Hemorrhage in the Atherosclerotic Carotid Plaque: A High-Resolution MRI Study

Abstract

Background and Purpose-High-resolution, multicontrast magnetic resonance imaging (MRI) has developed into an effective tool for the identification of carotid atherosclerotic plaque components, such as necrotic core, fibrous matrix, and hemorrhage/thrombus. Factors that may lead to plaque instability are lipid content, thin fibrous cap, and intraplaque hemorrhage. Determining the age of intraplaque hemorrhage can give insight to the history and current condition of the biologically active plaque. The aim of this study was to develop criteria for the identification of the stages of intraplaque hemorrhage using high-resolution MRI. Methods-Twenty-seven patients, scheduled for carotid endarterectomy (CEA), were imaged on a 1.5-T GE SIGNA scanner (sequences: 3-dimensional time of flight, double-inversion recovery, T1-weighted (T1W), PDW and T2W). Two readers, blinded to histology, reviewed MR images and grouped hemorrhage into fresh, recent, and old categories using a modified cerebral hemorrhage criteria. The CEA specimens were serially sectioned and graded as to presence and stage of hemorrhage. Results-Hemorrhage was histologically identified and staged in 145/189 (77%) of carotid artery plaque locations. MRI detected intraplaque hemorrhage with high sensitivity (90%) but moderate specificity (74%). Moderate agreement in classifying stages occurred between MRI and histology (Cohen ϭ0.7, 95% CI: 0.5 to 0.8 for reviewer 1 and 0.4, 95% CI: 0.2 to 0.6 for reviewer 2), with moderate agreement between the 2 MRI readers (ϭ0.4, 95% CI: 0.3 to 0.6). Conclusion-Multicontrast MRI can detect and classify carotid intraplaque hemorrhage with high sensitivity and moderate specificity.

Imaging of the Carotid Artery Vulnerable Plaque

“…MR can age IPH surface (white open arrows) for CT and US respectively. e, f Smooth plaque ulcers (white arrowheads) for CT and US respectively [48][49][50] by distinguishing different patterns on T1-w, T2-w, PD, and TOF images. Authors tried to identify IPH using CT and found a strong correlation between very low HU value and IPH [51,52].…”

Appropriate Selection of CAS or CEA and Proper Use of Protection Device in the Event of CAS According to Carotid Plaque Characteristics

“…Under these circumstances, qualitative assessment of plaques and accurate evaluation of their vulnerability have become possible by the black blood MRI technique for carotid artery plaque, by which the signals in the vascular lumen are suppressed, and the technique is applied to the pre-procedural assessment of unstable plaques, which are likely to cause complications in CAS. [16][17][18][19] High-risk unstable plaques are soft, have a thin capsule, and contain large atheroma or intraplaque hematoma, [14][15][16][17][18][19][20] and, as shown in Table 2, components of hematoma and atheroma exhibit high intensity signals (compared with the signal intensity of the submandibular or parotid gland) by fat-suppressed T1-and fat-suppressed T2-weighted imaging, respectively. 16,17) In contrast, stable plaques are hard, have a thick capsule, consist primarily of fibrosis, organization, and calcification, and are reported to show iso or low signal intensity by both fat-suppressed T1-and fat-suppressed T2-weighted imaging.…”

“…16,17) In contrast, stable plaques are hard, have a thick capsule, consist primarily of fibrosis, organization, and calcification, and are reported to show iso or low signal intensity by both fat-suppressed T1-and fat-suppressed T2-weighted imaging. [15][16][17][18][19] Therefore, MRI is considered to accurately distinguish components of carotid artery plaques. We have attached importance to this qualitative assessment of plaques for the selection between CEA and CAS as a surgical treatment for carotid artery stenosis and have selected the procedure using a Sp/Sm ratio on MRI of 2 as the cut-off value as reported previously.…”

Impact of MRI Characterization of the Carotid Artery in the Understanding of Stroke

“…In addition, contrastenhanced MRI may represent the only reliable tool to identify neovasculature that could add to plaque instability. Such new advances will improve our capability to identify the components of the atherosclerotic plaque in vivo and permit us to attain better categorization abilities [14].…”

“…Furthermore, the recognition of such hemorrhage could raise awareness to the physicians about the risk of plaque vulnerability. Thus, an improved classification of the plaques may offer significant clinical material for patient management [14].…”