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.