Monday, July 28, 1997Doctors soon able to 'walk' inside a brain aneurysm through power of 3-D imaging
RESEARCH:By Matt Grace
Daily Bruin Contributor
A small blister in the brain pulsates rhythmically with each flush of blood.
A physician, donning gloves and goggles, walks along the walls of the artery, searching for weaknesses and hidden cavities, carefully examining the flow of blood.
With the help of virtual reality, "walking" within arteries may soon become standard procedure.
The department of radiological sciences, in collaboration with the department of computer science is using 3-D simulations to plan and execute minimally invasive "patches" for brain aneurysms.
Brain aneurysms, the third leading cause of death in America, result from a weakness in an arterial wall. A rupture of this blister causes a microscopic explosion of blood a stroke killing an estimated 500,000 people each year.
Aneurysms can occur throughout the body, but the research has focued on the brain.
With computer simulations of a patient's anatomy and flow of blood, surgeons can explore an aneurysm before surgery and determine the appropriate course of action.
Aneurysms sometimes have unusual projections which cannot be detected by conventional imaging.
"For that reason, we require the extraordinary help of computer science," said Fernando Vinuela, director of the UCLA Endovascular Therapy Service.
"We bring the person into the computer, the computer simulates the aneurysm, and we treat it in the computer," Vinuela explained.
Led by Walter Karplus and Daniel J. Valentino, UCLA researchers have been developing a computer simulation for several years which mimics the dynamic forces affecting the aneurysm.
Mathematical models "express reality in a way that lets one predict what may happen in the future or if certain changes are made," Karplus said.
X-rays of the aneurysm, taken from all possible angles, create a 3-D representation. Combined with data describing the behavior of the blood, the computers translate the numbers and two-dimensional images into a fluctuating aneurysm alive in the world of virtual reality .
"We put them all together in a simulation package, and then it generates very detailed flow results for the aneurysm," said Valentino, director of imaging and information systems.
To enter this digital world, physicians must wear 3-D goggles and a data glove, which allows the user to manipulate the surroundings.
A graphics engine communicates with the head tracker in the goggles, accepting signals from the users movement and returning output.
Karplus predicts that the aneurysms created in UCLA labs can be sent to physicians all over the world via the Internet.
"The Internet allows for the technology to be used in places that do not have the equipment or specialized technical skills," Karplus said.
Physicians trained in the treatment but lacking the modeling equipment can interact in the virtual world, exploring the pressure, force and velocity of blood in the aneurysm.
From the interaction with the virtual aneurysm, the surgeons will be able to determine whether surgery is necessary.
"Neurosurgeons want to minimize the necessity of doing invasive brain surgery," Valentino said. "Only when it is appropriate."
Using minimally invasive treatment allows surgeons to bypass morbidity, the temporary and sometimes permanent loss of brain function associated with conventional neurosurgery, Valentino said.
By navigating a thin plastic tube through the circulatory system, doctors are able to fill the aneurysm with a soft wire coil, preventing blood flow into the aneurysm and rendering it harmless.
The new modeling techniques will help physicians determine "if the coil procedure is suitable for the (patient's) particular type of aneurysm," Valentino continued.
Although the project is still in its experimental stages, Valentino expects to apply the technology to human data on a research basis within the next year.
Until then, ethical restrictions limit the scientists to experimentation with animals. Currently, researchers are able to create artificial aneurysms and compare the results obtained from a parallel exploration in virtual reality.
According to Valentino, when the results begin to show a positive correlation, efforts to incorporate the virtual reality into clinical practice will begin. This will include a formal protocol proposal and permission from the Human Subjects Protection Committee.
ALEKSEY KOMPANIYCHENKO
Dr. Fernando Vinuela swims through a virtual-reality brain to determine whether an aneurysm can be operated on. Vinuela is a member of a UCLA research team developing this technique for clinical use.