Electronic Design

3D Ultrasound Penetrates Skull To Identify Strokes And Save Lives

Stroke is the third leading cause of death in the United States, according to the National Institutes of Health. But it doesn’t have to be. A five-year study by the National Institute of Neurological Disorders and Stroke shows that patients who take a drug called t-PA, which dissolves clots obstructing blood flow to the brain, within three hours of the start of stroke symptoms are 30% more likely to recover with little or no disability after three months. Of course, the key lies in rapid diagnosis.

Researchers at Duke University are working to make that happen with innovative 3D ultrasound technology that provides an accurate look inside the skull. Eventually, emergency medical technicians could use the technology to scan the heads of potential stroke victims while they are still in the ambulance and make a precise identification. Also, doctors could use it to monitor patients’ response to therapy in real time.

“To our knowledge, this is the first time that real-time 3D ultrasound provided clear images of the major arteries within the brain,” said Nikolas Ivancevich, a graduate student with Duke’s Pratt School of Engineering. “Also for the first time, we have been able to overcome the most challenging aspect of using ultrasound to scan the brain—the skull.”

The skull can be thick and uneven, making typical ultrasound difficult. To compensate, the researchers used sensors arranged in a checkerboard pattern, instead of the single rows that traditional 2D ultrasound employs. Duke developed these arrays over the past 10 years, and they have since been adopted by the industry for cardiac 3D imaging. This research marks the first time that real-time 3D ultrasound has been applied to brain imaging.

Next, the researchers applied transducers or “wands” including these checkerboards to the temples and at the base of the neck, where the skull is thinnest. The researchers developed the 3D display software that turned the wands’ signals into images, marking the first in vivo demonstration of skull aberration correction to improve brain image quality.

“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 said. “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.”

This 3D ultrasound is less expensive and faster than MRI or CT scanning, which are the traditional methods of evaluating blood flow in the brain, Ivancevich said. While it won’t displace MRI or CT scans, he added, Duke’s technology would give physicians more flexibility in treating their patients. The researchers plan on continuing to improve the skull correction software, including more in vivo testing. They also hope to collaborate with the existing ultrasound industry and see the technology adopted commercially.

“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,” said biomedical engineering professor Stephen Smith. First reported in Ultrasound in Medicine & Biology, the research was supported by the National Institutes of Health and the Duke Translational Medicine Institute, with assistance from the Duke Echocardiography Laboratory.

Duke University

www.duke.edu

National Institutes of Health

National Institute of Neurological Disorders and Stroke

www.ninds.nih.gov

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