Inspired by the human brain, Ruud van Sloun is revolutionizing medical ultrasound

TU/e’s Signal Processing Systems group develops smart algorithms that produce razor-sharp details on echoes.

With a bold vision and a deep curiosity, electrical engineer Ruud van Sloun and his research team are on a mission to transform medical ultrasound, making it faster, more affordable, and accessible to everyone. Drawing inspiration from the remarkable efficiency of the human brain, they came up with a daring idea that once seemed impossible. But now, that "crazy plan" is starting to become reality.

Interview: Michelle Wijma

Ruud van Sloun is the kind of scientist who enjoys working on entirely new ideas that no one else has touched yet. If that fresh idea is promising but no longer novel, he’s happy to hand it off to others better suited to develop it further, freeing him up to dive into a new challenge.

So around Christmas 2021, Van Sloun had taken a few weeks off to mess around with ideas freely, and ended up plopped in the middle of his living room. The floor around him was covered with dozens of neuroscience papers.

My passion is smart ultrasound - it has the potential to bring medical imaging to so many more people.

Ruud van Sloun

Van Sloun is an associate professor in the Signal Processing Systems group of the Department of Electrical Engineering. Usually, he focuses on algorithms for medical imaging, with ultrasound being a particular source of inspiration.

But not during that Christmas break. Van Sloun briefly stepped outside his field to take a deep dive into the human brain. He used his time off to learn everything about how the brain makes predictions, processes information, and makes decisions.

Medical imaging

"Can’t we use these principles for medical imaging, too?" Van Sloun wondered out loud, tossing another paper onto the last bare spot on the floor.

Medical ultrasound could become much better and more accessible that way. Van Sloun dreams of portable, affordable ultrasound devices that deliver excellent image quality --one as small as a smartphone that takes images so you can confidently and reliably make medical decision with them, for every patient.

Flashlight looking for keys

"Imagine you’ve lost your keys," Van Sloun explains the idea behind his thinking. "You walk through a pitch-dark room with a flashlight, shining it on the spots where your keys might be hiding. Something glints in the beam. You quickly move the light back. Gotcha."

Based on the information (something glinting in the light), your brain just figured out the best next move (shining the flashlight back there). That way, you found your keys quickly without wasting energy.

Your brain predicts the future

Van Sloun explains that this idea is known as active inference in neuroscience. "Your brain constantly makes predictions about what will happen next and then does everything possible to bring those predictions to life. Without active inference, searching for your keys would look very different."

For instance, instead of focusing on where something might be, you’d start at the top left corner of the room and painstakingly sweep the flashlight down centimeter by centimeter. Then, you’d move to the right and slowly scan upwards again. Only after you’ve scanned the entire room would you finally notice where the keys are.

Reflecting and creating pixels

"That’s exactly how an ultrasound image is formed," Van Sloun explains. "The device sends sound waves, which the body’s tissues reflect. Then, the software builds the image pixel by pixel. What the machine actually ’sees’ doesn’t matter - the program treats every pixel in every frame as equally important."

Not only does this method waste a lot of energy on measurements that aren’t informative, but the device also picks up a lot of noise and artifacts from tissues you don’t want to examine.

AI growth spurt

"I thought it would be cool to apply active inference to ultrasound," says Van Sloun. But that’s easier said than done. All the pixels in an ultrasound add up to an enormous number of parameters and dimensions-more zeros than you’d want to deal with. "You need exact statistical models, and that’s hard in such high dimensions."

Then generative AI made a giant leap forward. With a clever algorithm and a precise statistical model, it can create something entirely new out of nothing. ChatGPT uses a language model for this, and there are video models for images. "That’s exactly what we needed," Van Sloun says. "Suddenly, the hopeless problem wasn’t so hopeless anymore."

Right there in the middle of his living room floor, everything clicked. Generating ultrasounds with smart algorithms that make the images more efficient, better, and more accessible. Van Sloun went for it. Ambitious? Yes. A bit crazy? By his admission, definitely. Possible? Yes-at least maybe.

He returned to his role as an electrical engineer, wrote up his plan, and submitted it to the European Research Council. And he succeeded-at the end of 2022, he was awarded an ERC grant. Their message: "Go for it." "It was a bold idea-high risk, high gain," Van Sloun says.

It was a bold idea - high risk, high gain.

Ruud van Sloun

Shining more efficiently

Van Sloun and a team of about ten students and researchers have been working on his plan for over two years now. He shows a video to illustrate the project. The smart ultrasound device sends a sound wave, shown in orange, directed at the heart. The tissue there reflects the wave, and the device picks it up again.

That data goes into the algorithm, which then assesses how valuable the information is. Fewer sound waves are sent there if there’s not much to gain from that spot. However, the device collects more measurements if something interesting happens, like movement.

Just like the flashlight

"It works like the flashlight in the dark room," Van Sloun explains. "Instead of looking around randomly, the device sends sound waves to the spots where the most information is likely to be."

His method is more efficient than a traditional ultrasound. It requires less power to produce an image of similar quality. This could be a game-changer for wireless ultrasound devices, which are growing in popularity. They’re convenient, but you have to recharge the battery every hour, says Van Sloun. With his technology, that battery would last much longer.

Focusing on details

You can also use full power to capture an ultrasound with more detail. That’s what Van Sloun is currently focusing on in his research. "In the image below, you see a heart," he explains. The heart valves at the bottom are closed. "The image on the left is similar to a standard ultrasound. The right image has been enhanced by generative AI, which removes noise and reveals much more detail."

"Healthcare providers are often pleasantly surprised when I show them these images," Van Sloun continues. Cardiologists and sonographers have told him they get a good ultrasound image in only about one out of ten patients. Around seventy percent of ultrasounds are of moderate quality, and the image is even clinically unusable for ten to twenty percent.

"This problem is only getting worse," the researcher says. "Not because ultrasound technology is getting worse, but because the human body is changing." People generally have more fatty tissue than before. The more tissue an ultrasound wave has to pass through before reaching, in this case, the heart, the noisier and more out-of-focus it is. This is also a problem for pregnant women.

If an ultrasound is not clear enough to make a good diagnosis, the patient is referred for an MRI scan. This is inconvenient for the patient and expensive for healthcare, says Van Sloun. Better ultrasounds make care more accessible and inclusive. "That means a huge win for reducing pressure on the entire healthcare system."

Ultrasounds on your smartphone

It’s a promising prospect, but Van Sloun likes to dream even bigger-literally. "My passion is smart ultrasound technology, because it can bring medical imaging to many people."
According to the World Health Organization (WHO), two-thirds of the world’s population has no access to ultrasound or any other form of medical imaging. When it comes to high-quality imaging like MRI, that number rises to ninety percent.

"The differences between countries are striking," says Van Sloun. In Germany, there are 450 MRI scanners for every 13 million people. For those 13 million people, there’s just 1 MRI scanner in Africa, and some countries don’t even have any MRI scanners. "Working on MRI technology is rewarding, and I enjoy it, but no matter how advanced the technique gets, nine out of ten people simply don’t have access to it."

My passion is smart ultrasound technology, because it can bring medical imaging to a massive number of people.

Ruud van Sloun

Combining methods

The key to realizing his vision is merging different techniques to create more efficient measurements and higher-quality ultrasounds. If successful, reliable diagnoses could be made with only a smartphone, a small ultrasound device, a cable, and an internet connection. Today, such imaging still requires bulky, expensive equipment.

The second key is cloud computing, where all the data is processed-something a smartphone alone can’t handle. Van Sloun’s algorithms demand significant computing power, and he beams at the thought of making this a reality: high-end ultrasounds right on your smartphone. "That way, we bring medical imaging to millions who lack access and miss out on vital care."

Musical associations

Van Sloun loves algorithm development because it allows him to be creative. He compares it to writing songs-a hobby he enjoyed as a guitarist in various bands. "A song starts with a basic idea, like a few chords and a key. You build on that, adding and tweaking until you get the desired effect."

In music, that effect is often emotional; in algorithms, it’s usually functional, solving a problem. Van Sloun explains, "For the creative, iterative process, the exact effect doesn’t matter. There’s no fixed step-by-step plan in both cases-just brainstorming and connecting associative ideas."

Working with Massimo Mischi

Ultrasound became part of Van Sloun’s journey when he learned about the work of Professor Massimo Mischi. While Van Sloun was studying in Eindhoven, Mischi was developing ultrasound techniques to detect prostate cancer, reducing the need for MRIs. "I thought that was cool. I said to myself: I want to work with this guy."

And that’s precisely what happened. Van Sloun did his master’s project in Mischi’s group when Mischi was still a university lecturer. Not long after, Mischi invited him to pursue a PhD under his supervision. "Now, years later, I find myself in pretty much the same place Massimo was back then."

My team does what I hope to give others: the courage to dream big.

Ruud van Sloun

Is he a role model now? "I hate to answer that question. But I hope so. I hope I can inspire others the way Massimo inspired me."

The signs are promising. When asked what he’s most proud of, Van Sloun immediately points to his team. "Working with people who want to change the world is a privilege. They do exactly what I hope to give others: the courage to dream big."

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Photo: Marieke de Lorijn