Ultrasound scanner goes portable

Professor Jørgen Arendt Jensen’s daughter was born with the umbilical cord wrapped twice around her neck. Her pulse dropped several times during the birth, and the doctors took blood samples and tried desperately—but unsuccessfully—to work out what was wrong. If they had had an ultrasound scanner at hand they could have easily made a diagnosis.

Fortunately the birth went well, despite the dramatic complications, but for Jørgen Arendt Jensen the experience clearly showed the need for a portable ultrasound scanner that could fit in a lab coat pocket beside a stethoscope.

“Ultrasound is a fantastic tool for seeing inside the body, and without damaging any tissue. So ultrasound scanners need to be portable and much more readily available, in ambulances trauma wards, labour wards—anywhere,” he says.

And he is well on the way to making this vision a reality.

Many steps along the path

The principle of an ultrasound scanner is simple: You transmit a strong sound signal into the body at a frequency the ear cannot register, and measure how long it takes for the echo to return from the body's inner structures.

But behind this simple principle lies complicated technology and knowledge of diverse fields such as acoustics, electronics, transducer design, and signal and image processing. To make ultrasound instruments portable, the technology in the transducer you hold i your hand, the advanced electronics, and the signal processing in the scanner must be radically changed. Finally, the technology has to be clinical tested to show that the new methods are at least as good as the existing ones.

There is potential to optimize and tweak the technological parameters at every point, and work is being done on this in a major five-year project headed by Professor Jørgen Arendt Jensen, who is also head of the Centre for Fast Ultrasound Imaging at DTU Electrical Engineering. The project also involves researchers from DTU Nanotech, two enterprises—BK Medical and Meggitt A/S, the Alexandra Institute in Aarhus and Rigshospitalet.

“It’s crucial that we have the full range of expertise on our team if we are to achieve our goal of a cheap and readily available ultrasound device, which can become part of a general practitioner's standard equipment. And I believe this is definitely realistic. We’ve already achieved a lot of milestones and taken out a number of patents, and the project still has 18 months to run,” says Jørgen Arendt Jensen.

Simplification

Thirty years ago, not many people imagined that they would one day be able to fit a computer in their pocket. But Jørgen Arendt Jensen expects ultrasound devices to go the same way as our smartphones. One of the necessary conditions is a radically different way to record the ultrasound signals, an area in which DTU has been a pioneer.

“We have developed a new way to create images called synthetic aperture imaging. Instead of looking in one direction at a time, we look in all directions at the same time. This means we can create images much faster. We can display up to 1,000 images a second, allowing us to see the heart beating and blood flowing, while also having a sharper and more precise picture. We have also developed new probes for 3D imaging which reduce the volume of data by a factor of 60,” he says.

The fast imaging also demands rapid data processing, but this need not take place in the probe or the linked data device, as it does in normal ultrasound devices. Jørgen Arendt Jensen and his colleagues have developed calculation methods that require far less resources and have demonstrated that the required data can be processed on a smartphone or tablet.

You can even wirelessly send the data into the cloud, where several large computers can process it, and then things really start to get interesting. For example, researchers have experimented with sending data to Germany and back again to the tablet. There was a slight delay, but you could see the picture quite well as the probe was moved over the patient's body. And in randomized double-blind trials in Rigshospitalet’s radiological department, doctors could not see any difference between the new and the old images.

Netflix for scanners

A traditional ultrasound console is limited by the fact that there are only two kilowatts of power in the power outlets, and that it generates a lot of heat. With a portable scanner, the power requirement is shifted to a data centre somewhere else, making it practically unlimited. Once we have unlimited power, we can also perform more complex calculations, for example in 3D, predicts Jørgen Arendt Jensen:

“We can currently see the blood flow rate using ultrasound, but if we can do further calculations, we will also be able to see the pressure in the blood vessels. The current procedure involves inserting a catheter up to the heart through the groin, which is uncomfortable and carries risk, and it can be difficult to precisely hit the target."

In addition to extra diagnosis options, the simpler wireless equipment will make it possible to get help over the Internet from more experienced ultrasound users, allowing general practitioners anywhere in the world to use ultrasound in consultations.

Jørgen Arendt Jensen goes as far as to foresee a business model something like Netflix, where you buy an ultrasound service instead of a large device. The doctor leases the probe, while all necessary software is stored in the cloud and is constantly kept up-to-date. And just like Netflix recommends other movies, you can see suggestions for other scanning methods.