By Tomas Kellner
Cardiologist Bijoy Khandheria has been fixing broken hearts for more than three decades, listening to their muffled gallop and watching their grainy forms emerge and disappear, like some deep-sea life forms, on monitors in his darkened office. “Traditionally, ultrasound has allowed us to see the heart but not in as much detail as we might like,” he says. “We used the signal to image the heart layer by layer, almost like a butcher using a knife, and then mentally splice the layers together to see the whole picture,” he says. “The process has always involved some guesses.”
But Dr. Khandheria and his colleagues at Aurora St. Luke’s Medical Center in Milwaukee, Wis., have recently started using brand new ultrasound software that, for the first time, allows the team to see the heart in “extreme 4D” – the three spatial dimensions plus time. “The images are exquisite,” Khandheria says. “It’s like opening the chest and seeing the heart beating.”
Top GIF: A 3D view of the human heart’s mitral valve that opens and closes with each heartbeat. The mitral valve’s two leaflets ensure that blood flows in one direction. Above: Blood flows out of the heart and into a large blood vessel called the aorta. The aortic valve opens so blood can flow out and closes to keep blood from returning. GIF credits: GE Healthcare
The two left chambers of the heart’s four chambers. Both chambers are separated by the mitral valve. GIF credit: GE Healthcare
Khandheria says the software, which was developed by GE Healthcare for use on its newest cardiovascular ultrasound machines, delivers images so clear that it allows him observe how blood swirls around clots in arteries. “I can use it to measure the severity of blood leakage around the valves and assess the damage,” he says. “It’s almost as if I took out the valve and started turning it with my hands. This is invaluable information for the surgeons when they are preparing for an operation.”
An ultrasound machine sends beams of high-frequency sound waves – their pitch is too high for the human ear - into the body and uses their echoes to detect the shapes of internal organs. The technology is similar to SONAR used by submarines.
Top: The bulge on the lower valve indicates a failing mitral valve. With 3D views of the heart, there are several options to repair such a failure without open heart surgery. Above: Mending a broken heart. Literally. Surgeons inserted thin wires into this heart to implant an artificial valve without open heart surgery. GIF credits: GE Healthcare
Traditionally, heart ultrasound has relied on hardware “beamforming.” But this method is slow compared to the agility of software beamforming and limited to the finite amount of data it was originally built to handle in creating an image of the body. As a result, it often produces less detailed images and requires lengthy hardware redesigns.
The new software, called cSound, can collect a practically infinite amount of data to create an image of the human body. Rather than getting rid of the data it can’t process, which is what hardware does, the software stores it in the machine’s memory. GE’s engineering team developed algorithms that then process and analyze all of the data stored in the memory and cherry pick the best signals on a pixel-by-pixel basis.
This is an artificial mitral valve with sutures on the ring. The mitral valve ensures that blood flows in one direction. GIF credit: GE Healthcare
The cSound software is so powerful that it can process an amount of data equivalent to playing an entire DVD in just one second, in real-time. Its inner workings were based on a combination of supercomputer data processing and the transmitters and receivers used in radar, seismology and WiFi communications. (Unlike CT or X-rays, ultrasound uses sound waves, rather than ionizing radiation.)
The team started developing cSound by looking at GE’s other 4D ultrasound system used for imaging a fetus during pregnancy. “It’s a similar algorithm, but there are some important differences,” says Erik Steen, the GE software engineer who helped develop the technology. “When you are doing 4D fetal imaging, you want to see the nice smooth surface of the skin. But cardiologists want to see differences in the heart tissue. So we built them color maps that can do that.”
The right and main chambers as viewed from the apex of the heart. The moving structure in the center is the mitral valve and can be identified by its fish mouth shape when open. GIF credit: GE Healthcare
The software is especially useful in scanning patients with lung disease or those who are obese or in a critical condition, all of whom are currently hard to image. According to clinical studies, the most widely ordered cardiovascular test, transthoracic echocardiograms, are today inconclusive 10-15 percent of the time, resulting in additional testing at up to almost three times the original cost and with an increased burden on the patient.
This can add up. 5.1 million people suffer from heart failure in the U.S., adding an estimated cost of $32 billion to the country’s healthcare bill each year.
But Dr. Khandheria is seeing results. He says that the diagnostic accuracy has improved because of the software and that the technology has benefited 98 percent of his patients. “It’s a breakthrough in ultrasound imaging,” he says.
This is an artificial mitral valve with sutures on the ring. “Ultrasound is on the verge of delivering huge change in medical care because it allows doctors to see inside the human body like never before by touching a probe that’s smaller than the size of your hand to the patient’s body,” says Al Lojewski, general manager, cardiovascular ultrasound at GE Healthcare. “Especially with this new software, it may mean reduced burden for the patient and exceptional images of the heart for the doctor on the spot.” GIF credit: GE Healthcare