Classification of Human Carotid Atherosclerotic Lesions With In Vivo Multicontrast Magnetic Resonance Imaging

Abstract

Background-Recent studies demonstrated that in vivo and ex vivo MRI can characterize the components of the carotid atherosclerotic plaque, such as fibrous tissue, lipid/necrotic core, calcium, hemorrhage, and thrombus. The purpose of this study was to determine whether in vivo high-resolution multicontrast MRI could accurately classify human carotid atherosclerotic plaque according to the American Heart Association classification. Methods and Results-Sixty consecutive patients (mean age 70 years; 54 males) scheduled for carotid endarterectomy were imaged with a 1.5-T scanner after informed consent was obtained. A standardized protocol was used to obtain 4 different contrast-weighted images (time of flight and T1-, PD-, and T2-weighted) of the carotid arteries. Best voxel size was 0.25ϫ0.25ϫ1 mm 3 . Carotid plaques were removed intact and processed for histological examination. Both MR images and histological sections were independently reviewed, categorized, and compared. Overall, the classification obtained by MRI and the American Heart Association classifications showed good agreement, with Cohen's (95% CI) of 0.74 (0.67 to 0.82) and weighted of 0.79. The sensitivity and specificity, respectively, of MRI classification were as follows: type I-II lesions, 67% and 100%; type III lesions, 81% and 98%; type IV-V lesions, 84% and 90%; type VI lesions, 82% and 91%; type VII lesions, 80% and 94%; and type VIII lesions, 56% and 100%. Conclusions-In vivo high-resolution multicontrast MRI is capable of classifying intermediate to advanced atherosclerotic lesions in the human carotid artery and is also capable of distinguishing advanced lesions from early and intermediate atherosclerotic plaque.

Interstudy reproducibility of three‐dimensional volume‐selective fast spin echo magnetic resonance for quantifying carotid artery wall volume

“…As well as the tomographic assessment of atheroma burden by T1-weighted FSE, multiple contrastweighted CMR, or multispectral CMR, can identify fibrous cap rupture (16), distinguish advanced from early atheromatous lesions (17), and identify plaques that have a lipid rich necrotic core (18). The use of contrast agents such as gadolinium (19) and ultrasmall superparamagnetic particles (USPIOs) (20) can highlight areas of greater plaque neovasculature and macrophage density, respectively.…”

Comparison of 2D and multislab 3D magnetic resonance techniques for measuring carotid wall volumes

“…Using perpendicular 90°and 180°selection gradients, the 3D slab can be defined in two dimensions, leaving the tissue outside unexcited; hence, the FOV can be reduced in the primary phase-encode direction without leading to wraparound. The reduced FOV enables fewer phaseencoding steps to be used to spatially resolve that direction, leading to reduced imaging time (3,8,15).…”

“…Using perpendicular 90°and 180°selection gradients, the 3D slab can be defined in two dimensions, leaving the tissue outside unexcited; hence, the FOV can be reduced in the primary phase-encode direction without leading to wraparound. The reduced FOV enables fewer phaseencoding steps to be used to spatially resolve that direction, leading to reduced imaging time (3,8,15).Two other 3D techniques for arterial wall imaging are 3D GraSE (gradient-and spin-echo) (16) and, more recently, 3D balanced SSFP (steady-state with free precession) (17)(18)(19). The SSFP sequence has performed well in terms of contrast-to-noise ratio.…”

“…CARDIOVASCULAR MAGNETIC RESONANCE (MR) is a good technique for assessing atherosclerosis in the carotid artery, with much development over the last 15 years in plaque characterization and assessment of the structure and function of the arterial wall (1)(2)(3)(4)(5)(6). Quantitative carotid wall imaging typically requires a stack of two-dimensional (2D) images, which can be contoured and analyzed.…”

Atherosclerosis in stroke‐related vascular beds and stroke risk: A 3‐D MR vessel wall imaging study

“…Transesophageal echocardiography (TEE) can be utilized for detecting atherosclerotic plaques in aortic arch but this imaging technique is invasive. It is well established that MR vessel wall imaging is capable of characterizing carotid artery atherosclerosis validated by histology 7. Recently, investigators proposed three‐dimensional (3‐D) MR vessel wall imaging sequences which enable high isotropic resolution plaque imaging with large longitudinal coverage for craniocervical arteries8, 9 and aortic arch 10, 11.…”