Quantitative Evaluation of Carotid Plaque Composition by In Vivo MRI

Abstract

Objective-This study evaluates the ability of MRI to quantify all major carotid atherosclerotic plaque components in vivo. Methods and Results-Thirty-one subjects scheduled for carotid endarterectomy were imaged with a 1.5T scanner using time-of-flight-, T1-, proton density-, and T2-weighted images. A total of 214 MR imaging locations were matched to corresponding histology sections. For MRI and histology, area measurements of the major plaque components such as lipid-rich/necrotic core (LR/NC), calcification, loose matrix, and dense (fibrous) tissue were recorded as percentages of the total wall area. Intraclass correlation coefficients (ICCs) were computed to determine intrareader and inter-reader reproducibility. Key Words: atherosclerosis Ⅲ magnetic resonance imaging Ⅲ carotid artery Ⅲ plaque A therosclerosis and its thrombotic complications are the leading cause of morbidity and mortality in industrialized countries. Therefore, the need for new medical therapies and technology to treat and prevent cardiovascular atherosclerotic disease is enormous.Accurate information of atherosclerotic plaque morphology and plaque composition is necessary to identify the "vulnerable plaques" that are likely to cause embolic events. A noninvasive imaging modality that could provide such information would be an invaluable tool in studies of the relationship between plaque composition/morphology and plaque progression/regression. Furthermore, such imaging techniques may be used in clinical trials to monitor the effects of drugs on diseased arteries.B-Mode ultrasonography has been used widely in plaque progression/regression trials that involve either lipidlowering drugs or calcium channel blockers. 1 However, this modality is highly operator dependent, has limited soft tissue contrast, and requires a large number of subjects to detect a significant change in the intima-media thickness. 1 Intravascular ultrasound (IVUS) is used increasingly in atherosclerosis regression/progression trials that study coronary arteries. 2 Although IVUS is highly reproducible 3 and provides tomographic information about the vessel wall, 3 it is an invasive procedure and has limited capacity to discriminate between fibrous and fatty plaques. 4 Recent publications 5-11 have shown that in vivo MRI can identify the main components of the atherosclerotic plaque such as the lipid-rich/necrotic core (LR/NC), calcification, and hemorrhage. In addition, morphological information about the status of the fibrous cap 12 and the American Heart Association (AHA) lesion type 13 can be obtained noninvasively. Moreover, the tomographic orientation of MRI enables the full cross-sectional view of the vessel wall, which can be measured accurately 14 and reproducibly. 15 It has been demonstrated that ex vivo MRI of endarterectomy specimen is able to identify 16 and quantify 17,18 plaque components with high diagnostic accuracy. This study is aimed at evaluating the ability of MRI to quantify all major carotid atherosclerotic plaque components in vivo, using histolog...

Carotid Artery Stenting for Atherosclerotic Stenosis Associated With Non-bifurcating Cervical Carotid Artery

“…5) Recent high resolution MR imaging could identify plaque constituents, such as the necrotic core and intraplaque hemorrhage. 21,23) Although high resolution MR imaging was not performed in the present case, the findings of other examinations could explain the mechanism of amaurosis.…”

The influence of composition and location on the toughness of human atherosclerotic femoral plaque tissue

“…Additionally, existing clinical imaging tools are currently capable of characterising the composition of atherosclerotic plaques. Calcified tissue fraction, fibrous tissue and lipid content can be identified by optical coherence topography [70,71] and also by magnetic resonance imaging [72][73][74].…”

Study of reproducibility of human arterial plaque reconstruction and its effects on stress analysis based on multispectral in vivo magnetic resonance imaging

“…In total, seven 2D images were available for subject 1 for definition of the lipid core. Regions of lipid core, fibrous cap, and lumen appear slightly darker, brighter, and black, respectively (23)(24)(25). Combining the artery geometry from T2W images, the lipid core can be segmented manually, as shown in Fig.…”