Published online before print November 4, 2004, doi: 10.1161/01.ATV.0000149673.00564.0a
© 2005 American Heart Association, Inc.
Thrombosis |
MRI of Atherothrombosis Associated With Plaque Rupture
From the Department of Physiology and Biophysics (J.V., Y.Q., J.A.H.) and the Whitaker Cardiovascular Institute (F.L.R.), Boston University School of Medicine; and the Department of Medicine (A.S.P., K.D., M.J.), Cardiovascular Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Mass.
Correspondence to James A. Hamilton, Department of Physiology and Biophysics, Boston University School of Medicine, 700 Albany St, Rm W302, Boston, MA 02118. Email jhamilt{at}bu.edu
Objective— MRI would be a valuable noninvasive diagnostic tool to study plaque-associated thrombi. We defined the imaging characteristics of these thrombi, composed primarily of platelets and fibrin, and distinguished them clearly from the vessel lumen and underlying atherosclerotic plaque in an animal model of plaque rupture.
Methods and Results— After triggering plaque rupture in New Zealand White male rabbits, segments of infrarenal aorta containing either red or white thrombi were fixed in formalin. Compared with postmortem red cell–rich thrombi, atherothrombi yielded complex magnetic resonance images with intermediate signal intensity in standard T1- and T2-weighted imaging sequences and were often difficult to distinguish from the aortic wall. Diffusion-weighted imaging sequences revealed restricted diffusion of the atherothrombus relative to the vessel wall and provided excellent contrast. The apparent diffusion coefficient of the thrombus is 1.0x10–3 mm2/s, compared with 1.5x10–3 mm2/s in tissue. Similar results were obtained using purified aggregated platelets.
Conclusions— We present the first detailed description of the MRI appearance of plaque rupture–associated thrombosis in histologically validated platelet-rich thrombi. Diffusion-weighted imaging provided the best distinction between thrombus and vessel wall and has potential application for the noninvasive in vivo detection of atherothrombosis.
Excised aortas from atherosclerotic New Zealand rabbits after triggered plaque rupture were analyzed by MRI and histology. Platelet/fibrin-rich atherothrombi yielded imaging characteristics distinct from red cell–rich thrombi and were well resolved from the vessel wall by diffusion-weighted imaging. This technique has potential application for characterization of atherothrombosis.
Key Words: magnetic resonance imaging • thrombosis • atherosclerosis
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