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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2005;25:1729.)
© 2005 American Heart Association, Inc.

Atherosclerosis and Lipoproteins

Mineral Volume and Morphology in Carotid Plaque Specimens Using High-Resolution MRI and CT

Ronald L. Wolf; Suzanne L. Wehrli; Andra M. Popescu; John H. Woo; Hee Kwon Song; Alexander C. Wright; Emile R. Mohler, III; John D. Harding; Eric L. Zager; Ronald M. Fairman; Michael A. Golden; Omaida C. Velazquez; Jeffrey P. Carpenter; Felix W. Wehrli

From the Departments of Radiology (R.L.W., A.M.P., J.H.W., H.K.S., A.C.W., F.W.W.), Cardiology (E.R.M., J.D.H.), Neurosurgery (E.L.Z.), and Vascular Surgery (R.M.F., M.A.G., O.C.V., J.P.C.), University of Pennsylvania Medical System, Philadelphia; and Children’s Hospital of Philadelphia (S.L.W.), Penn.

Correspondence to Ronald L. Wolf, MD, PhD, University of Pennsylvania Medical Center, Section of Neuroradiology, Department of Radiology, 3400 Spruce St, Philadelphia, PA 19104. E-mail Ronald.Wolf{at}uphs.upenn.edu

Objective— High-resolution MRI methods have been used to evaluate carotid artery atherosclerotic plaque content. The purpose of this study was to assess the performance of high-resolution MRI in evaluation of the quantity and pattern of mineral deposition in carotid endarterectomy (CEA) specimens, with quantitative micro-CT as the gold standard.

Methods and Results— High-resolution MRI and CT were compared in 20 CEA specimens. Linear regression comparing mineral volumes generated from CT (V_CT) and MRI (V_MRI) data demonstrated good correlation using simple thresholding (V_MRI=–0.01+0.98V_CT; R²=0.90; threshold=4xnoise) and k-means clustering methods (V_MRI=–0.005+1.38V_CT; R²=0.93). Bone mineral density (BMD) and bone mineral content (BMC [mineral mass]) were calculated for CT data and BMC verified with ash weight. Patterns of mineralization like particles, granules, and sheets were more clearly depicted on CT.

Conclusions— Mineral volumes generated from MRI or CT data were highly correlated. CT provided a more detailed depiction of mineralization patterns and provided BMD and BMC in addition to mineral volume. The extent of mineralization as well as the morphology may ultimately be useful in assessing plaque stability.

High-resolution MRI was compared with micro-CT for evaluating quantity and pattern of mineral deposition in 20 carotid endarterectomy specimens. Mineral volumes generated from CT and MR data were highly correlated. Patterns of mineralization were more clearly depicted on CT. Extent and morphology of mineralization may help assess plaque stability.

Key Words: magnetic resonance imaging • computed tomography • carotid arteries • calcium