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This study compared sensitivity and specificity of multidetector-row computed tomography and duplex Doppler ultrasonography in detecting atherosclerotic carotid plaques complicated with intraplaque hemorrhage. Carotid plaques from 50 patients operated for carotid artery stenosis were analyzed. Carotid endarterectomy was performed within one week of...
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... curve analysis showed 100% sensitivity and 70.4% specificity of MDCT in detecting hemorrhage within atherosclerotic plaque with cut-off vaule of 33.8 HU (no plaque with tissue density over 33.8 HU was complcated with intraplaque hemorrhage) (Figure 4). Results of MDCT analysis for different plaque types are summarized in Table 3. On duplex Doppler ultraso- nography analysis 8 plaques (16%) were classified as type 1, 29 (58%) as type 2 and 13 (26%) as type 3. ...
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Citations
... 60 The sensitivity and specificity of CT to detect IPH was 100% and 64%, respectively. 61,62 Plaque inflammation and neovascularization: Plaque inflammation, another vulnerable plaque feature, remains predominantly investigative. MRA using ultrasmall superparamagnetic iron oxide nanoparticles as a surrogate marker of macrophage accumulation and activity has shown promising results. ...
Stroke represents a major cause of morbidity and mortality worldwide with carotid atherosclerosis responsible for a large proportion of ischemic strokes. Given the high burden of the disease , early diagnosis and optimal secondary prevention are essential elements in clinical practice. For a long time, the degree of stenosis had been considered the parameter to judge the severity of carotid atherosclerosis. Over the last 30 years, literature has shifted attention from stenosis to structural characteristics of atherosclerotic lesion, eventually leading to the "vulnerable plaque" model. These "vulnerable plaques" frequently demonstrate high-risk imaging features that can be assessed by various non-invasive imaging modalities.
... Carotid CTA-based measures of adventitial calcification and soft plaque could predict MRA-defined IPH using mixed-effects multivariable Poisson regression [106]. In addition, two more studies have shown that IPH can be identified using CT [107,108]. However, more evidence and validation studies are needed to determine the accuracy of CTA imaging to detect carotid IPH. ...
Purpose of Review
Vascular imaging is a complex field including numerous modalities and imaging markers. This review is focused on important and recent findings in atherosclerotic carotid artery plaque imaging with an emphasis on developments in magnetic resonance imaging (MRI) and computed tomography (CT).
Recent Findings
Recent evidence shows that carotid plaque characteristics and not only established measures of carotid plaque burden and stenosis are associated independently with cardiovascular outcomes. On carotid MRI, the presence of a lipid-rich necrotic core (LRNC) has been associated with incident cardiovascular disease (CVD) events independent of wall thickness, a traditional measure of plaque burden. On carotid MRI, intraplaque hemorrhage (IPH) presence has been identified as an independent predictor of stroke. The presence of a fissured carotid fibrous cap has been associated with contrast enhancement on CT angiography imaging.
Summary
Carotid artery plaque characteristics have been associated with incident CVD events, and advanced plaque imaging techniques may gain additional prominence in the clinical treatment decision process.
... There is evidence that "soft" plaque seen on CTA and echolucent plaque seen on US, likely has some component of IPH, as both of these plaque features confer increased risk. 30,31,[38][39][40] Lipid-rich necrotic core-Lipid-rich necrotic core (LRNC) is another "high-risk" plaque feature than can be appreciated on imaging. LRNC is also highly associated with future and recurrent stroke. ...
Carotid atherosclerosis is an important contributor to ischemic stroke. When imaging carotid atherosclerosis, it is essential to describe both the degree of luminal stenosis and specific plaque characteristics because both are risk factors for cerebrovascular ischemia. Carotid atherosclerosis can be accurately assessed using multiple imaging techniques, including ultrasonography, computed tomography angiography, and magnetic resonance angiography. By understanding the underlying histopathology, the specific plaque characteristics on each of these imaging modalities can be appreciated. This article briefly describes some of the most commonly encountered plaque features, including plaque calcification, intraplaque hemorrhage, lipid-rich necrotic core, and plaque ulceration.
... When soft plaque is present on the luminal border with surrounding, peripheral calcification, it is thought to be a marker of high risk and is strongly associated with IPH on MR imaging. 44 It can be difficult to differentiate IPH and LRNC when evaluating plaque visually on CTA, but IPH is thought to have lower Hounsfield units 32,45,46 than LRNC and fibrous elements with a mean Hounsfield units of 18 compared with LRNC (mean, 63 HU) and fibrous tissue (mean, 93 HU). 47 In clinical practice, these small differences in Hounsfield units are challenging to detect accurately. ...
Vessel wall imaging has been increasingly used to characterize plaque beyond luminal narrowing to identify patients who may be at the highest risk of cerebrovascular ischemia. Although detailed plaque information can be obtained from many imaging modalities, CTA is particularly appealing for carotid plaque imaging due to its relatively low cost, wide availability, operator independence, and ability to discern high-risk features. The present Review Article describes the current understanding of plaque characteristics on CTA by describing commonly encountered plaque features, including calcified and soft plaque, surface irregularities, neovascularization, and inflammation. The goal of this Review Article was to provide a more robust understanding of clinically relevant plaque features detectable on routine CTA of the carotid arteries.
... Some CT characteristics of AP like Hounsfield Unit (HU) attenuation and the presence of neovascularization, are associate with increased risk of ischaemic cerebrovascular events [48], even if identification of IPH in CTA is still debated [50]. Two different researches by Ajduk et al. [49,50] showed that IPH shows low HU values, between -17 and +31, whereas a study by Wintermark et al. [51] underlined that the densities of IPH and connective tissues are really similar. ...
... Some CT characteristics of AP like Hounsfield Unit (HU) attenuation and the presence of neovascularization, are associate with increased risk of ischaemic cerebrovascular events [48], even if identification of IPH in CTA is still debated [50]. Two different researches by Ajduk et al. [49,50] showed that IPH shows low HU values, between -17 and +31, whereas a study by Wintermark et al. [51] underlined that the densities of IPH and connective tissues are really similar. U-King-Im et al. [52] studied features of IPH in a comparative study between CT and MRI, and they found that the presence of plaque ulceration was a more reliable tool to predict the presence of IPH on MR in comparison with the mean plaque density on CTA, with high sensitivity, specificity and negative predictive value. ...
Intraplaque hemorrhage (IPH) is one of the main factors involved in atherosclerotic plaque (AP) instability. Its recognition is crucial for the correct staging and management of patients with carotid artery plaques to limit ischemic stroke. Imaging plays a crucial role in identifying IPH, even if the great variability of intraplaque vascularization and the limitations of our current imaging technologies make it difficult. The intent of this review is to give a general overview of the main features of intraplaque vascularization and IPH on Ultrasound (US), Computed Tomography (CT), Magnetic Resonance (MR) and Nuclear Medicine, and a brief description on the future prospectives.
... Intra-plaque hemorrhage: A few papers have assessed US performance in the detection of IPH and the results demonstrated low sensitivity and specificity 76,77 . ...
Identification of carotid artery atherosclerosis is conventionally based on measurements of luminal stenosis and surface irregularities using in vivo imaging techniques including sonography, CT and MR angiography, and digital subtraction angiography. However, histopathologic studies demonstrate considerable differences between plaques with identical degrees of stenosis and indicate that certain plaque features are associated with increased risk for ischemic events. The ability to look beyond the lumen using highly developed vessel wall imaging methods to identify plaque vulnerable to disruption has prompted an active debate as to whether a paradigm shift is needed to move away from relying on measurements of luminal stenosis for gauging the risk of ischemic injury. Further evaluation in randomized clinical trials will help to better define the exact role of plaque imaging in clinical decision-making. However, current carotid vessel wall imaging techniques can be informative. The goal of this article is to present the perspective of the ASNR Vessel Wall Imaging Study Group as it relates to the current status of arterial wall imaging in carotid artery disease.
... As a result, the focus of imaging techniques in carotid artery disease (CAD) is increasingly shifting toward identification of vulnerable plaque, rather than detection of high-grade stenosis (Hermus et al. 2010). Therefore diagnostic methods for evaluation of a carotid artery atherosclerotic plaque should also provide information about its histologic content and have the ability to detect characteristics that could indicate if it is vulnerable or unstable (Ajduk et al. 2013). ...
Stroke is a leading cause of morbidity and mortality worldwide, and characterization of vulnerable carotid plaque remains the spearhead of scientific research. Plaque destabilization, the key factor that induces the series of events leading to the clinical symptoms of carotid artery disease, is a consequence of complex mechanical, structural and biochemical processes. Novel imaging and molecular markers have been studied as predictors of disease outcome with promising results. The aim of this review is to present the current state of research on the association between ultrasound-derived echogenicity indices and blood parameters indicative of carotid plaque stability and activity. Bibliographic research revealed that there are limited available data. Among the biomarkers studied, those related to oxidative stress, lipoproteins and diabetes/insulin resistance are associated with echolucent plaques, whereas adipokines are associated with echogenic plaques. Biomarkers of inflammation and coagulation have not exhibited any conclusive relationship with plaque echogenicity, and it is not possible to come to any conclusion regarding calcification-, apoptosis- and neo-angiogenesis-related parameters because of the extremely limited bibliographic data.
... ,35 A further study showed good correlation of CTA with histology for large haemorrhages.36 ...
The current clinical practise to determine if a patient should undergo carotid intervention to prevent stroke is to determine the clinical features combined with degree of carotid stenosis. However, this does not accurately determine the individual patient's risk for future stroke. A thin fibrous cap, a large lipid core, high macrophage count, and intraplaque haemorrhage have all been identified as markers of the so-called "vulnerable" plaque being related to a higher stroke risk. There is a need to assess the accuracy of in vivo imaging to identify vulnerable plaque characteristics, thereby enabling in vivo risk stratification to guide clinical decision-making.
The aim of this topical review is to assess the roles of currently available imaging modalities that are applied in clinical practice and those experimental techniques that are close to clinical translation in defining carotid plaque characteristics and in informing clinical practice.
Ultrasound is a low cost and ready available low-risk tool, but it lacks the accuracy to reliably detect individual plaque components and characteristics. Computed tomography is considered to be the best imaging technique to identify calcification in the carotid plaque. Magnetic resonance imaging (MRI) can identify most described plaque characteristics with moderate to good agreement. Positron emission tomography allows assessment of specific metabolic functions with tracers labelled with positron emitting radio-isotopes, but limited spatial resolution makes anatomic precision imprecise.
MRI has demonstrated the most potential, with good sensitivity and specificity for most plaque characteristics. However, currently there is no single imaging modality that can reliably identify the vulnerable plaque in relation to development of future stroke.
Copyright © 2015 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.
... Several large randomized multicenter studies (NASCET, ECST, ACAS, ACST) showed the benefit of carotid endarterectomy (CEA), and recently other studies (CAVATAS, SAPPHIRE, CREST) and carotid artery stenting (CAS), for the prevention of stroke in both symptomatic and asymptomatic patients [4][5][6][7][8][9][10][11]. In these studies, the only criterion for patients' selection at high risk of stroke is the degree of stenosis of the internal carotid artery (ICA) [4,[12][13][14][15][16]. They also demonstrated that many patients with highgrade stenosis (>70%) did not get a stroke even with medication. ...
... They also demonstrated that many patients with highgrade stenosis (>70%) did not get a stroke even with medication. On the other hand, many authors indicate that most of the neurological symptoms are found in patients with carotid stenosis <70% [6,13,14,17]. It is clear that other factors such as histological composition of the plaque, in addition to the degree of stenosis, are responsible for determining the risk of stroke [5,6,18]. ...
BACKGROUND: The stroke is leading cause of death and severe disability worldwide. Atherosclerosis is responsible for over 30% of all ischemic strokes. It has been recently discovered that plaque morphology may help predict the clinical behavior of carotid atherosclerosis and determine the risk of stroke. The noninvasive imaging techniques have been developed to evaluate the vascular wall in an attempt to identify “vulnerable plaques”.
AIM: The purpose is to investigate the diagnostic accuracy of ultrasound, multidetector computed tomography and magnetic resonance imaging in the identification of plaque components associated with plaque vulnerability.
MATERIAL AND METHODS: One hundred patients were admitted for carotid endarterectomy for high grade carotid stenosis. We defined the diagnostic value of B-mode ultrasound of carotid plaque in a half, and the accuracy of multidetector computed tomography and magnetic resonance imaging, in the other group, for detection of unstable carotid plaque. The reference standard was histology.
RESULTS: Sensitivity of ultrasound, multidetector computed tomography and magnetic resonance imaging is 94%, 83% and 100%, and the specificity is 93%, 73% and 89% for detection of unstable carotid plaque.
CONCLUSION: The ultrasound has high accuracy for diagnostics of carotid plaque morphology, magnetic resonance imaging has high potential for tissue differentiation and multidetector computed tomography determines precisely degree of stenosis and presence of ulceration and calcifications. The three noninvasive imaging modalities are complementary for optimal evaluation of the morphology of carotid plaque. This will help to determine the risk of stroke and to decide on the best treatment – carotid endarterectomy or carotid stenting.
... Studies show that an increased risk of cerebrovascular events is expected (4,13). This is even more evident in recent studies that have demonstrated that the IPH in the plaque shows very low attenuation values (52,53). ...
Ischemic stroke currently represents one of the leading causes of severe disability and mortality in the Western World. Until now, angiography was the most used imaging technique for the detection of the extra-cranial and intracranial vessel pathology. Currently, however, non-invasive imaging tool like ultrasound (US), magnetic resonance (MR) and computed tomography (CT) have proven capable of offering a detailed analysis of the vascular system. CT in particular represents an advanced system to explore the pathology of carotid arteries and intracranial vessels and also offers tools like CT perfusion (CTP) that provides valuable information of the brain's vascular physiology by increasing the stroke diagnostic. In this review, our purpose is to discuss stroke risk prediction and detection using CT.
