U.S. Navy submarine sonar tech targets strokes

In much the same way submarine sensors can differentiate between whales and other vessels, portable device measures subtle skull pulsations that may indicate irregular blood flow.

Retired U.S. Navy sonar experts have helped create a novel portable device to detect, diagnose, and monitor strokes. The brain-imaging system uses a simple headset and laptop--and decades of submarine technology--to home in on brain activity that signifies trouble.

headset
The sensor-equipped headset measures skull pulsations that could indicate irregular blood flow. Dr. Kieran J. Murphy

The headset is equipped with six highly sensitive accelerometers. Instead of peering out through the rounded bow of a submarine, they are oriented inward toward the brain.

The brain's machinations (veins expanding and contracting, aneurysms wobbling) each have their own unique vibrations that cause slight skull pulsations. The headset sensors measure these movements to look for irregular blood flow in much the same way submarines measure motion and generate signals that are processed, analyzed, and matched to objects.

Data on the type and location of brain vascular abnormalities is then rapidly sent to the PC.

"As sonar sorts out whales and other objects from vessels, the device sorts out cerebral abnormalities such as aneurysms, arteriovenous malformations (AVMs, an abnormal connection between veins and arteries), ischemic strokes, and traumatic brain injury from normal variations in physiology," said Dr. Kieran J. Murphy, director of research and deputy chief of radiology at the University of Toronto and University Health Network in Toronto, in a release (PDF).

Murphy is presenting trial data on the device--developed by Mountain View, Calif.-based Jan Medical--at the Society of Interventional Radiology's 36th Annual Scientific Meeting in Chicago this week.

In a pilot study at Johns Hopkins Hospital that involved 40 stroke patients and 30 normal controls, a prototype system correctly identified stroke in 97.3 percent of cases and correctly ruled it out in 98.8 percent of normal patients. It was also able to separate patients with specific stroke conditions or vascular abnormalities into unique categories like ischemia, hemorrhage, aneurysm, stenosis, and arteriovenous malformations, according to Jan Medical. Its founder and CEO, Paul Lovoi, named the company after his wife, Jan, who died from a stroke at age 55.

"The system is very simple in principle, yet it yields exceedingly rich data," Murphy said.

The experimental device relies on submarine sonar technology that can differentiate objects such as whales from enemy vessels. Dr. Kieran J. Murphy

A stroke occurs when a blood clot blocks an artery or a blood vessel breaks, interrupting blood flow to part of the brain. With the sonar device, the initial diagnosis is said to take place within a couple of minutes--a selling point, researchers say, as time is widely understood to be of the essence in preventing permanent damage once a stroke has occurred.

Those working on the device say it's ideal for field emergency care and ambulances and on military battlefields and sports fields where CT scanners aren't readily available. They say they hope the technology can eventually be adapted for use in other areas of acute care, such as open heart surgery, where stroke is a concern.

Subsequent studies--and funding--will be needed before the device can hit the market.

Meanwhile, the last couple of years have seen several promising technological developments in the diagnosis and treatment of strokes. Among them, researchers in Italy developed a robotic arm whose movements could help stroke survivors re-learn how to use their hands, arms, and even shoulders. Recent research has suggested that playing the Wii may help recovering stroke patients improve their motor function. And new blood pressure measuring devices promise to reduce the risk of stroke and heart disease.

 

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