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Watch This: A Twist On The Doppler Effect Opens New Vistas On Tiny Hearts

P D Olson
May 25, 2018
Surgeons need steady hands. If you’re Wolfgang Arzt, you also need nerves of steel.
Arzt performs heart surgery on unborn babies, inserting a needle into the mother’s womb and carefully pushing it through a tiny valve in the fetus’ heart that’s just 2 millimeters in diameter, or about as wide as a pinhead. Then he perforates the valve. “If I go 1 or 2 millimeters too far, I tear off the vessel and everything is over,” he says from his office at Kepler University Hospital in Austria, where as head of prenatal care he has overseen more than 140 such procedures.

Recently Arzt has been watching the outcomes of his life-saving microsurgeries in 3D: the blood flowing properly through vessels with physical contours and shading. This new way of imaging the tiniest human blood vessels — Arzt called it the “wow effect” the first time he saw it — has come courtesy of Radiantflow, a remarkable new capability of GE’s Voluson E10 ultrasound system.* GE Healthcare’s Austrian engineers developed it using a twist on the Doppler effect, a 19th-century discovery by another Austrian, the physicist Christian Doppler.

Doppler figured out that a wave’s pitch depended on the relative speed of the source and the listener. It was higher when it approached him, and lower as it moved farther away — like the tailing off of an ambulance siren. Today researchers use it to build better radars and medical scanners, but also to measure the size of the universe.

Arzt first saw images from an ultrasound system with Radiantflow at a conference in September 2017. His first reaction to staff at GE was “Why haven’t you shown me this before?”

 width= Top and above: Arzt first saw images from an ultrasound system with Radiantflow at a conference in September 2017. His first reaction to staff at GE was “Why haven’t you shown me this before?” GIF credits: GE Healthcare.

To be sure, ultrasound engineers have been tinkering with the Doppler effect for a while. But the software is a step up from systems like color Doppler, which allows doctors to “see” blood flowing through the complex structures of the heart in different colors — red if it’s flowing one way, for instance, and blue for another. (Astronomers call this the red shift and blue shift, and use it to detect the directions and ages of distant stars.)

But GE engineers used Doppler’s equations to also figure out how to detect the contours of the vessels in 3D just by changing the ultrasound machine’s software.

The idea for the software was born when GE Healthcare software architect Gerald Schroecker and his team in Zipf, Austria, decided to apply 3D visualization techniques to the grainy, 2D ultrasound images most of us are used to. They found they could combine specific soundwaves caused by the blood flow with other components of the ultrasound signal. Some months of intensive development and testing later, the result allowed them to dramatically improve the image quality. Schroecker says that with Radiantflow’s new representation of blood flow, “you can clearly see the rounding of the vessels, and it’s easy for the brain to understand the structure.”

“Our team never stops innovating in making ultrasound easier to acquire and comprehend for doctors and patients alike,” says Roland Rott, general manager of Women’s Health Ultrasound at GE Healthcare. “From being a pioneer in 3D/4D ultrasound and its visualization through photorealistic rendering (HDlive), Radiantflow is the next industry-first innovation that will change how ultrasound is performed.”

For surgeons like Arzt, the system today already provides insight into the most difficult organ in the fetus to examine. He adds, with some understatement, that there is already “a lot of adrenaline” involved during a procedure. “When I do this with Radiantflow, the understanding is much better,” he says.

*Radiantflow has trademark and patents pending.