Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, March 20, 1990 TAG: 9003202377
SECTION: NATIONAL/INTERNATIONAL PAGE: A3 EDITION: METRO
SOURCE: Associated Press
DATELINE: NEW ORLEANS LENGTH: Medium
The developers of the technique will present preliminary results of their tests to a meeting of the American Academy of Cardiology today.
"This is potentially an extremely powerful tool," said one of the researchers, Dr. Kenneth Rosenfield of St. Elizabeth's Hospital in Boston.
The pictures clearly show cracks and breaks in the artery wall, bulges of fatty deposits and the layers of tissue that surround the blood vessel.
The development of three-dimensional images appears to be a significant improvement on the still-experimental use of inside-the-body ultrasound probes to take pictures of ailing arteries.
That technique, which is only about 2 years old, has been used to make two-dimensional pictures of cross sections of blood vessels. Even with its limitations, doctors often describe this approach as "a fantastic voyage" for its ability to give the illusion that they are traveling inside of blood vessels.
The two-dimensional images are simple slices of the artery that resemble pictures of donuts. The 3-D pictures have depth of field. On a TV screen, doctors can look down the artery, examine the muscle that surrounds it or even open it up and explore the rough, snaking surface that blood flows over.
The pictures can be rotated side to side or end to end to give doctors the best perspective on the contours they need to smooth away or work around.
With this extra information, the Boston doctors believe that cardiologists will be able to do a better job diagnosing the specific irregularities that interfere with blood flow so they can repair circulation to the heart and other parts of the body.
The system was created by computer software developers at ImageComm Systems in Santa Clara, Calif., in consultation with the St. Elizabeth's doctors.
When the arteries that feed the heart become clogged, the reduced flow of blood causes chest pain known as angina. Doctors routinely treat this condition with angioplasty. In this technique, a miniature balloon is blown up and then deflated inside the artery to push away the deposits. The arteries, however, often clog again within a few months, and doctors are working on even more aggressive cleaning techniques that they hope will keep blood flowing for years.
These procedures involve using lasers to burn away the deposits or whirling knives to scrape them off. Specialists say the 3-D pictures may be especially useful for guiding these new tools, because they will enable doctors to judge how deeply they can cut and burn.
To make the image, the doctor first inserts a thin tube through the circulatory system into the heart's arteries. The tube is tipped with ultrasound-producing crystals. As the doctor slowly pulls the crystals through the artery, they snap five ultrasound pictures per second.
Then, a computer stacks the cross-section pictures on top of each other like the slices in a loaf of bread. The computer makes assumptions about what lies in the spaces between each slice. The result is a continuous picture of the artery.
by CNB