subject.
The speed of the sound waves is faster in bone than it is in soft tissue, so we took measurements to better understand how the bone alters the movement of sound waves, Ivancevich explained. With this knowledge, we were able to program the computer to correct for the skulls interference, resulting in even clearer images of the arteries.
The key to obtaining these images lies in the design of the transducer. In traditional 2-D ultrasound, the sound is emitted by a row of sensors. In the new design, the sensors are arranged in a checkerboard fashion, allowing compensation for the skull's thickness over a whole area, instead of a single line.
The 3-D ultrasound has the benefit of being less expensive and faster than the traditional methods of assessing blood flow in the brain MRI or CT scanning, Ivancevich said. Though 3-D ultrasound will not totally displace MRI or CT scans, he said that the new technology would give physicians more flexibility in treating the
|Contact: Richard Merritt|