November 12, 1996
Media Contact: John Cramer
Phone: (410) 955-1534
Like tiny time bombs, unstable fatty deposits lurk within arteries until breaking off and blocking blood flow to the heart and brain. But a Johns Hopkins study shows that magnetic resonance imaging (MRI) may identify arterial deposits at high risk of rupturing.
Early identification and treatment of these unstable deposits may reduce the number of deaths from heart attack- and stroke-related atherosclerosis, the researchers say.
The study, which was supported by the Wideker Foundation, will be presented at 10 a.m., Nov. 11 at the American Heart Association's 69th annual Scientific Sessions in New Orleans.
Hopkins scientists used intravascular MRI on aortas from cadavers to measure a fatty substance called lipids in deposits along the inner lining of the vessel walls and to determine whether the deposits had ruptured because their lipid cores were decaying. The MRI results were compared with microscopic test findings.
The MRI results correctly identified 11 of 12 samples with no decaying lipid core and 14 of 19 cases of moderate to severe lipid deposits. The MRI and microscopic results agreed 80 percent of the time. MRI also identified two of three lipid deposits that had ruptured and correctly showed no rupture in 30 of 32 lipid deposits as determined by microscopic analysis.
"Intravascular MRI is able to identify and measure how much of the lipid core has decayed and how much bleeding that is causing, two of the most important predictors of atherosclerotic plaque rupture," says Joao Lima, M.D., the study's senior author and an assistant professor of medicine.
Atherosclerosis causes the inner walls of arteries to thicken, narrowing the channel and reducing blood flow. Arterial deposits consist of lipids, decaying muscle cells, fibrous tissue, clumps of platelets, cholesterol and sometimes calcium. Ruptured deposits send fragments into the bloodstream to block smaller vessels. Atherosclerotic heart disease and stroke are the first and third most common causes of death, respectively, in the United States.
Ergin Atalar, Ph.D., a study co-author, designed and built the intravascular MRI catheter, a new device that was developed from previous studies at Hopkins. The study's other authors are Hopkins' Luis C.L. Correia, M.D., Mark Keleman, M.D., Grover M. Hutchins, M.D., Gary Gerstenblith, M.D., and Elias Zerhouni, M.D., and NIH's Jerome L. Fleg, M.D.