In vivo accuracy of multispectral magnetic resonance imaging for identifying lipid-rich necrotic cores and intraplaque hemorrhage in advanced human carotid plaques

The relationship between fibrous cap status or plaque surface morphology and intraplaque hemorrhage volume over time: The PARISK Study

BACKGROUND

Carotid intraplaque hemorrhage (IPH) is a strong predictor of stroke, but factors contributing to IPH development are incompletely understood. Therefore, we investigate the longitudinal relationship between a thin/ruptured fibrous cap (TRFC)/disrupted plaque surface and IPH volume.

METHODS

116 ischemic TIA/stroke patients with ipsilateral carotid plaques underwent baseline and two-year follow-up MRI. IPH and fibrous cap status (thick versus TRFC) on MRI and disruption of the plaque surface (smooth versus fissure/ulceration) on CTA were assessed.

RESULTS

In the TRFC and disrupted plaque surface groups, the median IPH volume (tended) to decrease during follow-up (baseline: 97.3 IQR: [3.2-193.3] mm3 versus follow-up: 29.7 [0.0-115.1] mm3, p = 0.09, and baseline: 25.1 [0.0-166.2] mm3 versus follow-up: 11.2 [0.0-68.3] mm3, p = 0.04, respectively). In the group with a thick fibrous cap/smooth plaque surface, the median IPH volumes were zero at baseline and follow-up. The risk of IPH progression was higher in the TRFC/disrupted plaque groups (risk ratio (RR): 2.9 and 2.0, respectively) than in patients with a thick fibrous cap/smooth plaque surface.

CONCLUSION

TIA/stroke patients with a TRFC/disrupted plaque showed a net decrease in IPH volume over time, indicating plaque healing in some patients, but patients with a TRFC/disrupted plaque are still at increased risk for IPH progression.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01208025.

High-Resolution Magnetic Resonance Imaging Radiomics for Identifying High-Risk Intracranial Plaques

The rupture of vulnerable plaques is the principal cause of luminal thrombosis in acute ischemic stroke. The identification of plaque features that indicate risk for disruption may predict cerebrovascular events. Here, we aimed to build a high-risk intracranial plaque model that differentiates symptomatic from asymptomatic plaques using radiomic features based on high-resolution magnetic resonance imaging (HRMRI). One hundred and seventy-two patients with 188 intracranial atherosclerotic plaques (100 symptomatic and 88 asymptomatic) with available HRMRI data were recruited. Clinical characteristics and conventional plaque features on HRMRI were measured, including high signal on T1-weighted images (HST1), the degree of stenosis, normalized wall index, remodeling index, and enhancement ratio (ER). Univariate and multivariate analyses were performed to build a traditional model to differentiate between symptomatic and asymptomatic plaques. Radiomic features were extracted from pre-contrast and post-contrast HRMRI. A radiomic model based on HRMRI was constructed using random forests, ridge, least absolute shrinkage and selection operator, and deep learning (DL). A MIX model was constructed based on the radiomic model and the traditional model. Gender, HST1, and ER were associated with symptomatic plaques and were included in the traditional model, which had an area under the curve (AUC) of 0.697 in the training set and 0.704 in the test set. The radiomic model achieved an AUC of 0.982 in the training set and 0.867 in the test dataset for identifying symptomatic plaques. In the training set, the MIX model showed an AUC of 0.977. In the test set, the MIX model exhibited an improved AUC of 0.895, which outperformed the traditional model (p = 0.032). Radiomic analysis based on DL and machine learning can accurately identify high-risk intracranial plaques.

Correlation of intracranial and extracranial carotid atherosclerotic plaque characteristics with ischemic stroke recurrence: a high-resolution vessel wall imaging study

Objectives

To evaluate the ability of the plaque characteristics of extracranial carotid and intracranial arteries to predict large atherosclerotic ischemic stroke recurrence via head and neck combined high-resolution vessel wall imaging (HR-VWI).

Methods

This prospective cohort study included 169 patients with large atherosclerotic ischemic stroke who underwent head and neck combined HR-VWI from April 2022 to May 2023. The baseline clinical data and atherosclerotic plaque characteristics of the intracranial and extracranial carotid arteries were collected, and the patients were followed up for 1 year, with the endpoint event defined as recurrent ischemic stroke. Clinical and imaging data were compared between the recurrent and nonrecurrent groups. Independent risk factors associated with stroke recurrence were assessed via multivariate Cox regression analysis. The receiver operating characteristic (ROC) curves of the relevant variables were also plotted, and the area under the curve (AUC) was calculated to assess their ability to predict stroke recurrence. Kaplan-Meier survival curves were used to compare the probability of stroke recurrence.

Results

During the 12-month follow-up, stroke recurrence occurred in 35 of the 169 patients. Multivariate Cox regression analysis revealed that the total number of intracranial and extracranial carotid plaques (p = 0.010) and coexisting extracranial carotid plaques and intracranial significantly enhanced plaques (p = 0.047) were independent risk factors for recurrent ischemic stroke. The AUCs for predicting stroke recurrence were 0.787 and 0.710, respectively. The Kaplan-Meier survival curve revealed that the risk of stroke recurrence was significantly greater in patients whose total number of intracranial and extracranial carotid plaques was >4.5 than in patients whose total number of plaques was <4.5 (p < 0.001) and was significantly greater in patients with coexisting extracranial carotid plaques and intracranial significantly enhanced plaques than in patients without coexisting plaques (p < 0.001).

Conclusion

A greater total number of intracranial and extracranial carotid plaques and the coexistence of extracranial carotid plaques and intracranially significantly enhanced plaques are independent risk factors associated with recurrent ischemic stroke. Head and neck combined HR-VWI may provide new indicators for the prediction of stroke recurrence, thus helping clinicians identify high-risk patients and target therapy to reduce the recurrence of ischemic events.

Retrospective Analysis of a Novel Grading System for Evaluating the Long-Term Benefit of Revascularization on Carotid Artery Stenosis

BACKGROUND

To estimate revascularization benefit for carotid artery stenosis, with a novel grading system containing symptoms, stenosis, plaque, and collateral compensation (SSPC grading system).

METHODS

A retrospective multicenter study examined 945 consecutive patients diagnosed with carotid stenosis from January 2013 to December 2017. The cohort was classified into 2 groups: the revascularization group and the best medical therapy (BMT) group. Demographic, clinical, and lesion characteristics of all patients were recorded and 5-year nonprocedural stroke survival was calculated using Kaplan-Meier curve analyses.

RESULTS

Of the 945 patients, 514 underwent carotid revascularization (483 for carotid endarterectomy and 31 for transfemoral-carotid artery stenting) and 431 patients were treated with BMT. Patients in the revascularization group had a significantly higher proportion of preprocedural stroke/transient ischemic attack (TIA) and grades of stenosis. Of the patients in the revascularization group, 3.1% were classified as SSPC I, 10.3% as SSPC II, 41.4% as SSPC III, and 45.1% as SSPC IV. Meanwhile, 17.9% were classified as SSPC I, 19.7% as SSPC II, 49.2% as class III, and 13.2% had class IV in the BMT group. Procedural stroke developed in 13 patients (2.5%) following revascularization (10 of them were non-disabling). The overall rate of freedom from any nonprocedural stroke was 94.1 ± 1.1% in the revascularization group and 89.5 ± 1.6% in the BMT group (P = 0.01). Subgroup analysis was conducted for asymptomatic carotid stenosis (ACS) and carotid near-occlusion (CNO) patients. Nonsignificance was noted in the rate of freedom from any nonprocedural stroke between revascularization and BMT in both ACS and CNO subgroups (P = 0.09 and 0.12, respectively). Of note, in ACS patients graded as SSPC III, a significant difference in stroke survival was found between the revascularization and BMT group (96.0 ± 2.0% vs. 89.1 ± 2.4%, P = 0.04). Meanwhile, in symptomatic CNO patients, similar results were found regarding SSPC classification (94.8 ± 3.6% vs. 63.8 ± 14.9%, P = 0.01).

CONCLUSIONS

The SSPC grading system stratifies the patients with carotid artery stenosis and predicts the long-term benefits of revascularization. Meanwhile, potential revascularization benefits could be better attained via SSPC classes in specific patients with ACS and CNO.

Histological validation of three-dimensional variable flip angle turbo spin echo multi-contrast magnetic resonance vessel wall imaging in characterizing carotid vulnerable atherosclerotic plaques

BACKGROUND

Accurate assessment of the vulnerability of carotid atherosclerotic plaques is crucial for stroke prevention. The three-dimensional (3D) magnetic resonance (MR) vessel wall imaging (VWI) has been increasingly employed to evaluate carotid plaques due to its extensive coverage and isotropic high spatial resolution. However, the accuracy of such techniques lacks validation by histology. Therefore, this study aims to validate the accuracy of 3D multi-contrast MR VWI with variable-flip-angle (VFA) and turbo spin echo (TSE) readout in identifying vulnerable carotid plaques, using histological analysis as a reference.

METHODS

Twenty-one male patients (mean age: 64.4 ± 7.2 years old) scheduled for carotid endarterectomy (CEA) were recruited in this study. All patients underwent carotid multi-contrast MR VWI, including 3D T1- and T2-weighted VFA-TSE sequences, as well as 3D time of flight (TOF) MR angiography (MRA), using a 3.0T MR system before surgery. Histological processing was performed for carotid plaque specimens. The presence or absence, along with the area measurements, of lipid-rich necrotic core (LRNC), intraplaque hemorrhage (IPH), and calcifications (CA) were independently evaluated on both MR images and histological sections. Cohen's kappa (κ) analysis was utilized to determine the agreement between 3D multi-contrast MR VWI and histology in identifying carotid plaque compositions before and after excluding compositions bellow certain size threshold. Spearman's correlation analysis was also conducted to assess the agreement in quantifying plaque compositions.

RESULTS

A total of 81 slices of MR images were successfully matched with histological sections. Moderate to almost perfect agreements were observed between 3D MR VWI and histology in the identification of LRNC (κ: 0.85 and 0.89), IPH (κ: 0.65 and 0.69), and CA (κ: 0.46 and 0.62) before and after excluding compositions smaller than 0.79 mm2. Strong to very strong correlations were found in the quantification of plaque compositions including LRNC (r=0.88), IPH (r=0.80), and CA (r=0.74) between MR imaging and histology.

CONCLUSION

The 3D VFA-TSE multi-contrast MR VWI is capable of accurately characterizing vulnerable carotid atherosclerotic plaques.

The role of non-stenosing carotid artery plaques in embolic stroke of undetermined source, is it a silent offender? A review of literature

PURPOSE

Atherosclerotic cervical internal carotid artery disease is one of the major causes of ischemic stroke and transient ischemic attacks. The risk of stroke from mild to moderate stenoses (i.e. <50% stenosis) might be underestimated. There is increasing evidence that plaque morphological features reflect plaque instability that may harbor high risk for embolization. In this narrative review, we will review the literature on plaque features that predict vulnerability beyond the degree of stenosis, discuss the clinical association with stroke, and evaluate the evidence that these lesions serve as a source for embolic stroke of unknown source (ESUS).

METHODS

We performed a literature search using PubMed, EMBASE, and Web of Science. The terms "embolic stroke of undetermined source" and "plaque morphology" were used either alone or in combination with "non-flow limiting stenosis," "non-stenosing plaques," "high-risk plaque features" or "internal carotid artery plaque." Data on plaque morphology and ESUS were mainly taken from review articles, observational studies including retrospective cohort and cross-sectional studies, meta-analyses, and systematic reviews.

CONCLUSION

Nonstenosing carotid artery plaques with high-risk features carry a remarkable risk for stroke occurrence and randomized clinical trials are warranted for further evaluation of using carotid artery stenting or carotid endarterectomy to mitigate the risk of stroke.

Diagnostic accuracy of carotid plaque magnetic resonance imaging compared to histopathology in symptomatic carotid artery stenosis

INTRODUCTION

Vulnerable plaques have been shown to predict ipsilateral cerebral ischemic events and identifying them leads to appropriate secondary stroke prevention strategies. We evaluated the diagnostic accuracy of MR carotid plaque imaging in identifying plaque vulnerability when compared with histopathological findings in patients with symptomatic carotid stenosis who underwent carotid endarterectomy (CEA).

METHODS

A prospective cohort of forty-five consecutive patients with moderate to severe symptomatic carotid stenosis who underwent CEA at a tertiary Indian hospital had 3 T MRI plaque imaging with multi-parametric protocol between November 2021 and December 2022. Images were analyzed by a vascular radiologist blinded to histopathological data. High-risk plaque characteristics such as lipid rich necrotic core (LRNC), intraplaque hemorrhage (IPH), thin fibrous cap and ulceration were assessed and correlated with histopathological findings as per American Heart Association (AHA) classification using Cohen's kappa statistics to obtain diagnostic accuracies.

RESULTS

Of the 45 patients, 38(84 %) were males. The mean age was 65 ± 7.7 years and mean duration to CEA from the most recent event was 57 days (57 ± 46 days). A significant correlation between MR plaque imaging and histopathology was noted for IPH (sensitivity-91 %, specificity-86 %, κ = 0.774, p < 0.001), LRNC (sensitivity-92.1 %, specificity-85.7 %, κ = 0.697, p < 0.001), and plaque ulceration (sensitivity-84.6 %, specificity-78.1 %, κ = 0.563, p < 0.001). MRI had an overall sensitivity and specificity of 92.3 % and 84.2 % respectively (κ = 0.77, p < 0.001) in discriminating high risk plaques.

CONCLUSION

MR plaque imaging shows a very good correlation with histopathology and can identify unstable high-risk plaques with high accuracy. This may have implication in selection of patients for carotid revascularization in symptomatic carotid stenosis.

Diagnostic accuracy of carotid plaque instability by noninvasive imaging: a systematic review and meta-analysis

AIMS

There is increasing evidence that plaque instability in the extracranial carotid artery may lead to an increased stroke risk independently of the degree of stenosis. We aimed to determine diagnostic accuracy of vulnerable and stable plaque using noninvasive imaging modalities when compared to histology in patients with symptomatic and asymptomatic carotid atherosclerosis.

METHODS AND RESULTS

Medline Ovid, Embase, Cochrane Library, and Web of Science were searched for diagnostic accuracy of noninvasive imaging modalities (CT, MRI, US) in the detection of 1) vulnerable/stable plaque, and 2) vulnerable/stable plaque characteristics, compared to histology. The quality of included studies was assessed by QUADAS-2 and univariate and bivariate random-effect meta-analyses were performed. We included 36 vulnerable and 5 stable plaque studies in the meta-analysis, and out of 211 plaque characteristics from remaining studies, we classified 169 as vulnerable and 42 as stable characteristics (28 CT, 120 MRI, 104 US characteristics). We found that MRI had high accuracy [90% (95% CI: 82-95%)] in the detection of vulnerable plaque, similar to CT [86% (95% CI: 76-92%); P > 0.05], whereas US showed less accuracy [80% (95% CI: 75-84%); P = 0.013]. CT showed high diagnostic accuracy in visualizing characteristics of vulnerable or stable plaques (89% and 90%) similar to MRI (86% and 89%; P > 0.05); however, US had lower accuracy (77%, P < 0.001 and 82%, P > 0.05).

CONCLUSION

CT and MRI have a similar, high performance in detecting vulnerable carotid plaques, whereas US showed significantly less diagnostic accuracy. Moreover, MRI visualized all vulnerable plaque characteristics allowing for a better stroke risk assessment.

REGISTRATION

PROSPERO ID CRD42022329690.

Carotid and aortic plaque imaging using 3D gradient-echo imaging and the three-point Dixon method with improved motion-sensitized driven-equilibrium (iMSDE)

BACKGROUND

We devised a method that combines the 3D-Dixon-gradientecho (GRE) method with an improved motion-sensitized driven-equilibrium (iMSDE) to suppress blood flow signals.

PURPOSE

The purpose of this study was to evaluate the effectiveness of the new method we developed plaque imaging method (3D-Dixon-GRE with the iMSDE method).

STUDY TYPE

Retrospective cohort.

POPULATION

Thirty-nine patients who underwent cervical plaque imaging.

FIELD STRENGTH/SEQUENCE

3.0 T/3D-GRE.

ASSESSMENT

Signal intensities of the common carotid artery, aorta, plaque, muscle, and subcutaneous fat were measured through the VISTA and the 3D-Dixon-GRE with iMSDE methods, and each contrast was calculated.

STATISTICAL TEST

Used the Mann Whitney U test. P-values below 0.05 were considered statistically significant.

RESULTS

Plaque and muscle contrast estimated through the VISTA method and 3D-Dixon-GRE with iMSDE method was 1.60 ± 0.96 and 2.04 ± 1.06, respectively, (P < 0.05). The contrast between the flow (common carotid artery and Aorta) and muscle according to the VISTA method and 3D-Dixon-GRE with iMSDE method was 0.24 ± 0.11 and 0.40 ± 0.12, respectively (P < 0.001). Finally, the mean contrast for subcutaneous fat and muscle at six locations was 3.05 ± 1.25 and 0.81 ± 0.23 for the VISTA method and 3D-Dixon-GRE with the iMSDE method, respectively (P < 0.001).

DATA CONCLUSION

Compared to the conventional method (VISTA), the 3D-Dixon-GRE with iMSDE method is preferable in relation to the fat suppression effect, but it is disadvantageous regarding blood flow signal suppression. Therefore, the 3D-Dixon-GRE with the iMSDE method could be considered useful for plaque imaging.

Imaging of Carotid Stenosis: Where Are We Standing? Comparison of Multiparametric Ultrasound, CT Angiography, and MRI Angiography, with Recent Developments

Atherosclerotic disease of the carotid arteries is a crucial risk factor in predicting the likelihood of future stroke events. In addition, emerging studies suggest that carotid stenosis may also be an indicator of plaque load on coronary arteries and thus have a correlation with the risk of acute cardiovascular events. Furthermore, although in symptomatic patients the degree of stenosis is the main morphological parameter studied, recent evidence suggests, especially in asymptomatic patients, that plaque vulnerability should also be evaluated as an emerging and significant imaging parameter. The reference diagnostic methods for the evaluation of carotid stenosis are currently ultrasonography, magnetic resonance imaging (MRI), and computed tomography angiography (CTA). In addition, other more invasive methods such as 123I-metaiodobenzylguanidine (MIBG) scintigraphy and PET-CT, as well as digital subtraction angiography, can be used. Each method has advantages and disadvantages, and there is often some confusion in their use. For example, the usefulness of MRI is often underestimated. In addition, implementations for each method have been developed over the years and are already enabling a significant increase in diagnostic accuracy. The purpose of our study is to make an in-depth analysis of all the methods in use and in particular their role in the diagnostic procedure of carotid stenosis, also discussing new technologies.

Efficacy, safety and mechanism of Simiaoyongan decoction in the treatment of carotid atherosclerotic plaque: a randomized, double-blind, placebo-controlled clinical trial protocol

INTRODUCTION

Chronic inflammation is the major pathological feature of Atherosclerosis(As). Inflammation may accelerate plaque to develop, which is a key factor resulting in the thinning of the fibrous cap and the vulnerable rupture of plaque. Presently, clinical treatments are still lacking. It is necessary to find a safe and effective treatment for As inflammation. Simiaoyongan Decoction (SMYA) has potential anti-inflammatory and plaque protection effects. This protocol aims to evaluate the efficacy, safety, and mechanism of SMYA for patients with carotid atherosclerotic plaque.

METHODS/DESIGN

The assessment of SMYA clinical trial is designed as a randomized, double-blind, placebo-controlled study. The sample size is 86 cases in total, with 43 participants in the intervention group and the control group respectively. The intervention group takes SMYA, while the control group takes SMYA placebo. The medication lasts for 14 days every 10 weeks, with a total of 50 weeks. We will use carotid artery high resolution magnetic resonance imaging (HR-MRI) to measure plaque. The plaque minimum fiber cap thickness (PMFCT) is adopted as the primary outcome. The secondary outcomes include plaque fiber cap volume, volume percentage of fiber cap, lipid-rich necrotic core (LRNC) volume, volume percentage of LRNC, internal bleeding volume of plaque, internal bleeding volume percentage of plaque, plaque calcification volume, volume percentage of plaque calcification, lumen stenosis rate, average and a maximum of vessel wall thickness, vessel wall volume, total vessel wall load, carotid atherosclerosis score, hs-CRP, IL-1β and IL-6, the level of lipid profiles and blood glucose, blood pressure, and body weight.

DISCUSSION

We anticipate that patients with As plaque will be improved from SMYA by inhibiting inflammation to enhance plaque stability. This study analyzes plaque by using HR-MRI to evaluate the clinical efficacy and safety of SMYA. Moreover, we conduct transcriptome analysis, proteomic analysis, and metagenomic analysis of blood and stool of participants to study the mechanism of SMYA against As plaque. This is the first prospective TCM trial to observe and treat As plaque by inhibiting inflammatory reaction directly. If successful, the finding will be valuable in the treatment of As plaque and drug development, especially in the "statin era".

TRIAL REGISTRATION NUMBER

This trial is registered on Chinese Clinical Trials.gov with number ChiCTR2000039062 on October 15, 2020 ( http://www.chictr.org.cn ).

Characterization of carotid plaques using chemical exchange saturation transfer imaging

PURPOSE

The preoperative assessment of carotid plaques is necessary to render revascularization safe and effective. The aim of this study is to evaluate the usefulness of chemical exchange saturation transfer (CEST)-MRI, particularly amide proton transfer (APT) imaging as a preoperative carotid plaque diagnostic tool.

METHODS

We recorded the APT signal intensity on concentration maps of 34 patients scheduled for carotid endarterectomy. Plaques were categorized into group A (APT signal intensity ≥ 1.90 E-04; n = 12) and group B (APT signal intensity < 1.90 E-04; n = 22). Excised plaques were subjected to histopathological assessment and, using the classification promulgated by the American Heart Association, they were classified as intraplaque hemorrhage-positive [type VI-positive (tVI+)] and -negative [no intraplaque hemorrhage (tVI-)].

RESULTS

Of the 34 patients, 22 (64.7%) harbored tVI+- and 12 (35.3%) had tVI- plaques. The median APT signals were significantly higher in tVI+- than tIVI- patients (2.43 E-04 (IQR = 0.98-4.00 E-04) vs 0.54 E-04 (IQR = 0.14-1.09 E-04), p < .001). Histopathologically, the number of patients with tVI+ plaques was significantly greater in group A (100%, n = 12) than group B (45%, n = 22) (p < .01). The number of symptomatic patients or asymptomatic patients with worsening stenosis was also significantly greater in group A than group B (75% vs 36%, p < .01).

CONCLUSION

In unstable plaques with intraplaque hemorrhage and in patients with symptoms or progressive stenosis, the ATP signals were significantly elevated. CEST-MRI studies has the potential for the preoperative assessment of the plaques' characteristics.

High-resolution magnetic resonance vessel wall imaging in ischemic stroke and carotid artery atherosclerotic stenosis: A review

Ischemic stroke is a significant burden on human health worldwide. Carotid Atherosclerosis stenosis plays an important role in the comprehensive assessment and prevention of ischemic stroke patients. High-resolution vessel wall magnetic resonance imaging has emerged as a successful technique for assessing carotid atherosclerosis stenosis. This advanced imaging modality has shown promise in effectively displaying a wide range of characteristics associated with the condition, leading to a comprehensive evaluation. High-resolution vessel wall magnetic resonance imaging not only enables a comprehensive evaluation of the instability of carotid atherosclerosis stenosis plaques but also provides valuable information for understanding the pathogenesis and predicting the prognosis of ischemic stroke patients. The purpose of this article is to review the application of high-resolution magnetic resonance imaging in ischemic stroke and carotid atherosclerotic stenosis.

High-resolution magnetic resonance vessel wall imaging provides new insights into Moyamoya disease

Moyamoya disease (MMD) is a rare condition that affects the blood vessels of the central nervous system. This cerebrovascular disease is characterized by progressive narrowing and blockage of the internal carotid, middle cerebral, and anterior cerebral arteries, which results in the formation of a compensatory fragile vascular network. Currently, digital subtraction angiography (DSA) is considered the gold standard in diagnosing MMD. However, this diagnostic technique is invasive and may not be suitable for all patients. Hence, non-invasive imaging methods such as computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are often used. However, these methods may have less reliable diagnostic results. Therefore, High-Resolution Magnetic Resonance Vessel Wall Imaging (HR-VWI) has emerged as the most accurate method for observing and analyzing arterial wall structure. It enhances the resolution of arterial walls and enables quantitative and qualitative analysis of plaque, facilitating the identification of atherosclerotic lesions, vascular entrapment, myofibrillar dysplasia, moyamoya vasculopathy, and other related conditions. Consequently, HR-VWI provides a new and more reliable evaluation criterion for diagnosing vascular lesions in patients with Moyamoya disease.

Epidemiology, Pathophysiology, and Imaging of Atherosclerotic Intracranial Disease

Intracranial atherosclerotic disease (ICAD) is one of the most common causes of stroke worldwide. Among people with stroke, those of East Asia descent and non-White populations in the United States have a higher burden of ICAD-related stroke compared with Whites of European descent. Disparities in the prevalence of asymptomatic ICAD are less marked than with symptomatic ICAD. In addition to stroke, ICAD increases the risk of dementia and cognitive decline, magnifying ICAD societal burden. The risk of stroke recurrence among patients with ICAD-related stroke is the highest among those with confirmed stroke and stenosis ≥70%. In fact, the 1-year recurrent stroke rate of >20% among those with stenosis >70% is one of the highest rates among common causes of stroke. The mechanisms by which ICAD causes stroke include plaque rupture with in situ thrombosis and occlusion or artery-to-artery embolization, hemodynamic injury, and branch occlusive disease. The risk of stroke recurrence varies by the presumed underlying mechanism of stroke, but whether techniques such as quantitative magnetic resonance angiography, computed tomographic angiography, magnetic resonance perfusion, or transcranial Doppler can help with risk stratification beyond the degree of stenosis is less clear. The diagnosis of ICAD is heavily reliant on lumen-based studies, such as computed tomographic angiography, magnetic resonance angiography, or digital subtraction angiography, but newer technologies, such as high-resolution vessel wall magnetic resonance imaging, can help distinguish ICAD from stenosing arteriopathies.

Atherosclerotic plaque characteristics in extracranial carotid artery may indicate closer association with white matter hyperintensities than intracranial arteries: A CARE-II study

PURPOSE

This study aimed to investigate the associations of atherosclerotic plaque characteristics in intracranial and extracranial carotid arteries with severity of white matter hyperintensities (WMHs) in symptomatic patients using magnetic resonance (MR) imaging.

METHOD

Patients with cerebrovascular symptoms and carotid plaque were recruited from the cross-sectional, multicenter study of CARE-II. Luminal stenosis of intracranial and extracranial carotid arteries, carotid plaque compositional features, and WMHs were evaluated by brain structural and vascular MR imaging. The atherosclerotic plaque characteristics in intracranial and extracranial carotid arteries were compared between patients with and without moderate-to-severe WMHs (Fazekas score > 2), and their associations with severity of WMHs were analyzed using logistic regression.

RESULTS

Of the recruited 622 patients (mean age, 58.7 ± 10.9 years; 422 males), 221 (35.5 %) had moderate-to-severe WMHs with higher prevalence of moderate-to-severe luminal stenosis (17.0 % vs. 10.4 %), intraplaque hemorrhage (15.7 % vs. 9.0 %), thin/ruptured fibrous cap (30.2 % vs. 20.4 %), calcification (44.4 % vs. 22.2 %) and lipid-rich necrotic core (63.8 % vs. 51.1 %) in carotid artery compared to those without (all P < 0.05). Multivariate logistic regression showed that carotid calcification (OR, 1.854; 95 % CI, 1.187-2.898; P = 0.007) was independently associated with moderate-to-severe WMHs after adjusting for confounding factors. No significant association was found between intracranial atherosclerotic stenosis and moderate-to-severe WMHs (P > 0.05).

CONCLUSION

Carotid atherosclerotic plaque features, particularly presence of calcification, were independently associated with severity of WMHs, but such association was not found in intracranial atherosclerotic stenosis, suggesting that carotid atherosclerotic plaque characteristics may have closer association with severity of WMHs compared to intracranial atherosclerosis.

Quantifying Carotid Stenosis: History, Current Applications, Limitations, and Potential: How Imaging Is Changing the Scenario

Carotid artery stenosis is a major cause of morbidity and mortality. The journey to understanding carotid disease has developed over time and radiology has a pivotal role in diagnosis, risk stratification and therapeutic management. This paper reviews the history of diagnostic imaging in carotid disease, its evolution towards its current applications in the clinical and research fields, and the potential of new technologies to aid clinicians in identifying the disease and tailoring medical and surgical treatment.

T1-T2 Mismatch Sign as a Predictor of Ipsilateral Ischemic Change After Carotid Artery Stenting

BACKGROUND

Magnetic resonance (MR)-plaque imaging reflects the characteristics of carotid plaque. We evaluated the relationship between MR-plaque images and ischemic change after carotid artery stenting (CAS).

METHODS

MR-plaque images were acquired from patients with carotid artery stenosis before CAS treatment. We calculated the relative signal intensity of plaque components compared with that of the sternocleidomastoid muscle and evaluated the presence/absence of T1-T2 mismatch and match sign. We then assessed the appearance of new ischemic lesions after CAS on diffusion-weighted imaging (DWI). Factors associated with the appearance of a high-intensity lesion on DWI were retrospectively analyzed.

RESULTS

A total of 64 patients with carotid artery stenoses treated with CAS were included in this study. In univariate analysis, T1-T2 mismatch sign was associated with the appearance of high-intensity lesions on DWI after CAS (odds ratio [OR], 12.00; 95% confidence interval [CI], 3.593-40.072; P < 0.0001), whereas T1-T2 match sign and high intensity on T2-weighted imaging were negatively associated (OR, 0.061, 95% CI, 0.007-0.502, P = 0.009 and OR, 0.085; 95% CI, 0.022-0.334, P = 0.0004, respectively). In multivariate logistic regression analysis, T1-T2 mismatch sign was independently associated with the appearance of a high-intensity lesion on DWI after CAS (OR, 16.695; 95% CI, 1.324-210.52; P = 0.0295).

CONCLUSIONS

T1-T2 mismatch sign on MR-plaque imaging is significantly associated with the appearance of new ischemic lesions after CAS. T1-T2 mismatch sign may be useful in considering treatment strategies for carotid artery stenosis.

Application of mask images of contrast-enhanced MR angiography to detect carotid intraplaque hemorrhage in patients with moderate to severe symptomatic and asymptomatic carotid stenosis

PURPOSE

Carotid intraplaque hemorrhage (IPH) on MRI predicts stroke. Magnetization-prepared rapid acquisition gradient (MP-RAGE) is widely used to detect IPH. CE-MRA is used routinely to assess stenosis. Initial studies indicated that IPH can be identified on mask images of CE-MRA, while Time-of-Flight (TOF) images were reported to have high specificity but lower sensitivity. We investigated the diagnostic accuracy of detecting IPH on mask images of CE-MRA and TOF.

METHODS

Thirty-six patients with ≥ 50% stenosis enrolled in the ongoing 2nd European Carotid Surgery Trial underwent carotid MRI. A 5-point quality score was used. Inter-observer agreement between two independent readers was determined. The sensitivity and specificity of IPH detection on mask MRA and TOF were calculated with MP-RAGE as a reference standard.

RESULTS

Of the 36 patients included in the current analysis, 66/72 carotid arteries could be scored. The inter-observer agreements for identifying IPH on MP-RAGE, mask, and TOF were outstanding (κ: 0.93, 0.96, and 0.85). The image quality of mask (1.42 ± 0.66) and TOF (2.42 ± 0.66) was significantly lower than MP-RAGE (3.47 ± 0.61). When T1w images were used to delineate the outer carotid wall, very high specificities (>95%) of IPH detection on mask and TOF images were found, while the sensitivity was high for mask images (>81%) and poor for TOF (50-60%). Without these images, the specificity was still high (>97%), while the sensitivity reduced to 62-71%.

CONCLUSION

Despite the lower image quality, routinely acquired mask images from CE-MRA, but not TOF, can be used as an alternative to MP-RAGE images to visualize IPH.

Quantification of carotid plaque composition with a multi-contrast atherosclerosis characterization (MATCH) MRI sequence

Background and purpose

Carotid atherosclerotic plaques with a large lipid-rich necrotic core (LRNC), intraplaque hemorrhage (IPH), and a thin or ruptured fibrous cap are associated with increased stroke risk. Multi-sequence MRI can be used to quantify carotid atherosclerotic plaque composition. Yet, its clinical implementation is hampered by long scan times and image misregistration. Multi-contrast atherosclerosis characterization (MATCH) overcomes these limitations. This study aims to compare the quantification of plaque composition with MATCH and multi-sequence MRI.

Methods

MATCH and multi-sequence MRI were used to image 54 carotid arteries of 27 symptomatic patients with ≥2 mm carotid plaque on a 3.0 T MRI scanner. The following sequence parameters for MATCH were used: repetition time/echo time (TR/TE), 10.1/4.35 ms; field of view, 160 mm × 160 mm × 2 mm; matrix size, 256 × 256; acquired in-plane resolution, 0.63 mm2× 0.63 mm2; number of slices, 18; and flip angles, 8°, 5°, and 10°. Multi-sequence MRI (black-blood pre- and post-contrast T1-weighted, time of flight, and magnetization prepared rapid acquisition gradient echo; acquired in-plane resolution: 0.63 mm2 × 0.63 mm2) was acquired according to consensus recommendations, and image quality was scored (5-point scale). The interobserver agreement in plaque composition quantification was assessed by the intraclass correlation coefficient (ICC). The sensitivity and specificity of MATCH in identifying plaque composition were calculated using multi-sequence MRI as a reference standard.

Results

A significantly lower image quality of MATCH compared to that of multi-sequence MRI was observed (p < 0.05). The scan time for MATCH was shorter (7 vs. 40 min). Interobserver agreement in quantifying plaque composition on MATCH images was good to excellent (ICC ≥ 0.77) except for the total volume of calcifications and fibrous tissue that showed moderate agreement (ICC ≥ 0.61). The sensitivity and specificity of detecting plaque components on MATCH were ≥89% and ≥91% for IPH, ≥81% and 85% for LRNC, and ≥71% and ≥32% for calcifications, respectively. Overall, good-to-excellent agreement (ICC ≥ 0.76) of quantifying plaque components on MATCH with multi-sequence MRI as the reference standard was observed except for calcifications (ICC = 0.37-0.38) and fibrous tissue (ICC = 0.59-0.70).

Discussion and conclusion

MATCH images can be used to quantify plaque components such as LRNC and IPH but not for calcifications. Although MATCH images showed a lower mean image quality score, short scan time and inherent co-registration are significant advantages.

Medical and Surgical Management of Symptomatic and Asymptomatic Carotid Artery Stenosis: A Comprehensive Literature Review

Carotid artery stenosis is a condition where the carotid artery is blocked by fatty cholesterol deposits called plaque, increasing the risk of stroke. Elderly individuals with high cardiovascular risk are more susceptible, along with smokers, those with high cholesterol, males, and older individuals. Young females may also be affected by fibromuscular dysplasia. Carotid stenosis significantly raises stroke risk, and the severity is closely linked to stroke incidence and other cardiovascular events. Early detection and treatment are essential to prevent complications. Treatment options include medical and surgical interventions, such as carotid endarterectomy (CEA) and carotid artery stenting (CAS). The choice between surgery and medical management varies depending on patient characteristics and risk factors. This review explores carotid artery stenosis pathophysiology, risk factors, the importance of early detection and treatment, and the surgical approaches of CEA and CAS, addressing their roles and controversies. Healthcare professionals must understand these aspects to provide optimal care to patients with this condition.

Rapid MR Angiography Using 3D Gradient-echo Imaging and the Two-point Dixon Method to Evaluate Carotid Plaque

Liver acquisition with volume acceleration-flex (LAVA-Flex) acquires out-of-phase and in-phase echo images and automatically generates water-only and fat-only images from one single acquisition. The scan time of carotid MR angiography (MRA) using LAVA-Flex (LAVA MRA) is about one-fifth that of conventional time-of-flight MRA (cTOF MRA). We aimed to investigate whether LAVA MRA could provide useful information for the diagnosis of carotid plaque by utilizing the ability to acquire multiple sequences simultaneously. Comparing LAVA MRA and cTOF MRA images for carotid plaque, low-intensity plaques were more clearly identified in the in-phase images, and high-intensity plaques were more clearly identified in the water-only or out-of-phase images. None of the plaques exhibited superior visualization with the cTOF sequence. We concluded that LAVA MRA can provide more useful information on plaque evaluation using multiple sequences than cTOF MRA.

QSM Throughout the Body

Magnetic materials in tissue, such as iron, calcium, or collagen, can be studied using quantitative susceptibility mapping (QSM). To date, QSM has been overwhelmingly applied in the brain, but is increasingly utilized outside the brain. QSM relies on the effect of tissue magnetic susceptibility sources on the MR signal phase obtained with gradient echo sequence. However, in the body, the chemical shift of fat present within the region of interest contributes to the MR signal phase as well. Therefore, correcting for the chemical shift effect by means of water-fat separation is essential for body QSM. By employing techniques to compensate for cardiac and respiratory motion artifacts, body QSM has been applied to study liver iron and fibrosis, heart chamber blood and placenta oxygenation, myocardial hemorrhage, atherosclerotic plaque, cartilage, bone, prostate, breast calcification, and kidney stone.

Carotid atherosclerotic plaque segmentation in multi-weighted MRI using a two-stage neural network: advantages of training with high-resolution imaging and histology

Introduction

A reliable and automated method to segment and classify carotid artery atherosclerotic plaque components is needed to efficiently analyze multi-weighted magnetic resonance (MR) images to allow their integration into patient risk assessment for ischemic stroke. Certain plaque components such as lipid-rich necrotic core (LRNC) with hemorrhage suggest a greater likelihood of plaque rupture and stroke event. Assessment for presence and extent of LRNC could assist in directing treatment with impact upon patient outcomes.

Methods

To address the need to accurately determine the presence and extent of plaque components on carotid plaque MRI, we proposed a two-staged deep-learning-based approach that consists of a convolutional neural network (CNN), followed by a Bayesian neural network (BNN). The rationale for the two-stage network approach is to account for the class imbalance of vessel wall and background by providing an attention mask to the BNN. A unique feature of the network training was to use ground truth defined by both high-resolution ex vivo MRI data and histopathology. More specifically, standard resolution 1.5 T in vivo MR image sets with corresponding high resolution 3.0 T ex vivo MR image sets and histopathology image sets were used to define ground-truth segmentations. Of these, data from 7 patients was used for training and from the remaining two was used for testing the proposed method. Next, to evaluate the generalizability of the method, we tested the method with an additional standard resolution 3.0 T in vivo data set of 23 patients obtained from a different scanner.

Results

Our results show that the proposed method yielded accurate segmentation of carotid atherosclerotic plaque and outperforms not only manual segmentation by trained readers, who did not have access to the ex vivo or histopathology data, but also three state-of-the-art deep-learning-based segmentation methods. Further, the proposed approach outperformed a strategy where the ground truth was generated without access to the high resolution ex vivo MRI and histopathology. The accurate performance of this method was also observed in the additional 23-patient dataset from a different scanner.

Conclusion

In conclusion, the proposed method provides a mechanism to perform accurate segmentation of the carotid atherosclerotic plaque in multi-weighted MRI. Further, our study shows the advantages of using high-resolution imaging and histology to define ground truth for training deep-learning-based segmentation methods.

Biliverdin Reductase B Is a Plasma Biomarker for Intraplaque Hemorrhage and a Predictor of Ischemic Stroke in Patients with Symptomatic Carotid Atherosclerosis

BACKGROUND

Intraplaque hemorrhage (IPH) is a hallmark of atherosclerotic plaque instability. Biliverdin reductase B (BLVRB) is enriched in plasma and plaques from patients with symptomatic carotid atherosclerosis and functionally associated with IPH.

OBJECTIVE

We explored the biomarker potential of plasma BLVRB through (1) its correlation with IPH in carotid plaques assessed by magnetic resonance imaging (MRI), and with recurrent ischemic stroke, and (2) its use for monitoring pharmacotherapy targeting IPH in a preclinical setting.

METHODS

Plasma BLVRB levels were measured in patients with symptomatic carotid atherosclerosis from the PARISK study (n = 177, 5 year follow-up) with and without IPH as indicated by MRI. Plasma BLVRB levels were also measured in a mouse vein graft model of IPH at baseline and following antiangiogenic therapy targeting vascular endothelial growth factor receptor 2 (VEGFR-2).

RESULTS

Plasma BLVRB levels were significantly higher in patients with IPH (737.32 ± 693.21 vs. 520.94 ± 499.43 mean fluorescent intensity (MFI), p = 0.033), but had no association with baseline clinical and biological parameters. Plasma BLVRB levels were also significantly higher in patients who developed recurrent ischemic stroke (1099.34 ± 928.49 vs. 582.07 ± 545.34 MFI, HR = 1.600, CI [1.092-2.344]; p = 0.016). Plasma BLVRB levels were significantly reduced following prevention of IPH by anti-VEGFR-2 therapy in mouse vein grafts (1189 ± 258.73 vs. 1752 ± 366.84 MFI; p = 0.004).

CONCLUSIONS

Plasma BLVRB was associated with IPH and increased risk of recurrent ischemic stroke in patients with symptomatic low- to moderate-grade carotid stenosis, indicating the capacity to monitor the efficacy of IPH-preventive pharmacotherapy in an animal model. Together, these results suggest the utility of plasma BLVRB as a biomarker for atherosclerotic plaque instability.

The Role of High-Resolution Magnetic Resonance Imaging in Cerebrovascular Disease: A Narrative Review

High-resolution magnetic resonance imaging (HRMRI) is the most important and popular vessel wall imaging technique for the direct assessment of vessel wall and cerebral arterial disease. It can identify the cause of stroke in high-risk plaques and differentiate the diagnosis of head and carotid artery dissection, including inflammation, Moya Moya disease, cerebral aneurysm, vasospasm after subarachnoid hemorrhage, reversible cerebral vasoconstriction syndrome, blunt cerebrovascular injury, cerebral arteriovenous malformations, and other stenosis or occlusion conditions. Through noninvasive visualization of the vessel wall in vitro, quantified assessment of luminal stenosis and pathological features of the vessel wall can provide clinicians with further disease information. In this report, technical considerations of HRMRI are discussed, and current clinical applications of HRMRI are reviewed.

Atherosclerotic carotid plaque characteristics vary with time from ischemic event: A multicenter, prospective magnetic resonance vessel wall imaging registry study

Recent studies report that the rate of recurrent stroke is highest in the stages immediately following cerebral infarction and decreases over time in patients with atherosclerotic carotid stenosis. The purpose of this study was to identify temporal differences in early stage carotid plaque components from acute cerebrovascular ischemic events using carotid MRI. Carotid plaque images were obtained on 3 T MRI from 128 patients enrolled in MR-CAS. Among the 128 subjects, 53 were symptomatic and 75 asymptomatic. The symptomatic patients were classified into three groups based on interval from onset of symptoms to the date of the carotid MRI (Group <14 days; 15-30 days; and > 30 days). The volume of each plaque component was identified and quantified from MR images. The presence of juxtaluminal loose matrix/inflammation (LM/I) was identified as a possible indicator of inflammation on the luminal side. Plaque components were compared between groups using the Wilcoxon rank-sum or the Chi-square test. Patient characteristics and carotid plaque morphology were similar among all four groups. The median volume of LM/I in Group >30 days was significantly lower than in other groups (0 mm3 vs 12.3 mm3 and 18.1 mm3; p = 0.003). In addition, the prevalence of juxtaluminal LM/I decreased over time (ptrend = 0.002). There were no statistically significant differences in other plaque components between the symptomatic groups. The volume of LM/I was significantly smaller in Group >30 days and prevalence of juxtaluminal LM/I in the atherosclerotic carotid plaque was high in the early stages after events. This suggests that carotid plaques undergo rapid evolution after an acute cerebrovascular ischemic event.

Carotid Plaque Vulnerability Diagnosis by CTA versus MRA: A Systematic Review

Stenosis grade of the carotid arteries has been the primary indicator for risk stratification and surgical treatment of carotid artery disease. Certain characteristics of the carotid plaque render it vulnerable and have been associated with increased plaque rupture rates. Computed tomography angiography (CTA) and magnetic resonance angiography (MRA) have been shown to detect these characteristics to a different degree. The aim of the current study was to report on the detection of vulnerable carotid plaque characteristics by CTA and MRA and their possible association. A systematic review of the medical literature was executed, utilizing PubMed, SCOPUS and CENTRAL databases, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 guidelines. The study protocol has been registered to PROSPERO (CRD42022381801). Comparative studies reporting on both CTA and MRA carotid artery studies were included in the analysis. The QUADAS tools were used for risk of bias diagnostic imaging studies. Outcomes included carotid plaque vulnerability characteristics described in CTA and MRA and their association. Five studies, incorporating 377 patients and 695 carotid plaques, were included. Four studies reported on symptomatic status (326 patients, 92.9%). MRA characteristics included intraplaque hemorrhage, plaque ulceration, type VI AHA plaque hallmarks and intra-plaque high-intensity signal. Intraplaque hemorrhage detected in MRA was the most described characteristic and was associated with increased plaque density, increased lumen stenosis, plaque ulceration and increased soft-plaque and hard-plaque thickness. Certain characteristics of vulnerable carotid plaques can be detected in carotid artery CTA imaging studies. Nevertheless, MRA continues to provide more detailed and thorough imaging. Both imaging modalities can be applied for comprehensive carotid artery work-up, each one complementing the other.

Evidence of Carotid Atherosclerosis Vulnerability Regression in Real Life From Magnetic Resonance Imaging: Results of the MAGNETIC Prospective Study

Background Atherosclerosis vulnerability regression has been evidenced mostly in randomized clinical trials with intensive lipid-lowering therapy. We aimed to demonstrate vulnerability regression in real life, with a comprehensive quantitative method, in patients with asymptomatic mild to moderate carotid atherosclerosis on a secondary prevention program. Methods and Results We conducted a single-center prospective observational study (MAGNETIC [Magnetic Resonance Imaging as a Gold Standard for Noninvasive Evaluation of Atherosclerotic Involvement of Carotid Arteries]): 260 patients enrolled at a cardiac rehabilitation center were followed for 3 years with serial magnetic resonance imaging. Per section cutoffs (95th/5th percentiles) were derived from a sample of 20 consecutive magnetic resonance imaging scans: (1) lipid-rich necrotic core: 26% of vessel wall area; (2) intraplaque hemorrhage: 12% of vessel wall area; and (3) fibrous cap: (a) minimum thickness: 0.06 mm, (b) mean thickness: 0.4 mm, (c) projection length: 11 mm. Patients with baseline magnetic resonance imaging of adequate quality (n=247) were classified as high (n=63, 26%), intermediate (n=65, 26%), or low risk (n=119, 48%), if vulnerability criteria were fulfilled in ≥2 contiguous sections, in 1 or multiple noncontiguous sections, or in any section, respectively. Among high-risk patients, a conversion to any lower-risk status was found in 11 (17%; P=0.614) at 6 months, in 16 (25%; P=0.197) at 1 year, and in 19 (30%; P=0.009) at 3 years. Among patients showing any degree of carotid plaque vulnerability, 21 (16%; P=0.014) were diagnosed at low risk at 3 years. Conclusions This study demonstrates with a quantitative approach that vulnerability regression is common in real life. A secondary prevention program can promote vulnerability regression in asymptomatic patients in the mid to long term.

Comparison of imaging findings on three-dimensional black-blood enhanced MR imaging between intracranial atherosclerotic occlusion and thrombotic occlusion

PURPOSE

The purpose of this study was to compare the imaging findings on three-dimensional (3D) black-blood (BB) contrast-enhanced MR imaging between intracranial atherosclerotic occlusion (IAO) and thrombotic occlusion (TO) of the middle cerebral artery (MCA) territory.

MATERIALS AND METHODS

From August 2020 to September 2021, we retrospectively reviewed the BB contrast-enhanced MR imaging of patients visiting the emergency room for evaluation of acute ischemic stroke. In total, 77 patients with complete occlusion of the MCA territory on 3D BB contrast-enhanced MR imaging and cerebral angiography were enrolled in this study. We divided the IAO and TO groups according to occlusion causes based on angiography findings.

RESULTS

Of 77 patients, 44 (57.1%) had an IAO in the M1 and M2 and 33 had a TO. Lesion length contrast enhancement (CE) in patients with a TO was significantly longer than that in patients with an IAO (18.95 mm [IQR: 20.91] vs. 7.1 mm [8.92], p <0.001). Overall, 38 (39.4%) patients showed a disconnection of CE on 3D BB contrast-enhanced MR imaging, and 35 showed CE before and after the stenotic or thrombotic lesion. Symptomatic lesions on diffusion-weighted imaging in the TO group were significantly higher than that of the IAO group (97.0% vs, 70.5%, p = 0.003).

CONCLUSION

The long segment CE on 3D BB contrast-enhanced MR imaging was related to TO of MCA. CE before and after a stenotic or thrombotic lesion is a common finding on 3D BB contrast-enhanced MR imaging.

Characteristics of Calcification and Their Association with Carotid Plaque Vulnerability

BACKGROUND

Carotid plaque vulnerability is one of the important features for evaluating the risk of subsequent ischemic stroke. Although magnetic resonance imaging (MRI) is the gold standard modality for evaluating plaque vulnerability, some patients cannot undergo MRI because of physical or economic issues. Computed tomography (CT) is more readily available. The purpose of this study was to establish a new category of calcification on CT and to assess its usefulness for detecting vulnerable plaque.

MATERIALS AND METHODS

We retrospectively evaluated consecutive patients who underwent plaque imaging using CT and MRI before carotid revascularization at our institute. Calcifications were classified into 4 types according to the new calcium classification. The patients were divided into 2 groups, the double layer sign (DLS)-positive group and the DLS-negative group. Signal intensity ratio (SIR) of carotid plaque was measured on MRI for evaluating plaque vulnerability and compared between type of calcification and SIR.

RESULTS

Among the 132 patients evaluated, 50 patients (62.5%) in DLS positive group and 16 patients (30.8%) in DLS negative group had calcification with vulnerable plaque (SIR > 1.47) (P < 0.01). Substantial interobserver agreement of type of calcification was observed (kappa, 0.79; P < 0.01). Multivariate analysis showed that DLS (odds ratio 3.03; 95% confidence interval 1.35-6.8; P < 0.01) and male sex (odds ratio 3.15; 95% confidence interval 1.02-9.68; P = 0.04) were independent predictors of vulnerable plaque.

CONCLUSIONS

DLS in our new classification of calcification on CT reliably detects vulnerable plaque and could thus be used in patients who cannot undergo MRI.

Reliability and Value of 3D Sequential QUantitative T1 -T2 -T2 * MAppings (SQUMA) MR Multi-Parametric Imaging in Characterizing Carotid Artery Atherosclerosis

BACKGROUND

T₁ , T₂ , and T₂ * mappings are seldom performed in a single examination, and their values in evaluating symptomatic atherosclerosis are lacking.

PURPOSE

To perform three-dimensional (3D) quantitative T₁ , T₂ , and T₂ * mappings (SQUMA) multi-parametric imaging for carotid vessel wall and evaluate its reliability and value in assessing carotid atherosclerosis.

STUDY TYPE

Prospective.

SUBJECTS

Eight healthy subjects and 20 patients with symptomatic carotid atherosclerosis.

FIELD STRENGTH/SEQUENCE

3 T, SQUMA imaging T₁ -, T₂ -, and T₂ *-mapping, multi-contrast vessel wall imaging including T₁ - and T₂ -weighted, time-of-flight, and SNAP sequences.

ASSESSMENT

SQUMA was acquired in all subjects and multi-contrast images were acquired in healthy subjects. T₁ , T₂ , and T₂ * values and lumen area (LA), wall area (WA), mean wall thickness (MeanWT), and normalized wall index (NWI) of carotid arteries were measured. SQUMA and multi-contrast measurements were compared in healthy subjects and differences in SQUMA measurements between healthy subjects and patients were assessed. The discriminative value of SQUMA measurements for symptomatic vessel was determined.

STATISTICAL TESTS

Paired t or Wilcoxon signed-rank test, independent t or Mann-Whitney U test, area under the receiver operating characteristic curve (AUC), intraclass correlation coefficients, and Bland-Altman plots. Statistically significant level, P < 0.05.

RESULTS

There were no significant differences in LA (P = 0.340), WA (P = 0.317), MeanWT (P = 0.088), and NWI (P = 0.091) of carotid arteries between SQUMA and multi-contrast vessel wall images. The values of T₂ (50.9 ± 2.9 msec vs. 44.5 ± 4.2 msec), T₂ * (28.2 ± 4.3 msec vs. 24.7 ± 2.6 msec), WA (23.7 ± 4.6 mm² vs. 36.2 ± 7.7 mm² ), MeanWT (0.99 ± 0.05 mm vs. 1.50 ± 0.28 mm), and NWI (40.7 ± 3.0% vs. 53.8 ± 5.4%) of carotid arteries in healthy subjects were significantly different from those in atherosclerotic patients. The combination of quantitative T₁ , T₂ , and T₂ * values and MeanWT showed greatest AUC (0.81; 95% CI: 0.65-0.92) in discriminating symptomatic vessels.

DATA CONCLUSION

Carotid MR 3D quantitative multi-parametric imaging of SQUMA enables acquisition of T₁ , T₂ , and T₂ * maps, reliably measuring carotid morphology and discriminating carotid symptomatic atherosclerosis.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 2.

Clinical features and long-term outcomes of symptomatic low-grade carotid stenosis

OBJECTIVE

In symptomatic low-grade stenosis, most of the reports did not clarify the long-term outcome. This study aims to clarify the clinical features and long-term outcomes of symptomatic low-grade stenosis cases.

MATERIALS AND METHODS

We included 123 symptomatic patients with low-grade (<50%) carotid stenosis. The relative plaque signal intensity (rSI) and expansive remodeling rate (ERR) were measured using carotid magnetic resonance imaging (MRI). Antiplatelet therapy and treatment for atherosclerosis risk factors were administered in all cases. Carotid endarterectomy (CEA) was performed when ischemic symptoms appeared, or the percent stenosis progressed despite medical treatment.

RESULTS

The mean percent stenosis, rSI, and ERR on admission were 22.3, 1.70, and 2.01, respectively. The mean volume of the hyperintense plaque on carotid MRI was 641.4± 540 mm3. Sixty percent of cases involved intraplaque hemorrhage and expansive remodeling. During a mean follow-up of 52 months, recurrence of ischemic events was confirmed in 45 cases (36.6%). Of the 67 cases performed follow-up MRI, 34 cases (50%) had an increased volume of T1-hyperintense plaque. CEA or carotid artery stenting was performed in 49 cases. During a mean follow-up of 57.8 months after CEA, two cases of death (fatal intracerebral hemorrhage and asphyxia) and one case of brain stem lacunar infarction were observed, but ipsilateral ischemic events were not.

CONCLUSION

Most of the symptomatic patients with low-grade stenosis had both intraplaque hemorrhage and expansive remodeling and presented a high risk of recurrence and stenosis progression. CEA may have preventive effects against ischemic events in low-grade stenosis.

The role of cross-sectional imaging of the extracranial and intracranial vasculature in embolic stroke of undetermined source

Despite an extensive workup, nearly one third of ischemic strokes are defined as Embolic Stroke of Undetermined Source (ESUS), indicating that no clear etiologic cause has been identified. Since large vessel atherosclerotic disease is a major cause of ischemic stroke, we focus on imaging of large vessel atherosclerosis to identify further sources of potential emboli which may be contributing to ESUS. For a stroke to be considered ESUS, both the extracranial and intracranial vessels must have <50% stenosis. Given the recent paradigm shift in our understanding of the role of plaque vulnerability in ischemic stroke risk, we evaluate the role of imaging specific high-risk extracranial plaque features in non-stenosing plaque and their potential contributions to ESUS. Further, intracranial vessel-wall MR is another potential tool to identify non-stenosing atherosclerotic plaques which may also contribute to ESUS. In this review, we discuss the role of cross-sectional imaging of the extracranial and intracranial arteries and how imaging may potentially uncover high risk plaque features which may be contributing to ischemic strokes.

The 2nd European Carotid Surgery Trial (ECST-2): rationale and protocol for a randomised clinical trial comparing immediate revascularisation versus optimised medical therapy alone in patients with symptomatic and asymptomatic carotid stenosis at low to intermediate risk of stroke

Background

Carotid endarterectomy is currently recommended for patients with recently symptomatic carotid stenosis ≥50%, based on randomised trials conducted 30 years ago. Several factors such as carotid plaque ulceration, age and associated comorbidities might influence the risk-benefit ratio of carotid revascularisation. A model developed in previous trials that calculates the future risk of stroke based on these features can be used to stratify patients into low, intermediate or high risk. Since the original trials, medical treatment has improved significantly. Our hypothesis is that patients with carotid stenosis ≥50% associated with a low to intermediate risk of stroke will not benefit from additional carotid revascularisation when treated with optimised medical therapy. We also hypothesise that prediction of future risk of stroke in individual patients with carotid stenosis can be improved using the results of magnetic resonance imaging (MRI) of the carotid plaque.

Methods

Patients are randomised between immediate revascularisation plus OMT versus OMT alone. Suitable patients are those with asymptomatic or symptomatic carotid stenosis ≥50% with an estimated 5-year risk of stroke of <20%, as calculated using the Carotid Artery Risk score. MRI of the brain at baseline and during follow-up will be used as a blinded measure to assess the incidence of silent infarction and haemorrhage, while carotid plaque MRI at baseline will be used to investigate the hypotheses that plaque characteristics determine future stroke risk and help identify a subgroup of patients that will benefit from revascularisation. An initial analysis will be conducted after recruitment of 320 patients with baseline MRI and a minimum of 2 years of follow-up, to provide data to inform the design and sample size for a continuation or re-launch of the study. The primary outcome measure of this initial analysis is the combined 2-year rate of any clinically manifest stroke, new cerebral infarct on MRI, myocardial infarction or periprocedural death.

Discussion

ECST-2 will provide new data on the efficacy of modern optimal medical therapy alone versus added carotid revascularisation in patients with carotid stenosis at low to intermediate risk of future stroke selected by individualised risk assessment. We anticipate that the results of baseline brain and carotid plaque MRI will provide data to improve the prediction of the risk of stroke and the effect of treatment in patients with carotid stenosis.

Trial registration

ISRCTN registry ISRCTN97744893. Registered on 05 July 2012

Carotid vulnerable plaque coexisting with cerebral small vessel disease and acute ischemic stroke: a Chinese Atherosclerosis Risk Evaluation study

OBJECTIVES

We aimed to investigate the associations between carotid vulnerable plaque features coexisting with cerebral small vessel diseases (CSVDs) and acute ischemic stroke (AIS) and, furthermore, to determine whether coexisting diseases had a stronger association with AIS than a single disease.

METHODS

Patients with cerebrovascular symptoms and carotid plaque were recruited from the cross-sectional, multicenter CARE-II study. The population was divided into two groups (AIS and transient ischemic stroke (TIA)). MRI features of carotid plaques (including luminal stenosis and plaque vulnerabilities) and CSVDs (such as white matter hyperintensities (WMHs) and lacunes) were evaluated. Coexisting diseases were defined as the presence of at least one carotid plaque features and one or more CSVDs feature. Multivariate logistic regression was performed to examine the associations between coexisting diseases and AIS.

RESULTS

Of the recruited 634 patients (mean age: 59.1 ± 11.3 years; 429 males), 312 (49.2%) patients had AIS. These subjects had a higher prevalence of carotid vulnerable plaques, lacunes, and moderate-to-severe WMHs (a total Fazekas score of 3-6) than those with TIA (42.6% vs. 29.5%, 59.6% vs. 26.4%, 69.9% vs. 60.6%, respectively, all p < 0.05). Multivariate analysis revealed that carotid plaque features coexisting with lacunes or moderate-to-severe WMHs had a stronger association with AIS compared to carotid lesions alone (all p < 0.05) (i.e., vulnerable plaque coexisting with lacunes vs. vulnerable plaque alone, adjusted odds ratio: 3.67 vs. 1.62).

CONCLUSIONS

Carotid vulnerable plaque features coexisting with CSVDs, particularly lacunes, had a stronger association with AIS compared to carotid lesions alone in a large, symptomatic, cohort.

TRIAL REGISTRATION

Clinical trial registration URL: http://www.

CLINICALTRIALS

gov , unique identifier: NCT02017756 KEY POINTS: • Carotid vulnerable plaque features coexisting with cerebral small vessel diseases, such as lacunes, had a stronger association with acute ischemic stroke compared to single diseases in symptomatic patients. • A comprehensive assessment of coexisting cerebrovascular diseases may help stratify the risk of acute ischemic stroke.

Co-existing Hypertension and Hyperhomocysteinemia Increases the Risk of Carotid Vulnerable Plaque and Subsequent Vascular Event: An MR Vessel Wall Imaging Study

Purpose

This study sought to determine the associations of co-existing hypertension and hyperhomocysteinemia (H-Hcy) with carotid vulnerable plaque features and subsequent vascular events.

Methods

Symptomatic patients with carotid atherosclerosis were enrolled and underwent carotid magnetic resonance (MR) vessel wall imaging. The patients were divided into the following groups: co-existing hypertension and H-Hcy group; isolated hypertension group; isolated H-Hcy group; and control group. The morphological and compositional characteristics of carotid plaques were assessed on MR images and compared among different groups. Univariate and multivariate cox regressions were used to calculate the hazard ratio (HR) and corresponding 95% confidence interval (CI) of co-existing hypertension and H-Hcy in predicting subsequent vascular events after at least 1-year followed-up.

Results

In total, 217 patients (mean age, 59.4 ± 11.9 years; 154 males) were recruited. Patients in co-existing hypertension and H-Hcy group had a significantly higher prevalence of carotid lipid-rich necrotic core (LRNC) than isolated H-Hcy and control group (73.2 vs. 43.3 vs. 50%, p = 0.015). During the median follow-up time of 12.2 ± 4.3 months, 61 (39.8%) patients experienced vascular events. After adjusting for baseline confounding factors, co-existing hypertension and H-Hcy (HR, 1.82; 95% CI, 1.01–3.27; p = 0.044), presence of carotid LRNC (HR, 2.25; 95% CI, 1.09–4.65; p = 0.029), and combination of co-existing hypertension and H-Hcy and carotid LRNC (HR, 2.39; 95% CI, 1.26–4.43; p = 0.007) were significantly associated with subsequent vascular events.

Conclusions

Co-existing hypertension and H-Hcy are associated with carotid vulnerable plaque features, such as LRNC. Combining co-existing hypertension and H-Hcy with carotid vulnerable plaque features has a stronger predictive value for subsequent vascular events than each measurement alone.

Detection of Vulnerable Coronary Plaques Using Invasive and Non-Invasive Imaging Modalities

Acute coronary syndrome (ACS) mostly arises from so-called vulnerable coronary plaques, particularly prone for rupture. Vulnerable plaques comprise a specific type of plaque, called the thin-cap fibroatheroma (TFCA). A TCFA is characterized by a large lipid-rich necrotic core, a thin fibrous cap, inflammation, neovascularization, intraplaque hemorrhage, microcalcifications or spotty calcifications, and positive remodeling. Vulnerable plaques are often not visible during coronary angiography. However, different plaque features can be visualized with the use of intracoronary imaging techniques, such as intravascular ultrasound (IVUS), potentially with the addition of near-infrared spectroscopy (NIRS), or optical coherence tomography (OCT). Non-invasive imaging techniques, such as computed tomography coronary angiography (CTCA), cardiovascular magnetic resonance (CMR) imaging, and nuclear imaging, can be used as an alternative for these invasive imaging techniques. These invasive and non-invasive imaging modalities can be implemented for screening to guide primary or secondary prevention therapies, leading to a more patient-tailored diagnostic and treatment strategy. Systemic pharmaceutical treatment with lipid-lowering or anti-inflammatory medication leads to plaque stabilization and reduction of cardiovascular events. Additionally, ongoing studies are investigating whether modification of vulnerable plaque features with local invasive treatment options leads to plaque stabilization and subsequent cardiovascular risk reduction.

Proximal Region of Carotid Atherosclerotic Plaque Shows More Intraplaque Hemorrhage: The Plaque at Risk Study

BACKGROUND AND PURPOSE

Intraplaque hemorrhage contributes to lipid core enlargement and plaque progression, leading to plaque destabilization and stroke. The mechanisms that contribute to the development of intraplaque hemorrhage are not completely understood. A higher incidence of intraplaque hemorrhage and thin/ruptured fibrous cap (upstream of the maximum stenosis in patients with severe [≥70%] carotid stenosis) has been reported. We aimed to noninvasively study the distribution of intraplaque hemorrhage and a thin/ruptured fibrous cap in patients with mild-to-moderate carotid stenosis.

MATERIALS AND METHODS

Eighty-eight symptomatic patients with stroke (<70% carotid stenosis included in the Plaque at Risk study) demonstrated intraplaque hemorrhage on MR imaging in the carotid artery plaque ipsilateral to the side of TIA/stroke. The intraplaque hemorrhage area percentage was calculated. A thin/ruptured fibrous cap was scored by comparing pre- and postcontrast black-blood TSE images. Differences in mean intraplaque hemorrhage percentages between the proximal and distal regions were compared using a paired-samples t test. The McNemar test was used to reveal differences in proportions of a thin/ruptured fibrous cap.

RESULTS

We found significantly larger areas of intraplaque hemorrhage in the proximal part of the plaque at 2, 4, and 6 mm from the maximal luminal narrowing, respectively: 14.4% versus 9.6% (P = .04), 14.7% versus 5.4% (P < .001), and 11.1% versus 2.2% (P = .001). Additionally, we found an increased proximal prevalence of a thin/ruptured fibrous cap on MR imaging at 2, 4, 6, and 8 mm from the MR imaging section with the maximal luminal narrowing, respectively: 33.7% versus 18.1%, P = .007; 36.1% versus 7.2%, P < .001; 33.7% versus 2.4%, P = .001; and 30.1% versus 3.6%, P = .022.

CONCLUSIONS

We demonstrated that intraplaque hemorrhage and a thin/ruptured fibrous cap are more prevalent on the proximal side of the plaque compared with the distal side in patients with mild-to-moderate carotid stenosis.

Multi-Sequence MRI Registration of Atherosclerotic Carotid Arteries Based on Cross-Scale Siamese Network

Cardiovascular disease (CVD) is a common disease with high mortality rate, and carotid atherosclerosis (CAS) is one of the leading causes of cardiovascular disease. Multisequence carotid MRI can not only identify carotid atherosclerotic plaque constituents with high sensitivity and specificity, but also obtain different morphological features, which can effectively help doctors improve the accuracy of diagnosis. However, it is difficult to evaluate the accurate evolution of local changes in carotid atherosclerosis in multi-sequence MRI due to the inconsistent parameters of different sequence images and the geometric space mismatch caused by the motion deviation of tissues and organs. To solve these problems, we propose a cross-scale multi-modal image registration method based on the Siamese U-Net. The network uses sub-networks with image inputs of different sizes to extract various features, and a special padding module is designed to make the network available for training on cross-scale features. In addition, to improve the registration performance, a multi-scale loss function under Gaussian smoothing is applied for optimization. For the experiments, we have collected a multi-sequence MRI image dataset from 11 patients with carotid atherosclerosis for a retrospective study. We evaluate our overall architectures by cross-validation on our carotid dataset. The experimental results show that our method can generate precise and reliable results with cross-scale multi-sequence inputs and the registration accuracy can be greatly improved by using the Gaussian smoothing loss function. The DSC of our Siamese structure can reach 84.1% on the carotid data set with cross-size input. With the use of GDSC loss, the average DSC can be improved by 5.23%, while the average distance between fixed landmarks and moving landmarks can be decreased by 6.46%.Our code is made publicly available at: https://github.com/MingHan98/Cross-scale-Siamese-Unet.

Risk Factors for Asymptomatic and Symptomatic Intracranial Atherosclerosis Determined by Magnetic Resonance Vessel Wall Imaging in Chinese Population: A Case–Control Study

Background and Purpose

The association between risk factors and intracranial atherosclerosis disease (ICAD) determined by magnetic resonance (MR) vessel wall imaging in Chinese population has not been investigated. The aim of this study was to investigate the associations of conventional vascular risk factors with asymptomatic and symptomatic ICAD using MR vessel wall imaging in Chinese population.

Methods

The study population was recruited from two cohort studies of ICASMAP and CAMERA comprised 104 symptomatic ICAD subjects (57.1 ± 11.1 years; 35.6% females), 51 asymptomatic ICAD subjects (70.1 ± 8.4 years; 50.0% females) and 418 controls (58.0 ± 13.3 years; 61.0% females) defined as asymptomatic subjects without ICAD on MR vessel wall imaging. We compared the vascular risk factors between the three groups using a multivariate logistic regression analysis.

Results

Compared with controls, there was a significant positive association between age (OR: 1.07, 95% CI: 1.03–1.10, p < 0.001) and hypertension (OR: 3.03, 95% CI: 1.45–6.36, p = 0.003) and asymptomatic ICAD. There was a positive association of smoking (OR: 3.41, 95% CI: 1.57–7.42, p = 0.001), hypertension (OR: 7.43, 95% CI: 3.81–14.49, p < 0.001) and diabetes (OR: 3.54, 95% CI: 1.93–6.49, p < 0.001) and an inverse association of high-density lipoprotein (HDL) (p < 0.017) with symptomatic ICAD. Compared to asymptomatic ICAD, there was a significant inverse association of age (OR: 0.86, 95% CI: 0.81–0.92, p < 0.001) and HDL (p < 0.001) with symptomatic ICAD.

Conclusion

Old age and hypertension are associated with asymptomatic ICAD and smoking, hypertension, diabetes and lower HDL are associated with an increased risk of symptomatic ICAD in Chinese population.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT03417063.

Free-Breathing Three-Dimensional Isotropic-Resolution MR sequence for simultaneous vessel wall imaging of bilateral renal arteries and abdominal aorta: Feasibility and reproducibility

PURPOSE

Many diseases can simultaneously involve renal arteries and the adjacent abdominal aorta. The study proposed a free-breathing three-dimensional (3D) isotropic-resolution MR sequence for simultaneous vessel wall imaging of bilateral renal arteries and adjacent abdominal aorta.

METHODS

A respiratory triggered isotropic-resolution sequence which combined the improved motion-sensitized driven-equilibrium (iMSDE) preparation with the spoiled gradient recalled (SPGR) readout (iMSDE-SPGR) was proposed for simultaneous vessel wall imaging of renal arteries and abdominal aorta. The proposed iMSDE-SPGR sequence was optimized by positioning spatial saturation pulses (i.e. REST slabs) elaborately to further alleviate respiratory and gastrointestinal motion artifacts and selecting appropriate first-order gradient moment (m₁ ) of the iMSDE preparation. Thirteen healthy subjects and thirteen patients with renal artery stenosis (RAS) underwent simultaneous vessel wall imaging with the optimized iMSDE-SPGR sequence at 3.0T. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and morphology of renal arterial wall and aortic wall were measured. Reproducibility of intra-observer, inter-observer and scan-rescan (n = 13 healthy subjects) in measuring SNR, CNR and morphology was evaluated. For the reproducibility test, the agreement was determined using intraclass correlation coefficients (ICC) and the differences were compared using paired-t test or non-parametric Wilcoxon test when appropriate. Bland-Altman plots were used to calculate the bias between observers and between scans.

RESULTS

The proposed iMSDE-SPGR sequence was feasible for simultaneous vessel wall imaging both in the healthy subjects and the patients. The sequence showed good to excellent inter-observer (ICC:0.615-0.999), excellent intra-observer (ICC:0.801-0.998) and scan-rescan (ICC:0.768-0.998) reproducibility in measuring morphology, SNR and CNR. There were no significant differences in SNR, CNR and morphology measurements between observers and between scans (all P>0.05). Bland-Altman plots showed small bias in assessing SNR, CNR and morphology.

DATA CONCLUSION

The proposed free-breathing 3D isotropic-resolution iMSDE-SPGR technique is feasible and reproducible for simultaneous vessel wall imaging of bilateral renal arteries and adjacent abdominal aorta. This article is protected by copyright. All rights reserved.

CT angiographic biomarkers help identify vulnerable carotid artery plaque

OBJECTIVE

Current risk assessment for patients with carotid atherosclerosis relies primarily on measuring the degree of stenosis. More reliable risk-stratification could improve patient selection for targeted treatment. We developed and validated a model to predict major adverse neurological events (MANE; stroke, transient ischemic attack, and amaurosis fugax) incorporating a combination of plaque morphology, patient demographics, and patient clinical information.

METHODS

We enrolled 221 patients with asymptomatic carotid stenosis of any severity who had CT angiography at baseline and at least 6 months later. Images were analyzed for carotid plaque morphology (plaque geometry and tissue composition). Data were partitioned (training and validation cohorts). 190 patients had complete records and were advanced to analysis. The training cohort was used to develop the best model for predicting MANE, incorporating patient and plaque features. First, single-variable correlation and unsupervised clustering were performed. Next, several multi-variable models were implemented for the response variable of MANE. The best model was selected by optimizing area under the receiver operating characteristic curve (AUC, ROC) and Kappa. The model was validated on the sequestered data to demonstrate generalizability.

RESULTS

Sixty-two patients suffered a MANE on follow-up. Unsupervised clustering of patient and plaque features identified single-variable predictors of MANE. Multi-variable predictive modeling showed that a combination of plaque features at baseline (matrix, intra-plaque hemorrhage (IPH), wall thickness, plaque burden) with clinical features (age, BMI, lipid levels) best predicted MANE (AUC 0.79), while percent diameter stenosis performed worst (AUC 0.55). The strongest single variable in discriminating between patients with and without events was IPH, and the most predictive model was produced when IPH was considered together with wall remodeling. The selected model also performed well on the validation dataset (AUC of 0.64) and maintained superiority over percent diameter stenosis (AUC of 0.49).

CONCLUSIONS

A composite of plaque geometry, plaque tissue composition, patient demographics, and clinical information predicts MANE better than the traditionally utilized degree of stenosis alone in carotid atherosclerosis. Implementing this predictive model in the clinical setting can help identify patients at high-risk for major adverse neurological events.

Carotid Artery Plaque Calcifications: Lessons From Histopathology to Diagnostic Imaging

The role of calcium in atherosclerosis is controversial and the relationship between vascular calcification and plaque vulnerability is not fully understood. Although calcifications are present in ≈50% to 60% of carotid plaques, their association with cerebrovascular ischemic events remains unclear. In this review, we summarize current understanding of carotid plaque calcification. We outline the role of calcium in atherosclerotic carotid disease by analyzing laboratory studies and histopathologic studies, as well as imaging findings to understand clinical implications of carotid artery calcifications. Differences in mechanism of calcium deposition express themselves into a wide range of calcification phenotypes in carotid plaques. Some patterns, such as rim calcification, are suggestive of plaques with inflammatory activity with leakage of the vasa vasourm and intraplaque hemorrhage. Other patterns such as dense, nodular calcifications may confer greater mechanical stability to the plaque and reduce the risk of embolization for a given degree of plaque size and luminal stenosis. Various distributions and patterns of carotid plaque calcification, often influenced by the underlying systemic pathological condition, have a different role in affecting plaque stability. Modern imaging techniques afford multiple approaches to assess geometry, pattern of distribution, size, and composition of carotid artery calcifications. Future investigations with these novel technologies will further improve our understanding of carotid artery calcification and will play an important role in understanding and minimizing stroke risk in patients with carotid plaques.

Additional Effect of Coronary High-Intensity Plaque on T1-Weighted Magnetic Resonance Imaging With Circulating Malondialdehyde-Modified Low-Density Lipoprotein on Cardiac Events

BACKGROUND

Although elevated levels of oxidized low-density lipoprotein (LDL) could play a critical role in vulnerable plaque, there are no studies that have compared coronary high-intensity plaque (HIP) and circulating malondialdehyde-modified (MDA)-LDL levels for the prediction of cardiac events.

METHODS AND RESULTS

A total of 139 patients with coronary artery stenosis (>70%) were examined with non-contrast T1-weighted magnetic resonance imaging (MRI) (HIP: n=64, non-HIP: n=75). Scheduled percutaneous coronary intervention (PCI) for culprit lesions was performed within 48 h after MRI. HIP was defined as a signal intensity of coronary plaque to cardiac muscle ratio (PMR) ≥1.4. We evaluated the subsequent major adverse cardiac events (MACE) during the follow-up period (5.6±1.3 years). MDA-LDL levels were independently associated with the presence of HIP (P<0.0001). The incidence of MACE was 15%, and it was significantly higher in patients with HIP (27%) than in those without HIP (5%; P=0.011). Cox proportional hazard analysis showed MDA-LDL levels (P=0.007) and PMR (P=0.016) were significantly associated with MACE. For MACE prediction, C-statistic values for MDA-LDL, PMR, and PMR+MDA-LDL were 0.724, 0.791, and 0.800, respectively. Compared with MDA-LDL alone, the addition of PMR to MDA-LDL increased net reclassification improvement by 0.78 (P=0.012).

CONCLUSIONS

MDA-LDL levels might be associated with the presence of HIP in patients with coronary artery disease. Furthermore, adding PMR to MDA-LDL levels markedly improved prediction of subsequent MACE after PCI.