Positive remodeling of the coronary arteries detected by magnetic resonance imaging in an asymptomatic population: MESA (Multi-Ethnic Study of Atherosclerosis)

Clinical quantitative coronary artery stenosis and coronary atherosclerosis imaging: a Consensus Statement from the Quantitative Cardiovascular Imaging Study Group

The detection and characterization of coronary artery stenosis and atherosclerosis using imaging tools are key for clinical decision-making in patients with known or suspected coronary artery disease. In this regard, imaging-based quantification can be improved by choosing the most appropriate imaging modality for diagnosis, treatment and procedural planning. In this Consensus Statement, we provide clinical consensus recommendations on the optimal use of different imaging techniques in various patient populations and describe the advances in imaging technology. Clinical consensus recommendations on the appropriateness of each imaging technique for direct coronary artery visualization were derived through a three-step, real-time Delphi process that took place before, during and after the Second International Quantitative Cardiovascular Imaging Meeting in September 2022. According to the Delphi survey answers, CT is the method of choice to rule out obstructive stenosis in patients with an intermediate pre-test probability of coronary artery disease and enables quantitative assessment of coronary plaque with respect to dimensions, composition, location and related risk of future cardiovascular events, whereas MRI facilitates the visualization of coronary plaque and can be used in experienced centres as a radiation-free, second-line option for non-invasive coronary angiography. PET has the greatest potential for quantifying inflammation in coronary plaque but SPECT currently has a limited role in clinical coronary artery stenosis and atherosclerosis imaging. Invasive coronary angiography is the reference standard for stenosis assessment but cannot characterize coronary plaques. Finally, intravascular ultrasonography and optical coherence tomography are the most important invasive imaging modalities for the identification of plaques at high risk of rupture. The recommendations made in this Consensus Statement will help clinicians to choose the most appropriate imaging modality on the basis of the specific clinical scenario, individual patient characteristics and the availability of each imaging modality.

Effects of Lipid Lowering Therapies on Vulnerable Plaque Features: An Updated Narrative Review of the Literature

The clinical evidence on the efficacy of lipid lowering therapy in patients with coronary artery disease (CAD) is unequivocally established. However, the effects of these therapies on plaque composition and stability are less clear. The use of intracoronary imaging (ICI) technologies has emerged as a complement to conventional angiography to further characterize plaque morphology and detect high-risk plaque features related to cardiovascular events. Along with clinical outcomes studies, parallel imaging trials employing serial evaluations with intravascular ultrasound (IVUS) have shown that pharmacological treatment has the capacity to either slow disease progression or promote plaque regression, depending on the degree of lipid lowering achieved. Subsequently, the introduction of high-intensity lipid lowering therapy led to much lower levels of low-density lipoprotein cholesterol (LDL-C) levels than achieved in the past, resulting in greater clinical benefit. However, the degree of atheroma regression showed in concomitant imaging trials appeared more modest as compared to the magnitude of clinical benefit accrued from high-intensity statin therapy. Recently, new randomized trials have investigated the additional effects of achieving very low levels of LDL-C on high-risk plaque features-such as fibrous cap thickness and large lipid accumulation-beyond its size. This paper provides an overview of the currently available evidence of the effects of moderate to high-intensity lipid lowering therapy on high-risk plaque features as assessed by different ICI modalities, reviews data supporting the use of these trials, and analyse the future perspectives in this field.

Chronic obstructive pulmonary disease and atherosclerosis: common mechanisms and novel therapeutics

Chronic obstructive pulmonary disease (COPD) and atherosclerosis are chronic irreversible diseases, that share a number of common causative factors including cigarette smoking. Atherosclerosis drastically impairs blood flow and oxygen availability to tissues, leading to life-threatening outcomes including myocardial infarction (MI) and stroke. Patients with COPD are most likely to die as a result of a cardiovascular event, with 30% of all COPD-related deaths being attributed to cardiovascular disease (CVD). Both atherosclerosis and COPD involve significant local (i.e. lung, vasculature) and systemic inflammation and oxidative stress, of which current pharmacological treatments have limited efficacy, hence the urgency for the development of novel life-saving therapeutics. Currently these diseases must be treated individually, with no therapies available that can effectively reduce the likelihood of comorbid CVD other than cessation of cigarette smoking. In this review, the important mechanisms that drive atherosclerosis and CVD in people with COPD are explained and we propose that modulation of both the oxidative stress and the inflammatory burden will provide a novel therapeutic strategy to treat both the pulmonary and systemic manifestations related to these diseases.

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

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

Non-invasive Multimodality Imaging of Coronary Vulnerable Patient

Atherosclerotic plaque rupture or erosion remain the primary mechanism responsible for myocardial infarction and the major challenge of cardiovascular researchers is to develop non-invasive methods of accurate risk prediction to identify vulnerable plaques before the event occurs. Multimodal imaging, by CT-TEP or CT-SPECT, provides both morphological and activity information about the plaque and cumulates the advantages of anatomic and molecular imaging to identify vulnerability features among coronary plaques. However, the rate of acute coronary syndromes remains low and the mechanisms leading to adverse events are clearly more complex than initially assumed. Indeed, recent studies suggest that the detection of a state of vulnerability in a patient is more important than the detection of individual sites of vulnerability as a target of focal treatment. Despite this evolution of concepts, multimodal imaging offers a strong potential to assess patient's vulnerability. Here we review the current state of multimodal imaging to identify vulnerable patients, and then focus on emerging imaging techniques and precision medicine.

Assessing the characteristics and diagnostic value of plaques for patients with acute stroke using high-resolution magnetic resonance imaging

BACKGROUND

A comprehensive understanding of atherosclerotic plaques aids physicians in evaluation and treatment of stroke. This study set out to evaluate the characteristics and diagnostic value of atherosclerotic plaques in patients with acute stroke and stenotic middle cerebral artery (MCA) using high-resolution magnetic resonance imaging.

METHODS

Sixty-five consecutive patients with transient ischemic attack or recent ischemic stroke were prospectively recruited. All enrolled patients underwent routine magnetic resonance scans and cross-sectional scans of the stenotic MCA vascular wall. Differences in vascular wall parameters and location, the enhancement degree, and remodelling patterns of plaques in the stenotic MCA were compared between symptomatic (n=30) and asymptomatic (n=35) groups of patients. The statistically significant indicators were then subjected to logistic regression analysis to identify which factors could better predict acute stroke.

RESULTS

Compared with the asymptomatic group, the symptomatic group had a smaller lumen area (LA) (P=0.027), larger plaque area (P<0.001), larger remodelling index (P<0.001), more superior/posterior plaques (P=0.001), more obviously enhanced plaques (P<0.001), and a greater number of PR patterns (P<0.001) in the stenotic MCA. Logistic regression analysis showed that the plaque area, remodelling patterns, LA in the stenotic MCA, enhancement degree, and plaque location were predictors of acute stroke. The combination of the plaque area and LA in the stenotic MCA, and the plaque enhancement degree had optimal predictive value (area under the curve =0.927).

CONCLUSIONS

A larger plaque area and smaller LA in the stenotic MCA, and obvious plaque enhancement might indicate that a patient is prone to acute stroke.

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

PURPOSE

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

METHODS

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

RESULTS

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

DATA CONCLUSION

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

The Relationship between Patterns of Remodeling and Degree of Enhancement in Patients with Atherosclerotic Middle Cerebral Artery Stenosis: A High-Resolution MRI Study

PURPOSE

The aim of this research was to investigate the relationship between remodeling patterns and degree of enhancement in patients with atherosclerotic middle cerebral artery (MCA) stenosis using high-resolution magnetic resonance imaging (HR-MRI).

MATERIALS AND METHODS

From August 2015 to May 2016, 38 consecutive patients with unilateral MCA stenosis on time-of-flight (TOF) MR angiography were prospectively enrolled. The routine MR scan and cross-sectional images of the stenotic MCA vessel wall on HR-MRI were performed in all patients. Among them, 17 patients displayed positive remodeling (PR) and the other 21 patients displayed negative remodeling or non-remodeling (non-PR). The patients displaying hyperintense on diffusion-weighted imaging (DWI) in the territory of ipsilateral stenotic MCA were considered to have had acute stroke. Subsequently, the differences in the degree of enhancement and the number of acute stroke patients between the PR group and the non-PR group were compared. The Spearman rank correlation analysis of the enhancement degree (ED) and the remodeling index (RI) was calculated. Then, receiver operating curve (ROC) was used to evaluate diagnostic efficiency of RI and ED for acute infarction.

RESULTS

The PR group had more obvious enhancement plaques than the non-PR group (10 versus 3, P = 0.006). The PR group also had a larger number of acute stroke patients than the non-PR group (15 versus 4, P = 0.000). The spear-man rank correlation analysis showed that the degree of enhancement had a weak positive correlation with the remodeling index (r = 0.379, P = 0.019). The area under the curve (AUC) of RI and ED was higher than that of RI (0.924: 0.842).

CONCLUSION

The PR, obvious enhancement predicted vulnerable plaques that were more prone to causing acute stroke. RI and ED had valuable diagnostic efficiency for acute infarction.

Atherosclerotic Burden and Remodeling Patterns of the Popliteal Artery as Detected in the Magnetic Resonance Imaging Osteoarthritis Initiative Data Set

Background

An artificial intelligence vessel segmentation tool, Fully Automated and Robust Analysis Technique for Popliteal Artery Evaluation (FRAPPE), was used to analyze a large databank of popliteal arteries imaged through the OAI (Osteoarthritis Initiative) to study the impact of atherosclerosis risk factors on vessel dimensions and characterize remodeling patterns.

Methods and Results

Magnetic resonance images from 4668 subjects contributing 9189 popliteal arteries were analyzed using FRAPPE. Age ranged from 45 to 79 years (median, 61), and 58% were women. Mean lumen diameter, mean outer wall diameter, and mean wall thickness (MWT) were measured per artery. Their median values were 5.8 mm (interquartile range, 5.2–6.5 mm), 7.3 mm (interquartile range, 6.7–8.1 mm), and 0.78 mm (interquartile range, 0.73–0.84 mm) respectively. MWT was associated with multiple cardiovascular risk factors, with age (4.2% increase in MWT per 10‐year increase in age; 95% CI, 3.9%–4.5%) and sex (8.6% higher MWT in men than women; 95% CI, 7.7%–9.3%) being predominant. On average, lumen and outer wall diameters increased with increasing MWT until the thickness was 0.92 mm for men and 0.84 mm for women. After this point, lumen diameter decreased steadily, more rapidly in men than women (−7.9% versus −6.1% per 25% increase in MWT; P<0.001), with little change in outer wall diameter.

Conclusions

FRAPPE has enabled the analysis of the large OAI knee magnetic resonance imaging data set, successfully showing that popliteal atherosclerosis is predominantly associated with age and sex. The average vessel remodeling pattern consisted of an early phase of compensatory enlargement, followed by a negative remodeling, which is more pronounced in men.

Evaluating renal arterial wall by non-enhanced 2D and 3D free-breathing black-blood techniques: Initial experience

OBJECTIVES

To evaluate the feasibility and reproducibility of 2D and 3D black-blood sequences in measuring morphology of renal arterial wall.

METHODS

The 2D and 3D imaging sequences used variable-refocusing-flip-angle and constant-low-refocusing-flip-angle turbo spin echo (TSE) readout respectively, with delicately selected black-blood scheme and respiratory motion trigger for free-breathing imaging. Fourteen healthy subjects and three patients with Takayasu arteritis underwent renal artery wall imaging with 3D double inversion recovery (DIR) TSE and 2D Variable Flip Angle-TSE (VFA-TSE) black-blood sequences at 3.0 T. Four healthy subjects were randomly selected for scan-rescan reproducibility experiments. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and morphology of arterial wall were measured and compared using paired-t-test or Wilcoxon signed-rank test between 2D and 3D sequences. The inter-observer, intra-observer and scan-rescan agreements of above measurements were determined using intraclass correlation coefficient (ICC).

RESULTS

The 2D and 3D imaging sequences showed similar morphological measurements (lumen area, wall area, mean wall thickness and maximum wall thickness) of renal arterial wall (all P > 0.05) and excellent agreement (ICC: 0.853-0.954). Compared to 2D imaging, 3D imaging exhibited significantly lower SNR_lumen (P < 0.01) and SNR_wall (P = 0.037), similar contrast-to-noise ratio (CNR) (P = 0.285), and higher CNR efficiency (CNR_eff) (P < 0.01). Both 2D and 3D imaging showed good to excellent inter-observer (ICC: 0.723-0.997), intra-observer (ICC: 0.749-0.996) and scan-rescan (ICC: 0.710-0.992) reproducibility in measuring renal arterial wall morphology, SNR and CNR, respectively.

CONCLUSIONS

Both high-resolution free-breathing 2D VFA-TSE and 3D DIR TSE black-blood sequences are feasible and reproducible in high-resolution renal arterial wall imaging. The 2D imaging has high SNR, whereas 3D imaging has high imaging efficiency.

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.

Noninvasive Imaging to Assess Atherosclerotic Plaque Composition and Disease Activity: Coronary and Carotid Applications

Cardiovascular disease is one of the leading causes of mortality and morbidity worldwide. Atherosclerosis imaging has traditionally focused on detection of obstructive luminal stenoses or measurements of plaque burden. However, with advances in imaging technology it has now become possible to noninvasively interrogate plaque composition and disease activity, thereby differentiating stable from unstable patterns of disease and potentially improving risk stratification. This manuscript reviews multimodality imaging in this field, focusing on carotid and coronary atherosclerosis and how these novel techniques have the potential to complement current imaging assessments and improve clinical decision making.

Molecular and Nonmolecular Magnetic Resonance Coronary and Carotid Imaging

Atherosclerosis is the leading cause of cardiovascular morbidity and mortality. Over the past 2 decades, increasing research attention is converging on the early detection and monitoring of atherosclerotic plaque. Among several invasive and noninvasive imaging modalities, magnetic resonance imaging (MRI) is emerging as a promising option. Advantages include its versatility, excellent soft tissue contrast for plaque characterization and lack of ionizing radiation. In this review, we will explore the recent advances in multicontrast and multiparametric imaging sequences that are bringing the aspiration of simultaneous arterial lumen, vessel wall, and plaque characterization closer to clinical feasibility. We also discuss the latest advances in molecular magnetic resonance and multimodal atherosclerosis imaging.

Simultaneous 3D whole-heart bright-blood and black blood imaging for cardiovascular anatomy and wall assessment with interleaved T2 prep-IR

PURPOSE

To develop a motion-corrected 3D flow-insensitive imaging approach interleaved T₂ prepared-inversion recovery (iT₂ prep-IR) for simultaneous lumen and wall visualization of the great thoracic vessels and cardiac structures.

METHODS

A 3D flow-insensitive approach for simultaneous cardiovascular lumen and wall visualization (iT₂ prep) has been previously proposed. This approach requires subject-dependent weighted subtraction to completely null the arterial blood signal in the black-blood volume. Here, we propose an (T₂ prep-IR) approach to improve wall visualization and remove need for weighted subtraction. The proposed sequence is based on the acquisition and direct subtraction of 2 interleaved 3D whole-heart data sets acquired with and without T₂ prep-IR preparation. Image navigators are acquired before data acquisition to enable 2D translational and 3D non-rigid motion correction allowing 100% respiratory scan efficiency. The proposed approach was evaluated in 10 healthy subjects and compared with the conventional 2D double inversion recovery (DIR) sequence and the 3D iT₂ prep sequence. Additionally, 5 patients with congenital heart disease were acquired to test the clinical feasibility of the proposed approach.

RESULTS

The proposed iT₂ prep-IR sequence showed improved blood nulling compared to both DIR and iT₂ prep techniques in terms of SNR (SNR_blood = 6.9, 12.2, and 18.2, respectively) and contrast-to-noise-ratio (CNR_myoc-blood = 28.4, 15.4, and 15.3, respectively). No statistical difference was observed between iT₂ prep-IR, iT₂ prep and DIR atrial and ventricular wall thickness quantification.

CONCLUSION

The proposed interleaved T₂ prep-IR sequence enables the simultaneous lumen and wall visualization of cardiac structures and shows promising results in terms of SNR, CNR, and wall thickness measurement.

Recent Advances in Cardiac Magnetic Resonance Imaging

Cardiac magnetic resonance (CMR) imaging provides accurate anatomic information and advanced soft contrast, making it the reference standard for assessing cardiac volumes and systolic function. In this review, we summarize the recent advances in CMR sequences. New technical development has widened the use of CMR imaging beyond the simple characterization of myocardial scars and assessment of contractility. These novel CMR sequences offer comprehensive assessments of coronary plaque characterization, myocardial fiber orientation, and even metabolic activity, and they can be readily applied in clinical settings. CMR imaging is able to provide new insights into understanding the pathophysiologic process of underlying cardiac disease, and it can help physicians choose the best treatment strategies. Although several limitations, including the high cost and time-consuming process, have limited the widespread clinical use of CMR imaging so far, recent advances in software and hardware technologies have made the future more promising.

Optimization of Computed Tomography Coronary Angiography for Improved Plaque Detection

OBJECTIVE

The study aims to optimize visualization of the coronary wall during computed tomography coronary angiography.

METHODS

A coronary plaque phantom was scanned on a wide-volume computed tomography scanner. Spatial resolution, contrast resolution, and vessel wall thickness were measured at different x-ray tube currents and voltages.

RESULTS

Spatial resolution ranged from 0.385 to 0.625 mm and was significantly lower at higher currents. Contrast-to-noise ratio was significantly higher at higher currents. The most accurate wall thickness measurements were quantified at 300 and 400 mA for 80 and 100 kVp and 300 mA for 120 and 135 kVp.

CONCLUSIONS

Lower spatial resolution at higher currents was due to added blur from increased focal spot size. Contrast-to-noise ratio was higher at higher currents owing to decreased quantum noise. Wall thickness was measured more accurately at intermediate currents with midrange contrast-to-noise ratio but optimal spatial resolution. For accurate coronary wall thickness measurement, contrast-to-noise ratio is compromised to achieve optimal spatial resolution.

Coronary Artery Plaque Imaging

PURPOSE OF REVIEW

This short review summarizes the recent development in clinical and experimental imaging techniques for coronary atherosclerosis.

RECENT FINDINGS

Coronary atherosclerosis is the underlying disease of myocardial infarction, the leading cause of death in the industrialized world. Conventional ways of risk assessment, including evaluation of traditional risk factors and interrogation of luminal stenosis, have proven imprecise for the prediction of major events. Rapid advances in noninvasive imaging techniques including MRI, CT, and PET, as well as catheter-based methods, have opened the doors to more in-depth interrogation of plaque burden, composition, and many crucial pathological processes such as inflammation and hemorrhage. These emerging imaging modalities and methodologies, combined with conventional imaging evidences of anatomy and ischemia, offer the promises to provide comprehensive information of the disease status. There is tremendous clinical potential for imaging to improve the current management of coronary atherosclerosis, including the identification of high-risk patients for aggressive therapies and guiding personalized treatment. In this review, we provide an overview of the state-of-the-art coronary plaque imaging techniques focusing on their respective strengths and weaknesses, as well as their clinical outlook.

Carotid Artery Remodeling Is Segment Specific: An In Vivo Study by Vessel Wall Magnetic Resonance Imaging

OBJECTIVE

Early atherosclerosis is often undetected due in part to compensatory enlargement of the outer wall, termed positive remodeling. Variations in hemodynamic conditions and clinical factors influence the patterns of remodeling. The carotid artery provides an opportunity to examine these variations because of the unique geometry of the carotid bulb. This study aimed to determine differences in remodeling of the common, internal, and bifurcation segments of the carotid using magnetic resonance imaging.

APPROACH AND RESULTS

Carotid arteries of 525 subjects without history of cardiovascular disease were imaged by magnetic resonance imaging. The carotid artery was divided into 3 segments: common carotid artery; bifurcation; and internal carotid artery. Remodeling patterns were characterized using linear regression analysis of lumen and total vessel areas (dependent variables) compared with maximum wall thickness (independent variable) for each segment, adjusted for age, sex, and height. The common carotid artery demonstrated a pattern consistent with positive remodeling, whereas the bifurcation demonstrated negative remodeling. The internal carotid artery demonstrated a mixed pattern of outer wall expansion and lumen constriction. Females and subjects with diabetes mellitus showed more positive remodeling, hypertension was associated with attenuated positive remodeling, and those with hypercholesterolemia showed more negative remodeling.

CONCLUSIONS

In this cohort of 55- to 80-year-old individuals without history of cardiovascular disease, the pattern of early carotid artery remodeling was segment specific and appeared to be associated with sex and clinical characteristics. These findings provide the groundwork for longitudinal studies to define local and systemic factors such as hemodynamic and clinical conditions on carotid artery remodeling.

Coronary magnetic resonance imaging after routine implantation of bioresorbable vascular scaffolds allows non-invasive evaluation of vascular patency

Background

Evaluation of recurrent angina after percutaneous coronary interventions is challenging. Since bioresorbable vascular scaffolds (BVS) cause no artefacts in magnetic resonance imaging (MRI) due to their polylactate-based backbone, evaluation of vascular patency by MRI might allow for non-invasive assessment and triage of patients with suspected BVS failure.

Methods

Patients with polylactate-based ABSORB-BVS in proximal coronary segments were examined with 3 Tesla MRI directly (baseline) and one year after implantation. For assessment of coronary patency, a high-resolution 3D spoiled gradient echo pulse sequence with fat-saturation, T2-preparation (TE: 40 ms), respiratory and end-diastolic cardiac gating, and a spatial resolution of (1.08 mm)³ was positioned parallel to the course of the vessel for bright blood imaging. In addition, a 3D navigator-gated T2-weighted variable flip angle turbo spin echo (TSE) sequence with dual-inversion recovery black-blood preparation and elliptical k-space coverage was applied with a voxel size of (1.14 mm)³. For quantitative evaluation lumen diameters of the scaffolded areas were measured in reformatted bright and black blood MR angiography data.

Results

11 patients with implantation of 16 BVS in the proximal coronary segments were included, of which none suffered from major adverse cardiac events during the one year follow up. Vascular patency in all segments implanted with BVS could be reliably assessed by MRI at baseline and after one year, whereas segments with metal stents could not be evaluated due to artefacts. Luminal diameter within the BVS remained constant during the one year period. One patient with atypical angina after BVS implantation was noninvasively evaluated showing a patent vessel, also confirmed by coronary angiography.

Conclusions

Coronary MRI allows contrast-agent free and non-invasive assessment of vascular patency after ABSORB-BVS implantation. This approach might be supportive in the triage and improvement of diagnostic workflows in patients with postinterventional angina and scaffold implantation.

Trial registration

German Register of Clinical Studies DRKS00007456

Contrast-enhanced magnetic resonance imaging for the detection of ruptured coronary plaques in patients with acute myocardial infarction

Purpose

X-ray coronary angiography (XCA) is the current gold standard for the assessment of lumen encroaching coronary stenosis but XCA does not allow for early detection of rupture-prone vulnerable plaques, which are thought to be the precursor lesions of most acute myocardial infarctions (AMI) and sudden death. The aim of this study was to investigate the potential of delayed contrast-enhanced magnetic resonance coronary vessel wall imaging (CE-MRCVI) for the detection of culprit lesions in the coronary arteries.

Methods

16 patients (13 male, age 61.9±8.6 years) presenting with sub-acute MI underwent CE-MRCVI within 24-72h prior to invasive XCA. CE-MRCVI was performed using a T1-weighted 3D gradient echo inversion recovery sequence (3D IR TFE) 40±4 minutes following the administration of 0.2 mmol/kg gadolinium-diethylenetriamine-pentaacetic acid (DTPA) on a 3T MRI scanner equipped with a 32-channel cardiac coil.

Results

14 patients were found to have culprit lesions (7x LAD, 1xLCX, 6xRCA) as identified by XCA. Quantitative CE-MRCVI correctly identified the culprit lesion location with a sensitivity of 79% and excluded culprit lesion formation with a specificity of 99%. The contrast to noise ratio (CNR) of culprit lesions (9.7±4.1) significantly exceeded CNR values of segments without culprit lesions (2.9±1.9, p<0.001).

Conclusion

CE-MRCVI allows the selective visualization of culprit lesions in patients immediately after myocardial infarction (MI). The pronounced contrast uptake in ruptured plaques may represent a surrogate biomarker of plaque activity and/or vulnerability.

Magnetic resonance imaging in heart failure, including coronary imaging: numbers, facts, and challenges

Coronary artery disease (CAD) is a major risk factor for the incidence and progression of heart failure (HF). HF is characterized by a substantial morbidity and mortality and its lifetime risk is estimated at approximately 20% for men and women. As patients are in most cases identified only after developing overt clinical symptoms, detecting early stages of CAD and HF is of paramount importance. Due to its non‐invasiveness, excellent soft‐tissue contrast, high spatial resolution, and multiparametric nature, cardiovascular magnetic resonance (CMR) imaging has emerged as a promising radiation‐free technique to assess a wide range of cardiovascular diseases such as CAD or HF, enabling a comprehensive evaluation of myocardial anatomy, regional and global function, and viability with the additional benefit of in vivo tissue characterization. CMR has the potential to enhance our understanding of coronary atherosclerosis and the aetiology of HF on functional and biological levels, to identify patients at risk for CAD or HF, and to enable individualized patient management and improved outcomes. Even though larger‐scale studies on the different applications of CMR for the assessment of heart failure are scarce, recent research highlighted new possible clinical applications for CMR in the evaluation of CAD and HF.

Cardiovascular magnetic resonance in an adult human population: serial observations from the multi-ethnic study of atherosclerosis

The Multi-Ethnic Study of Atherosclerosis (MESA) is the first large-scale multi-ethnic population study in the U.S. to use advanced cardiovascular magnetic resonance (CMR) imaging. MESA participants were free of cardiovascular disease at baseline between 2000 and 2002, and were followed up between 2009 and 2011 with repeated CMR examinations as part of MESA. CMR allows the clinician to visualize and accurately quantify volume and dimensions of all four cardiac chambers; measure systolic and diastolic ventricular function; assess myocardial fibrosis; assess vessel lumen size, vessel wall morphology, and vessel stiffness. CMR has a number of advantages over other imaging modalities such as echocardiography, computed tomography, and invasive angiography, and has been proposed as a diagnostic strategy for high-risk populations. MESA has been extensively evaluating CMR imaging biomarkers, as markers of subclinical disease, in the last 15 years for low-risk populations. On a more practical level, some of the imaging biomarkers developed and studied are translatable to at-risk populations. In this review, we discuss the progression of subclinical cardiovascular disease and the mechanisms responsible for the transition to symptomatic clinical outcomes based on our findings from MESA.

Local coronary wall eccentricity and endothelial function are closely related in patients with atherosclerotic coronary artery disease

BACKGROUND

Coronary endothelial function (CEF) in patients with coronary artery disease (CAD) varies among coronary segments in a given patient. Because both coronary vessel wall eccentricity and coronary endothelial dysfunction are predictors of adverse outcomes, we hypothesized that local coronary endothelial dysfunction is associated with local coronary artery eccentricity.

METHODS

We used 3 T coronary CMR to measure CEF as changes in coronary cross-sectional area (CSA) and coronary blood flow (CBF) during isometric handgrip exercise (IHE), a known endothelial-dependent stressor, in 29 patients with known CAD and 16 healthy subjects. Black-blood MRI quantified mean coronary wall thickness (CWT) and coronary eccentricity index (EI) and CEF was determined in the same segments.

RESULTS

IHE-induced changes in CSA and CBF in healthy subjects (10.6 ± 6.6% and 38.3 ± 29%, respectively) were greater than in CAD patients 1.3 ± 7.7% and 6.5 ± 19.6%, respectively, p < 0.001 vs. healthy for both measures), as expected. Mean CWT and EI in healthy subjects (1.1 ± 0.3 mm 1.9 ± 0.5, respectively) were less than those in CAD patients (1.6 ± 0.4 mm, p < 0.0001; and 2.6 ± 0.6, p = 0.006 vs. healthy). In CAD patients, we observed a significant inverse relationship between stress-induced %CSA change and both EI (r = -0.60, p = 0.0002), and CWT (r = -0.54, p = 0.001). Coronary EI was independently and significantly related to %CSA change with IHE even after controlling for mean CWT (adjusted r = -0.69, p = 0.0001). For every unit increase in EI, coronary CSA during IHE is expected to change by -6.7 ± 9.4% (95% confidence interval: -10.3 to -3.0, p = 0.001).

CONCLUSION

There is a significant inverse and independent relationship between coronary endothelial macrovascular function and the degree of local coronary wall eccentricity in CAD patients. Thus anatomic and physiologic indicators of high-risk coronary vascular pathology are closely related. The noninvasive identification of coronary eccentricity and its relationship with underlying coronary endothelial function, a marker of vascular health, may be useful in identifying high-risk patients and culprit lesions.

Sex, body mass index, and blood pressure are related to aortic characteristics in healthy, young adults using magnetic resonance vessel wall imaging: the AMBITYON study

Objectives

More detailed evaluation of atherosclerosis and its key determinants in young individuals is warranted to improve knowledge on the pathophysiology of its development and progression. This study evaluated associations of magnetic resonance imaging (MRI)-derived aortic wall area, wall thickness, and pulse wave velocity (PWV) with cardiovascular risk factors in asymptomatic, young adults.

Materials and methods

In 124 adults (age: 25–35 years) from the general population-based Atherosclerosis Monitoring and Biomarker Measurements in the Young study, demography, anthropometry, and blood samples were collected. The studied MRI-parameters were measured using a 3.0T MRI system. Relations between cardiovascular risk factors and aortic characteristics were assessed using multivariable linear regression analyses.

Results

Mean age was 31.8 years, 47.6% was male. Aortic wall area was positively associated with age [β = 0.01, (95% confidence interval (CI) 2.00 × 10⁻³, 0.02), p = 0.01] and BMI [β = 0.01, (0.01, 0.02), p = 0.003] and negatively associated with sex (reference: men) [β = −0.06, (−0.11, −0.01), p = 0.02]. Natural logarithm transformed (ln) aortic wall thickness was positively associated with BMI [β = 0.01, (1.00 × 10⁻³, 0.02), p = 0.02]. Ln aortic PWV was positively associated with 10 mmHg increment of SBP [β = 0.06, (0.03, 0.09), p < 0.001] and DBP [β = 0.06, (0.02, 0.09), p = 0.006]. No relations were observed for smoking and lipids.

Conclusions

Already in early adulthood, aortic wall geometry and stiffness vary by age, sex, BMI, and blood pressure.

A High-Resolution MRI Study of Relationship between Remodeling Patterns and Ischemic Stroke in Patients with Atherosclerotic Middle Cerebral Artery Stenosis

Purpose: Recently, high-resolution magnetic resonance imaging (HR-MRI) has been used to depict the wall characteristics of the intracranial arteries. The aim of this study was to explain the relationship between the remodeling patterns and acute ischemic stroke in patients with atherosclerotic middle cerebral artery (MCA) stenosis using HR-MRI. Materials and Methods: From August 2015 to May 2016, we prospectively screened 33 consecutive patients with unilateral MCA stenosis using time-to-flight MR angiography, including 15 patients with symptomatic MCA stenosis and 18 patients with asymptomatic MCA stenosis. Among them, 14 patients were diagnosed as positive remodeling (PR) and 19 as negative remodeling or non-remodeling. The cross-sectional images of the stenotic MCA wall on HR-MRI including T1WI, T2WI, and PDWI were compared between the symptomatic group and the asymptomatic group as well as the PR group and the non-PR group, based on the vessel area, lumen area, wall area, plaque area, degree of stenosis, remodeling index, and NIHSS score. Results: The symptomatic group had larger wall area (P = 0.040), plaque area (P<0.001), degree of stenosis (P = 0.038), remodeling index (P < 0.001), and NIHSS score (P = 0.003) as well as smaller lumen area (P = 0.001) than the asymptomatic group. In addition, more PR patients were observed in symptomatic group. The PR group had larger plaque area (P = 0.014) and NIHSS score (P = 0.037) than the non-PR group. Demographic and clinical characteristics between the symptomatic group and the asymptomatic group, the PR group and the non-PR group showed no statistical difference. Conclusion: The current study suggests that the HR-MRI has emerged as a promising tool to detect the characteristics of intracranial arteries wall and reveal the relationship between remodeling patterns and ischemic stroke. The PR is an unsafe remodeling way and is prone to cause acute ischemic stroke.

Invasive or non-invasive imaging for detecting high-risk coronary lesions?

INTRODUCTION

Advances in our understanding about atherosclerotic evolution have enabled us to identify specific plaque characteristics that are associated with coronary plaque vulnerability and cardiovascular events. With constant improvements in signal and image processing an arsenal of invasive and non-invasive imaging modalities have been developed that are capable of identifying these features allowing in vivo assessment of plaque vulnerability. Areas covered: This review article presents the available and emerging imaging modalities introduced to assess plaque morphology and biology, describes the evidence from the first large scale studies that evaluated the efficacy of invasive and non-invasive imaging in detecting lesions that are likely to progress and cause cardiovascular events and discusses the potential implications of the in vivo assessment of coronary artery pathology in the clinical setting. Expert commentary: Invasive imaging, with its high resolution, and in particular hybrid intravascular imaging appears as the ideal approach to study the mechanisms regulating atherosclerotic disease progression; whereas non-invasive imaging is expected to enable complete assessment of coronary tree pathology, detection of high-risk lesions, more accurate risk stratification and thus to allow a personalized treatment of vulnerable patients.

Relation between baseline plaque features and subsequent coronary artery remodeling determined by optical coherence tomography and intravascular ultrasound

Atherosclerosis often leads to myocardial infarction and stroke. We examined the influence of baseline plaque characteristics on subsequent vascular remodeling in response to changes in plaque size. Using optical coherence tomography (OCT) and intravascular ultrasound (IVUS), we examined 213 plaques from 138 patients with acute coronary syndrome at baseline and repeated IVUS at the 12-month follow-up. The change in external elastic membrane (EEM) area for each 1 mm2 change in plaque area (i.e., the slope of the regression line) was calculated as a measure of vascular remodeling capacity. In plaques with static positive remodeling, the slope was smaller than in plaques without static positive remodeling. In addition, the slope of the regression line for lesions with a large plaque burden was much smaller than that for lesions with a small plaque burden. Multivariate linear regression analysis showed that diabetes, calcification and static positive remodeling were inversely and independently associated with the level of change in EEM area/change in plaque area. Lesions with a large plaque burden, calcifications or static positive remodeling had less remodeling capacity, and calcification and static positive remodeling were independent predictors of reduced subsequent remodeling. Therefore, calcifications and static positive remodeling could be used as morphological biomarkers to predict decreased subsequent arterial remodeling.

Coronary artery plaque imaging: Comparison of black‐blood MRI and 64‐multidetector computed tomography

Objective

To comparatively evaluate black-blood coronary arterial wall MRI and 64-multidetector computed tomography (64-MDCT) for detection and classification of coronary artery plaques.

Methods

We included 15 patients with confirmed coronary artery plaques in the proximal or middle segments of coronary arteries by 64-MDCT, who underwent black-blood coronary wall MRI at 1.5 T within 10 days. Cross-sectional coronary wall images were acquired using a 2D double-inversion-recovery, electrocardiograph-triggered, navigator-gated, fat-suppressed, turbo-spin-echo sequence on the coronary arteries with lesions from the ostium to the middle segment continuously without gap. The vessel cross-sectional area (CSA), luminal CSA, maximal wall thickness, plaque burden, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) were measured in each slice and subsequently compared with computed tomography angiography (CTA) images. CTA images were divided into 5-mm segments for side-by-side comparison with MRI.

Results

Of the 15 patients, 12 were enrolled in the study. Coronary plaques were found in 46 slices on both CTA and MRI. Plaques were classified to 3 groups based on CTA: calcified plaques (n = 11), soft plaques (n = 23), and mixed plaques (n = 12). In MRI, the plaque burden, maximal wall thickness, SNR, and CNR in the coronary walls containing plaques were greater than in the normal coronary walls (0.83 ± 0.08 vs. 0.73 ± 0.08, 1.88 ± 0.51 vs. 1.51 ± 0.26 mm, 12.95 ± 2.78 vs. 9.93 ± 2.31, and 6.76 ± 2.52 vs. 3.89 ± 1.54, respectively; P < 0.05). The luminal CSA at the plaque was smaller than in normal coronary walls (2.50 ± 1.50 vs. 4.72 ± 2.28 mm²; P < 0.05). The SNR in the soft plaque was significantly greater than in calcified and mixed plaques (P < 0.05).

Conclusions

Coronary wall MRI can identify coronary plaques in the proximal and middle segments and has the potential to differentiate plaque types based on signal intensity.

Imaging Atherosclerosis

Advances in atherosclerosis imaging technology and research have provided a range of diagnostic tools to characterize high-risk plaque in vivo; however, these important vascular imaging methods additionally promise great scientific and translational applications beyond this quest. When combined with conventional anatomic- and hemodynamic-based assessments of disease severity, cross-sectional multimodal imaging incorporating molecular probes and other novel noninvasive techniques can add detailed interrogation of plaque composition, activity, and overall disease burden. In the catheterization laboratory, intravascular imaging provides unparalleled access to the world beneath the plaque surface, allowing tissue characterization and measurement of cap thickness with micrometer spatial resolution. Atherosclerosis imaging captures key data that reveal snapshots into underlying biology, which can test our understanding of fundamental research questions and shape our approach toward patient management. Imaging can also be used to quantify response to therapeutic interventions and ultimately help predict cardiovascular risk. Although there are undeniable barriers to clinical translation, many of these hold-ups might soon be surpassed by rapidly evolving innovations to improve image acquisition, coregistration, motion correction, and reduce radiation exposure. This article provides a comprehensive review of current and experimental atherosclerosis imaging methods and their uses in research and potential for translation to the clinic.

MR Imaging Measures of Intracranial Atherosclerosis in a Population-based Study

Purpose To implement a magnetic resonance (MR) imaging protocol to measure intracranial atherosclerotic disease (ICAD) in a population-based multicenter study and report examination and reader reliability of these MR imaging measurements and descriptive statistics representative of the general population. Materials and Methods This prospective study was approved by the institutional review boards and compliant with HIPAA. Atherosclerosis Risk in Communities (ARIC) study participants (n = 1980) underwent brain MR imaging from 2011 to 2013 at four ARIC sites. Imaging included three-dimensional black-blood MR imaging and time-of-flight MR angiography. One hundred two participants returned for repeat MR imaging to estimate examination and reader variability. Plaque presence according to vessel segment was recorded. Quantitative measurements included lumen size and degree of stenosis, wall and/or plaque thickness, area and volume, and normalized wall index for each vessel segment. Reliability was assessed with percentage agreement, κ statistics, and intraclass correlation coefficients. Results Of the 1980 participants, 1755 (mean age, 77.6 years; 1026 women [59%]; 1234 white [70%]) completed examinations with adequate to excellent image quality. The weighted ICAD prevalence was 34.4% (637 of 1755 participants) and was higher in men than women (38.5% [302 of 729 participants] vs 31.7% [335 of 1026 participants], respectively; P = .012) and in African Americans compared with whites (41.1% [215 of 518 participants] vs 32.4% [422 of 1234 participants], respectively; P = .002). Percentage agreement of plaque identification per participant was 87.0% (interreader estimate), 89.2% (intrareader estimate), and 89.9% (examination estimate). Examination and reader reliability ranged from fair to good (κ, 0.50-0.78) for plaque presence and from good to excellent (intraclass correlation coefficient, 0.69-0.99) for quantitative vessel wall measurements. Conclusion Vessel wall MR imaging is a reliable tool for identifying and measuring ICAD and provided insight into ICAD distribution across a U.S. community-based population. (©) RSNA, 2016 Online supplemental material is available for this article.

Association between epicardial adipose tissue volume and myocardial salvage in patients with a first ST-segment elevation myocardial infarction: An epicardial adipose tissue paradox

BACKGROUND

Epicardial adipose tissue (EAT), defined as the adipose tissue between the visceral pericardium and the outer margin of the myocardium, is associated with coronary artery disease in the general population. However, the clinical implications of EAT in patients with ST-segment elevation myocardial infarction (STEMI) remain unclear.

METHODS

A total of 142 patients with a first STEMI, who received reperfusion therapy within 12h from symptom onset, were enrolled. All patients underwent cardiac magnetic resonance imaging to evaluate infarct core (Core), area at risk (AAR), and EAT volume. Myocardial salvage index (MSI) was defined as AAR minus Core divided by AAR. Patients in the lower tertile of EAT volume were classified as the low EAT group (group L) and the other two-thirds as the high EAT group (group H).

RESULTS

The mean MSI was lower in group L than in group H (0.43±0.13 vs 0.49±0.13, p=0.01), and the mean extent of Core was higher in group L than in group H (25±10% vs 19±10%, p<0.01). Multivariate linear regression analysis including coronary risk factors and previously reported predictors of infarct size demonstrated that EAT volume was an independent predictor of MSI (β coefficient=0.002 per 1mL, p=0.002).

CONCLUSIONS

A lower EAT volume is associated with less myocardial salvage and larger infarct size in patients with a first STEMI.

Golden angle dual-inversion recovery acquisition coupled with a flexible time-resolved sparse reconstruction facilitates sequence timing in high-resolution coronary vessel wall MRI at 3 T

PURPOSE

The need for performing dual-inversion recovery (DIR) coronary vessel wall MRI in correspondence to minimal cardiac motion and optimal blood signal nulling is a major challenge. We propose to address this hurdle by combining DIR with a prolonged acquisition window in conjunction with a golden angle radial trajectory and k-t sparse sensitivity encoding (SENSE) reconstruction to enable a flexible a-posteriori selection of optimized imaging parameters.

METHODS

Coronary vessel wall data acquisition was performed with DIR golden angle radial imaging in n=15 healthy subjects. Images reconstructed using k-t sparse SENSE and different reconstruction window settings were quantitatively (vessel wall conspicuity, thickness, acquisition, and reconstruction window settings) compared with those obtained with more conventional radial DIR imaging.

RESULTS

A flexible retrospective selection of the reconstruction window width and position improved vessel wall conspicuity with respect to baseline acquisitions (P < 0.01). Vessel wall thickness remained unchanged (P = nonsignificant (NS)). Temporal window widths were similar for both approaches (P = NS), yet their position within the cardiac cycle differed significantly (P < 0.02).

CONCLUSIONS

A flexible DIR coronary vessel wall MRI technique that alleviates constraints associated with sophisticated sequence timing was proposed. When compared with a more conventional approach, the technique significantly improved image quality. Magn Reson Med 77:961-969, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Noninvasive Imaging of Atherosclerotic Plaque Progression: Status of Coronary Computed Tomography Angiography

The process of coronary artery disease progression is infrequently visualized. Intravascular ultrasound has been used to gain important insights but is invasive and therefore limited to high-risk patients. For low-to-moderate risk patients, noninvasive methods may be useful to quantitatively monitor plaque progression or regression and to understand and personalize atherosclerosis therapy. This review discusses the potential for coronary computed tomography angiography to evaluate the extent and subtypes of coronary plaque. Computed tomographic technology is evolving and image quality of the method approaches the level required for plaque progression monitoring. Methods to quantify plaque on computed tomography angiography are reviewed as well as a discussion of their use in clinical trials. Limitations of coronary computed tomography angiography compared with competing modalities include limited evaluation of plaque subcomponents and incomplete knowledge of the value of the method especially in patients with low-to-moderate cardiovascular risk.

Imaging of cardiovascular complications in patients with systemic lupus erythematosus

In the long-term survival of patients with systemic lupus erythematosus (SLE), cardiovascular disease (CVD) is a leading cause of death. Recently, multimodality cardiovascular imaging methods have been adopted for the evaluation of cardiovascular risk, which has shown to be associated with both traditional cardiovascular risk factors and SLE-specific conditions. Quantitative imaging biomarkers, which can describe both morphological and functional abnormalities in the heart, are expected to provide new insights to stratify cardiovascular risks and to guide SLE management by assessing individual responses to therapies either protecting the cardiovascular system or suppressing the autoimmune reactions. In this review, we will discuss cutting-edge cardiovascular imaging techniques and potential clinical applications and limitations of those techniques for the evaluation of major SLE-related heart disorders.

New Insights from Major Prospective Cohort Studies with Cardiovascular Magnetic Resonance (CMR)

Since 1948, epidemiology studies played an important role in understanding cardiovascular disease and afforded an opportunity to learn about newer diagnostic tests. In 2000, the MESA Study incorporated several advanced cardiovascular imaging modalities including cardiac magnetic resonance imaging (MRI) and coronary artery calcium scans. The decade of follow-up enabled prognosis studies, an important step beyond association studies. In brief, left ventricular hypertrophy by cardiac MRI predicted incident heart failure and stroke. In the MESA Study, coronary artery calcium was a better predictor of coronary artery disease end points than the non-contrast-enhanced MRI scan. In the ICELAND MI substudy of the AGES-Reykjavik Study, a contrast-enhanced MRI scan detected many more unrecognized myocardial infarctions (MIs) (UMIs) than detected by electrocardiography and documented these UMI had adverse prognostic significance. Thus, cardiac MRI has been successfully incorporated into large population studies and shown added value over conventional measurements of cardiovascular disease.

MR imaging of the coronary vasculature: imaging the lumen, wall, and beyond

The characteristics of coronary artery disease are gradual thickening of the coronary walls and narrowing of the vascular lumen by the buildup of atherosclerosis plaques. These morphologic changes can be noninvasively detected by coronary magnetic resonance (MR) imaging/MR angiography (MRA). In addition, functional changes, such as coronary wall distensibility and flow changes, may also be evaluated with MR imaging. However, the application of current MR imaging/MRA techniques is limited in clinical practice because of several adverse technical and physiologic factors, such as cardiac and respiratory motion. Many technical innovations have been adopted to address these problems from multiple aspects.

Three-dimensional coronary dark-blood interleaved with gray-blood (cDIG) magnetic resonance imaging at 3 tesla

PURPOSE

Three-dimensional (3D) dark-blood MRI has shown great potential in coronary artery plaque evaluation. However, substantial variability in quantification could result from superficial calcification because of its low signal. To address this issue, a 3D coronary dark-blood interleaved with gray-blood (cDIG) technique was developed.

METHODS

cDIG is based on a balanced steady-state free precession readout combined with a local re-inversion-based double-inversion-recovery (LocReInv-DIR) preparation. The LocReInv-DIR is applied every two RR intervals. Dark-blood and gray-blood contrasts are collected in the first and second RR interval, respectively. To improve the respiratory gating efficiency, two independent navigators were developed to separately gate the respiratory motion for the two interleaved acquisitions. In vivo experiments in eight healthy subjects and one patient were conducted to validate the technique.

RESULTS

cDIG provided dual-contrasts without compromise in scan time. The dark-blood images with cDIG demonstrated excellent wall and lumen signal performances and morphological measurements. Advantageously, cDIG yielded a second contrast that was shown to help identify the superficial calcification in the coronary plaque of a patient.

CONCLUSION

A novel technique was developed for obtaining 3D coronary vessel wall and gray lumen images. The additional contrast may aid in identifying calcified nodules and thus potentially improve the evaluation of coronary plaque burden.

High-resolution MRI of the vessel wall in patients with symptomatic atherosclerotic stenosis of the middle cerebral artery

Intracranial atherosclerosis is associated with recurrent ischemic stroke. High-resolution MRI (HR MRI) can provide information about atheroma in vivo. We aimed to analyze and compare vascular wall imaging characteristics between patients with symptomatic and asymptomatic atherosclerotic stenosis of the middle cerebral artery (MCA) using 3.0 Tesla HR MRI. The HR MRI protocol included four different scans: black blood T1-weighted, T2-weighted and proton density-weighted MRI, as well as three-dimensional turbo spin echo imaging techniques with multiplanar reconstruction. Plaque characteristics, including location, morphology, and signal intensity, were analyzed in 51 patients (29 symptomatic, 22 asymptomatic) with atherosclerotic stenosis of the middle cerebral artery. The vessel wall area, lumen area, and plaque area (PA) were also calculated and compared between the symptomatic and asymptomatic groups. We found that PA, remodeling index (RI), and positive remodeling (PR) prevalence were significantly greater in the symptomatic group than in the asymptomatic group (PA: p=0.033; RI: p=0.020; PR: p=0.032). Plaque location in the superior aspect of the vessel wall and irregular plaque surface were more frequently observed in the symptomatic group than in the asymptomatic group (superior location: p=0.031; irregular surface: p=0.036). Moreover, multivariate logistic regression identified plaque location on the superior wall as an independent predictor of symptomatic MCA stenosis (odds ratio: 4.471; p=0.039). Therefore, we can conclude that patients with symptomatic atherosclerotic stenosis of the MCA are more likely to have larger plaques, PR, superiorly located plaques, and irregular plaque surface. These characteristics are promising factors for stratifying stroke risk.

The role of latency period in quality management for free-breathing coronary wall MRI

The aim of the present study was to determine the effects of the latency period on the performance of free-breathing coronary wall MRI. With the approval of IRB, 70 participants were recruited for coronary wall magnetic resonance imaging (MRI) and provided written informed consent. In 35 subjects, right coronary segments (RCA1-3) were imaged first; in the remaining subjects, the left coronary segments (LM and LAD1-3) were imaged first. The images were classified into groups; group 1 contained right coronary images from the subjects whose right coronary segments were imaged first and left coronary images from the subjects whose left coronary segments were imaged first. Group 2 contained the other coronary segments. The image scores (ranked1-3), latency periods, drift of the position of the navigator (NAV), scan efficiency were compared between image groups. Image group 1 has higher scores (1.66 ± 0.55 vs. 1.46 ± 0.51), shorter latency periods (32.04 ± 4.24 vs. 44.22 ± 5.57 min), lower drift in the location of the NAV (1.90 ± 1.27 mm vs. 2.61 ± 1.71 mm) and higher scan efficiency (32.7 ± 7.6 vs. 29.9 ± 7.9%) than group 2. Long latency periods have a significantly negative impact on the image quality of coronary wall MRI.

Individualized cardiovascular risk assessment by cardiovascular magnetic resonance

Cardiovascular magnetic resonance (CMR) is gaining clinical importance in preventive medicine. Evidence on diagnostic accuracy and prognostic value, in addition to the development of faster imaging, increased availability of equipment and imaging expertise have led to a wide-spread use of CMR in a growing number of clinical indications. The first part of this review summarizes the role of CMR biomarkers for risk assessment focusing on the patients groups that benefit from the use of CMR. In the second part, the future directions for CMR are discussed and their role in prevention of cardiovascular disease.

Coronary artery wall imaging

Like X-Ray contrast angiography, MR coronary angiograms show the vessel lumens rather than the vessels themselves. Consequently, outward remodeling of the vessel wall, which occurs in subclinical coronary disease before luminal narrowing, cannot be seen. The current gold standard for assessing the coronary vessel wall is intravascular ultrasound, and more recently, optical coherence tomography, both of which are invasive and use ionizing radiation. A noninvasive, low-risk technique for assessing the vessel wall would be beneficial to cardiologists interested in the early detection of preclinical disease and for the safe monitoring of the progression or regression of disease in longitudinal studies. In this review article, the current state of the art in MR coronary vessel wall imaging is discussed, together with validation studies and recent developments.

Increased coronary vessel wall thickness in HIV-infected young adults

BACKGROUND

Individuals with long-term human immunodeficiency virus (HIV) infection are at risk for premature vasculopathy and cardiovascular disease (CVD). We evaluated coronary vessel wall thickening, coronary plaque, and epicardial fat in patients infected with HIV early in life compared with healthy controls.

METHODS

This is a prospective cross-sectional study of 35 young adults who acquired HIV in early life and 11 healthy controls, free of CVD. Time resolved phase-sensitive dual inversion recovery black-blood vessel wall magnetic resonance imaging (TRAPD) was used to measure proximal right coronary artery (RCA) wall thickness, and multidetector computed tomography (CT) angiography was used to quantify coronary plaque and epicardial fat.

RESULTS

RCA vessel wall thickness was significantly increased in HIV-infected patients compared with sex- and race-matched controls (1.32 ± 0.21 mm vs 1.09 ± 0.14 mm, P = .002). No subject had discrete plaque on CT sufficient to cause luminal narrowing, and plaque was not related to RCA wall thickness. In multivariate regression analyses, smoking pack-years (P = .004) and HIV infection (P = .007) were independently associated with thicker RCA vessel walls. Epicardial fat did not differ between groups. Among the HIV-infected group, duration of antiretroviral therapy (ART) (P = .02), duration of stavudine exposure (P < .01), low-density lipoprotein cholesterol (P = .04), and smoking pack-years (P < .01) were positively correlated with RCA wall thickness.

CONCLUSIONS

This investigation provides evidence of subclinical coronary vascular disease among individuals infected with HIV in early life. Increased duration of ART, hyperlipidemia, and smoking contributed to proximal RCA thickening, independent of atherosclerotic plaque quantified by CT. These modifiable risk factors appear to influence early atherogenesis as measured by coronary wall thickness and may be important targets for CVD risk reduction.

Cardiovascular magnetic resonance profiling of coronary atherosclerosis: vessel wall remodelling and related myocardial blood flow alterations

AIMS

To determine the association between coronary vessel wall morphology and haemodynamic consequences to the myocardium using a combined cardiovascular magnetic resonance (CMR) imaging protocol. Non-invasive CMR profiling of coronary atherosclerotic wall changes and related myocardial blood flow impairment has not been established yet.

METHODS AND RESULTS

Sixty-three patients (45 men, 61.5 ± 10.7 years) with suspected or known coronary artery disease underwent 3.0 Tesla CMR imaging. The combined CMR protocol consisted of the following imaging modules at rest: 3D vessel wall imaging and flow measurement of the proximal right coronary artery (RCA), myocardial T2*, and first-pass perfusion imaging. During adenosine stress coronary flow, T2* and first-pass perfusion imaging were repeated. Coronary X-ray angiography classified patient groups: (i) all-smooth (n = 19); (ii) luminal irregular (diameter reduction < 30%; n = 35); and (iii) stenosed RCA (diameter reduction ≥ 50%; n = 9). The ratio of CMR-derived vessel wall area-to-lumen area significantly increased stepwise for the comparison of all-smooth vs. luminal irregular vs. stenosed RCA (1.9 ± 0.6 vs. 2.6 ± 0.6 vs. 3.6 ± 0.9, P < 0.01). Epicardial coronary flow reserve exhibited a stepwise significant decrease (3.4 ± 0.5 vs. 2.9 ± 0.7 vs. 1.7 ± 0.3, P < 0.01). On the myocardial level, stress-induced percentage gain of T2* values (ΔT2*) was significantly decreased between groups (29.2 ± 10.6 vs. 9.0 ± 9.8 vs. 2.2 ± 11.8%, P < 0.01) while perfusion reserve index decreased in the presence of stenosed RCA only (2.2 ± 0.6 vs. 2.0 ± 0.4 vs. 1.3 ± 0.3, P = ns and P < 0.01, respectively).

CONCLUSION

The proposed comprehensive CMR imaging protocol provided a non-invasive approach for direct assessment of coronary vessel wall remodelling and resultant pathophysiological consequences on the level of epicardial coronary and myocardial blood flow in patients.