Assessment of Carotid Plaque Stability Based on the Dynamic Enhancement Pattern in Plaque Components With Multidetector CT Angiography

Abstract

Background and Purpose-Recent studies have investigated plaque morphology to determine patients who are at high risk of carotid atherosclerosis. In this study, we investigated whether a difference in dynamic enhancement pattern in plaque components could be useful to assess plaque stability with multidetector CT angiography. Methods-Fifty-nine lesions with moderate to severe carotid atherosclerosis in 51 patients (33 symptomatic, 18 asymptomatic) were consecutively included. Early-and delayed-phase images were obtained in 3 equivalent axial slices with multidetector CT angiography. Hounsfield units (HU) in the early phase were subtracted from those in the delayed phase in plaques (⌬HU) and compared with clinical features, MRI-based plaque characteristics, and histological findings with 20 surgical specimens acquired from carotid endarterectomy. Results-The ⌬HU was significantly higher in asymptomatic than that in symptomatic presentation (Pϭ0.02). With MRI, a higher ⌬HU was negatively correlated with signal intensity on T1-weighted imaging (rϭϪ0.56, PϽ0.0001). Histology confirmed that ⌬HU was positively correlated with fibrous tissue (rϭ0.67, Pϭ0.001) and negatively correlated with a lipid-rich necrotic core with hemorrhage (rϭϪ0.70, PϽ0.001). Moreover, less neovascularization and inflammation was found in plaques with a higher ⌬HU. Conclusions-Delayed-phase images provide information regarding the dynamic change in contrast media from the early arterial phase. An increase in HU from the early phase on multidetector CT angiography indicates plaque stability with more fibrous tissue and a less lipid-rich necrotic core, intraplaque hemorrhage, and neovascularization. (Stroke. 2012; 43:393-398.)

Carotid Artery Plaque Characterization Using CT Multienergy Imaging

“…Regarding this significant reduction in attenuation going from 66 to 86 keV, we think that the enhancement of the carotid arteries may play a role. 11,12 Some recently published investigations have demonstrated that carotid artery plaques analyzed by CT can show contrast enhancement, 12,13 and Saba et al 13 demonstrated that the degree of intraplaque neovascularization is statistically associated with carotid plaque enhancement. Therefore, it is likely that the molecules of contrast medium get into carotid plaques because they are vascularized.…”

Contemporary carotid imaging: from degree of stenosis to plaque vulnerability

“…This is likely related to the presence of neovascularization within unstable plaques leading to increase washout of contrast on delayed images. 42 Other MDCTA findings associated with symptomatology include a fissured fibrous cap and LRNC. 88,120 A summary of CT characteristics of stable and vulnerable plaques is provided in Table 2.…”

“…32 Furthermore, many patients with a high degree of stenosis have stable plaques that are thought to be at low risk of rupture. 42 Because of such findings, over the last decade there has been a paradigm shift on the imaging-based risk stratification of carotid disease from static measurements of carotid artery stenosis to characterization of the dynamic biological processes occurring within carotid plaques. It is important for neurosurgeons to be aware of this paradigm shift as it allows for improved risk stratification of patients with both high-and low-degree carotid artery stenosis.…”

Imaging of the Carotid Artery Vulnerable Plaque

“…However, the reproducibility and utility of this modality for clinical care are not well established [76]. On CT, the identification of plaque neovascularization is based on few studies [77][78][79][80][81] that demonstrated the ability of CT to detect contrast plaque enhancement (CPE) related to the degree of neovascularization (Fig. 7).…”