New 3-D ultrasound could improve stroke diagnosis, care

“I think it’s safe to say that within five to 10 years, the technology will be miniaturized to the point where EMTs in an ambulance can scan the brain of a stroke patient and transmit the results ahead to the hospital,” Smith continued. “Speed is important because the only approved medical treatment for stroke must be given within three hours of the first symptoms.”

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 skull’s 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 their patients.

Other Duke members of the team were Gianmarco Pinton of Pratt, and Duke University Medical Center division of neurology researchers Heather Nicoletto, Ellen Bennett and Daniel Laskowitz.