MRI plaque imaging reveals high-risk carotid plaques especially in diabetic patients irrespective of the degree of stenosis

Associations between carotid plaque shape, biomechanical parameters, and ischemic stroke in mild carotid stenosis with a single plaque

PURPOSE

This cross-sectional cohort-comparison observational study investigated the value of high-frame-rate vector flow (V Flow) imaging for evaluating differences in carotid plaque shape and biomechanical parameters in patients with mild stenosis according to a recent history of ipsilateral ischemic stroke.

METHODS

The present study included 352 patients from February 2023 to October 2023, who were categorized as symptomatic or asymptomatic based on a history of recent ischemic stroke and ipsilateral ischemic lesions detected on head computed tomography or magnetic resonance imaging. A Mindray Resona R9 system was used for B-mode ultrasonography and V Flow imaging. The upstream and downstream surfaces of the plaques were examined at the carotid bifurcation for wall shear stress (WSS), oscillatory shear index (OSI), and turbulence index, which performed peri-plaque biomechanical condition. Multivariable logistic regression models were used to determine associations between plaque shape, V Flow parameters, and ischemic stroke.

RESULTS

Symptomatic patients exhibited higher WSS values for the upstream and downstream surfaces of carotid plaque, as well as higher OSI and turbulence index values for the downstream surface. Type Ⅲ plaques and higher WSS and OSI values for the downstream surface of the plaque were significantly associated with ischemic stroke. Type Ⅲ plaques were more prevalent in symptomatic patients and demonstrated much higher WSS and OSI values for the downstream plaque surface in both groups.

CONCLUSION

High-frame-rate V Flow imaging could assess peri-plaque biomechanical forces and may provide effective imaging biomarkers for early prediction of ischemic stroke in patients with mild stenosis.

CD40-targeting magnetic nanoparticles for MRI/optical dual-modality molecular imaging of vulnerable atherosclerotic plaques

BACKGROUND AND AIMS

Acute coronary syndrome caused by vulnerable plaque rupture or erosion is a leading cause of death worldwide. CD40 has been reported to be highly expressed in atherosclerotic plaques and closely related to plaque stability. Therefore, CD40 is expected to be a potential target for the molecular imaging of vulnerable plaques in atherosclerosis. We aimed to design a CD40-targeted magnetic resonance imaging (MRI)/optical multimodal molecular imaging probe and explore its ability to detect and target vulnerable atherosclerotic plaques.

METHODS

CD40-Cy5.5 superparamagnetic iron oxide nanoparticles (CD40-Cy5.5-SPIONs), which comprise a CD40-targeting multimodal imaging contrast agent, were constructed by conjugating CD40 antibody and Cy5.5-N-hydroxysuccinimide ester with SPIONs. During this in vitro study, we observed the binding ability of CD40-Cy5.5-SPIONs with RAW 264.7 cells and mouse aortic vascular smooth muscle cells (MOVAS) after different treatments, using confocal fluorescence microscopy and Prussian blue staining. An in vivo study involving ApoE^-/- mice fed a high-fat diet for 24-28 weeks was performed. 24 h after intravenous injection of CD40-Cy5.5-SPIONs, fluorescence imaging and MRI were performed.

RESULTS

CD40-Cy5.5-SPIONs bind specifically to tumor necrosis factor (TNF)-α-treated macrophages and smooth muscle cells. Fluorescence imaging results showed that, compared with the control group and the atherosclerosis group injected with non-specific bovine serum albumin (BSA)-Cy5.5-SPIONs, the atherosclerotic group injected with CD40-Cy5.5-SPIONs had a stronger fluorescence signal. T2-weighted images showed that the carotid arteries of atherosclerotic mice injected with CD40-Cy5.5-SPIONs had a significant substantial T2 contrast enhancement effect.

CONCLUSIONS

CD40-Cy5.5-SPIONs could potentially serve as an effective MRI/optical probe for vulnerable atherosclerotic plaques during non-invasive detection.

Predictive Value of Non-high-Density Lipoprotein Cholesterol and Neutrophil-Lymphocyte Ratio for Coronary Artery Vulnerable Plaques in Type 2 Diabetes Mellitus

Background

Patients with diabetes have an increased risk of developing vulnerable plaques (VPs), in which dyslipidemia and chronic inflammation play important roles. Non-high-density lipoprotein cholesterol (non-HDL-C) and neutrophil-lymphocyte ratio (NLR) have emerged as potential markers of both coronary artery VPs and cardiovascular prognosis. This study aimed to investigate the predictive value of non-HDL-C and NLR for coronary artery VPs in patients with type 2 diabetes mellitus (T2DM).

Methods

We retrospectively enrolled 204 patients with T2DM who underwent coronary computed tomography angiography between January 2018 and June 2020. Clinical data including age, sex, hypertension, smoking, total cholesterol, low-density lipoprotein cholesterol, HDL-C, triglyceride, non-HDL-C, glycated hemoglobin, neutrophil count, lymphocyte count, NLR, and platelet count were analyzed. Multivariate logistic regression was used to estimate the association between non-HDL-C, NLR, and coronary artery VPs. Receiver operating curve analysis was performed to evaluate the value of non-HDL-C, NLR, and their combination in predicting coronary artery VPs.

Results

In our study, 67 patients (32.84%) were diagnosed with VPs, 75 (36.77%) with non-VP, and 62 (30.39%) with no plaque. Non-HDL-C and NLR were independent risk factors for coronary artery VPs in patients with T2DM. The areas under the ROC curve of non-HDL-C, NLR, and their combination were 0.748 [95% confidence interval (CI): 0.676-0.818], 0.729 (95% CI: 0.650-0.800), and 0.825 (95% CI: 0.757-0.887), respectively.

Conclusion

Either non-HDL-C or NLR could be used as a predictor of coronary artery VPs in patients with T2DM, but the predictive efficiency and sensitivity of their combination would be better.

Association of Carotid Plaque Vulnerability and Cardiovascular Risk Factors in Patients Undergoing Carotid Endarterectomy

BACKGROUND

The association between high-risk cardiovascular factors and atherosclerotic is well established. However, whether plaque vulnerability is related to specific cardiovascular risk factors remains unknown. The association between plaque vulnerability and cardiovascular risk factors was evaluated in plaques removed in a carotid endarterectomy.

METHODS

Consecutive subjects scheduled for a carotid endarterectomy were recruited. All patients' baseline characteristics, risk factors, laboratory results, cardiovascular disease history, and medication use history were collected preoperatively. Histopathologic features within the vulnerable plaques were analyzed postoperatively. Risk factors for plaque vulnerability were assessed by univariate and multivariate analyses with adjustment for potential confounders.

RESULTS

A total of 128 carotid plaques were removed during the carotid endarterectomy. On multivariate analysis, hypertension (odds ratio [OR] 5.971, 95% confidence interval [CI] 1.959-18.203, P = 0.002) and dyslipidemia (OR 3.822, 95% CI 1.317-11.089, P = 0.014) were independently associated with plaque vulnerability. Hypertension was independently associated with the presence of a ruptured fibrous cap (OR 6.122, 95% CI 2.318-16.166, P < 0.001), intraplaque hemorrhage (OR 3.535, 95% CI 1.551-8.055, P = 0.003), and a large lipid core (OR 2.335, 95% CI 1.053-5.180, P = 0.037). The incidence of having a large lipid core was increased by 3.216-fold in patients with dyslipidemia (95% CI 1.409-7.340, P = 0.006). When the multivariate analysis was restricted to symptomatic patients, hypertension (OR 5.005, 95% CI 1.294-19.350, P = 0.020) was the most significant risk factor associated with vulnerable plaque.

CONCLUSION

The composition heterogeneity in the atherosclerotic plaque was significantly correlated to specific cardiovascular risk factors.

Complex Aortic Arch Atherosclerosis in Acute Ischemic Stroke Patients with Non-Valvular Atrial Fibrillation

AIM

Aortic arch atherosclerosis, particularly complex aortic arch plaques (CAPs), is an important source of cerebral emboli. CAPs and atrial fibrillation (AF) often co-exist; however, the prevalence and risk of CAPs in acute ischemic stroke patients with AF is unclear.

METHODS

In patients with acute ischemic stroke with non-valvular AF admitted to Jichi Medical University Hospital during April 2016 to September 2019, we retrospectively evaluated the presence of CAPs on transesophageal echocardiography (TEE).

RESULTS

CAPs were observed in 41 (38.7 %) of 106 patients with non-valvular AF. Older age, diabetes mellitus, chronic kidney disease, low high-density lipoprotein cholesterol (HDL-C) levels, higher levels of glycohemoglobin A1c (HbA1c), higher CHADS2 and CHA2DS2-VASc scores, and intracranial or carotid artery stenosis were more frequently observed in CAPs-positive than in CAPs-negative patients. In multivariable analyses, older age (odds ratio [OR]: 1.2 per year increase; 95% confidence interval [CI]: 1.07-1.24; P＜0.0001), diabetes mellitus (OR: 4.7; 95%CI: 1.27-17.35; P＜0.05), and low HDL-C (OR: 0.95 per 1 mg/dl increase; 95%CI: 0.92-0.99; P＜0.01) were independent risk factors for CAPs. The prevalence of CAPs was age-dependent, and there was a significantly higher risk in patients aged either 75-84 years or ＞84 years than in those aged ＜65 (OR: 7.6; 95%CI: 1.50-38.62, and OR: 32.1; 95%CI: 5.14-200.11, respectively).

CONCLUSIONS

Even in patients with ischemic stroke with non-valvular AF, concomitant CAPs should be considered in older individuals and those who have diabetes or low HDL-C.

Association between type 2 diabetes mellitus, especially recently uncontrolled glycemia, and intracranial plaque characteristics: A high-resolution magnetic resonance imaging study

AIMS/INTRODUCTION

Type 2 diabetes mellitus is a specific risk factor for intracranial atherosclerosis. The purpose of this study was to investigate the relationship between type 2 diabetes mellitus, especially uncontrolled glycemia, and intracranial plaque characteristics using high-resolution magnetic resonance imaging.

MATERIALS AND METHODS

A total of 263 patients (182 men; mean age 62.6 ± 11.5 years) with intracranial atherosclerotic plaques detected on high-resolution magnetic resonance imaging from December 2017 to March 2019 were included in this study. Patients were divided into different groups: (i) patients with and without type 2 diabetes mellitus; (ii) diabetes patients with uncontrolled glycemia (glycated hemoglobin level ≥7.0%) and controlled glycemia; and (iii), diabetes patients with diabetes duration of <5, 5-10 and >10 years. Comparisons of plaque features between groups were made, respectively.

RESULTS

Type 2 diabetes mellitus was diagnosed in 118 patients (44.9%). Diabetes patients had a significantly greater prevalence of enhanced plaque, greater maximum plaque length, maximum wall thickness and more severe luminal stenosis than non-diabetes patients. Compared with diabetes patients with controlled glycemia, those with uncontrolled glycemia had a significantly greater prevalence of enhanced plaque and greater maximum plaque length (all P < 0.05). There were no significant differences in plaque features among patients with different durations of type 2 diabetes mellitus. Uncontrolled glycemia was an independent factor for plaque enhancement after adjustment for potential confounding factors (odds ratio 5.690; 95% confidence interval 1.748-18.526; P = 0.004).

CONCLUSIONS

Type 2 diabetes mellitus is closely related to intracranial plaque enhancement and burden. Recently uncontrolled glycemia might play an important role in the development of enhanced plaque.

Carotid plaque imaging profiling in subjects with risk factors (diabetes and hypertension)

Carotid artery stenosis (CAS) due to the presence of atherosclerotic plaque (AP) is a frequent medical condition and a known risk factor for stroke, and it is also known from literature that several risk factors promote the AP development, in particular aging, smoke, male sex, hypertension, hyperlipidemia, smoke, diabetes type 1 and 2, and genetic factors. The study of carotid atherosclerosis is continuously evolving: even if the strategies of treatment still depends mainly on the degree of stenosis (DoS) determined by the plaque, in the last years the attention has moved to the study of the plaque components in order to identify the so called "vulnerable" plaque: features like the fibrous cap status and thickness, the volume of the lipid-rich necrotic core and the presence of intraplaque hemorrhage (IPH) are risk factors for plaque rupture, that can be studied with modern imaging techniques. The aim of this review is to give a general overview of the principle histological and imaging features of the subcomponent of carotid AP (CAP), focalizing in particular on the features of CAP of patients affected by hypertension and diabetes (in particular type 2 diabetes mellitus).

Differences in Carotid Plaques Between Symptomatic Patients With and Without Diabetes Mellitus

Objective- Diabetes mellitus is associated with high-risk atherosclerotic plaques. This study aimed to compare characteristics of carotid atherosclerotic plaques in symptomatic Chinese diabetic and nondiabetic patients using vessel wall magnetic resonance imaging. Approach and Results- Patients with cerebral ischemic symptoms in the anterior circulation and carotid atherosclerotic plaque determined by ultrasound were recruited from a cross-sectional, observational, multicenter study of CARE-II (Chinese Atherosclerosis Risk Evaluation). All patients underwent magnetic resonance imaging for carotid arteries. The morphological and compositional characteristics of carotid plaques were compared between diabetic and nondiabetic patients using linear (continuous variables) and logistic regression (binary variables). In a total of 584 recruited patients, 182 (31.2%) had diabetes mellitus. From the univariate analysis, diabetic patients had significantly greater mean wall area (33.7 versus 31.1 mm²; P=0.002), maximum wall thickness (3.2 versus 2.8 mm; P<0.001), and mean normalized wall index (43.8% versus 41.0%; P<0.001) and had significantly higher prevalence of calcification (51.6% versus 36.6%; P=0.001), lipid-rich necrotic core (77.5% versus 58.5%; P<0.001), and high-risk plaque (29.7% versus 19.9%; P=0.011) than nondiabetic patients. After adjusting for clinical characteristics, the differences in presence of calcification ( P=0.018) and lipid-rich necrotic core ( P=0.001) remained statistically significant. Conclusions- Symptomatic Chinese diabetic patients are more likely to have carotid plaques with calcification and lipid-rich necrotic core than nondiabetic patients, suggesting that diabetic patients may develop more severe atherosclerotic disease that should be accounted for in their clinical management.

Negative Carotid Artery Remodeling in Early Type 2 Diabetes Mellitus and Increased Carotid Plaque Vulnerability in Obesity as Assessed by Magnetic Resonance Imaging

Background Ischemic stroke from carotid plaque embolism remains a major cause of morbidity in patients with type 2 diabetes mellitus (T2 DM ). However, the effect of early T2 DM and obesity on carotid remodeling and plaque burden remains elusive. We assessed carotid remodeling and plaque composition by carotid magnetic resonance imaging in patients with short-duration T2 DM compared with a sex- and age-matched control group. Methods and Results One hundred patients with T2 DM (duration <5 years) and 100 sex- and age-matched controls underwent bilateral carotid artery magnetic resonance imaging in a 1.5-T magnetic resonance imaging scanner. Plaque burden was quantified by normalized wall index, maximum wall thickness, maximum wall area, and minimum lumen size. Plaque morphology was quantified by calcified plaque volume, necrotic core volume, and loose matrix volume. Magnetic resonance imaging data were available for 149 and 177 carotid arteries from T2 DM patients and controls, respectively. Adjusted for age and sex, T2 DM was associated with increased plaque burden indicated by a higher normalized wall index (ratio 1.03 [95% confidence interval, 1.002; 1.06], P=0.03), and negative remodeling indicated by a lower minimum lumen area (ratio 0.81 [0.74; 0.89], P<0.001), and lower maximum wall area (ratio 0.94 [0.88; 1.00], P=0.048) compared with controls. In both T2 DM and controls, body mass index ≥30.0 kg/m2 was associated with an 80% increase in total calcified plaque volume, and a 44% increase in necrotic core volume compared with body mass index <25.0 kg/m2. Conclusions Short-duration T2 DM was associated with increased carotid plaque burden and negative remodeling. Obesity was associated with increased carotid artery necrotic core volume and calcification independently of diabetes mellitus status. Clinical Trial Registration URL : https://www.clinicaltrials.gov . Unique identifier: NCT 00674271.

Association between carotid plaque characteristics and acute cerebral infarction determined by MRI in patients with type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) might aggravate the carotid plaque vulnerability, and increase the risk for ischemic stroke. Few studies reported the acute stroke subtype with carotid plaque characteristics in T2DM patients. This study aimed to investigate the association between carotid plaque characteristics and acute cerebral infarct (ACI) lesion features determined by MRI in T2DM patients.

METHODS

Patients with acute cerebrovascular syndrome in internal carotid artery territory were recruited. All patients were stratified into T2DM and non-T2DM groups and underwent both carotid and brain MRI scans. Ipsilateral carotid plaque morphological and compositional characteristics, intracranial and extracranial carotid artery stenosis were also determined. Stroke subtype based on the Trial of ORG 10172 in Acute Stroke Treatment classification and ACI lesion patterns were evaluated.

RESULTS

Of the recruited 140 patients, 68 (48.6%) patients had T2DM (mean age 64.16 ± 11.38 years, 40 males). T2DM patients exhibited higher prevalence of carotid type IV-VI lesions, larger plaque burden as well as larger lipid-rich necrotic core (LRNC) compared with non-T2DM patients. Among the patients with carotid LRNC on symptomatic side, more concomitant large perforating artery infarct patterns and larger ACI size in the internal carotid artery territory were found in T2DM group than those in non-T2DM group. Carotid plaque with LRNC% > 22.0% was identified as an independent risk factor for the presence of ACI lesions confined to the carotid territory in T2DM patients, regardless of other risk factors.

CONCLUSIONS

This study shows that more concomitant large perforating artery infarct patterns and larger ACI size in the internal carotid artery territory were found in the T2DM patients with ipsilateral carotid LRNC plaque than those in non-T2DM patients. Quantification of the carotid plaque characteristics, particularly the LRNC% by MRI has the potential usefulness for stroke risk stratification.

Pathology of Human Coronary and Carotid Artery Atherosclerosis and Vascular Calcification in Diabetes Mellitus

The continuing increase in the prevalence of diabetes mellitus in the general population is predicted to result in a higher incidence of cardiovascular disease. Although the mechanisms of diabetes mellitus-associated progression of atherosclerosis are not fully understood, at clinical and pathological levels, there is an appreciation of increased disease burden and higher levels of arterial calcification in these subjects. Plaques within the coronary arteries of patients with diabetes mellitus generally exhibit larger necrotic cores and significantly greater inflammation consisting mainly of macrophages and T lymphocytes relative to patients without diabetes mellitus. Moreover, there is a higher incidence of healed plaque ruptures and positive remodeling in hearts from subjects with type 1 diabetes mellitus and type 2 diabetes mellitus, suggesting a more active atherogenic process. Lesion calcification in the coronary, carotid, and other arterial beds is also more extensive. Although the role of coronary artery calcification in identifying cardiovascular disease and predicting its outcome is undeniable, our understanding of how key hormonal and physiological alterations associated with diabetes mellitus such as insulin resistance and hyperglycemia influence the process of vascular calcification continues to grow. Important drivers of atherosclerotic calcification in diabetes mellitus include oxidative stress, endothelial dysfunction, alterations in mineral metabolism, increased inflammatory cytokine production, and release of osteoprogenitor cells from the marrow into the circulation. Our review will focus on the pathophysiology of type 1 diabetes mellitus- and type 2 diabetes mellitus-associated vascular disease with particular focus on coronary and carotid atherosclerotic calcification.

Imaging Modalities to Identity Inflammation in an Atherosclerotic Plaque

Atherosclerosis is a chronic, progressive, multifocal arterial wall disease caused by local and systemic inflammation responsible for major cardiovascular complications such as myocardial infarction and stroke. With the recent understanding that vulnerable plaque erosion and rupture, with subsequent thrombosis, rather than luminal stenosis, is the underlying cause of acute ischemic events, there has been a shift of focus to understand the mechanisms that make an atherosclerotic plaque unstable or vulnerable to rupture. The presence of inflammation in the atherosclerotic plaque has been considered as one of the initial events which convert a stable plaque into an unstable and vulnerable plaque. This paper systemically reviews the noninvasive and invasive imaging modalities that are currently available to detect this inflammatory process, at least in the intermediate stages, and discusses the ongoing studies that will help us to better understand and identify it at the molecular level.

Oleacein enhances anti-inflammatory activity of human macrophages by increasing CD163 receptor expression

BACKGROUND

Oleacein (dialdehydic form of decarboxymethyl elenolic acid linked to hydroxytyrosol; 3,4-DHPEA-EDA) have been proven to possess antioxidant and anti-inflammatory activity.

PURPOSE

In this study, we examined whether oleacein could increase CD163 and IL-10 receptor expression as well as HO-1 intracellular secretion in human macrophages.

METHODS

Effect of oleacein (10 and 20 μmol/l) or oleacein together with complexes of haemoglobin (Hb) and haptoglobin 1-1 (Hp11) or haptoglobin 2-2 (Hp22) on expression of IL-10 and CD163 receptor was determined by Flow Cytometry. Expression of CD163mRNA was measured by real-time quantitative RT-PCR. Heme oxygenase 1 (HO-1) intracellular secretion in macrophages was investigated by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Oleacein (OC) together with complexes HbHp11 or HbHp22 stimulated the expression of CD163 (30-100-fold), IL-10 (170-300-fold) and HO-1 secretion (60-130-fold) after 5 days of coincubation. The 2-fold (24 h), 4-fold (48 h) increase of CD163 mRNA level and its final (72 h) decrease was also observed.

CONCLUSION

Our results suggested that oleacein enhances anti-inflammatory activity of complexes haemoglobin with haptoglobin 1-1 and 2-2 and could play a potential role in the prevention of inflammatory disease related to atherosclerosis.

Semiautomated analysis of carotid artery wall thickness in MRI

PURPOSE

To develop a semiautomatic method based on level set method (LSM) for carotid arterial wall thickness (CAWT) measurement.

MATERIALS AND METHODS

Magnetic resonance imaging (MRI) of diseased carotid arteries was acquired from 10 patients. Ground truth (GT) data for arterial wall segmentation was collected from three experienced vascular clinicians. The semiautomatic variational LSM was employed to segment lumen and arterial wall outer boundaries on 102 MR images. Two computer-based measurements, arterial wall thickness (WT) and arterial wall area (AWA), were computed and compared with GT. Linear regression, Bland-Altman, and bias correlation analysis on WT and AWA were applied for evaluating the performance of the semiautomatic method.

RESULTS

Arterial wall thickness measured by radial distance measure (RDM) and polyline distance measure (PDM) correlated well between GT and variational LSM (r = 0.83 for RDM and r = 0.64 for PDM, P < 0.05). The absolute arterial wall area bias between LSM and three observers is less than 10%, suggesting LSM can segment arterial wall well compared with manual tracings. The Jaccard Similarity (Js ) analysis showed a good agreement for the segmentation results between proposed method and GT (Js 0.71 ± 0.08), the mean curve distance for lumen boundary is 0.34 ± 0.2 mm between the proposed method and GT, and 0.47 ± 0.2 mm for outer wall boundary.

CONCLUSION

The proposed LSM can generate reasonably accurate lumen and outer wall boundaries compared to manual segmentation, and can work similar to a human reader. However, it tends to overestimate CAWT and AWA compared to the manual segmentation for arterial wall with small area.

Quantitative imaging biomarkers for the evaluation of cardiovascular complications in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a prevalent condition in aged populations. Cardiovascular diseases are leading causes of death and disability in patients with T2DM. Traditional strategies for controlling the cardiovascular complications of diabetes primarily target a cluster of well-defined risk factors, such as hyperglycemia, lipid disorders and hypertension. However, there is controversy over some recent clinical trials aimed at evaluating efficacy of intensive treatments for T2DM. As a powerful tool for quantitative cardiovascular risk estimation, multi-disciplinary cardiovascular imaging have been applied to detect and quantify morphological and functional abnormalities in the cardiovascular system. Quantitative imaging biomarkers acquired with advanced imaging procedures are expected to provide new insights to stratify absolute cardiovascular risks and reduce the overall costs of health care for people with T2DM by facilitating the selection of optimal therapies. This review discusses principles of state-of-the-art cardiovascular imaging techniques and compares applications of those techniques in various clinical circumstances. Individuals measurements of cardiovascular disease burdens from multiple aspects, which are closely related to existing biomarkers and clinical outcomes, are recommended as promising candidates for quantitative imaging biomarkers to assess the responses of the cardiovascular system during diabetic regimens.

Central nervous system imaging in diabetic cerebrovascular diseases and white matter hyperintensities

Diabetes mellitus is an important vascular risk factor for cerebrovascular disease. This occurs through pathophysiologic changes to the microcirculation as arteriolosclerosis and to the macrocirculation as large artery atherosclerosis. Imaging techniques can provide detailed visualization of the cerebrovasculature using CT (computed tomography) angiography and MR (magnetic resonance) angiography. Newer techniques focused on advanced parenchymal imaging include CT perfusion, quantitative MRI, and diffusion tensor imaging; each identifies brain lesion burden due to diabetes mellitus. These imaging approaches have provided insights into the diabetes mellitus brain and cerebral circulation pathophysiology. Imaging has taught us that diabetics develop cerebral atrophy, silent infarcts, and white matter disease more rapidly than other patient populations. Longitudinal studies are needed to quantify the rate and extent of such structural brain and blood vessel changes and how they relate to cognitive decline. Diabetes prevention and treatment strategies will then be possible to slow the development of such changes.

Characterization of carotid artery plaque components on magnetic resonance imaging using signal intensity of the phantom as a reference

RATIONALE AND OBJECTIVES

To evaluate the properties of plaque by the use of magnetic resonance imaging (MRI), it is necessary to use a material with stable signal intensity (eg, muscle or submandibular gland) as a reference. However, there may be differences between individuals. Therefore, we used a small phantom set on the circumference of the neck as a reference. The signal intensity ratio (SIR) methods using the phantom as a reference were reviewed for discrimination of the properties of plaque in the carotid artery.

MATERIALS AND METHODS

Three phantoms (phantom 1: water; phantom 2: 5 μmol gadopentetate dimeglumine; and phantom 3: 2.5 μmol gadopentetate dimeglumine) were set around the neck. SIR was calculated for each region of interest and compared according to pathological grade.

RESULTS

The method using a phantom as a reference reduced the standard deviations of tissue ratios to 0.16 from 0.27 in comparison with the method using muscle and showed a close correlation with pathological grade. In addition, the agreement rates with pathological grade and grades from each SIR using signal intensity of the phantom as a reference were higher than using signal intensity of the muscle as a reference to 0.86 from 0.63 for two-dimensional images and to 0.86 from 0.71 for three-dimensional images.

CONCLUSIONS

The method described here reduced error compared to the method using muscle as a reference, and the results were closely correlated with pathological grade.

Molecular imaging of inflammation in atherosclerosis

Acute rupture of vulnerable plaques frequently leads to myocardial infarction and stroke. Within the last decades, several cellular and molecular players have been identified that promote atherosclerotic lesion formation, maturation and plaque rupture. It is now widely recognized that inflammation of the vessel wall and distinct leukocyte subsets are involved throughout all phases of atherosclerotic lesion development. The mechanisms that render a stable plaque unstable and prone to rupture, however, remain unknown and the identification of the vulnerable plaque remains a major challenge in cardiovascular medicine. Imaging technologies used in the clinic offer minimal information about the underlying biology and potential risk for rupture. New imaging technologies are therefore being developed, and in the preclinical setting have enabled new and dynamic insights into the vessel wall for a better understanding of this complex disease. Molecular imaging has the potential to track biological processes, such as the activity of cellular and molecular biomarkers in vivo and over time. Similarly, novel imaging technologies specifically detect effects of therapies that aim to stabilize vulnerable plaques and silence vascular inflammation. Here we will review the potential of established and new molecular imaging technologies in the setting of atherosclerosis, and discuss the cumbersome steps required for translating molecular imaging approaches into the clinic.

MRI plaque imaging detects carotid plaques with a high risk for future cerebrovascular events in asymptomatic patients

PURPOSE

The aim of this study was to investigate prospectively whether MRI plaque imaging can identify patients with asymptomatic carotid artery stenosis who have an increased risk for future cerebral events. MRI plaque imaging allows categorization of carotid stenosis into different lesion types (I-VIII). Within these lesion types, lesion types IV-V and VI are regarded as rupture-prone plaques, whereas the other lesion types represent stable ones.

METHODS

Eighty-three consecutive patients (45 male (54.2%); age 54-88 years (mean 73.2 years)) presenting with an asymptomatic carotid stenosis of 50-99% according to ECST-criteria were recruited. Patients were imaged with a 1.5-T scanner. T1-, T2-, time-of-flight-, and proton-density weighted studies were performed. The carotid plaques were classified as lesion type I-VIII. Clinical endpoints were ischemic stroke, TIA or amaurosis fugax. Survival analysis and log rank test were used to ascertain statistical significance.

RESULTS

Six out of 83 patients (7.2%) were excluded: 4 patients had insufficient MR image quality; 1 patient was lost-to-follow-up; 1 patient died shortly after the baseline MRI plaque imaging. The following results were obtained by analyzing the remaining 77 patients. The mean time of follow-up was 41.1 months. During follow-up, n = 9 (11.7%) ipsilateral ischemic cerebrovascular events occurred. Only patients presenting with the high-risk lesion types IV-V and VI developed an ipsilateral cerebrovascular event versus none of the patients presenting with the stable lesion types III, VII, and VIII (n = 9 (11.7%) vs. n = 0 (0%) during follow-up). Event-free survival was higher among patients with the MRI-defined stable lesion types (III, VII, and VIII) than in patients with the high-risk lesion types (IV-V and VI) (log rank test P<0.0001).

CONCLUSIONS

MRI plaque imaging has the potential to identify patients with asymptomatic carotid stenosis who are particularly at risk of developing future cerebral ischemia. MRI could improve selection criteria for invasive therapy in the future.

An initial evaluation of analyser-based phase-contrast X-ray imaging of carotid plaque microstructure

Carotid artery plaque instability can result in rupture and lead to ischaemic stroke. Stability of plaques appears to be a function of composition. Current non-invasive imaging techniques are limited in their ability to classify distinct histological regions within plaques. Phase-contrast (PC) X-ray imaging methods are an emerging class of techniques that have shown promise for identifying soft-tissue features without use of exogenous contrast agents. This is the first study to apply analyser-based X-ray PC imaging in CT mode to provide three-dimensional (3D) images of excised atherosclerotic plaques. The results provide proof of principle for this technique as a promising method for analysis of carotid plaque microstructure. Multiple image radiography CT (MIR-CT), a tomographic implementation of X-ray PC imaging that employs crystal optics, was employed to image excised carotid plaques. MIR-CT imaging yields three complementary images of the plaque's 3D X-ray absorption, refraction and scatter properties. These images were compared with histological sections of the tissue. X-ray PC images were able to identify the interface between the plaque and the medial wall. In addition, lipid-rich and highly vascularized regions were visible in the images as well as features depicting inflammation. This preliminary research shows MIR-CT imaging can reveal details about plaque structure not provided by traditional absorption-based X-ray imaging and appears to identify specific histological regions within plaques. This is the first study to apply analyser-based X-ray PC imaging to human carotid artery plaques to identify distinct soft-tissue regions.

Are two readers more reliable than one? A study of upper neck ligament scoring on magnetic resonance images

Background

Magnetic resonance imaging (MRI) studies typically employ either a single expert or multiple readers in collaboration to evaluate (read) the image results. However, no study has examined whether evaluations from multiple readers provide more reliable results than a single reader. We examined whether consistency in image interpretation by a single expert might be equal to the consistency of combined readings, defined as independent interpretations by two readers, where cases of disagreement were reconciled by consensus.

Methods

One expert neuroradiologist and one trained radiology resident independently evaluated 102 MRIs of the upper neck. The signal intensities of the alar and transverse ligaments were scored 0, 1, 2, or 3. Disagreements were resolved by consensus. They repeated the grading process after 3–8 months (second evaluation). We used kappa statistics and intraclass correlation coefficients (ICCs) to assess agreement between the initial and second evaluations for each radiologist and for combined determinations. Disagreements on score prevalence were evaluated with McNemar’s test.

Results

Higher consistency between the initial and second evaluations was obtained with the combined readings than with individual readings for signal intensity scores of ligaments on both the right and left sides of the spine. The weighted kappa ranges were 0.65-0.71 vs. 0.48-0.62 for combined vs. individual scoring, respectively. The combined scores also showed better agreement between evaluations than individual scores for the presence of grade 2–3 signal intensities on any side in a given subject (unweighted kappa 0.69-0.74 vs. 0.52-0.63, respectively). Disagreement between the initial and second evaluations on the prevalence of grades 2–3 was less marked for combined scores than for individual scores (P ≥ 0.039 vs. P ≤ 0.004, respectively). ICCs indicated a more reliable sum score per patient for combined scores (0.74) and both readers’ average scores (0.78) than for individual scores (0.55-0.69).

Conclusions

This study was the first to provide empirical support for the principle that an additional reader can improve the reproducibility of MRI interpretations compared to one expert alone. Furthermore, even a moderately experienced second reader improved the reliability compared to a single expert reader. The implications of this for clinical work require further study.

Virtual histology analysis of carotid atherosclerotic plaque: plaque composition at the minimum lumen site and of the entire carotid plaque

BACKGROUND

Virtual Histology intravascular ultrasound (VH IVUS) volumetric analysis (analysis of the entire plaque responsible for stenosis) has been used for carotid plaque diagnosis. Knowing the carotid plaque characteristics by analyzing the plaque composition only at the minimum lumen site will facilitate plaque diagnosis using VH IVUS.

PURPOSE

To detect the relationship between the VH IVUS volumetric analysis of the entire plaque responsible for carotid artery stenosis and the VH IVUS cross-section plaque analysis at the minimum lumen site.

METHODS

Forty-eight atherosclerotic cervical carotid stenoses in 45 consecutive patients were included in the study. VH IVUS was obtained during the carotid artery stenting procedure.

RESULTS

Simple regression analysis revealed that the volumetric proportion of each plaque type correlated significantly with the corresponding plaque-type area at the minimum lumen site. The adjusted coefficients of determination of the simple regression analyses were .782 (P < .001) for fibrous tissue, .741 (P < .001) for fibrofatty tissue, .864 (P < .001) for dense calcium, and .918 (P < .001) for necrotic core.

CONCLUSION

The plaque composition at the minimum lumen site represents the volumetric composition of the entire carotid plaque that causes atherosclerotic cervical carotid artery stenosis.

Cardiovascular disease in children and adolescents with diabetes: where are we, and where are we going?

The increasing prevalence of type 1 and type 2 diabetes mellitus combined with advancement in early detection of cardiovascular disease (CVD) has placed CVD as a significant concern for preventative pediatric medicine. The public health burden of type 2 diabetes is predicted to parallel increasing obesity in children with a projected increase of early CVD in adulthood. In this article, we review practice guidelines for cardiovascular health in children and adolescents with diabetes and data on which they are based. We then focus on imaging modalities that are promising tools to expand our understanding of the cardiovascular risk imposed on youths with diabetes.

Advances in noninvasive imaging for evaluating clinical risk and guiding therapy in carotid atherosclerosis

Managing asymptomatic carotid atherosclerosis with a view to preventing ischemic stroke is a challenging task. As the annual risk of stroke in untreated asymptomatic patients on average is less than the risk of surgical intervention, the key question is how to identify those asymptomatic individuals whose risk of stroke is elevated and who would benefit from surgery, while sparing low-risk asymptomatic patients from the risks of surgical intervention. The advent of a multitude of noninvasive carotid imaging techniques offers an opportunity to improve risk stratification in patients and to monitor the response to medical therapies; assessing efficacy at individual and population levels. As part of this, plaque measurement techniques (using ultrasound, computed tomography or MRI) may be employed in monitoring plaque/component regression and progression. Novel imaging applications targeted to plaque characteristics, inflammation and neovascularization, including contrast-enhanced ultrasound and MRI, dynamic contrast-enhanced MRI, and fluorodeoxyglucose-PET, are also being explored. Ultimately, noninvasive imaging and other advances in risk stratification aim to improve and individualize the management of patients with carotid atherosclerosis.

Videodensitometric analysis of advanced carotid plaque: correlation with MMP-9 and TIMP-1 expression

Background

Matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of MMP (TIMP) promote derangement of the extracellular matrix, which is ultimately reflected in plaque images seen on ultrasound. Videodensitometry can identify structural disturbances in plaques.

Objectives

To establish the correlations between values determined using videodensitometry in B-mode ultrasound images of advanced carotid plaques and the total expression of MMP-9 and TIMP-1 in these removed plaques.

Methods

Thirty patients underwent ultrasonic tissue characterization of carotid plaques before surgery, using mean gray level (MGL), energy, entropy and homogeneity. Each patient was assigned preoperatively to one of 2 groups: group I, symptomatic patients (n = 16; 12 males; mean age 66.7 ± 6.8 years), and group II, asymptomatic patients (n = 14; 8 males; mean age 67.6 ± 6.81 years). Tissue specimens were analyzed for MMP-9 and TIMP-1 expression. Nine carotid arteries were used as normal tissue controls.

Results

MMP-9 expression levels were elevated in group II and in normal tissues compared to group I (p < 0.001). TIMP-1 levels were higher in group II than in group I, and significantly higher in normal tissues than in group I (p = 0.039). The MGL was higher in group II compared to group I (p = 0.038). Energy had greater values in group II compared to group I (p = 0.02). There were no differences between patient groups in homogeneity and entropy. Energy positively correlated with MMP-9 and TIMP-1 expression (p = 0.012 and p = 0.031 respectively). Homogeneity positively correlated with MMP-9 and TIMP-1 expression (p = 0.034 and p = 0.047 respectively). There were no correlations between protein expression and MGL or entropy.

Conclusions

Videodensitometric computer analysis of ultrasound scanning images can be used to identify stable carotid plaques, which have higher total expression levels of MMP-9 and TIMP-1 than unstable plaques.

Determinants of magnetic resonance imaging detected carotid plaque components: the Rotterdam Study

AIMS

Components of carotid atherosclerotic plaque such as intraplaque haemorrhage and lipid core are important determinants of plaque progression and destabilization. The association between plaque components and risk factors for cardiovascular disease is not well studied.

METHODS AND RESULTS

Participants from the population-based Rotterdam Study with carotid wall thickening on ultrasound (n = 1006) underwent high-resolution magnetic resonance imaging for carotid plaque characterization. Maximum wall thickening, the degree of stenosis, and the presence of intraplaque haemorrhage, lipid core, and calcification were assessed in both carotid arteries and their associations with cardiovascular risk factors were investigated. Intraplaque haemorrhage and lipid core were present in almost 25% of plaques, respectively, and occurred simultaneously in 9% of plaques. In men, intraplaque haemorrhage and lipid core were more prevalent compared with women (28.8 vs. 18.3 and 28.9 vs. 21.7%, respectively). Intraplaque haemorrhage occurred more frequently at older age [odds ratio (OR) per 10 years 1.8, 95% confidence interval 1.6-2.1], in men (OR 2.2, 1.7-2.9), in persons with hypertension (multivariate adjusted OR 1.4, 1.1-1.8), and in current smokers (multivariate adjusted OR 1.6, 1.2-2.3). Men (OR 1.5, 1.2-1.9) and subjects with hypercholesterolaemia (multivariate adjusted OR 1.4, 1.1-1.7) more often exhibited a lipid core.

CONCLUSION

In subjects from the general population with carotid wall thickening, intraplaque haemorrhage and lipid core-both considered indicators of unstable plaque-are highly frequent and more prevalent in men compared with women. Furthermore, different risk factors are associated with these plaque components: hypertension and current smoking were risk factors for the presence of intraplaque haemorrhage, and hypercholesterolaemia was the only risk factor for lipid core presence.

MRI plaque imaging and its role in population-based studies

Noninvasive direct vessel wall (plaque) imaging may provide a good opportunity to study unique aspects of atherosclerotic lesions in different populations. The article published by Esposito et al. provides new insights into our understanding of diabetic atherosclerotic vascular disease by using direct plaque imaging techniques. The findings from this article call for attention to more in vivo imaging to understand the nature of high-risk atherosclerosis, especially in prospective studies in diabetic patients.