The Pioneers of 3D Ultrasound

April 1, 2018

How advancements in ultrasound technology paved the way for future innovation 

Most people are familiar with ultrasound as a tool that allows pregnant couples to see their baby before it’s born. Thirty years ago, ultrasound images typically showed vague black and gray shapes, and it could be difficult to distinguish between a baby’s nose or foot without a doctor’s explanation. But today, these images are so clear that new parents can even see their baby sucking on its thumb.

This difference in clarity is due to the use of 3D ultrasound, created by Olaf von Ramm, Stephen Smith and John Oxaal through their company Volumetrics Medical Imaging, Inc.

Von Ramm (PhD ’73) and Smith (PhD ’75) first began working together at Duke as PhD students in the lab of Frederick Thurstone, an ultrasound researcher who was recruited to work in Duke’s biomedical engineering department as a faculty member in 1967. At the time, ultrasound was a relatively new technology, and it wasn’t widely used in clinical applications. This changed after von Ramm and Thurstone helped revolutionize the ultrasound scanner, a device that both transmits and receives ultrasound pulses.

By designing a phase array ultrasound scanner that could emit thousands of pulses at once, the tool could receive more detailed images from the scanned tissue, giving physicians a better look at what was going on inside the body. While this advancement was effective, von Ramm and Smith wanted to continue to improve the technology to see three-dimensional moving images in real-time.

“We ended up sketching out our idea on a napkin,” says Smith. “To test it out, we filled a garbage can with water from the Eno River and dropped a wrench into it, and we were able to see the wrench through this muddy water. That experiment really gave us the idea to pursue real time 3D ultrasound for medical use.”

To make their plan a reality, Smith and von Ramm aimed to increase the sensitivity of their device. Rather than keep the sensors in a row like previous ultrasound probes, they arranged hundreds of sensors in a checkerboard pattern to better analyze more complex ultrasound reflections. They also created their own computer systems to quickly read the feedback and show the image.

“I had thought of doing 3D when we had developed 2D ultrasound in the ’70s, but we didn’t have the technology that would allow for that,” says von Ramm. “We were only able to make our first 3D image by 1987, and even then, it wasn’t very good. But the images we made improved each year.”

The team applied for patents in 1986 and 1987, and shortly after they were joined by John Oxaal, a biomedical engineer who had graduated from Duke in 1976 and had previously worked with von Ramm on 2D ultrasound. Together, they formed Volumetrics Medical Imaging in 1992 to develop the first real-time 3D commercial system.

Renting space in downtown Durham, the team formed a collaboration between Volumetrics and Duke’s Department of Biomedical Engineering, relying on funding from the National Science Foundation as they built their initial prototype. By 2000, the company had sold nearly 20 3D scanners, which were used for obstetrics and cardiovascular imaging. Since then the basis of their technology has been widely used in clinics in nearly every developed country around the world.

In the intervening years, von Ramm has continuously looked for ways to improve the technology, especially for cardiology. Today, he’s contributing to research relating to high-speed ultrasound imaging, which shows upwards of 1,000 frames a second. With this improved view, he says, physicians and researchers could visualize the depolarization of the heart, potentially limiting the need for invasive procedures that examine heart muscle.

“We’d be able to examine areas that aren’t contracting well and potentially learn why they aren’t contracting well, or we could examine regions that are contracting prematurely and reducing the efficiency of the heart,” says von Ramm. “Right now, there are only very difficult ways to map the electrical excitation of the heart. You’d have to do it invasively with a catheter, and it can take four hours. If this works out, we’d be able to do it easily and non-invasively.”

Smith has also continued to advance ultrasound probes, designing esophageal probes that can clearly examine a patient’s heart by circumventing the lungs and fatty tissue. One of his long-term goals is to use ultrasound imaging to visualize the brain through the skull, potentially giving physicians an easier way to diagnose issues like a stroke and immediately start treatment.

“We’re always looking for good, non-invasive ways to monitor the body, and ultrasound imaging has played a vital role,” says Smith. “The goal of our work has always been to change the practice of medicine for the better.”

John Oxaal: The Entrepreneurial Alumnus 

After graduating from biomedical engineering at Duke with his bachelor of science in engineering degree in 1976, Oxaal enrolled at the University of Chicago, earning his business degree before returning to Duke to help start Volumetrics Medical Imaging with von Ramm and Smith. Oxaal continued to work at the company until 1999, after which he moved to the west coast to work as a venture capitalist at Sevin Rosen funds. While there, his entrepreneurial work focused on a variety of scientific topics, including imaging and photonics. 

His experience as both an entrepreneur at Volumetrics and as a venture capitalist led BME Chair Ashutosh Chilkoti to invite Oxaal back to Duke to serve as the first entrepreneur-in-residence in the department for the 2015–2016 school year, providing support and guidance to new entrepreneurs in the BME department. Through this role, Oxaal helped Charles Gersbach found Element Genomics in 2015, eventually becoming CEO of the company.

After years of experience in the entrepreneurial world, Oxaal was pleased to return to his alma mater and help a new generation of entrepreneurs. “The BME department at Duke has always been full of leaders in the field, and it’s given them a very clear idea of where the unmet needs are,” says Oxaal. “Engineers are an entrepreneurial bunch, and they’re solving real-world problems in ways that can have enormous benefits.”