Intraplaque Hemorrhage as a Marker of Stroke Risk

Association between high-resolution magnetic resonance vessel wall imaging characteristics and recurrent stroke in patients with intracranial atherosclerotic steno-occlusive disease: A prospective multicenter study

BACKGROUND

High-resolution magnetic resonance vessel wall imaging (HRMR-VWI) is a promising technique for identifying intracranial vulnerable plaques beyond lumen narrowing. However, the association between HRMR-VWI characteristics and recurrent stroke remains uncertain.

AIMS

This study aimed to investigate the association between HRMR-VWI characteristics and recurrent ipsilateral stroke in patients with symptomatic intracranial atherosclerotic steno-occlusive disease (ICAS).

METHODS

This multicenter, observational study recruited first-ever acute ischemic stroke patients attributed to ICAS (>50% stenosis or occlusion) within 7 days after onset. Participants were assessed by multiparametric magnetic resonance imaging (MRI) including diffusion-weighted imaging, three-dimension time-of-flight magnetic resonance angiography, and three-dimensional T1-weighted HRMR-VWI. The patients were recommended to receive best medical therapy and were systematically followed up for 12 months. The association between HRMR-VWI characteristics and the time to recurrent ipsilateral stroke was investigated by univariable and multivariable analysis.

RESULTS

Two hundred and fifty-five consecutive patients were enrolled from 15 centers. The cumulative 12 month ipsilateral recurrence incidence was 4.1% (95% confidence interval (CI): 1.6-6.6%). Patients with recurrent ipsilateral stroke exhibited higher rates of intraplaque hemorrhage (IPH) (30.0% vs 6.5%) and eccentric plaque (90.0% vs 48.2%), and lower occurrence of occlusive thrombus (10.0% vs 23.7%). Plaque length (5.69 ± 2.21 mm vs 6.67 ± 4.16 mm), plaque burden (78.40 ± 7.37% vs 78.22 ± 8.32%), degree of stenosis (60.25 ± 18.95% vs 67.50% ± 22.09%) and remodeling index (1.07 ± 0.27 vs 1.03 ± 0.35) on HRMR-VWI did not differ between patients with and without recurrent ipsilateral stroke. In the multivariable Cox regression analysis, IPH (hazard ratio: 6.64, 95% CI: 1.23-35.8, p = 0.028) was significantly associated with recurrent ipsilateral stroke after adjustment.Conclusions:Our results suggest intraplaque hemorrhage (IPH) is significantly associated with recurrent ipsilateral stroke and has potential value in the selection of patients for aggressive treatment strategies.

DATA ACCESS STATEMENT

Data from this study are available and can be accessed upon request.

Systematic Review on Magnetic Resonance Angiography with Vessel Wall Imaging for the Characterization of Symptomatic Carotid Artery Plaque

BACKGROUND

To perform a systematic literature review to assess the usefulness of performing magnetic resonance angiography (MRA) with vessel wall imaging (VWI) sequences for the assessment of symptomatic carotid artery plaques and the identification of risky plaque features predisposing for stroke.

METHODS

We performed a systematic review of the literature pertaining to MRA with VWI techniques in patients with carotid artery disease, focusing on symptomatic patients' plaque features and morphology. Independent reviewers screened and analyzed data extracted from eligible studies, and a modified Newcastle-Ottawa Scale was used to appraise the quality of the design and content of the selected manuscripts to achieve an accurate interpretation.

RESULTS

This review included nineteen peer-reviewed manuscripts, all of them including MRA and VWI assessments of the symptomatic carotid artery plaque. We focused on patients' comorbidities and reviewed plaque features, including intraplaque hemorrhage, a lipid-rich necrotic core, a ruptured fibrous cap, and plaque ulceration.

CONCLUSIONS

MRA with VWI is a useful tool in the evaluation of carotid artery plaques. This imaging technique allows clinicians to identify plaques at risk of causing a neurovascular event. The presence of intraplaque hemorrhage, plaque ulceration, a ruptured fibrous cap, and a lipid-rich necrotic core are associated with neurovascular symptoms. The timely identification of these features could have a positive impact on neurovascular event prevention.

Sex Differences in Intracranial Atherosclerotic Plaques Among Patients With Ischemic Stroke

Objective

High-risk intracranial arterial plaques are the most common cause of ischemic stroke and their characteristics vary between male and female patients. However, sex differences in intracranial plaques among symptomatic patients have rarely been discussed. This study aimed to evaluate sex differences in intracranial atherosclerotic plaques among Chinese patients with cerebral ischemia.

Methods

One hundred and ten patients who experienced ischemic events underwent 3T cardiovascular magnetic resonance vessel wall scanning for the evaluation of intracranial atherosclerotic disease. Each plaque was classified according to its likelihood of causing a stroke (as culprit, uncertain, or non-culprit). The outer wall area (OWA) and lumen area of the lesion and reference sites were measured, and the wall and plaque areas, remodeling ratio, and plaque burden (characterized by a normalized wall index) were further calculated. The composition (T1 hyperintensity, enhancement) and morphology (surface irregularity) of each plaque were analyzed. Sex differences in intracranial plaque characteristics were compared between male and female patient groups.

Results

Overall, 311 plaques were detected in 110 patients with ischemic stroke (81 and 29 male and female patients, respectively). The OWA (P < 0.001) and wall area (P < 0.001) of intracranial arterial lesions were significantly larger in male patients. Regarding culprit plaques, the plaque burden in male patients was similar to that in female patients (P = 0.178, odds ratio [OR]: 0.168, 95% confidence interval [CI]: −0.020 to 0.107). However, the prevalence of plaque T1 hyperintensity was significantly higher than that in female patients (P = 0.005, OR: 15.362, 95% CI: 2.280–103.49). In the overall ischemic stroke sample, intracranial T1 hyperintensity was associated with male sex (OR: 13.480, 95% CI: 2.444–74.354, P = 0.003), systolic blood pressure (OR: 1.019, 95% CI: 1.002–1.036, P = 0.031), and current smoker (OR: 3.245, 95% CI: 1.097–9.598, P = 0.033).

Conclusion

For patients with ischemic stroke, the intracranial plaque burden in male patients was similar to that in female patients; however, the plaque characteristics in male patients are associated with higher risk, especially in culprit plaques.

Differential Gene Expression and Immune Cell Infiltration in Carotid Intraplaque Hemorrhage Identified Using Integrated Bioinformatics Analysis

Background

Intraplaque hemorrhage (IPH) is an important feature of unstable plaques and an independent risk factor for cardiovascular events. However, the molecular mechanisms contributing to IPH are incompletely characterized. We aimed to identify novel biomarkers and interventional targets for IPH and to characterize the role of immune cells in IPH pathogenesis.

Methods

The microarray dataset GSE163154 which contain IPH and non-IPH plaque samples was obtained from the Gene Expression Omnibus (GEO). R software was adopted for identifying differentially expressed genes (DEGs) and conducting functional investigation. The hub genes were carried by protein-protein interaction (PPI) network and were validated by the GSE120521 dataset. CIBERSORT deconvolution was used to determine differential immune cell infiltration and the relationship of immune cells and hub genes. We confirmed expression of proteins encoded by the hub genes by immunohistochemistry and western blotting in 8 human carotid endarterectomy samples with IPH and 8 samples without IPH (non-IPH).

Results

We detected a total of 438 differentially expressed genes (DEGs), of which 248 were upregulated and 190 were downregulated. DEGs were mainly involved in inflammatory related pathways, including neutrophil activation, neutrophil degranulation, neutrophil-mediated immunity, leukocyte chemotaxis, and lysosomes. The hub genes found through the method of degree in the PPI network showed that ITGB2 and ITGAM might play an important role in IPH. Receiver operating characteristic (ROC) results also showed a good performance of these two genes in the test and validation dataset. We found that the proportions of infiltrating immune cells in IPH and non-IPH samples differed, especially in terms of M0 and M2 macrophages. Immunohistochemistry and western blotting analysis showed that expression levels of ITGB2 and ITGAM increased significantly in carotid atherosclerotic plaques with IPH.

Conclusion

ITGB2 and ITGAM are key hub genes of IPH and may play an important role in the biological process of IPH. Our findings advance our understanding of the underlying mechanisms of IPH pathogenesis and provide valuable information and directions for future research into novel targets for IPH diagnosis and immunotherapy.

Integrated head and neck imaging of symptomatic patients with stroke using simultaneous non-contrast cardiovascular magnetic resonance angiography and intraplaque hemorrhage imaging as compared with digital subtraction angiography

BACKGROUND

Both stenosis rate and intraplaque hemorrhage (IPH) are important predictors of stroke risk. Simultaneous non-contrast angiography and intraplaque hemorrhage (SNAP) cardiovascular magnetic resonance (CMR) imaging can detect both stenosis rate and IPH. We aimed to evaluate consistency between SNAP and digital subtraction angiography (DSA) to assess symptomatic patients with stroke and explore the performance of SNAP to identify IPH and the clinical factors associated with IPH.

METHODS

Eighty-one symptomatic patients with stroke, admitted to Wuhan Union Hospital who underwent CMR high-resolution vessel wall imaging (HR-VWI) and SNAP, were retrospectively identified. For patients who received interventional therapy, the imaging functions of SNAP and HR-VWI were compared with DSA. The diameters of the intracranial and carotid vessels were measured, and stenotic vessels were identified. The consistency of SNAP and HR-VWI in identifying IPH was also examined, and the correlations between IPH and clinical factors were analyzed.

RESULTS

SNAP was more consistent with DSA than HR-VWI in measuring vascular stenosis (intraclass correlation coefficient [ICC]SNAP-DSA = 0.917, ICC HR-VWI-DSA = 0.878). Regarding the diameter measurements of each intracranial and carotid vessel segment, SNAP was superior or similar to HR-VWI, and both were consistent with DSA in the measurement of major intracranial vascular segments. HR-VWI and SNAP exhibited acceptable agreement in identifying IPH (Kappa = 0.839, 95% confidence interval [CI]: 0.704-0.974). Patients who underwent interventional therapy had a higher plaque burden (P < 0.001). Patients with IPH had lower levels of high-density lipoprotein cholesterol (HDL) (P = 0.038) and higher levels of blood glucose (P = 0.007) and cystatin C (P = 0.040).

CONCLUSIONS

CMR SNAP is consistent with DSA in measuring vessel diameters and identifying atherosclerosis stenosis in each intracranial and carotid vessel segment. SNAP is also a potential alternative to HR-VWI in identifying stenosis and IPH.

Mathematical modeling of plaque progression and associated microenvironment: How far from predicting the fate of atherosclerosis?

Mathematical modeling contributes to pathophysiological research of atherosclerosis by helping to elucidate mechanisms and by providing quantitative predictions that can be validated. In turn, the complexity of atherosclerosis is well suited to quantitative approaches as it provides challenges and opportunities for new developments of modeling. In this review, we summarize the current 'state of the art' on the mathematical modeling of the effects of biomechanical factors and microenvironmental factors on the plaque progression, and its potential help in prediction of plaque development. We begin with models that describe the biomechanical environment inside and outside the plaque and its influence on its growth and rupture. We then discuss mathematical models that describe the dynamic evolution of plaque microenvironmental factors, such as lipid deposition, inflammation, smooth muscle cells migration and intraplaque hemorrhage, followed by studies on plaque growth and progression using these modelling approaches. Moreover, we present several key questions for future research. Mathematical models can complement experimental and clinical studies, but also challenge current paradigms, redefine our understanding of mechanisms driving plaque vulnerability and propose future potential direction in therapy for cardiovascular disease.

Correlation between computed tomography angiography and histology of carotid artery atherosclerosis: Can semi-automated imaging software predict a plaque's composition?

BACKGROUND

Using computed tomography angiography to differentiate between components of carotid atherosclerotic lesions remains largely elusive. This study sought to validate a semi-automated software for computed tomography angiography plaque analysis using histologic comparisons.

MATERIALS AND METHODS

A retrospective review was performed of consecutive patients that underwent a carotid endarterectomy, with pre-procedural computed tomography angiography imaging of the cervical arterial vasculature available for review. Images were evaluated using a commercially-available software package, which produced segmented analyses of intraplaque components (e.g. intraplaque hemorrhage, lipid-rich necrotic core, and calcifications). On imaging, each component was assessed in terms of its (1) presence or absence, and (2) both volume and proportion of the total plaque volume (if present). On histological evaluation of carotid endarterectomy specimens, each component was evaluated as an estimated proportion of total plaque volume.

RESULTS

Of 80 included patients, 30 (37.5%) were female. The average age was 69.7 years (SD = 9.1). Based on imaging, intraplaque hemorrhage was the smallest contributor to plaque composition (1.2% of volumes on average). Statistically significant linear associations were noted between the proportion of intraplaque hemorrhage, lipid-rich necrotic core, and calcifications on histology and the volume of each component on imaging (p values ranged from 0.0008 to 0.01). Area under curve were poor for intraplaque hemorrhage and lipid-rich necrotic core (0.59 and 0.61, respectively) and acceptable for calcifications (0.73).

CONCLUSION

Semi-automated analyses of computed tomography angiography have limited diagnostic accuracy in the detection of intraplaque hemorrhage and lipid-rich necrotic core in carotid artery plaques. However, volumetric imaging measurements of different components corresponded with histologic analysis.

A promising tool to tackle the risk of cerebral vascular disease, the emergence of novel carotid wall imaging

Stroke is a heterogeneous vascular disease. Carotid artery atherosclerosis is associated with almost one-quarter of ischemic strokes. Moreover, a large percentage of preventable strokes are currently attributed to carotid atherosclerosis. Over the past three decades, the management of carotid artery disease has evolved. The benefits of carotid revascularization alongside medical therapy have early been recognized. Nonetheless, the debate regarding the optimal strategy is still ongoing, particularly in patients with asymptomatic carotid artery disease. One of the challenges is the use of luminal stenosis to quantify the severity of the carotid artery disease and to guide decision-making regarding invasive revascularization. Characterizing carotid atherosclerotic plaque is a promising tool to identify vulnerable plaque. Certain features such as large lipid core have already been linked to acute vascular events, not only at the plaque level but also to predict systemic cardiovascular events. Recently, a quantitative T2 mapping magnetic resonance imaging technique was developed and validated against histology. The ability to accurately quantify plaque lipid content using this technique opens several new opportunities. In this review articles, we will discuss the current challenges in the management of carotid artery disease and the future roles of T2 mapping to aid therapeutic options. These roles may include how to determine the mode of invasive carotid revascularization in symptomatic patients. Moreover, there may be a rational to use T2 mapping as a risk stratification tool in asymptomatic patients with carotid artery stenosis. It may also provide an opportunity to stage atherosclerosis and identify patients with coronary atherosclerosis who may benefit maximally from intensive lipid interventions.