Imaging in coronary artery disease. Cardiac magnetic resonance

Imaging in coronary artery disease should be regarded as a tool supporting patients’ management. Imaging helps physicians to diagnose patients more precisely and to treat them more effectively. There is a constant need to improve the decision-making process in patients with coronary artery disease. The growing number of cardiac magnetic resonance (CMR) centres, patients undergoing CMR studies and the plethora of evidence for the use of CMR both in patients with stable coronary artery disease, as well as acute coronary syndromes, justify reviewing its capabilities. Although research applications and technical developments are of particular value for progress being made in the field of imaging, clinical applications are the most crucial for patients and treating physicians, thus they will be discussed.     

Cardiovascular magnetic resonance imaging in myocarditis

Cardiovascular magnetic resonance imaging (CMR) has become the leading modality in noninvasive imaging of myocarditis. Consensus on the use of 3 CMR criteria for myocarditis, referred to as edema, early, and late enhancement, has standardized CMR protocol for assessing myocarditis. Although definite diagnosis of myocarditis remains challenging, the outcome of this disease necessitates further investigation with the objective of providing robust noninvasive tests. Moreover, relative to current tools such as endomyocardial biopsy, CMR is a promising technique in the setting of this insidious and complex disease.     

Cardiovascular magnetic resonance imaging for valvular heart disease

Valvular heart disease (VHD) is a clinically important diagnosis, with significant associated morbidity and mortality. Multiple imaging modalities exist to characterize valvular and associated cardiac anatomy. Cardiovascular magnetic resonance (CMR) has emerged as a comprehensive noninvasive imaging modality for VHD. With use of well-established, standardized imaging sequences, CMR can accurately and precisely diagnose valvular structural abnormalities, assess severity of regurgitant and stenotic lesions, and potentially define patient prognosis. This article reviews the clinical applications of CMR in assessment of VHD.     

The role of cardiovascular magnetic resonance in the evaluation of valve disease

Echocardiography is the primary imaging modality for initial assessment and longitudinal evaluation of patients with valvular heart disease. Cardiovascular magnetic resonance (CMR) has emerged as an additional or alternative modality in these patients providing clinically useful information not only about the valve lesion itself but also about the consequences for the relevant ventricle. Other unique capabilities of CMR include the assessment of surrounding anatomy (eg, great vessels) and the evaluation of myocardial scar or fibrosis. This review will highlight the role of CMR in the assessment of patients with valve disease with particular emphasis on the advantages of this imaging modality in key areas.     

MRI of left ventricular function.

Cardiac magnetic resonance imaging (CMR) is widely recognized as the most accurate noninvasive imaging modality for the assessment of left ventricular (LV) function. By use of state-of-the-art magnetic resonance imaging (MRI) scanners, electrocardiography (ECG)-gated cine images depicting LV function with high contrast and excellent spatial and temporal resolution are readily acquired in breath-holds of 5 to 10 heartbeats. For patients in whom breath-holding and ECG gating are difficult, real-time cine imaging without ECG gating and breath-holding can be performed. LV function can be qualitatively assessed from cine images, or alternatively, parameters such as LV volumes, ejection fraction, and mass may be quantified via computer-based analysis software. In addition, techniques such as myocardial tagging and newer variants can be used to qualitatively or quantitatively assess regional intramyocardial strain, twist, and torsion. Many of the CMR methods have undergone clinical evaluation in the settings of high-dose dobutamine stress testing and determination of myocardial viability. These methods are also very accurate for prognosis in coronary heart disease patients and may be quite useful for the detection of contractile dyssynchrony. When used together with other CMR techniques such as first-pass perfusion imaging or late gadolinium enhancement, CMR of LV function provides a wealth of information in a single imaging study.     

Assessment of stable coronary artery disease by cardiovascular magnetic resonance imaging: Current and emerging techniques

Coronary artery disease(CAD) is a leading cause of death and disability worldwide. Cardiovascular magnetic resonance(CMR) is established in clinical practice guidelines with a growing evidence base supporting its use to aid the diagnosis and management of patients with suspected or established CAD. CMR is a multi-parametric imaging modality that yields high spatial resolution images that can be acquired in any plane for the assessment of global and regional cardiac function, myocardial perfusion and viability, tissue characterisation and coronary artery anatomy, all within a single study protocol and without exposure to ionising radiation. Advances in technology and acquisition techniques continue to progress the utility of CMR across a wide spectrum of cardiovascular disease, and the publication of large scale clinical trials continues to strengthen the role of CMR in daily cardiology practice. This article aims to review current practice and explore the future directions of multi-parametric CMR imaging in the investigation of stable CAD.     

The emerging clinical role of cardiovascular magnetic resonance imaging

Starting as a research method little more than a decade ago, cardiovascular magnetic resonance (CMR) imaging has rapidly evolved to become a powerful diagnostic tool used in routine clinical cardiology. The contrast in CMR images is generated from protons in different chemical environments and, therefore, enables high-resolution imaging and specific tissue characterization in vivo, without the use of potentially harmful ionizing radiation.CMR imaging is used for the assessment of regional and global ventricular function, and to answer questions regarding anatomy. State-of-the-art CMR sequences allow for a wide range of tissue characterization approaches, including the identification and quantification of nonviable, edematous, inflamed, infiltrated or hypoperfused myocardium. These tissue changes are not only used to help identify the etiology of cardiomyopathies, but also allow for a better understanding of tissue pathology in vivo. CMR tissue characterization may also be used to stage a disease process; for example, elevated T2 signal is consistent with edema and helps differentiate acute from chronic myocardial injury, and the extent of myocardial fibrosis as imaged by contrast-enhanced CMR correlates with adverse patient outcome in ischemic and nonischemic cardiomyopathies.The current role of CMR imaging in clinical cardiology is reviewed, including coronary artery disease, congenital heart disease, nonischemic cardiomyopathies and valvular disease.     

Plasma catecholamine levels in the acute and subacute stages of takotsubo syndrome: Results from the Stockholm myocardial infarction with normal coronaries 2 study

AimsIt is well‐accepted that takotsubo syndrome (TS) is characterized by a massive surge of plasma catecholamines despite lack of solid evidence. The objective of this study was to examine the hypothesis of a massive catecholamine elevation in TS by studying plasma‐free catecholamine metabolites in patients participating in the Stockholm myocardial infarction (MI) with normal coronaries 2 (SMINC‐2) study where TS constituted more than one third of the patients.Methods and resultsThe patients included in the SMINC‐2 study were classified, according to cardiac magnetic resonance (CMR) imaging findings (148 patients), which was performed at a median of 3 days after hospital admission. Plasma‐free catecholamine metabolites; metanephrine, normetanephrine, and methoxy‐tyramine were measured on day 2–4 after admission. Catecholamine metabolite levels were available in 125 patients. One hundred and ten (88%) of the 125 patients included in SMINC‐2 study, and 38 (86.4%) of the 44 patients with TS had completely normal plasma metanephrine and normetanephrine levels. All patients had normal plasma methoxy‐tyramine levels. Fourteen (11.2%) of the 125 patients included in SMINC‐2 study, and 5 (11.6%) of the 43 patients with TS had mild elevations (approximately 1.2 times the upper normal limits) of either plasma metanephrine or normetanephrine. One patient with pheochromocytoma‐triggered TS had marked elevation of plasma metanephrine and mild elevation of plasma normetanephrine. There were no significant differences between the number or degree of catecholamine metabolite elevations between the different groups of patients with CMR imaging diagnosis included in SMINC‐2 study.ConclusionThere was no evidence of massive catecholamine elevations in the acute and subacute stages of TS apart from one patient with pheochromocytoma‐induced TS. Most of the TS patients had normal catecholamine metabolites indicating that blood‐borne catecholamines do not play a direct role in the pathogenesis of TS.     

The Role of Cardiovascular Magnetic Resonance for Surveillance of Cardiac Performance upon Receipt of Potentially Cardiotoxic Cancer Therapeutics

Purpose of Review

Advancements in cancer treatment have resulted in improved cancer-related survival and consequently an increase in the number of cancer survivors. Unfortunately, associated with this increase in cancer-related survivorship, cardiac events have occurred with increasing frequency in cancer survivors. Recognition that cancer survivors are at increased risk for cardiovascular (CV) morbidity has generated interest to develop cardiac imaging techniques that identify subclinical CV disease during receipt of potentially cardiotoxic cancer treatment. Since subclinical cardiovascular disease precedes future cardiac events, early recognition of subclinical CV disease during receipt of potentially cardiotoxic cancer treatment offers the opportunity to initiate strategies that prevent further evolution of subclinical CV disease as well as cardiac events.

Recent Findings

Cardiovascular magnetic resonance imaging (CMR) is an advanced imaging technique that identifies imaging markers of subclinical cardiovascular disease in patients receiving potentially cardiotoxic cancer treatment regimens. In this article, we review the use of CMR for identifying subclinical cardiac disease in patients receiving potentially cardiotoxic cancer treatment regimens.

Summary

The ability of contemporary CMR to accurately define cardiac anatomy, function, and tissue characteristics may represent a critical tool to assess patients with cancer.

     

Computed tomography and cardiac magnetic resonance imaging in pulmonary hypertension

Recent advances in imaging technology have allowed for better temporal and spatial resolution in cardiovascular imaging. The idea of a “one-stop shop” for anatomical and functional cardiopulmonary and vascular assessment in patients with pulmonary hypertension is very appealing since diagnostic, prognostic, and therapeutic response can be measured. Modalities, such as computed tomography (CT) and cardiac magnetic resonance (CMR), are better suited to image the right heart and associated structures in multiple projections allowing for three-dimensional data sets and image reconstruction. This review will focus on the use of CT and CMR in the assessment of the right ventricle and pulmonary structures as they relate to pulmonary vascular disease.     

Emerging MRI Methods in Translational Cardiovascular Research

Cardiac magnetic resonance imaging (CMR) has become a reference standard modality for imaging of left ventricular (LV) structure and function and, using late gadolinium enhancement, for imaging myocardial infarction. Emerging CMR techniques enable a more comprehensive examination of the heart, making CMR an excellent tool for use in translational cardiovascular research. Specifically, emerging CMR methods have been developed to measure the extent of myocardial edema, changes in ventricular mechanics, changes in tissue composition as a result of fibrosis, and changes in myocardial perfusion as a function of both disease and infarct healing. New CMR techniques also enable the tracking of labeled cells, molecular imaging of biomarkers of disease, and changes in calcium flux in cardiomyocytes. In addition, MRI can quantify blood flow velocity and wall shear stress in large blood vessels. Almost all of these techniques can be applied in both pre-clinical and clinical settings, enabling both the techniques themselves and the knowledge gained using such techniques in pre-clinical research to be translated from the lab bench to the patient bedside.     

Application of cardiac magnetic resonance imaging in cardiomyopathy

Cardiomyopathies account for a significant portion of morbidity and mortality in patients with heart disease. The diagnosis and identification of the underlying disorder are essential for directing appropriate life-saving therapy. Cardiac magnetic resonance imaging (CMR) is an ideal method for the noninvasive evaluation of cardiomyopathies of unknown etiology. In addition, there is increasing prognostic evidence to support the use of this technology in patient risk stratification. CMR is not limited by anatomic barriers and is able to characterize tissue abnormalities that previously could often be identified only through biopsy. This review discusses the utility of CMR in the assessment of cardiomyopathies, including specific imaging techniques and their application in ischemic and nonischemic settings.     

Hybrid Cardiac Magnetic Resonance/Fluorodeoxyglucose Positron Emission Tomography to Differentiate Active From Chronic Cardiac Sarcoidosis

ObjectivesThe purpose of this study was to investigate the diagnostic value of simultaneous hybrid cardiac magnetic resonance (CMR) and ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) for detection and differentiation of active (aCS) from chronic (cCS) cardiac sarcoidosis.BackgroundLate gadolinium enhancement (LGE) CMR and FDG-PET are both established imaging techniques for the detection of CS. However, there are limited data regarding the value of a comprehensive simultaneous hybrid CMR/FDG-PET imaging approach that includes CMR mapping techniques.MethodsForty-three patients with biopsy-proven extracardiac sarcoidosis (median age: 48 years, interquartile range: 37-57 years, 65% male) were prospectively enrolled for evaluation of suspected CS. After dietary preparation for suppression of myocardial glucose metabolism, patients were evaluated on a 3-T hybrid PET/MR scanner. The CMR protocol included T1 and T2 mapping, myocardial function, and LGE imaging. We assumed aCS if PET and CMR (ie, LGE or T1/T2 mapping) were both positive (PET+/CMR+), cCS if PET was negative but CMR was positive (PET?/CMR+), and no CS if patients were CMR negative regardless of PET findings.ResultsAmong the 43 patients, myocardial glucose uptake was suppressed successfully in 36 (84%). Hybrid CMR/FDG-PET revealed aCS in 13 patients (36%), cCS in 5 (14%), and no CS in 18 (50%). LGE was present in 14 patients (39%); T1 mapping was abnormal in 10 (27%) and T2 mapping abnormal in 2 (6%). CS was diagnosed based on abnormal T1 mapping in 4 out of 18 CS patients (22%) who were LGE negative. PET FDG uptake was present in 17 (47%) patients.ConclusionsComprehensive simultaneous hybrid CMR/FDG-PET imaging is useful for the detection of CS and provides additional value for identifying active disease. Our results may have implications for enhanced diagnosis as well as improved identification of patients with aCS in whom anti-inflammatory therapy may be most beneficial.     

Cardiac magnetic resonance imaging in patients with coronary disease

Opinion statement Cardiac magnetic resonance (CMR) has emerged as a versatile noninvasive tool for the comprehensive evaluation of patients with suspected or established coronary artery disease (CAD). In a single imaging session, CMR can assess left ventricular anatomy and function, myocardial perfusion, viability, and coronary luminal stenosis. Using specific pulse sequences, left ventricular global and regional function can be assessed by cine CMR at rest and in response to inotropic stress; first-pass perfusion quantified by vasodilator stress; myocardial viability evaluated by delayed enhancement imaging and also by functional reserve; and coronary artery stenosis assessed by angiography. All these modalities can be achieved with high spatial resolution and image contrast, without exposure to ionizing radiation, and within a reasonable time frame of about 1 hour of scan time. Also, the imaging planes can be programmed to provide identical views of the heart for each type of image, thereby facilitating intermodality comparisons. There is early but accumulating evidence that the accuracy and prognostic values of many of these modalities are comparable or superior to radionuclide scintigraphy and echocardiography in head-to-head studies. Current limitations unique to CMR include the inability to perform exercise stress testing inside the CMR suite and exclusion of patients with indwelling metallic devices such as defibrillators and pacemakers. Despite these limitations, CMR is unique in its multifaceted approach that can be specifically tailored to the clinical question at hand, making it arguably the best tool for the diagnosis and management of CAD. With the rapid pace of advancement in CMR hardware and pulse sequence technologies, the clinical use of this powerful technique is likely to grow even greater in this area.     

The role of cardiovascular magnetic resonance in patients with acute coronary syndromes

Cardiovascular magnetic resonance (CMR) imaging is a recognized technique for characterization of myocardial tissue in stable ischemic heart disease. In addition, CMR is emerging as a noninvasive imaging tool that can provide supporting information to guide treatment in acute coronary syndromes (ACSs). The advantages of using CMR acutely could potentially include triage/differential diagnosis in patients presenting with chest pain and troponin rise but without diagnostic electrocardiogram changes, assessment of severity of myocardial injury (irreversible vs reversible damage) in patients with ST-elevation myocardial infarction and non–ST-elevation myocardial infarction, and risk stratification and assessment of prognosis in patients with ACS. This review evaluates a potential clinical role of CMR in the acute setting, highlighting its advantages and limitations. This critical approach emphasizes areas of uncertainty and ongoing controversies but aims to equip the reader to evaluate the potential clinical application and the practicalities of CMR in patients presenting with ACS.     

Canadian Society for Cardiovascular Magnetic Resonance (CanSCMR) Recommendations for Cardiovascular Magnetic Resonance Image Analysis and Reporting

Cardiovascular magnetic resonance (CMR) imaging is a rapidly developing technology that is becoming increasingly important in the diagnostic assessment of heart disease. Recognizing the need for recommendations to optimize the use of this technique, the Canadian Society for Cardiovascular Magnetic Resonance developed a task force to generate recommendations on the clinical use of parameters acquired by CMR imaging and how they should be reported. This article is the consensus report generated by the task force. The online material of this report provides such parameters for all relevant clinical settings, including pediatric and congenital applications. It considers the current clinical role of CMR, general requirements for CMR imaging, components of CMR studies, quantitative CMR image analysis, and appropriate contents of CMR reports. The recommendations are based on previously published recommendations on analysis and reporting and are the first of their kind. It is hoped that the use of these recommendations to guide daily clinical routine will help institutions offering CMR to adhere to high standards of quality according to the present state of the art.     

Future prospects in magnetic resonance imaging

Cardiovascular magnetic resonance (CMR) is widely regarded as capable of providing a cornucopia of detailed diagnostic information. However, of that information, very little is truly unique, and can be obtained by a combination of alternate diagnostic modalities. Given this, it is anticipated that in the short term (1-5 years) CMR will find use primarily as a modality to service patients whose diagnosis is inaccessible to established technologies such as ultrasound and radionuclide imaging. Due to the evolving emphasis on finding new and more efficient approaches to disease detection and prevention, as outlined in a policy-setting speech given by the director of the National Institutes of Health, it is anticipated that the scientific and clinical trial communities will adopt CMR at a more rapid pace due to its inherent dimensional accuracy and comprehensive nature. CMR is particularly well suited to participate in the approaching explosion of nanoparticle technologies, as they are applied to diagnostic and therapeutic approaches. In the longer term (5-10 years), as paradigms of disease detection likely expand beyond evaluation of symptoms and risk factors, the comprehensive nature of information provided by CMR will drive the increase of its use as a primary, first-tier, diagnostic modality. In summary, the use of CMR will become increasingly common, and as understanding of disease processes expand, it will emerge as a diagnostic modality that provides an abundance of unique information.     

The Role of MRI in Assessing Risk of Future Cardiovascular Disease Events, Including Heart Failure

Cardiovascular magnetic resonance (CMR) is the currently available gold standard non-invasive imaging modality for determining myocardial anatomy, structure and function. In this article, we discuss the role of CMR in evaluation of patients with cardiovascular disease with a particular emphasis on the additional information obtained from the recent developments in the imaging techniques.     

Cardiovascular MRI in clinical trials: expanded applications through novel surrogate endpoints

Recent advances in cardiovascular magnetic resonance (CMR) now allow the accurate and reproducible measurement of many aspects of cardiac and vascular structure and function, with prognostic data emerging for several key imaging biomarkers. These biomarkers are increasingly used in the evaluation of new drugs, devices and lifestyle modifications for the prevention and treatment of cardiovascular disease. This review outlines a conceptual framework for the application of imaging biomarkers to clinical trials, highlights several important CMR techniques which are in use in randomised studies, and reviews certain aspects of trial design, conduct and interpretation in relation to the use of CMR.