TIA patients with higher ABCD3-I scores are prone to a higher incidence of intracranial stenosis, unstable carotid plaques and multiple-vessel involvement

The ABCD3-I criteria have proved to be effective for use in regular clinical practice to assist in transient ischemic attack (TIA) risk stratification and treatment. In this prospective study we aimed to explore the relationships between risk stratification and arterial stenosis location, carotid plaque morphology and vessel involvement in 90 TIA patients, stratifying risk by ABCD3-I scores. Clinical variables such as total cholesterol, triglyceride, low-density lipoprotein cholesterol, glycosylated hemoglobin, homocysteine and high-sensitive C-reactive protein levels were recorded. The endpoint was subsequent stroke at seven-day follow-up. Ninety patients were divided into three risk groups on the basis of their ABCD3-I scores. The results revealed that patients with higher ABCD3-I scores showed a higher occurrence of intracranial stenosis (P < 0.05), less organized carotid plaques (P < 0.05) and multiple-vessel involvement (P < 0.05).

[Diagnostic value of carotid atherosclerosis score for ischemic stroke]

OBJECTIVE

To discuss the diagnostic value of carotid atherosclerosis score for ischemic stroke.

METHODS

In the study, 151 patients with ischemic stroke were enrolled, who were diagnosed by cranial CT scan or cranial MRI scan, and examined with carotid duplex ultrasound, and 151 healthy check-up cases matched by age and sex were chosen as control group, who were excluded ischemic stroke by cranial CT scan or cranial MRI scan. All the control cases were examined with carotid duplex ultrasound also. Intima-media thickness (IMT), the number of carotid plaques, the size of each plaque, the location of the plaque and each plaque's echo, texture, surface regularity were estimated by carotid duplex ultrasound.

RESULTS

The IMT of the case group and the control group were (0.946±0.185) mm and (0.863±0.148) mm, and there were significant differences (P<0.001); The parameters of arterial plaque correlated with ischemic stroke were plaque's echo, texture and surface regularity, however the plaque size and location were not correlated with ischemic stroke. The median and quartile of carotid artery plaque score were 3 and 2 respectively in case group, 1 and 2 respectively in control group, and there were significant differences (P<0.001); The parameters of carotid arterial atherosclerosis associated with ischemic stroke were carotid artery plaque score,carotid stenosis degree and IMT, but not the number of carotid plaques. The median and quartile of carotid arterial atherosclerosis score were 5 and 4 respectively in case group, 2 and 4 respectively in control group, and there were significant differences (P<0.001); The area under the curve (AUC) for IMT, the number of carotid plaques, carotid artery plaque score and carotid arterial atherosclerosis score were 0.679, 0.677, 0.704 and 0.805,respectively (P<0.001). The accuracy of carotid atherosclerosis score was the highest.

CONCLUSION

Carotid artery plaque score and carotid atherosclerosis score can be used for the diagnosis of ischemic stroke, and the accuracy of carotid atherosclerosis score is higher.

Characterization of intracranial atherosclerotic stenosis using high-resolution MRI study--rationale and design

BACKGROUND

Intracranial atherosclerosis is a leading cause of stroke, but little is known about the composition of the intracranial atherosclerotic lesion and how intracranial plaque morphology is related to the risk of stroke. High-resolution magnetic resonance imaging (HR MRI) has been used in patients with extracranial carotid atherosclerosis as an in vivo tool to identify, with high-interrater agreement, histologically defined plaque components (i.e., intraplaque hemorrhage, fibrous cap, and lipid core), which have been shown to be predictors of recurrent stroke. With careful imaging the components of atherosclerotic plaque can be visualized in the intracranial arteries using HR MRI, but there are no reports of reproducibility or interrater reliability.

METHODS/STUDY DESIGN

The Characterization of intracranial atherosclerotic stenosis using high-resolution MRI (CHIASM) study is a single-center NIH-funded prospective observational study, to (1) demonstrate high -interrater agreement for identifying intracranial plaque components on HR MRI, (2) determine the frequency of these components in symptomatic versus asymptomatic plaques, and (3) estimate the 1-year rate of stroke in the territory of high-risk plaque components. CHIASM will recruit 90 patients with 50-99% intracranial atherosclerosis to undergo HRMRI of the intracranial artery plaque at enrollment and 1-year follow-up. Both symptomatic and asymptomatic subjects will be recruited.

CONCLUSION

Determination of good interrater reliability is an important first step in the development of HR MRI as a tool to predict risk in patients with intracranial atherosclerosis. This study will inform the design of future multicenter studies to determine the prevalence and prognosis of intracranial atherosclerotic plaque components. Such studies could lead to new understanding of the pathophysiological mechanisms of cerebral ischemia in patients with atherosclerotic intracranial stenosis, improvements in risk stratification, and potentially to new treatments of this common and serious disease.

Nanoparticle uptake by macrophages in vulnerable plaques for atherosclerosis diagnosis

The composition of atherosclerotic (AS) plaques is crucial concerning rupture, thrombosis and clinical events. Two plaque types are distinguished: stable and vulnerable plaques. Vulnerable plaques are rich in inflammatory cells, mostly only M1 macrophages, and are highly susceptible to rupture. These plaques represent a high risk particularly with the standard invasive diagnosis by coronary angiography. So far there are no non-invasive low-risk clinical approaches available to detect and distinguish AS plaque types in vivo. The perspective review introduces a whole work-flow for a novel approach for non-invasive detection and classification of AS plaques using the diffusion reflection method with gold nanoparticle loaded macrophages in combination with flow and image cytometric analysis for quality assurance. Classical biophotonic methods for AS diagnosis are summarized. Phenotyping of monocytes and macrophages are discussed for specific subset labelling by nanomaterials, as well as existing studies and first experimental proofs of concept for the novel approach are shown. In vitro and in vivo detection of NP loaded macrophages (MΦ). Different ways of MΦ labelling include (1) in vitro labelling in suspension (whole blood or buffy coat) or (2) labelling of short-term MΦ cultures with re-injection of MΦ-NP into the animal to detect migration of the cells in the plaques and (3) in vivo injection of NP into the organism.

Atherosclerotic Plaque Destabilization in Mice: A Comparative Study

Atherosclerosis-associated diseases are the main cause of mortality and morbidity in western societies. The progression of atherosclerosis is a dynamic process evolving from early to advanced lesions that may become rupture-prone vulnerable plaques. Acute coronary syndromes are the clinical manifestation of life-threatening thrombotic events associated with high-risk vulnerable plaques. Hyperlipidemic mouse models have been extensively used in studying the mechanisms controlling initiation and progression of atherosclerosis. However, the understanding of mechanisms leading to atherosclerotic plaque destabilization has been hampered by the lack of proper animal models mimicking this process. Although various mouse models generate atherosclerotic plaques with histological features of human advanced lesions, a consensus model to study atherosclerotic plaque destabilization is still lacking. Hence, we studied the degree and features of plaque vulnerability in different mouse models of atherosclerotic plaque destabilization and find that the model based on the placement of a shear stress modifier in combination with hypercholesterolemia represent with high incidence the most human like lesions compared to the other models.

Repeatability of in vivo quantification of atherosclerotic carotid artery plaque components by supervised multispectral classification

Objective

To evaluate the agreement and scan–rescan repeatability of automated and manual plaque segmentation for the quantification of in vivo carotid artery plaque components from multi-contrast MRI.

Materials and methods

Twenty-three patients with 30–70 % stenosis underwent two 3T MR carotid vessel wall exams within a 1 month interval. T1w, T2w, PDw and TOF images were acquired around the region of maximum vessel narrowing. Manual delineation of the vessel wall and plaque components (lipid, calcification, loose matrix) by an experienced observer provided the reference standard for training and evaluation of an automated plaque classifier. Areas of different plaque components and fibrous tissue were quantified and compared between segmentation methods and scan sessions.

Results

In total, 304 slices from 23 patients were included in the segmentation experiment, in which 144 aligned slice pairs were available for repeatability analysis. The correlation between manual and automated segmented areas was 0.35 for lipid, 0.66 for calcification, 0.50 for loose matrix and 0.82 for fibrous tissue. For the comparison between scan sessions, the coefficient of repeatability of area measurement obtained by automated segmentation was lower than by manual delineation for lipid (9.9 vs. 17.1 mm²), loose matrix (13.8 vs. 21.2 mm²) and fibrous tissue (24.6 vs. 35.0 mm²), and was similar for calcification (20.0 vs. 17.6 mm²).

Conclusion

Application of an automated classifier for segmentation of carotid vessel wall plaque components from in vivo MRI results in improved scan–rescan repeatability compared to manual analysis.

An objective method to optimize the MR sequence set for plaque classification in carotid vessel wall images using automated image segmentation

A typical MR imaging protocol to study the status of atherosclerosis in the carotid artery consists of the application of multiple MR sequences. Since scanner time is limited, a balance has to be reached between the duration of the applied MR protocol and the quantity and quality of the resulting images which are needed to assess the disease. In this study an objective method to optimize the MR sequence set for classification of soft plaque in vessel wall images of the carotid artery using automated image segmentation was developed. The automated method employs statistical pattern recognition techniques and was developed based on an extensive set of MR contrast weightings and corresponding manual segmentations of the vessel wall and soft plaque components, which were validated by histological sections. Evaluation of the results from nine contrast weightings showed the tradeoff between scan duration and automated image segmentation performance. For our dataset the best segmentation performance was achieved by selecting five contrast weightings. Similar performance was achieved with a set of three contrast weightings, which resulted in a reduction of scan time by more than 60%. The presented approach can help others to optimize MR imaging protocols by investigating the tradeoff between scan duration and automated image segmentation performance possibly leading to shorter scanning times and better image interpretation. This approach can potentially also be applied to other research fields focusing on different diseases and anatomical regions.

Understanding symptomatology of atherosclerotic plaque by image-based tissue characterization

Characterization of carotid atherosclerosis and classification into either symptomatic or asymptomatic is crucial in terms of diagnosis and treatment planning for a range of cardiovascular diseases. This paper presents a computer-aided diagnosis (CAD) system (Atheromatic) that analyzes ultrasound images and classifies them into symptomatic and asymptomatic. The classification result is based on a combination of discrete wavelet transform, higher order spectra (HOS) and textural features. In this study, we compare support vector machine (SVM) classifiers with different kernels. The classifier with a radial basis function (RBF) kernel achieved an average accuracy of 91.7% as well as a sensitivity of 97%, and specificity of 80%. Thus, it is evident that the selected features and the classifier combination can efficiently categorize plaques into symptomatic and asymptomatic classes. Moreover, a novel symptomatic asymptomatic carotid index (SACI), which is an integrated index that is based on the significant features, has been proposed in this work. Each analyzed ultrasound image yields on SACI number. A high SACI value indicates that the image shows symptomatic and low value indicates asymptomatic plaques. We hope this SACI can support vascular surgeons during routine screening for asymptomatic plaques.

Ultrasonographic characterization and identification of symptomatic carotid plaques

Carotid plaques are the main cause of neurological symptoms due to distal embolization or flow reduction. An objective classification of such lesions into symptomatic or asymptomatic is crucial for optimal treatment planning.

[Value of the spectral analysis of radiofrequency intravascular ultrasound data in the evaluation of nonsignificant coronary lesions in chronic CHD patients]

Plaque complication depends on its composition and phenotype rather than on the degree of stenosis. Plaque rupture predominantly occurs in areas with large lipid core rich in cholesterol and thin fibrous cap. Features of unstable atheromas are mostly described in patients with acute coronary syndromes (ACS). The aim of our study was to assess the plaque characterization and arterial remodeling process in non-significant stenoses of patients with chronic coronary heart disease (CHD) using intravascular ultrasound (IVUS) radiofrequency (RF) data. Methods. The study included 22 stable patients (68% men, mean age 54+/-6 years) with CHD and clinical indications for coronary angiography (CAG). Diameter stenosis of the target coronary artery for IVUS procedure had to be less than 60%. Thin-cap fibroatheroma (TCFA) was defined as plaque burden &gt;40% and amount of NC &gt;10% without detectable overlying fibrous cap segment. Results. Sample size calculations based on the IVUS evaluation showed 54 atheromas in 29 target arteries. Features of vulnerability determined as TCFA were detected in 14 (26%) lesions. Compared with stable lesions VPs were associated with a greater plaque burden (48.5+/-8.0 mm2 vs 55.8+/-9.3 mm2, p=0.03), larger quantity of necrotic core (37.1+/-9.1% vs 24.0+/-12.6%, p=0.0045) and calcium content (22.7+/-8.5% vs 5.6+/-5.2%, p&lt;0.000l), and less fibrous component (34.8+/-7.0% vs 60.4+/-12.4%, p&lt;0.0001), respectively. Significant correlation was obtained between positive remodeling (defined as remodeling index &gt;1.05) and NC percent area (r=0.389. p=0.005). Conclusion. In chronic CHD patients about 25% of atherosclerotic lesions responsible for less than 60% stenosis could be classified as vulnerable plaques. These borderline lesions contain more necrotic and calcium components compared with stable plaques, and are associated with positive arterial remodeling.