Hip replacement, open-heart surgery, organ transplants — none of the wonders of 21st-century medical care would be possible without the tools that engineers design. At U.Va., engineering students come away with a sense of the complexity that must be mastered to engineer products for the human body.

Precise Drug Delivery

Catheters are one of the marvels of medical science. They can be used to deliver radiocontrast agents or stents, they can be inserted to drain urine from the bladder and they can be threaded into the coronary artery to measure pressures in the heart.

Over the last 20 years, SEAS mechanical engineering professors George Gillies and Joseph Humphrey, in partnership with Dr. William Broaddus at Virginia Commonwealth University, have developed a series of innovative catheter designs. Ali Hemyari (EE ’07) won a coveted 2006 Harrison Undergraduate Research Award from the University to work with them.

One use for catheters is to deliver a therapeutic agent through a blood vessel to a specific area of the body. The challenge is to keep the medication in place, where it can do the most good, rather than being swept away by the flowing blood. One approach is to use a balloon to block the blood flow periodically, but this poses the risk of tissue damage. U.Va. engineers are hoping that by improving the design of the catheter itself, they might keep the agent at its intended site longer.

Hemyari is working with Humphrey as his senior thesis adviser, in collaboration with George Gillies, to construct a large-scale model of this catheter. “The model will enable us to test different approaches and provide the essential data needed to produce a computer simulation,” says Hemyari.

Faster CAT Scans

A hundred years ago, all surgery was exploratory. If you wanted to find out what was the matter with a patient, you operated. Today, physicians have a suite of noninvasive diagnostic tools at their disposal, from X-rays to ultrasound to magnetic resonance imaging.

Drew Maier (CS ’07) is part of an effort to take one of the most powerful of these diagnostic tools, the 3-D CAT scan, and make it more useful in the operating room.

A CAT scan is essentially an X-ray on steroids. While a simple X-ray image shows the body in profile, a CAT scan machine rotates around the body and takes a series of very narrow X-rays that can be assembled into a cross section.

A 3-D CAT scan takes this a step further, stacking these slices — in essence creating a virtual, threedimensional reproduction that radiologists can explore as if they were moving through the body. The problem for surgeons is that reconstruction of these images can take as long as 10 minutes to complete.

In an effort to slash this time, members of the Division of Interventional Radiology at the U.Va. Health System approached Associate Professor of Computer Science Kevin Skadron, who in turn enlisted Maier in the project.

“We approached the problem systematically,” Maier says. “We determined that the bottleneck was not in the scanning or in the data transfer but in the reconstruction process.” Together with Professor Skadron, Maier is exploring the effect of replacing the system’s serial computer processing unit (CPU) with a powerful NVIDIA graphics card. The card can process nongraphical data in parallel, potentially shortening reconstruction time.

Maier’s task is to extract the CPU code and translate it into code that the card’s graphics processing unit can read. He meets with Skadron weekly, which keeps him on track, but adds, “When you’re doing research, you’re on your own to find the information you need.”

An Active Leg Brace

People with cerebral palsy often turn to leg braces to make their stride more efficient. Typically made of rigid materials, leg braces provide passive support and stability.

Marie Toluwani Adeyemi is working with Pradip Sheth, an associate professor of mechanical engineering, on an NSF-funded study to create an active leg brace, one that captures the excess energy that we all produce during our initial heelstrike and uses this energy to create a more efficient toe-off. She’s working with researchers at the University’s Motion Analysis and Motor Performance Laboratory at the Kluge Children’s Rehabilitation Center, one of the best-equipped centers of its kind in the United States. “Our goal is to help people with cerebral palsy walk more accurately and be more stable,” she says.

A third-year student in the School of Mechanical, Materials and Manufacturing Engineering at the University of Nottingham, Adeyemi has come to U.Va. for a year abroad. Her extensive background made her the logical choice to do a functional analysis of the prototype brace. She’s responsible for offering suggestions about materials, mechanisms and manufacturing and producing a 3-D model of an improved design.

“Before I came, Professor Sheth and I discussed a number of possible projects, but I chose this one because it combined a number of my interests,” she explains, “mechanics, innovation and a passion for working with kids.”