Relationships among regional arterial inflammation, calcification, risk factors, and biomarkers: a prospective fluorodeoxyglucose positron-emission tomography/computed tomography imaging study

Preclinical evaluation of high-resolution CT, 18F-FDG, and 18F-NaF PET imaging for longitudinal monitoring of atherosclerosis

RATIONALE

Detection of atherosclerosis is essential to the management and prevention of life-threatening cardiovascular events. Although non-invasive imaging modalities, such as 18F-sodium fluoride (18F-NaF), 18F-fluorodeoxyglucose (18F-FDG) PET, and CT, visualize distinct hallmarks of atherosclerosis, there has yet to be a singular multi-cohort interrogation of their strengths and limitations. Thus, we focused on identifying the optimal approach for visualizing atherosclerosis at different stages of disease progression.

METHODS

In this study, 6-week-old, male, ApoE deficient mice (Apoe-/-) were placed on a high cholesterol diet for 12-20 weeks to induce calcific atherosclerotic disease. Age-matched, male, wildtype (WT) C57BL/6 mice fed with regular chow served as the control group. Mice were imaged at 12, 15, 18, and 20 weeks after starting their respective diets. To follow the progression of calcified atherosclerotic lesions, at each time point, in vivo, 18F-NaF microPET/CT images were acquired 1 h and 3 h post tracer i.v. injection. In a separate cohort, in vivo 18F-FDG PET/CT images were acquired at 3 and 5 h post tracer i.v. injection to follow inflammation as a result of progressive atherosclerotic lesion formation. High-resolution microCT images were acquired for all mice to visualize aorta calcification. After each imaging session, a subset (n = 3) was euthanized from each group and histological analysis of the aorta was performed to confirm disease progression.

RESULTS

In this comparative study, within the same cohort, 18F-NaF PET detected atherosclerotic calcification earlier than microCT. At both 1 and 3 h post-injection (p.i.), calcified lesions were clearly detected by 18F-NaF with a six-fold higher signal in Apoe-/- compared to WT mice. Interestingly, 18F-NaF signal peaked at week 18, whereas aortic CT signal progressively increased with a 13-, 16-, and 29-fold at 15, 18, and 20 weeks, respectively. 18F-FDG arortic accumulation at weeks 12 and 15, were significantly greater in Apoe -/- mice than WT control when images were acquired at 5 h but not at 3 h p.i.. In contrast to histological analysis, at ≥ 16 weeks where inflammation is significantly elevated, 18F-FDG was equivalent in Apoe-/- and WT control mice and significantly reduced with disease progression.

CONCLUSIONS

Our results show that 18F-NaF PET and 18F-FDG PET are sensitive imaging modalities for the early detection of atherosclerotic lesions. However, both 18F-NaF PET and high-resolution microCT prove to be effective methods for monitoring late-stage and progressive disease.

Stroke risk management in carotid atherosclerotic disease: a clinical consensus statement of the ESC Council on Stroke and the ESC Working Group on Aorta and Peripheral Vascular Diseases

Carotid atherosclerotic disease continues to be an important cause of stroke, often disabling or fatal. Such strokes could be largely prevented through optimal medical therapy and carotid revascularization. Advancements in discovery research and imaging along with evidence from recent pharmacology and interventional clinical trials and registries and the progress in acute stroke management have markedly expanded the knowledge base for clinical decisions in carotid stenosis. Nevertheless, there is variability in carotid-related stroke prevention and management strategies across medical specialities. Optimal patient care can be achieved by (i) establishing a unified knowledge foundation and (ii) fostering multi-specialty collaborative guidelines. The emergent Neuro-Vascular Team concept, mirroring the multi-disciplinary Heart Team, embraces diverse specializations, tailors personalized, stratified medicine approaches to individual patient needs, and integrates innovative imaging and risk-assessment biomarkers. Proposed approach integrates collaboration of multiple specialists central to carotid artery stenosis management such as neurology, stroke medicine, cardiology, angiology, ophthalmology, vascular surgery, endovascular interventions, neuroradiology, and neurosurgery. Moreover, patient education regarding current treatment options, their risks and advantages, is pivotal, promoting patient's active role in clinical care decisions. This enables optimization of interventions ranging from lifestyle modification, carotid revascularization by stenting or endarterectomy, as well as pharmacological management including statins, novel lipid-lowering and antithrombotic strategies, and targeting inflammation and vascular dysfunction. This consensus document provides a harmonized multi-specialty approach to multi-morbidity prevention in carotid stenosis patients, based on comprehensive knowledge review, pinpointing research gaps in an evidence-based medicine approach. It aims to be a foundational tool for inter-disciplinary collaboration and prioritized patient-centric decision-making.

Quantification of perivascular adipose tissue attenuation does not add incremental prognostic value in patients undergoing transcatheter aortic valve implantation

Aims

Perivascular adipose tissue attenuation (PVAT) has emerged as a novel coronary computed tomography angiography (CCTA)-based biomarker predicting cardiovascular events by capturing inflammation around the coronary arteries. We assessed whether PVAT adds incremental prognostic value in patients undergoing transcatheter aortic valve implantation (TAVI).

Methods and results

A total of 510 patients underwent CCTA imaging prior to TAVI between November 2015 and June 2020 at the Medical University of Vienna. PVAT was obtained from CCTA images and was measured around the right coronary artery [PVAT(RCA)] and the aortic valve [PVAT(valve)]. Following application of exclusion criteria, 372 patients [mean age 80.6 ± 6.8 years; 169 (45%) women] were analysed. Over a median follow-up of 3.0 (IQR 2.5-3.6) years, 52 (14%) individuals experienced a major adverse cardiovascular event (MACE, a composite of non-fatal stroke or myocardial infarction, cardiac death, or vascular intervention). Individuals exhibiting elevated PVAT[valve] displayed a heightened surgical risk according to European System for Cardiac Operative Risk Evaluation II, a lower body mass index, reduced left ventricular ejection fraction, prolonged hospitalization following TAVI, and elevated levels of circulating inflammatory markers compared with those in the low PVAT[valve] group (P < 0.05). However, neither PVAT[valve] nor PVAT[RCA] were independently associated with the occurrence of MACE in adjusted multi-variable analyses (PVAT[valve]: sub-distribution hazard ratio [SHR] 1.14, 95% CI:0.63-2.05, P = 0.672); PVAT[RCA]: SHR 1.16 [95% CI: 0.81-1.66], P = 0.417).

Conclusion

Measuring PVAT around either the right coronary artery or the aortic valve does not provide additional prognostic value beyond established risk factors for the prediction of MACE in patients undergoing TAVI.

Peptide Receptor Radionuclide Therapy Using 90Y- and 177Lu-DOTATATE Modulating Atherosclerotic Plaque Inflammation: Longitudinal Monitoring by 68Ga-DOTATATE Positron Emissions Tomography/Computer Tomography

Background: Atherosclerosis and its sequels, such as coronary artery disease and cerebrovascular stroke, still represent global health burdens. The pathogenesis of atherosclerosis consists of growing calcified plaques in the arterial wall and is accompanied by inflammatory processes, which are not entirely understood. This study aims to evaluate the effect of peptide receptor radionuclide therapy (PRRT) using 90Y- and 177Lu-DOTATATE on atherosclerotic plaque inflammation. Methods: Atherosclerotic plaques in 57 cancer patients receiving PRRT using 90Y- and 177Lu-DOTATATE were longitudinally monitored by 68Ga-DOTATATE PET/CT. The target-to-background ratio (TBR) and overall vessel uptake (OVU) were measured in eight distinct arterial regions (ascending aorta, aortic arch, descending aorta, abdominal aorta, both iliac arteries, and both carotid arteries) to monitor calcified plaques. Results: PET/CT analysis shows a positive correlation between calcified plaque scores and the 68Ga-DOTATATE overall vessel uptake (OVU) in cancer patients. After PRRT, an initially high OVU was observed to decrease in the therapy group compared to the control group. An excellent correlation could be shown for each target-to-background ratio (TBR) to the OVU, especially the ascending aorta. Conclusions: The ascending aorta could present a future reference for estimating generalized atherosclerotic inflammatory processes. PRRT might represent a therapeutic approach to modulating atherosclerotic plaques.

FDG Uptake Caused by Right Varicocele

ABSTRACT

A 67-year-old man underwent 18 F-FDG PET/CT for lung cancer staging. Interestingly, the PET scan revealed strip-shaped FDG uptake in the right inguinal contoured area, which was later confirmed as a right varicocele through ultrasound imaging.

Biomarkers of Cardiovascular Risk in Patients With Rheumatoid Arthritis: Results From the TARGET Trial

Cardiovascular disease remains an important comorbidity in patients with rheumatoid arthritis (RA), but traditional models do not accurately predict cardiovascular risk in patients with RA. The addition of biomarkers could improve prediction.

METHODS AND RESULTS

The TARGET (Treatments Against RA and Effect on FDG PET/CT) trial assessed whether different treatment strategies in RA differentially impact cardiovascular risk as measured by the change in arterial inflammation on arterial target to background ratio on fluorodeoxyglucose positron emission tomography/computed tomography scans conducted 24 weeks apart. A group of 24 candidate biomarkers supported by prior literature was assessed at baseline and 24 weeks later. Longitudinal analyses examined the association between baseline biomarker values, measured in plasma EDTA, and the change in arterial inflammation target to background ratio. Model fit was assessed for the candidate biomarkers only, clinical variables only, and models combining both. One hundred nine patients with median (interquartile range) age 58 years (53-65 years), RA duration 1.4 years (0.5-6.6 years), and 82% women had biomarkers assessed at baseline and follow-up. Because the main trial analyses demonstrated significant target to background ratio decreases with both treatment strategies but no difference across treatment groups, we analyzed all patients together. Baseline values of serum amyloid A, C-reactive protein, soluble tumor necrosis factor receptor 1, adiponectin, YKL-40, and osteoprotegerin were associated with significant change in target to background ratio. When selected candidate biomarkers were added to the clinical variables, the adjusted R2 improved from 0.20 to 0.33 (likelihood ratio P=0.0005).

CONCLUSIONS

A candidate biomarker approach identified several promising biomarkers that associate with baseline and treatment-associated changes in arterial inflammation in patients with RA. These will now be tested in an external validation cohort.

Simultaneous 18-FDG PET and MR imaging in lower extremity arterial disease

Background

Simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) is a novel hybrid imaging method integrating the advances of morphological tissue characterization of MRI with the pathophysiological insights of PET applications.

Aim

This study evaluated the use of simultaneous 18-FDG PET/MR imaging for characterizing atherosclerotic lesions in lower extremity arterial disease (LEAD).

Methods

Eight patients with symptomatic stenoses of the superficial femoral artery (SFA) under simultaneous acquisition of 18-FDG PET and contrast-enhanced MRI using an integrated whole-body PET/MRI scanner. Invasive plaque characterization of the SFA was performed by intravascular imaging using optical coherence tomography. Histological analysis of plaque specimens was performed after directional atherectomy.

Results

MRI showed contrast enhancement at the site of arterial stenosis, as assessed on T2-w and T1-w images, compared to a control area of the contralateral SFA (0.38 ± 0.15 cm vs. 0.23 ± 0.11 cm; 1.77 ± 0.19 vs. 1.57 ± 0.15; p-value <0.05). On PET imaging, uptake of 18F-FDG (target-to-background ratio TBR > 1) at the level of symptomatic stenosis was observed in all but one patient. Contrast medium-induced MR signal enhancement was detected in all plaques, whereas FDG uptake in PET imaging was increased in lesions with active fibroatheroma and reduced in fibrocalcified lesions.

Conclusion

In this multimodal imaging study, we report the feasibility and challenges of simultaneous PET/MR imaging of LEAD, which might offer new perspectives for risk estimation.

Risk Factors for Medial and Intimal Intracranial Internal Carotid Artery Calcification in Men and Women with Cardiovascular Disease: The UCC-SMART Study

INTRODUCTION

Calcifications of the intracranial internal carotid artery (iICA) can lead to an increased risk for stroke. Two types of iICA calcification are known: those affecting the tunica intima or the tunica media. In extracranial arteries, risk factors and calcification patterns are different in women and men, but little is known regarding the iICA. In this study, we aimed to identify sex-specific risk profiles and medications associated to intimal and medial iICA calcification in patients with cardiovascular disease (CVD).

METHODS

Participants of the UCC-SMART cohort undergoing a non-contrast head CT within 6 months from the study inclusion were considered (n = 475). Intimal or medial iICA calcification pattern was assessed using a previously histology-validated method. Sex-stratified associations between calcification pattern and cardiovascular risk factors, laboratory parameters, and medication use were calculated using Poisson regression analysis with robust standard errors.

RESULTS

Two hundred and four women and 271 men (age range 24-79 years) were included. 45.4% of men and 34.8% of women showed intimal iICA calcification, while 28.4% of men and 24.0% of women showed medial iICA calcification. Minimal or no iICA calcification was observed in 26.2% of men and in 41.2% of women (reference group). Older age was associated with both calcification patterns in women and men. In women, use of vitamin K antagonists and lipid-lowering drugs was associated to medial calcification, while systolic blood pressure and glucose levels were associated to intimal calcification. In men, current smoking was associated to intimal calcification.

CONCLUSIONS

Women and men with CVD show differences in risk profiles and medication use associated to intimal and medial iCA calcification.

Homocysteine Combined with Apolipoprotein B as Serum Biomarkers for Predicting Carotid Atherosclerosis in the Oldest-Old

Background

The measurement of serum biomarkers is a promising decision aid in the assessment of atherosclerosis. However, data on the levels and epidemiological distribution of serum biomarkers of carotid atherosclerosis (CAS) in the oldest-old are limited. This study aimed to investigate the characteristics of CAS serum biomarkers in the oldest-old over 80 and explore their predictive value for CAS.

Methods

As part of the China Hainan Centenarian Cohort Study, a total of 1565 individuals over 80 years old were included. Atherosclerosis was assessed by carotid plaque and carotid intima-media thickness. Serum biomarker levels, demographic indicators, and physical examination indicators were detected. Prediction factors correlated to the CAS were explored by logistic regression and verified by receiver operating characteristic curve analysis. Multivariate regression models were fitted, along with subgroup analysis and robustness tests.

Results

Among the oldest-old population, 83.5% (1306) had CAS. In a fully adjusted multivariate logistic regression model, systolic blood pressure (SBP), heart rhythm (HR), serum homocysteine (Hcy), and apolipoprotein B (ApoB) levels were significantly and positively associated with CAS in the oldest-old (PS < 0.001). ROC analysis indicated that the combination of serum Hcy, ApoB, SBP, and HR increased the predictive value for CAS in the oldest-old (area under the curve: 0.856, 95% CI: 0.803-0.879; sensitivity: 81.8%; specificity: 85.9%).

Conclusion

SBP, HR, Hcy and ApoB are independent risk factors for CAS in the oldest-old. The specific set of biomarkers and their combination with other risk markers may be a promising strategy for assessing CAS in the elderly, especially in global aging.

Longitudinal Assessment of Inflammatory Activity in Acute Type B Aortic Dissection with Integrated Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Imaging

OBJECTIVE

The significance of the inflammatory response in the natural course of acute type B aortic dissection (ATBAD) is unknown. The aim was to characterise inflammation and its transformation over time in ATBAD using 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) with contrast enhanced magnetic resonance imaging (MRI).

METHODS

Ten patients underwent FDG-PET/MRI within two weeks of ATBAD (acute phase), three to four months (subacute phase), nine to 12 months (early chronic phase), and 21 to 24 months (late chronic phase) after ATBAD. Target background ratios (TBRs) were measured in the ascending aorta, aortic arch, and descending aorta. MRI inflammatory markers were assessed in the descending aorta.

RESULTS

Ten patients were included: median age 69 years, median clinical follow up 32 months. In the acute phase there was increased FDG uptake in the descending aorta (maximum TBR 5.8, SD [standard deviation] 1.3) compared with the ascending aorta (TBR 3.3, SD 0.8, p < .010) and arch (TBR 4.2, SD 0.6, p = .010). The maximum TBR of the descending aorta decreased from the acute to subacute phase (TBR 3.5, SD 0.6, p = .010) and further to the early chronic phase (TBR 2.9, SD 0.4, p = .030) but was stable thereafter. The acute phase maximum TBR in the ascending aorta (TBR 3.3) and arch (TBR 4.2) decreased to the subacute phase (ascending: TBR 2.8, SD 0.6, p = .020; arch: TBR 2.7, SD 0.4, p = .010) and was stable thereafter. Four patients underwent surgical aortic repair (three for aortic dilatation at one, five, and 28 months and one for visceral ischaemia at three weeks). MRI signs of inflammation were present in all surgically treated patients vs. two of six of medically treated patients (p= .048).

CONCLUSION

ATBAD is associated with increased FDG uptake in the acute phase primarily in the descending aorta, but also involving the aortic arch and ascending aorta, indicating an inflammatory response in the whole aorta. Inflammation subsides early in the ascending aorta and arch (three months), whereas it stabilised later in the descending aorta (nine to 12 months). MRI signs of inflammation were more frequent in patients who later needed surgical treatment and merit further investigation.

Pre-discharge 18F-Flourodeoxyglucose uptake pattern following transcatheter aortic-valve replacement and adverse prognostic features in aortic stenosis

18F-Flourodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) has been shown to be of utility in transcatheter aortic valve replacement (TAVR) patients with suspected prosthetic valve endocarditis. In the present study, we sought to analyze the relationship between 18F-FDG-PET/CT performed before discharge in TAVR patients and adverse prognostic features of aortic stenosis. We analyzed the association between 18F-FDG-PET/CT uptake pattern and degree of left ventricular mass index, aortic root dilatation, and aortic leaflet calcification extent. This is the first study to demonstrate that pre-discharge 18F-FDG-PET/CT in patients undergoing TAVR shows a significant negative correlation between 18F-FDG uptake pattern and adverse prognostic features.

Imaging Carotid Plaque Inflammation Using Positron Emission Tomography: Emerging Role in Clinical Stroke Care, Research Applications, and Future Directions

Atherosclerosis is a chronic systemic inflammatory condition of the vasculature and a leading cause of stroke. Luminal stenosis severity is an important factor in determining vascular risk. Conventional imaging modalities, such as angiography or duplex ultrasonography, are used to quantify stenosis severity and inform clinical care but provide limited information on plaque biology. Inflammatory processes are central to atherosclerotic plaque progression and destabilization. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a validated technique for quantifying plaque inflammation. In this review, we discuss the evolution of FDG-PET as an imaging modality to quantify plaque vulnerability, challenges in standardization of image acquisition and analysis, its potential application to routine clinical care after stroke, and the possible role it will play in future drug discovery.

Multi-Modality Imaging of Atheromatous Plaques in Peripheral Arterial Disease: Integrating Molecular and Imaging Markers

Peripheral artery disease (PAD) is a common and debilitating condition characterized by the narrowing of the limb arteries, primarily due to atherosclerosis. Non-invasive multi-modality imaging approaches using computed tomography (CT), magnetic resonance imaging (MRI), and nuclear imaging have emerged as valuable tools for assessing PAD atheromatous plaques and vessel walls. This review provides an overview of these different imaging techniques, their advantages, limitations, and recent advancements. In addition, this review highlights the importance of molecular markers, including those related to inflammation, endothelial dysfunction, and oxidative stress, in PAD pathophysiology. The potential of integrating molecular and imaging markers for an improved understanding of PAD is also discussed. Despite the promise of this integrative approach, there remain several challenges, including technical limitations in imaging modalities and the need for novel molecular marker discovery and validation. Addressing these challenges and embracing future directions in the field will be essential for maximizing the potential of molecular and imaging markers for improving PAD patient outcomes.

Positron Emission Tomography (PET) Scan as a Diagnostic Tool for Giant Cell Arteritis

Giant cell arteritis (GCA) is an inflammatory vasculitis that typically affects the elderly, preferentially involving large and medium-sized arteries and can potentially cause irreversible loss of vision. Early diagnosis and treatment are necessary to prevent this dreaded complication. Temporal artery biopsy has been the gold standard test in diagnosing GCA, however, false negative results due to presence of skip lesions, restricted inflammation, and early initiation of steroids have limited its diagnostic significance. We report a case of a 67-year-old female with headache, blurry vision, posterior scalp tenderness, feeble left temporal artery pulse on a physical exam with normal inflammatory markers. Temporal artery biopsy showed disruption and reduplication of internal elastic lamina without any evidence of giant cells or inflammatory cells. Owing to high clinical suspicion, fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) was further done which revealed mildly increased uptake in the thoracic aorta, consistent with a diagnosis of large vessel vasculitis.

Nuclear medicine in the assessment and prevention of cancer therapy-related cardiotoxicity: prospects and proposal of use by the European Association of Nuclear Medicine (EANM)

Cardiotoxicity may present as (pulmonary) hypertension, acute and chronic coronary syndromes, venous thromboembolism, cardiomyopathies/heart failure, arrhythmia, valvular heart disease, peripheral arterial disease, and myocarditis. Many of these disease entities can be diagnosed by established cardiovascular diagnostic pathways. Nuclear medicine, however, has proven promising in the diagnosis of cardiomyopathies/heart failure, and peri- and myocarditis as well as arterial inflammation. This article first outlines the spectrum of cardiotoxic cancer therapies and the potential side effects. This will be complemented by the definition of cardiotoxicity using non-nuclear cardiovascular imaging (echocardiography, CMR) and biomarkers. Available nuclear imaging techniques are then presented and specific suggestions are made for their application and potential role in the diagnosis of cardiotoxicity.

The Role of the Coagulation System in Peripheral Arterial Disease: Interactions with the Arterial Wall and Its Vascular Microenvironment and Implications for Rational Therapies

Peripheral artery disease (PAD) is a clinical manifestation of atherosclerotic disease with a large-scale impact on the economy and global health. Despite the role played by platelets in the process of atherogenesis being well recognized, evidence has been increasing on the contribution of the coagulation system to the atherosclerosis formation and PAD development, with important repercussions for the therapeutic approach. Histopathological analysis and some clinical studies conducted on atherosclerotic plaques testify to the existence of different types of plaques. Likely, the role of coagulation in each specific type of plaque can be an important determinant in the histopathological composition of atherosclerosis and in its future stability. In this review, we analyze the molecular contribution of inflammation and the coagulation system on PAD pathogenesis, focusing on molecular similarities and differences between atherogenesis in PAD and coronary artery disease (CAD) and discussing the possible implications for current therapeutic strategies and future perspectives accounting for molecular inflammatory and coagulation targets. Understanding the role of cross-talking between coagulation and inflammation in atherosclerosis genesis and progression could help in choosing the right patients for future dual pathway inhibition strategies, where an antiplatelet agent is combined with an anticoagulant, whose role, despite pathophysiological premises and trials' results, is still under debate.

Association of Plaque Inflammation With Stroke Recurrence in Patients With Unproven Benefit From Carotid Revascularization

BACKGROUND AND OBJECTIVES

In pooled analyses of endarterectomy trials for symptomatic carotid stenosis, several subgroups experienced no net benefit from revascularization. The validated SCAIL score includes stenosis severity and inflammation measured by Positron-Emission Tomography (PET) and improves the identification of patients with recurrent stroke compared with lumen-stenosis alone. We investigated if the SCAIL score improves the identification of recurrent stroke in subgroups with uncertain benefit from revascularization in endarterectomy trials.

METHODS

We did an individual-participant data pooled analysis of three prospective cohort studies (DUCASS, 2008-2011; BIOVASC, 2014-2018; Barcelona Plaque Study, 2015-2018). Eligible patients had a recent non-severe (modified Rankin Score≤3) anterior circulation ischaemic stroke/TIA and either: ipsilateral mild carotid stenosis (<50%); ipsilateral moderate carotid stenosis (50-69%) plus at least one of female sex, age <65 years, diabetes mellitus, TIA, or delay >14 days to revascularization; or monocular loss of vision. Patients underwent co-registered carotid ¹⁸F-FDG PET/CT angiography (≤7 days from inclusion). The primary outcome was 90-day ipsilateral ischaemic stroke. Multivariable Cox regression modelling was performed.

RESULTS

We included 135 patients. All patients started optimal modern-era medical treatment at admission and 62 (45.9%) underwent carotid revascularization (36 within the first 14 days and 26 beyond). At 90 days, 18 (13.3%) patients had experienced at least one stroke recurrence. The risk of recurrence increased progressively according to the SCAIL score (0.0% in patients scoring 0-1, 15.1% scoring 2-3 and 26.7% scoring 4-5; p=0.04). The adjusted (age, smoking, hypertension, diabetes mellitus, carotid revascularization, antiplatelets and statins) Hazard Ratio for ipsilateral recurrent stroke per 1-point SCAIL increase was 2.16 (95% CI 1.32-3.53; p=0.002). A score ≥2 had a sensitivity of 100% for recurrence.

DISCUSSION

The SCAIL score improved the identification of early recurrent stroke in subgroups that did not experience benefit in endarterectomy trials. Randomized trials are needed to test if a combined stenosis-inflammation strategy will improve selection for carotid revascularization where benefit is currently uncertain.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that in patients with recent anterior circulation ischemic stroke who do not benefit from carotid revascularization, the SCAIL score accurately distinguishes those at risk for recurrent ipsilateral ischemic stroke.

Positron Emission Tomography in Atherosclerosis Research

Positron emission tomography (PET) is a quantitative imaging technique that uses molecules labeled with positron-emitting radionuclides to visualize and measure biochemical processes in the tissues of living subjects. In recent years, different PET tracers have been evaluated for their ability to characterize the atherosclerotic process in order to study the activity of the disease. Here, we describe detailed PET methods for preclinical studies of atherosclerosis and summarize the key methodological aspects of PET imaging in clinical studies of atherosclerosis.

Carotid Plaque Inflammation Imaged by PET and Prediction of Recurrent Stroke at 5 Years

OBJECTIVE

To determine whether carotid plaque inflammation identified by ¹⁸F-fluorodeoxyglucose (¹⁸FDG)-PET is associated with late (5-year) recurrent stroke.

METHODS

We did an individual-participant data pooled analysis of three prospective studies with near-identical study methods. Eligible patients had recent non-severe (modified Rankin Score ≤3) ischaemic stroke/TIA and ipsilateral carotid stenosis (50-99%). Participants underwent carotid ¹⁸FDG-PET/CT angiography ≤14 days after recruitment. ¹⁸FDG uptake was expressed as maximum standardized uptake value (SUV_max) in the axial single hottest slice of symptomatic plaque. We calculated the previously-validated Symptomatic Carotid Atheroma Inflammation Lumen-stenosis (SCAIL) score, which incorporates a measure of stenosis severity and ¹⁸FDG uptake. The primary outcome was 5-year recurrent ipsilateral ischaemic stroke after PET imaging.

RESULTS

Of 183 eligible patients, 181 patients completed follow-up (98.9%). The median duration of follow-up was 4.9 years (interquartile range 3.3-6.4, cumulative follow-up period 901.8 patient-years). After PET imaging, 17 patients had a recurrent ipsilateral ischemic strokes at 5 years (recurrence rate 9.4%, 95% CI 5.6-14.6%). Baseline plaque SUV_max independently predicted 5-year ipsilateral recurrent stroke after adjustment for age, gender, carotid revascularization, stenosis severity, NIH Stroke Scale, and diabetes mellitus (adjusted HR 1.98; 95 % CI, 1.10-3.56, p=0.02, per 1g/mL increase SUV_max). On multivariable Cox regression, SCAIL score predicted 5-year ipsilateral stroke (adjusted HR 2.73 per 1-point increase; 95% CI 1.52-4.90, p=0.001).

CONCLUSION

Plaque inflammation-related ¹⁸FDG uptake improved identification of 5-year recurrent ipsilateral ischaemic stroke. Addition of plaque inflammation to current selection strategies may target patients most likely to have late as well as early benefit from carotid revascularization.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that in individuals with recent ischemic stroke/TIA and ipsilateral carotid stenosis, carotid plaque inflammation-related ¹⁸FDG uptake on PET/CT angiography was associated with 5-year recurrent ipsilateral stroke.

Carotid Atheroinflammation Is Associated With Cerebral Small Vessel Disease Severity

Background: Atherosclerosis is a systemic inflammatory disease, with common inflammatory processes implicated in both atheroma vulnerability and blood-brain barrier disruption. This prospective multimodal imaging study aimed to measure directly the association between systemic atheroma inflammation (“atheroinflammation”) and downstream chronic cerebral small vessel disease severity.

Methods: Twenty-six individuals with ischemic stroke with ipsilateral carotid artery stenosis of >50% underwent ¹⁸fluoride-fluorodeoxyglucose-positron emission tomography within 2 weeks of stroke. Small vessel disease severity and white matter hyperintensity volume were assessed using 3-tesla magnetic resonance imaging also within 2 weeks of stroke.

Results: Fluorodeoxyglucose uptake was independently associated with more severe small vessel disease (odds ratio 6.18, 95% confidence interval 2.1–18.2, P < 0.01 for the non-culprit carotid artery) and larger white matter hyperintensity volumes (coefficient = 14.33 mL, P < 0.01 for the non-culprit carotid artery).

Conclusion: These proof-of-concept results have important implications for our understanding of the neurovascular interface and potential therapeutic exploitation in the management of systemic atherosclerosis, particularly non-stenotic disease previously considered asymptomatic, in order to reduce the burden of chronic cerebrovascular disease.

Atherosclerosis imaging using PET: Insights and applications

PET imaging is able to harness biological processes to characterise high-risk features of atherosclerotic plaque prone to rupture. Current radiotracers are able to track inflammation, microcalcification, hypoxia, and neoangiogenesis within vulnerable plaque. 18 F-fluorodeoxyglucose (18 F-FDG) is the most commonly used radiotracer in vascular studies and is employed as a surrogate marker of plaque inflammation. Increasingly, 18 F-FDG and other PET tracers are also being used to provide imaging endpoints in cardiovascular interventional trials. The evolution of novel PET radiotracers, imaging protocols, and hybrid scanners are likely to enable more efficient and accurate characterisation of high-risk plaque. This review explores the role of PET imaging in atherosclerosis with a focus on PET tracers utilised in clinical research and the applications of PET imaging to cardiovascular drug development.

Quantification of perivascular inflammation does not provide incremental prognostic value over myocardial perfusion imaging and calcium scoring

AIMS

Perivascular fat attenuation index (FAI) has emerged as a novel coronary computed tomography angiography (CCTA)-based biomarker predicting cardiovascular outcomes by capturing early coronary inflammation. It is currently unknown whether FAI adds prognostic value beyond that provided by single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) and CCTA findings including coronary artery calcium scoring (CACS).

METHODS AND RESULTS

A total of 492 patients (mean age 62.5 ± 10.8 years) underwent clinically indicated multimodality CCTA and electrocardiography (ECG)-gated 99mTc-tetrofosmin SPECT-MPI between May 2005 and December 2008 at our institution, and follow-up data on major adverse cardiovascular events (MACE) was obtained for 314 patients. FAI was obtained from CCTA images and was measured around the right coronary artery (FAI[RCA]), the left anterior descending artery (FAI[LAD]), and the left main coronary artery (FAI[LMCA]). During a median follow-up of 2.7 years, FAI[RCA] > - 70.1 was associated with an increased rate of MACE (log rank p = 0.049), while no such association was seen for FAI[LAD] or FAI[LMCA] (p = NS). A multivariate Cox regression model accounting for cardiovascular risk factors, CCTA and SPECT-MPI findings identified FAI[RCA] as an independent predictor of MACE (HR 2.733, 95% CI: 1.220-6.123, p = 0.015). However, FAI[RCA] was no longer a significant predictor of MACE after adding CACS (p = 0.279). A first-order interaction term consisting of sex and FAI[RCA] was significant in both models (HR 2.119, 95% CI: 1.218-3.686, p = 0.008; and HR 2.071, 95% CI: 1.111-3.861, p = 0.022).

CONCLUSION

FAI does not add incremental prognostic value beyond multimodality MPI/CCTA findings including CACS. The diagnostic value of FAI[RCA] is significantly biased by sex.

Atherosclerosis and Bone Loss in Humans-Results From Deceased Donors and From Patients Submitted to Carotid Endarterectomy

Background and Aims: Atherosclerosis and osteoporosis share common risk factors, as well as inflammatory mechanisms. Our aim was to understand how atherosclerotic lesions are related with disturbances in bone.

Methods: Gene expression of pro-inflammatory and bone metabolism related proteins (IL-1β, IL-6, IL-17A, TNF, RANKL, OPG, COL1, CTSK, OCL, TRAP, CBFA1, DKK1, SOST, ADIPOQ, and ADIPOR1) were analyzed in arteries and bones from 45 deceased donors and adipose tissue was used as control. Additionally, in 139 patients with advanced atherosclerosis submitted to carotid endarterectomy we compared calcium content (Alizarin red) and plaque inflammatory scores (CD3⁺, CD68⁺, and adiponectin) of patients with normal bone mineral density (BMD) with those with low BMD and explored the associations between gene expression in atherosclerotic plaques and BMD. Serum levels of pro-inflammatory and bone related proteins were measured both in donors and patients. Associations were investigated by the Pearson or Spearman correlation tests, and multivariate regression analyzes were performed when justified.

Results: Gene expression of bone remodeling and pro-inflammatory proteins correlated positively in bone and aorta, independently of age and sex of donors, but not in adipose tissue. The expression of bone formation genes was significantly higher in atheroma plaques from endarterectomized patients with normal vs. low BMD as well as inflammatory CD68⁺ scores, regardless of patients' age and sex, but not of body mass index. No relationship was observed between serum levels and gene expression levels of pro-inflammatory or bone remodeling proteins.

Conclusions: Our results suggest that the relationship between bones and vessels in the context of atherosclerotic disease and osteoporosis may rely on the intrinsic connection between the tissues involved, independently of disease stage. Serum measurements of pro-inflammatory and bone-remodeling proteins do not accurately translate tissue pathologic processes.

Arterial wall inflammation in rheumatoid arthritis is reduced by anti-inflammatory treatment

BACKGROUND

Rheumatoid arthritis (RA) patients have an increased risk of cardiovascular disease (CVD), partly due to an increased prevalence of cardiovascular risk factors, but also due to chronic systemic inflammation inducing atherosclerotic changes of the arterial wall. The aim of this study was to determine whether anti-inflammatory therapy for the treatment of RA has favorable effects on arterial wall inflammation in RA patients.

METHODS

Arterial wall inflammation before and after 6 months of anti-inflammatory treatment was assessed in 49 early and established RA patients using 18F-fluorodeoxyglucose-positron emission tomography with computed tomography (18F-FDG-PET/CT). Arterial 18F-FDG uptake was quantified as maximum standardized uptake value (SUVmax) in the thoracic aorta, abdominal aorta, carotid, iliac and femoral arteries. Early RA patients (n = 26) were treated with conventional synthetic disease modifying anti-rheumatic drugs with or without corticosteroids, whereas established RA patients (n = 23) were treated with adalimumab.

RESULTS

In RA patients, overall SUVmax was over time reduced by 4% (difference -0.06, 95%CI -0.12 to -0.01, p = 0.02), with largest reductions in carotid (-8%, p = 0.001) and femoral arteries (-7%, p = 0.005). There was no difference in arterial wall inflammation change between early and established RA patients (SUVmax difference 0.003, 95%CI -0.11 to 0.12, p = 0.95). Change in arterial wall inflammation significantly correlated with change in serological inflammatory markers (erythrocyte sedimentation rate and C-reactive protein).

CONCLUSION

Arterial wall inflammation in RA patients is reduced by anti-inflammatory treatment and this reduction correlates with reductions of serological inflammatory markers. These results suggest that anti-inflammatory treatment of RA has favorable effects on the risk of cardiovascular events in RA patients.

Correlation between calcium, water contents and ultrasonographic appearance of atherosclerotic lesions of carotid artery lesions

Background

We tested the hypothesis whether there is a correlation between the echogenicity and calcium and water contents of carotid plaques.

Patients and methods

Ninety carotid befurcations from 45 deceased patients were removed during autopsy. Thirty-four plaques were categorized as homogenous echolucent (HEL), homogenous echogenic (HEG) and heterogenous (HE) plaques based on premortem B-mode image. Water content was expressed in % of wet weight. Ca was determined by proton-induced X-ray emission and expressed in ppm. Relative optical density of the B-mode images was analyzed offline using a computer program.

Results

HEL plaques had lower Ca content (medians and IQRs: 6,145 [4,465–6,536 ppm]) compared to HEG (74,100 [15,300–1,44,500−ppm]), P ≤ 0.001). HE plaques showed an intermediate calcium content (7,310 [4,840–9,920 ppm]) that was statistically not different from echolucent plaques. Water content of HEG plaques was statistically not different from HEL and HE (HEG:53.5 [35.5–64%], HEL: 73.5 [69.7–78.5%], HE: 70.6 [67.4–73.9%]). HEG plaques had the highest relative optical densities (196 [188–217%]). HEL and HE had similar relative optical densities (HEL: 176 [164–187%], HE: 164 [144–188%], respectively). A significant positive correlation was found between the Ca content and relative optical density of plaques.

Conclusions

Echogenicity of carotid plaques increases along with their calcium content. Water content may be an important factor in differentiation of different plaques.

Lymphoma Severity and Type Are Associated With Aortic FDG Uptake by 18F-FDG PET/CT Imaging

BACKGROUND

There is evidence that metabolic disease burden in lymphoma influences patient outcome. However, the impact of disease severity on the cardiovascular system is unknown.

OBJECTIVES

The aim of this study was to examine whether lymphoma is associated with arterial inflammation by investigating the relationship between disease metabolic burden and arterial fluorodeoxyglucose (FDG) uptake.

METHODS

Sixty-two chemotherapy-naïve patients with active Hodgkin's or non-Hodgkin's lymphoma were matched (2:1) to individual control groups of lymphoma patients previously treated and free of active disease. All groups underwent 18F-FDG position emission tomography-computed tomography imaging. Disease severity was quantified by metabolic tumor volume (MTV) and total lesion glycolysis corresponding to standardized uptake values (SUVs) ≥41% or ≥2.5 of the maximum SUV within lymphoma regions, and aortic FDG uptake was quantified through the target-to-background ratio (TBR). Inflammatory and disease severity biomarkers were also measured.

RESULTS

MTV and total lesion glycolysis measurements were significantly correlated with inflammatory and disease biomarkers. Aortic TBR was higher in patients with active non-Hodgkin's lymphoma compared with control subjects (median difference 0.51; 95% confidence interval [CI]: 0.28 to 0.78; p < 0.001). Similarly, patients with active Hodgkin's lymphoma had higher values of aortic TBR compared with control subjects (median difference 0.31; 95% CI: 0.15 to 0.49; p < 0.001). In addition, aortic TBR was modestly increased in patients with stage III to IV disease compared with those with stage I to II disease (median aortic TBR: 2.23 [interquartile range: 2.01 to 2.54] vs. 2.06 [interquartile range: 1.83 to 2.27; p = 0.050). In multivariable analysis, aortic FDG uptake and MTV≥2.5 values were independently associated (β = 0.425; 95% CI: 0.189 to 0.662; p = 0.001; R2 = 0.208), as were aortic FDG uptake and MTV≥41% (β = 0.407; 95% CI: 0.167 to 0.649, p = 0.001; R2 = 0.191).

CONCLUSIONS

Aortic wall FDG uptake is related with disease severity indicative of a possible vascular effect of lymphoma. This work highlights a new potential role of molecular imaging in cardio-oncology for evaluating disease severity and its consequences on the vasculature.

A Preliminary 18F-FDG-PET/MRI Study Shows Increased Vascular Inflammation in Moderate-to-Severe Atopic Dermatitis

BACKGROUND

Recent data suggest that patients with atopic dermatitis (AD) have increased systemic immune activation and cardiovascular risk. However, unlike psoriasis, evaluation of active vascular inflammation using state-of-the-art imaging is lacking in AD.

OBJECTIVE

To assess aortic and carotid vascular inflammation using 18F-fluorodeoxyglucose-positron emission tomography/magnetic resonance imaging (18F-FDG-PET/MRI) imaging in moderate-to-severe AD versus healthy individuals.

METHODS

A total of 27 patients with moderate-to-severe AD and 12 healthy controls were imaged using 18F-FDG-PET/MRI. Target-to-background ratio (TBR) values were calculated in multiple segments of the aorta and carotid vessels.

RESULTS

Patients with AD had elevated aortic max TBR (fold change [FCH] = 1.45, P = .057) versus healthy controls and significantly elevated mean TBR (FCH = 1.20; P < .05) in the right carotid (RC) arteries versus controls. When examining greatest focal inflammation (most diseased segment [MDS] TBR), patients with AD had higher aortic inflammation (FCH = 1.28; P = .052). AD clinical severity significantly correlated with C-reactive protein (ρ = 0.60, P < .01) and with RC mean TBR levels (ρ = 0.60, P = .04). Stratifying patients into moderate-to-severe and very severe AD showed greater RC mean TBR in patients with very severe AD versus controls (FCH = 1.31; P = .02) and versus patients with moderate/severe AD (FCH = 1.23, P = .05). Aortic inflammation was also significantly greater in patients with very severe AD versus controls (max TBR: FCH = 1.6, P = .04; MDS TBR: FCH = 1.73, P = .03).

CONCLUSIONS

This preliminary study is the first that establishes greater vascular (aorta and carotid) inflammation in moderate-to-severe AD versus healthy controls. Furthermore, very severe AD showed higher inflammation than both moderate/severe patients and healthy controls. Future studies with larger patient cohorts and evaluation before and after treatment are needed to determine the extent to which vascular inflammation in AD is modifiable.

Hot Aortic Nodules

Atherosclerotic cardiovascular disease is the leading cause of death worldwide. Morbidity of the dreaded thrombotic complications of atherosclerosis such as cerebrovascular accident and myocardial infarction may be severe. Early detection of fulminant disease is therefore important for risk stratification and selecting a treatment strategy. In this report we present four patients in which 18-fluorodeoxyglucose uptake was identified in atherosclerotic plaques at positron emission tomography, performed for other indications. The study aims to showcase the potential implications of 18-fluorodeoxyglucose avid plaques, which may be otherwise overlooked at positron emission tomography. Early detection may aid in prevention of complications of atherosclerotic cardiovascular disease through aggressive lifestyle modification, as well as pharmacologic or other intervention, such as endovascular atherectomy.

Vascular findings on FDG PET/CT

Since its introduction into clinical practice, 2-deoxy-2-[18F]flu-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) has become firmly established in the field of oncological imaging, with a growing body of evidence demonstrating its use in infectious and inflammatory vascular pathologies. This pictorial review illustrates the utility of FDG PET/CT as a diagnostic tool in the investigation of vascular disease and highlights some of the more common incidental vascular findings that PET reporters may encounter on standard oncology FDG PET/CTs, including atherosclerosis, large vessel vasculitis, complications of vascular grafts, infectious aortitis and acute aortic syndromes.

Extracellular Matrix Remodeling Factors as Markers of Carotid Artery Atherosclerosis

Materials and Methods

20 patients undergoing routine carotid endarterectomy and 40 healthy volunteers were enrolled in this study. MMPs activity and OPG and FN concentrations were measured in atherosclerotic plaques and nonchanged contiguous tissue after homogenization as well as in plasma from patients and reference group. The activity of MMPs was evaluated by gelatin zymography, and the concentration of OPG and FN was assessed by ELISA.

Results

OPG concentration and MMP-9 activity showed differences between plaque and nonchanged tissue; OPG was higher in adjacent tissue (P=0.0009), whereas MMP-9 was higher in plaque (proMMP-9 P=0.0003; MMP-9 P < 0.0001). The OPG plasma concentration and both MMPs plasma activity were higher in patients (OPG P < 0.001; proMMP-2 P=0.0292; and proMMP-9 P=0.0374), while FN plasma concentration was lower in patients than in the reference group (P=0.0004). The ROC curves analysis showed the highest AUC for OPG (0.943) with 85.0% sensitivity and 92.1% specificity.

Conclusions

The atherosclerotic plaque and the contiguous artery wall are biochemically different. OPG shows the highest potential to be a marker of advanced carotid atherosclerosis.

Cohort profile: BIOVASC-late, a prospective multicentred study of imaging and blood biomarkers of carotid plaque inflammation and risk of late vascular recurrence after non-severe stroke in Ireland

PURPOSE

Inflammation is important in stroke. Anti-inflammatory therapy reduces vascular events in coronary patients. ¹⁸F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) identifies plaque inflammation-related metabolism. However, long-term prospective cohort studies investigating the association between carotid plaque inflammation, identified on ¹⁸F-FDG PET and the risk of recurrent vascular events, have not yet been undertaken in patients with stroke.

PARTICIPANTS

The Biomarkers Imaging Vulnerable Atherosclerosis in Symptomatic Carotid disease (BIOVASC) study and Dublin Carotid Atherosclerosis Study (DUCASS) are two prospective multicentred observational cohort studies, employing near-identical methodologies, which recruited 285 patients between 2008 and 2016 with non-severe stroke/transient ischaemic attack and ipsilateral carotid stenosis (50%-99%). Patients underwent coregistered carotid ¹⁸F-FDG PET/CT angiography and phlebotomy for measurement of inflammatory cytokines. Plaque ¹⁸F-FDG-uptake is expressed as maximum standardised uptake value (SUV_max) and tissue-to-background ratio. The BIOVASC-Late study is a follow-up study (median 7 years) of patients recruited to the DUCASS/BIOVASC cohorts.

FINDINGS TO DATE

We have reported that ¹⁸F-FDG-uptake in atherosclerotic plaques of patients with symptomatic carotid stenosis predicts early recurrent stroke, independent of luminal narrowing. The incorporation of ¹⁸F-FDG plaque uptake into a clinical prediction model also improves discrimination of early recurrent stroke, when compared with risk stratification by luminal stenosis alone. However, the relationship between ¹⁸F-FDG-uptake and late vascular events has not been investigated to date.

FUTURE PLANS

The primary aim of BIOVASC-Late is to investigate the association between SUV_max in symptomatic 'culprit' carotid plaque (as a marker of systemic inflammatory atherosclerosis) and the composite outcome of any late major vascular event (recurrent ischaemic stroke, coronary event or vascular death). Secondary aims are to investigate associations between: (1) SUV_max in symptomatic plaque, and individual vascular endpoints (2) SUV_max in asymptomatic contralateral carotid plaque and SUV_max in ipsilateral symptomatic plaque (3) SUV_max in asymptomatic carotid plaque and major vascular events (4) inflammatory cytokines and vascular events.

Current Advances in the Diagnostic Imaging of Atherosclerosis: Insights into the Pathophysiology of Vulnerable Plaque

Atherosclerosis is a lipoprotein-driven inflammatory disorder leading to a plaque formation at specific sites of the arterial tree. After decades of slow progression, atherosclerotic plaque rupture and formation of thrombi are the major factors responsible for the development of acute coronary syndromes (ACSs). In this regard, the detection of high-risk (vulnerable) plaques is an ultimate goal in the management of atherosclerosis and cardiovascular diseases (CVDs). Vulnerable plaques have specific morphological features that make their detection possible, hence allowing for identification of high-risk patients and the tailoring of therapy. Plaque ruptures predominantly occur amongst lesions characterized as thin-cap fibroatheromas (TCFA). Plaques without a rupture, such as plaque erosions, are also thrombi-forming lesions on the most frequent pathological intimal thickening or fibroatheromas. Many attempts to comprehensively identify vulnerable plaque constituents with different invasive and non-invasive imaging technologies have been made. In this review, advantages and limitations of invasive and non-invasive imaging modalities currently available for the identification of plaque components and morphologic features associated with plaque vulnerability, as well as their clinical diagnostic and prognostic value, were discussed.

Integrated cardiovascular assessment of atherosclerosis using PET/MRI

Atherosclerosis is a systemic inflammatory disease typified by the development of lipid-rich atheroma (plaques), the rupture of which are a major cause of myocardial infarction and stroke. Anatomical evaluation of the plaque considering only the degree of luminal stenosis overlooks features associated with vulnerable plaques, such as high-risk morphological features or pathophysiology, and hence risks missing vulnerable or ruptured non-stenotic plaques. Consequently, there has been interest in identifying these markers of vulnerability using either MRI for morphology, or positron emission tomography (PET) for physiological processes involved in atherogenesis. The advent of hybrid PET/MRI scanners offers the potential to combine the strengths of PET and MRI to allow comprehensive assessment of the atherosclerotic plaque. This review will discuss the principles and technical aspects of hybrid PET/MRI assessment of atherosclerosis, and consider how combining the complementary modalities of PET and MRI has already furthered our understanding of atherogenesis, advanced drug development, and how it may hold potential for clinical application.

Dual-Tracer Positron-Emission Tomography for Identification of Culprit Carotid Plaques and Pathophysiology In Vivo

BACKGROUND

Inflammation and microcalcification are interrelated processes contributing to atherosclerotic plaque vulnerability. Positron-emission tomography can quantify these processes in vivo. This study investigates (1) ¹⁸F-fluorodeoxyglucose (FDG) and ¹⁸F-sodium fluoride (NaF) uptake in culprit versus nonculprit carotid atheroma, (2) spatial distributions of uptake, and (3) how macrocalcification affects this relationship.

METHODS

Individuals with acute ischemic stroke with ipsilateral carotid stenosis of ≥50% underwent FDG-positron-emission tomography and NaF-positron-emission tomography. Tracer uptake was quantified using maximum tissue-to-background ratios (TBR_max) and macrocalcification quantified using Agatston scoring.

RESULTS

In 26 individuals, median most diseased segment TBR_max (interquartile range) was higher in culprit than in nonculprit atheroma for both FDG (2.08 [0.52] versus 1.89 [0.40]; P<0.001) and NaF (2.68 [0.63] versus 2.39 [1.02]; P<0.001). However, whole vessel TBR_max was higher in culprit arteries for FDG (1.92 [0.41] versus 1.71 [0.31]; P<0.001) but not NaF (1.85 [0.28] versus 1.79 [0.60]; P=0.10). NaF uptake was concentrated at carotid bifurcations, while FDG was distributed evenly throughout arteries. Correlations between FDG and NaF TBR_max differed between bifurcations with low macrocalcification (r_s=0.38; P<0.001) versus high macrocalcification (r_s=0.59; P<0.001).

CONCLUSIONS

This is the first study to demonstrate increased uptake of both FDG and NaF in culprit carotid plaques, with discrete distributions of pathophysiology influencing vulnerability in vivo. These findings have implications for our understanding of the natural history of the disease and for the clinical assessment and management of carotid atherosclerosis.

Inflammation imaging to define vulnerable plaque or vulnerable patient

The role of nuclear imaging in the characterization of high-risk atherosclerotic plaque is increasing thanks to its high sensitivity to detect radiopharmaceuticals signal in tissues. Currently, 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is the most studied and widely used radiopharmaceutical for the molecular imaging of atherosclerotic plaques with positron emission tomography (PET). [18F]FDG PET is a valuable tool to non-invasively detect, monitor and quantify inflammatory processes occurring in atherosclerotic plaques. The aim of this review is to gather insights provided by [18F]FDG PET to better understand the role of inflammation in the definitions of the vulnerable plaque and the vulnerable patient. Alternatives radiopharmaceuticals targeting inflammation and other potential high-risk plaque related processed are also discussed.

Elevated circulating metalloproteinase 7 predicts recurrent cardiovascular events in patients with carotid stenosis: a prospective cohort study

BACKGROUND

Major adverse cardiovascular events are the main cause of morbidity and mortality over the long term in patients undergoing carotid endarterectomy. There are few reports assessing the prognostic value of markers of inflammation in relation to the risk of cardiovascular disease after carotid endarterectomy. Here, we aimed to determine whether matrix metalloproteinases (MMP-1, MMP-2, MMP-7, MMP-9 and MMP-10), tissue inhibitor of MMPs (TIMP-1) and in vivo inflammation studied by ¹⁸F-FDG-PET/CT predict recurrent cardiovascular events in patients with carotid stenosis who underwent endarterectomy.

METHODS

This prospective cohort study was carried out on 31 consecutive patients with symptomatic (23/31) or asymptomatic (8/31) severe (> 70%) carotid stenosis who were scheduled for carotid endarterectomy between July 2013 and March 2016. In addition, 26 healthy controls were included in the study. Plasma and serum samples were collected 2 days prior to surgery and tested for MMP-1, MMP-2, MMP-7, MMP-9, MMP-10, TIMP-1, high-density lipoprotein, low-density lipoprotein, high-sensitivity C-reactive protein and erythrocyte sedimentation rate. ¹⁸F-FDG-PET/CT focusing on several territories' vascular wall metabolism was performed on 29 of the patients because of no presurgical availability in 2 symptomatic patients. Histological and immunohistochemical studies were performed with antibodies targeting MMP-10, MMP-9, TIMP-1 and CD68.

RESULTS

The patients with carotid stenosis had significantly more circulating MMP-1, MMP-7 and MMP-10 than the healthy controls. Intraplaque TIMP-1 was correlated with its plasma level (r = 0.42 P = .02) and with ¹⁸F-FDG uptake (r = 0.38 P = .05). We did not find any correlation between circulating MMPs and in vivo carotid plaque metabolism assessed by ¹⁸F-FDG-PET. After a median follow-up of 1077 days, 4 cerebrovascular, 7 cardiovascular and 11 peripheral vascular events requiring hospitalization were registered. Circulating MMP-7 was capable of predicting events over and above the traditional risk factors (HR = 1.15 P = .006). When the model was associated with the variables of interest, the risk predicted by ¹⁸F-FDG-PET was not significant.

CONCLUSIONS

Circulating MMP-7 may represent a novel marker for recurrent cardiovascular events in patients with moderate to severe carotid stenosis. MMP-7 may reflect the atherosclerotic burden but not plaque inflammation in this specific vascular territory.

Vascular Inflammation in Subclinical Atherosclerosis Detected by Hybrid PET/MRI

BACKGROUND

Atherosclerosis is a chronic inflammatory disease, but data on arterial inflammation at early stages is limited.

OBJECTIVES

The purpose of this study was to characterize vascular inflammation by hybrid ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/magnetic resonance imaging (PET/MRI).

METHODS

Carotid, aortic, and ilio-femoral ¹⁸F-FDG PET/MRI was performed in 755 individuals (age 40 to 54 years; 83.7% men) with known plaques detected by 2-/3-dimensional vascular ultrasound and/or coronary calcification in the PESA (Progression of Early Subclinical Atherosclerosis) study. The authors evaluated the presence, distribution, and number of arterial inflammatory foci (increased ¹⁸F-FDG uptake) and plaques with or without inflammation (coincident ¹⁸F-FDG uptake).

RESULTS

Arterial inflammation was present in 48.2% of individuals (24.4% femorals, 19.3% aorta, 15.8% carotids, and 9.3% iliacs) and plaques in 90.1% (73.9% femorals, 55.8% iliacs, and 53.1% carotids). ¹⁸F-FDG arterial uptakes and plaques significantly increased with cardiovascular risk factors (p < 0.01). Coincident ¹⁸F-FDG uptakes were present in 287 of 2,605 (11%) plaques, and most uptakes were detected in plaque-free arterial segments (459 of 746; 61.5%). Plaque burden, defined by plaque presence, number, and volume, was significantly higher in individuals with arterial inflammation than in those without (p < 0.01). The number of plaques and ¹⁸F-FDG uptakes showed a positive albeit weak correlation (r = 0.25; p < 0.001).

CONCLUSIONS

Arterial inflammation is highly prevalent in middle-aged individuals with known subclinical atherosclerosis. Large-scale multiterritorial PET/MRI allows characterization of atherosclerosis-related arterial inflammation and demonstrates ¹⁸F-FDG uptake in plaque-free arterial segments and, less frequently, within plaques. These findings suggest an arterial inflammatory state at early stages of atherosclerosis. (Progression of Early Subclinical Atherosclerosis [PESA]; NCT01410318).

Systemic atherosclerotic plaque vulnerability in patients with Coronary Artery Disease with a single Whole Body FDG PET-CT scan

OBJECTIVES

Cardiovascular disease is a leading cause of morbimortality with over half cardiovascular events occurring in the asymptomatic population by traditional risk stratification. This preliminary study aimed to evaluate systemic plaque vulnerability in patients with prior Coronary Artery Disease (CAD) with a single Whole Body [FDG] PET-CT scan in terms of plaque inflammation and calcifications.

METHODS

Twenty-two patients referred for oncological evaluation and with prior history of advanced CAD or age and gender matched controls without cardiovascular disease, underwent a Whole Body PET-CT scan 90 min after injection of 18F-FDG. A total of 975 transaxial PET images were retrospectively analysed to assess plaque inflammation using a standardized method of analysis with averaged Target-to-Background Ratios (TBRs) at different levels, in the thoracic and abdominal aorta, carotids, LAD, common iliac and femoral arteries, and were correlated with calcium scores from the CT images.

RESULTS

TBRs from the thoracic aorta were higher in male patients than controls (1.49±0.11, p<0.05) and a gradient was observed (ascending > descending > aortic arch), and were also higher in the carotids in female patients (1.43±0.07) versus controls (p<0.05). A tendency for higher levels of plaque inflammation in the abdominal aorta was noted in all groups, but no significant FDG uptake was found either in the iliac or femoral arteries in any group. Plaque inflammation was also higher in the LAD in males but with large variations. Higher levels of calcifications were noted in the LAD, infra-renal abdominal aorta and common iliac arteries, but without significant correlation with plaque inflammation except sporadic overlapping.

CONCLUSION

Patients with advanced CAD are at risk for vulnerable inflamed atheromas in other territories such as the thoracic aorta and carotid arteries, underpinning the systemic nature of the atherosclerotic disease. Coexistence with calcifications is rare, suggesting a different functional status of the plaques and different stages of the disease. Evaluation of subclinical systemic plaque vulnerability in CAD with a Whole Body [FDG] PET-CT scan is feasible and a potentially useful biomarker to assess subclinical vascular risk for risk stratification and treatment optimization, but further studies are needed.

Role of pentraxin-3 in risk assessment of patients with metabolic syndrome

BACKGROUND

Inflammation plays a major role in the development of metabolic syndrome (MetS) and its progression. Recent studies have shown that pentraxin-3 (PTX-3), osteoprogerin (OPG), and tumor necrosis factor-alpha (TNF-α) are key factors in MetS pathophysiology, but evidence for endorsing their clinical use is currently unclear and insufficient.

AIM

The study aimed to evaluate the association between the inflammatory biomarkers' levels and the severity of MetS.

METHODS

The study was observational, transversal, prospective, cohort, and analytical type. We enrolled 80 patients (M:F = 1, mean age = 55 ± 10.77 years) who met MetS criteria. The study protocol included: medical history, physical examination, 6-min walk test distance (6MWTD), biochemical tests, electrocardiogram, echocardiography, and carotid ultrasonography. We also performed plasmatic measurement of PTX-3, OPG, and TNF-α, in addition to standard biochemical tests.

RESULTS

Subjects with severe MetS had higher values of body mass index (BMI) and waist circumference (p < 0.001, p = 0.001). PTX-3 levels were significantly higher in patients with severe MetS (p = 0.03) and the values were not influenced by age or gender. OPG positively correlated with BMI (r = 0.264, p = 0.018). 6MWTD was lower in patients with severe MetS (p = 0.005), whereas CCA-IMT was higher in this group of patients (p = 0.005). In addition, the receiver operating characteristic (ROC) curve analysis for PTX-3 identified a cut-off value of 10.7 ng/dl that differentiates between mild and severe MetS [AUC 0.656; sensitivity =47.1% (95% CI = 36.1%-62.3%); specificity = 78.9% (95% CI = 54.4%-93.9%)].

CONCLUSION

PTX-3 was correlated with the severity of MetS, with other inflammatory parameters and cardiovascular tests. CCA-IMT and 6MWTD are useful in differentiating between mild and severe MetS.

Monocyte and Macrophage Dynamics in the Cardiovascular System: JACC Macrophage in CVD Series (Part 3)

It has long been recognized that the bone marrow is the primary site of origin for circulating monocytes that may later become macrophages in atherosclerotic lesions. However, only in recent times has the complex relationship among the bone marrow, monocytes/macrophages, and atherosclerotic plaques begun to be understood. Moreover, the systemic nature of these interactions, which also involves additional compartments such as extramedullary hematopoietic sites (i.e., spleen), is only just becoming apparent. In parallel, progressive advances in imaging and cell labeling techniques have opened new opportunities for in vivo imaging of monocyte/macrophage trafficking in atherosclerotic lesions and at the systemic level. In this Part 3 of a 4-part review series covering the macrophage in cardiovascular disease, the authors intersect systemic biology with advanced imaging techniques to explore monocyte and macrophage dynamics in the cardiovascular system, with an emphasis on how events at the systemic level might affect local atherosclerotic plaque biology.

Correlation Between Cerebral Microbleeds and Vulnerable Plaque in Patients with Severe Carotid Artery Stenosis; Comparative Magnetic Resonance Imaging Study

GOAL

There are an increasing idea that the inflammation contributes to vascular diseases in various organs. The pathogenesis of both cerebral small vessel disease such as cerebral microbleeds and carotid plaque may be associated with chronic inflammation. This study was aimed to evaluate the correlation between microbleeds and carotid plaque characteristics.

MATERIALS AND METHODS

This study enrolled 85 patients who underwent surgical/endovascular treatments for carotid artery stenosis between January 2009 and July 2016. Their clinical data were precisely analyzed. T2*-weighted magnetic resonance (MR) imaging was performed to detect the cerebral microbleeds. The carotid plaque with high signal intensity on T1-weighted MR imaging was categorized into vulnerable plaque.

FINDINGS

The microbleeds was detected in 17 of 85 (20%). The prevalence of vulnerable carotid plaque and previous symptomatic lacunar infarction was significantly greater in the patients with microbleeds than in those without (P = .001 and P = .03, respectively). Multiple logistic regression analysis showed that the vulnerable plaque was significantly associated with the presence of microbleeds when adjusted for age, alcohol intake, antiplatelet drug use, the presence of previous symptomatic lacunar infarction, and coronary artery disease (P = .009, OR = 5.38, 95% CI = 1.51-21.0).

CONCLUSIONS

These findings suggest the correlation between microbleeds and vulnerable plaque in patients with severe (>70%) carotid artery stenosis. Systemic, chronic inflammation may play a key role in both small and large arteries' disease of the brain. The knowledge may be valuable to fully understand the entity of cerebrovascular diseases as one of systemic, chronic inflammation.

Review of serum biomarkers in carotid atherosclerosis

BACKGROUND

Carotid artery atherosclerotic stenosis is a preventable major cause of stroke, but there is still a need for definition of high-risk plaque in asymptomatic patients who might benefit from interventional therapies. Several image markers are recommended to characterize unstable plaques. The measurement of serum biomarkers is a promising method to assist in decision making, but the lack of robust evidence in the carotid environment burdens their potential as a standard of care. The goal of this review was to offer an updated state-of-the-art study of available serum biomarkers with clinical implications, with focus on those that may predict carotid symptom development.

METHODS

The Cochrane Library and MEDLINE databases were searched (all until September 2018) for studies on carotid plaque and serum biomarkers of atherosclerosis. Nonhuman, basic science, and histology studies were excluded, focusing on clinical studies. Selected abstracts were screened to include the most relevant articles on atherosclerotic plaque presence, progression, instability or symptom development.

RESULTS

Some well-established biomarkers for coronary disease are not relevant to carotid atherosclerosis and other inflammatory biomarkers, lipids, interleukins, homocysteine, and adipokines may be useful in quantifying carotid disease-related risk. Some serum biomarkers combined with image features may assist vascular specialists in selecting patients at high risk for stroke and in need of intervention.

CONCLUSIONS

Prospective studies applying a combination of biomarkers are essential to prove clinical usefulness.

Anti-inflammatory effect of statin is continuously working throughout use: a prospective three time point 18F-FDG PET/CT imaging study

No data exist whether statins have robust anti-inflammatory effects of atherosclerotic plaques primarily during the early treatment period or continuously throughout use. This prospective three time point ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) study of the carotid artery assessed anti-inflammatory effects of statin during the early treatment period (initiation to 3 months) and late treatment period (3 months to 1 year) and their correlation with lipid and inflammatory profile changes during a year of therapy. Nine statin-naïve stable angina patients with inflammatory carotid plaques received 20 mg/day atorvastatin after undergoing initial ¹⁸F-FDG PET/CT scanning of carotid arteries and ascending thoracic aorta, and then completed serial ¹⁸F-FDG PET/CT imaging at 3 and 12 months whose data were analyzed. The primary outcome was the inter-scan percent change in target-to-background ratio (ΔTBR) within the index vessel. At 3 months of atorvastatin treatment, mean serum low-density lipoprotein cholesterol (LDL-C) level decreased by 36.4% to < 70 mg/dL (p = 0.001) and mean serum high-density lipoprotein cholesterol level increased to > 40 mg/dL (p = 0.041), with both maintained with no further reduction up to 1 year (p = 0.516 and 0.715, respectively) while mean serum high sensitivity C-reactive protein level only numerically decreased (p = 0.093). The index vessel ΔTBR showed continuous plaque inflammation reduction over 1 year, by 4.4% (p = 0.015) from the initiation to 3rd months and 6.2% (p = 0.009) from 3rd months to 1 year, respectively, without correlation with lipid profile changes. The ΔTBR of the bilateral carotid arteries and ascending aorta also continuously decreased from 3 months to 1 year. Three time point ¹⁸F-FDG PET/CT imaging demonstrates that statin's anti-inflammatory effect continues throughout its use up to 1 year, even though yielding stable below-target plasma LDL-C levels at 3 months.

CCR2 expression on circulating monocytes is associated with arterial wall inflammation assessed by 18F-FDG PET/CT in patients at risk for cardiovascular disease

Aims

Circulating monocytes infiltrate the plaque and differentiate into macrophages, contributing to an inflammatory environment which is associated with higher risk of cardiovascular events. Although the pivotal role of circulating monocytes in plaque inflammation has been firmly established, the search continues to identify specific monocyte subsets that may be especially atherogenic. Therefore, we evaluated the relation between monocyte phenotype, particularly surface receptor expression, and arterial wall inflammation in patients at increased cardiovascular risk.

Methods and results

We performed a multivariate linear regression analysis in 79 patients at increased cardiovascular risk who had both an 18F-fluorodeoxyglucose positron emission tomography/computed tomography to assess arterial wall inflammation and extensive monocyte characterization (using flow cytometry). We found that CCR2, a monocyte chemokine receptor essential for transmigration, significantly correlates with arterial wall inflammation. This relationship was independent of traditional cardiovascular risk factors and statin use (β = 0.429, P = 0.015). We found no relation between arterial wall inflammation and monocyte count or monocyte subsets, namely CD14+CD16-, CD14+CD16+, CD14+CD16 ++, CCR5+, CD18+, CD11b+, or CD11c+ monocytes.

Conclusion

Monocyte CCR2 expression is associated with arterial wall inflammation in patients at increased cardiovascular risk. Our data warrant further studies to assess if inhibition of CCR2 may attenuate atherosclerotic plaque inflammation.

3-D Strain Imaging of the Carotid Bifurcation: Methods and in-Human Feasibility

Atherosclerotic plaque development in the carotid artery bifurcation elevates the risk for stroke, which is often initiated by plaque rupture. The risk-to-rupture of a plaque is related to its composition. Two-dimensional non-invasive carotid elastography studies have found a correlation between wall strain and plaque composition. This study introduces a technique to perform non-invasive volumetric elastography in vivo. Three-dimensional ultrasound data of carotid artery bifurcations were acquired in four asymptomatic individuals using an electrocardiogram-triggered multislice acquisition device that scanned over a length of 35 mm (350 slices) using a linear transducer (L11-3, f_c = 9 MHz). For each slice, three-angle ultrasound plane wave data were acquired and beamformed. A correction for breathing-induced motion was applied to spatially align the slices, enabling 3-D cross-correlation-based compound displacement, distensibility and strain estimation. Distensibility values matched with previously published values, while the corresponding volumetric principal strain maps revealed locally elevated compressive and tensile strains. This study presents for the first time 3-D elastography of carotid arteries in vivo.