Mason Professor Uses Colorized Computer Models to Evaluate Aneurysms
By Michele McDonald
Juan Cebral’s complex computer model does more than simply show blood swirling in a brain aneurysm’s labyrinthian pattern; it helps doctors determine whether the aneurysm is about to rupture and needs surgery.
Cebral, a professor at Mason’s Center for Computational Fluid Dynamics in the College of Science, studies fluids and how they move. He works with surgeons and other researchers to map out how blood flows in the brain, specifically in aneurysms. Brain aneurysms happen when blood bulges against a weak arterial wall and creates what resembles a balloon in the artery. It’s unknown why aneurysms happen.
Cebral is working with Inova Fairfax Hospital; the University of California, Los Angeles; the Mayo Clinic; the Buenos Aires, Argentina-based Clinical Institute ENERI; and Philips Healthcare in the Netherlands.
“I feel very excited that maybe my work will help doctors or patients,” says Cebral. “If you look at the history of medical advances, doctors and scientists working together have made these advances. The doctors don’t have the time to do research most of the time. The scientists need patients to do the research. It’s difficult to get the right combination.”
Technology is catching up with the complexity of the human brain and is making it possible to study the interaction between blood flow and neurons. Past models were idealized, says Cebral, who earned his doctorate in computational fluid dynamics from Mason in 1996. “For instance, when you build a glass model of an aneurysm, it’s just a straight glass tube with an aneurysm. And that never happens in the human body.”
But now computerized models are a wonder of colors, and Cebral’s models give surgeons a picture of the aneurysm that they wouldn’t have had otherwise. He starts with the gray x-ray image of a patient’s aneurysm and transforms it into swirling colors to show the complex blood flow. Blue is normal blood flow, while red shows problematic blood flow. It can take a day or two to build a complex model and then another day to run the simulation.
“You can use the arterial geometry of specific patients and then you can simulate what that blood flow looks like,” Cebral says. “You can study specific flow dynamics. We can provide some information that the doctors don’t have today, which is the fluid dynamics of each individual patient.”
About 5 to 8 percent of people have a brain aneurysm, but less than 1 percent rupture every year, Cebral says. Intervention is risky; it may not be worth taking that risk if the aneurysm isn’t going to rupture.
“So the first question we need to ask is, which aneurysm is most likely to rupture?” Cebral says. His computer models work to answer that question by measuring the force of blood on the arterial wall and compiling statistics of the results.
“With that information we look at what happened with these aneurysms. Did they rupture? Did they not rupture? We look for the conditions in ruptured aneurysms and how they are different from the conditions in unruptured aneurysms. If we find that, for instance, an unruptured aneurysm has smoother, simpler blood flow than a ruptured aneurysm, we can use that information to try to predict whether an aneurysm will rupture.
“So if someone comes into the hospital and we see pressure on the arterial wall, then we can say, ‘I’ve seen these characteristics on most of the ruptured aneurysms, so this is more likely to rupture.’”
That brings treatment into the picture. Cebral is working with Ram Kadirvel, an assistant professor of radiology at the Mayo Clinic, on a $2 million grant from the National Institutes of Health to study a new treatment. Work started in late spring 2012, and Kadirvel credits Cebral as the main reason they received the grant.
Currently, surgeons use platinum coils inserted into the aneurysm to avoid open skull surgery. But this option doesn’t last, and patients need to be re-treated, Kadirvel says. They’re testing whether a stent—a mesh metallic device placed across the aneurysm’s neck—could offer a better option. They’re also studying high-flow, medium-flow, and low-flow density stents to see which offer the best chance for healing the aneurysm.
“Juan puts all the data together and then he creates a model for before and after the stent,” Kadirvel says. The stents could be used in humans in four to five years.
Cebral says more options could be possible as researchers are able to study aneurysms in greater detail. In 2005, he had 60 aneurysm models taken from patients, and that was top of the line. Today, he can compare as many as 200 patients.
Fluid dynamics also can be applied to the heart, legs, and other arteries. “There are many fluid mechanics problems in the human body,” Cebral says.
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