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.     

Role of cardiac MRI in nonischemic cardiomyopathies

Cardiac magnetic resonance (CMR) with its higher spatial resolution is considered the gold standard for evaluating ventricular mass, volumes, and ejection fraction. CMR can be used for accurate diagnosis of several conditions, especially cardiomyopathies. The purpose of this article is to review the utility of CMR in the diagnosis and management of nonischemic cardiomyopathies. We have reviewed both common and rare types of nonischemic cardiomyopathies in detail and elaborated on the specific CMR findings in each. We believe that CMR is an invaluable tool, not only in differentiating nonischemic from ischemic cardiomyopathy, but also in aiding the accurate diagnosis and management of the subtype of nonischemic cardiomyopathy. CMR should routinely be integrated in the diagnostic workup of various cardiomyopathies.     

The emerging role of MRI in the diagnosis and management of cardiomyopathies

Cardiac magnetic resonance (CMR) has emerged as an important tool for the evaluation of cardiomyopathies, providing highly accurate information on the macroscopic changes of cardiac morphology, function, and tissue composition. For myocardial tissue characterization, the technique of myocardial delayed enhancement is a potentially promising tool for diagnosis, management, and prognosis. Several CMR approaches are now available to better diagnose and prognosticate dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular disease, myocarditis, and other cardiomyopathies.     

The current and emerging role of cardiovascular magnetic resonance in the diagnosis of nonischemic cardiomyopathies

Imaging plays a crucial role in the diagnosis, management, and prognosis assessment of patients with nonischemic cardiomyopathies. Over the past decade, the role of cardiovascular magnetic resonance imaging in clinical practice has been rapidly expanding. The technique's unsurpassed accuracy in defining cardiac morphology and function and ability to provide tissue characterization make it particularly well suited for the study of patients with nonischemic cardiomyopathies. In this review article, we provide an overview of the main cardiovascular magnetic resonance features of nonischemic cardiomyopathies, highlighting the diagnostic and prognostic utility of the technique in this heterogenous group of diseases.     

Myocardial Amyloidosis: The Exemplar Interstitial Disease

Cardiac involvement drives prognosis and treatment choices in cardiac amyloidosis. Echocardiography is the first-line examination for patients presenting with heart failure, and it is the imaging modality that most often raises the suspicion of cardiac amyloidosis. Echocardiography can provide an assessment of the likelihood of cardiac amyloid infiltration versus other hypertrophic phenocopies and can assess the severity of cardiac involvement. Visualizing myocardial amyloid infiltration is challenging and, until recently, was restricted to the domain of the pathologist. Two tests are transforming this: cardiac magnetic resonance (CMR) imaging and bone scintigraphy. After the administration of contrast, CMR is highly sensitive and specific for the 2 main types of ventricular myocardial amyloidosis, light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR). CMR structural and functional assessment combined with tissue characterization can redefine cardiac involvement by tracking different disease processes, ranging from amyloid infiltration, to the myocardial response associated with amyloid deposition, through the visualization and quantification of myocardial edema and myocyte response. Bone scintigraphy (paired with exclusion of serum free light chains) is emerging as the technique of choice for distinguishing ATTR from light chain cardiac amyloidosis and other cardiomyopathies; it has transformed the diagnostic pathway for ATTR, allowing noninvasive diagnosis of ATTR without the need for a tissue biopsy in the majority of patients. CMR with tissue characterization and bone scintigraphy are rewriting disease understanding, classification, and definition, and leading to a change in patient care.     

The Role of Cardiac MR in New-Onset Heart Failure

In patients with heart failure, cardiovascular magnetic resonance imaging (CMR) allows a multifaceted approach to cardiac evaluation by enabling an assessment of morphology, function, perfusion, viability, tissue characterization, and blood flow during a single comprehensive examination. Given its accuracy and reproducibility, many believe CMR is the reference standard for the noninvasive assessment of ventricular volumes, mass, and function, and offers an ideal means for the serial assessment of disease progression or treatment response in individual patients. Delayed-enhancement (DE)-CMR provides a direct assessment of myopathic processes. This permits a fundamentally different approach than that traditionally taken to ascertaining the etiology of cardiomyopathy, which is vital in patients with nonischemic cardiomyopathy and incidental coronary artery disease and patients with mixed, ischemic and nonischemic cardiomyopathy. Precise tissue characterization with DE-CMR also improves the diagnosis of left ventricular thrombus, for which it is the emerging clinical reference standard. There is a growing body of literature on the utility of CMR for patient risk stratification, and its potential role in important management decisions such as for cardiac resynchronization therapy and defibrillator placement.     

Cardiac magnetic resonance imaging:Which information is useful for the arrhythmologist?

Cardiac magnetic resonance(CMR) is a non-invasive,nonionizing,diagnostic technique that uses magnetic fields,radio waves and field gradients to generate images with high spatial and temporal resolution.After administration of contrast media(e.g.,gadolinium chelate),it is also possible to acquire late images,which make possible the identification and quantification of myocardial areas with scar/fibrosis(late gadolinium enhancement,LGE).CMR is currently a useful instrument in clinical cardiovascular practice for the assessment of several pathological conditions,including ischemic and nonischemic cardiomyopathies and congenital heart disease.In recent years,its field of application has also extended to arrhythmology,both in diagnostic and prognostic evaluation of arrhythmic risk and in therapeutic decisionmaking.In this review,we discuss the possible useful applications of CMR for the arrhythmologist.It is possible to identify three main fields of application of CMR in this context:(1) arrhythmic and sudden cardiac death risk stratification in different heart diseases;(2) decisionmaking in cardiac resynchronization therapy device implantation,presence and extent of myocardial fibrosis for left ventricular lead placement and cardiac venous anatomy; and(3) substrate identification for guiding ablation of complex arrhythmias(atrial fibrillation and ventricular tachycardias).     

Edema and fibrosis imaging by cardiovascular magnetic resonance: How can the experience of Cardiology be best utilized in rheumatological practice?

Objectives

CMR, a non-invasive, non-radiating technique can detect myocardial oedema and fibrosis.

Method

CMR imaging, using T2-weighted and T1-weighted gadolinium enhanced images, has been successfully used in Cardiology to detect myocarditis, myocardial infarction and various cardiomyopathies.

Results

Transmitting this experience from Cardiology into Rheumatology may be of important value because: (a) heart involvement with atypical clinical presentation is common in autoimmune connective tissue diseases (CTDs). (b) CMR can reliably and reproducibly detect early myocardial tissue changes. (c) CMR can identify disease acuity and detect various patterns of heart involvement in CTDs, including myocarditis, myocardial infarction and diffuse vasculitis. (d) CMR can assess heart lesion severity and aid therapeutic decisions in CTDs.

Conclusion

The CMR experience, transferred from Cardiology into Rheumatology, may facilitate early and accurate diagnosis of heart involvement in these diseases and potentially targeted heart treatment.     

Cardiac Magnetic Resonance Fingerprinting: Technical Overview and Initial Results

Cardiovascular magnetic resonance is a versatile tool that enables noninvasive characterization of cardiac tissue structure and function. Parametric mapping techniques have allowed unparalleled differentiation of pathophysiological differences in the myocardium such as the delineation of myocardial fibrosis, hemorrhage, and edema. These methods are increasingly used as part of a tool kit to characterize disease states such as cardiomyopathies and coronary artery disease more accurately. Currently conventional mapping techniques require separate acquisitions for T₁ and T₂ mapping, the values of which may depend on specifics of the magnetic resonance imaging system hardware, pulse sequence implementation, and physiological variables including blood pressure and heart rate. The cardiac magnetic resonance fingerprinting (cMRF) technique has recently been introduced for simultaneous and reproducible measurement of T₁ and T₂ maps in a single scan. The potential for this technique to provide consistent tissue property values independent of variables including scanner, pulse sequence, and physiology could allow an unbiased framework for the assessment of intrinsic properties of cardiac tissue including structure, perfusion, and parameters such as extracellular volume without the administration of exogenous contrast agents. This review seeks to introduce the basics of the cMRF technique, including pulse sequence design, dictionary generation, and pattern matching. The potential applications of cMRF in assessing diseases such as nonischemic cardiomyopathy are also briefly discussed, and ongoing areas of research are described.     

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.     

Gewebedifferenzierung mittels Kontrast-MRT („late enhancement“)

Cardiovascular MR (CMR) is a new diagnostic technique that not only provides morphologic and functional information about the entire cardiovascular system, but also allows non-invasive tissue characterization of the myocardium. Myocardial tissue characterization is mainly based on contrast-enhanced CMR. The main principle of contrast-enhanced CMR is the accumulation of gadolinium-based MR contrast agents in myocardial areas with enlarged extracellular space, such as regions of necrosis, fibrosis or deposits of abnormal proteins (e.g., amyloid), in the absence of contrast enhancement in normal myocardium. Based on the evidence presented in this review article, it is safe to conclude that contrast CMR can reliably detect acute and chronic myocardial infarcts in clinical routine, and that contrast CMR is capable of predicting recovery of wall motion after revascularization with a high degree of accuracy. In addition, contrast CMR is a valuable tool for the work up of new-onset heart failure, since the myocardial distribution of contrast enhancement often points to the underlying disease by providing insight into the myocardium in vivo that could previously only be obtained by postmortem examination. This information about the distribution of abnormal myocardial regions is also important for improving the sensitivity of endomyocardial biopsies that may be necessary in certain myocardial diseases, e.g., myocarditis.     

Imaging myocardial scar and arrhythmic risk prediction—a role for the electrocardiogram?

Risk stratification for sudden cardiac death (SCD) has become increasingly important to identify candidates for implantable cardioverter-defibrillators (ICDs). Existing clinical guidelines to identify patients for ICDs focus on reduced left ventricular ejection fraction (LVEF); however, the average annual rate of appropriate ICD shocks is only 5.1% in this select group (LVEF ≤35%), and these patients only represent a small fraction of the total number of patients who die of SCD. Magnetic resonance imaging (MRI) with late gadolinium enhancement has recently emerged as the in vivo gold standard for detecting and quantifying myocardial scar after infarction and in nonischemic cardiomyopathies. Myocardial scar, particularly in the scar border zone, interrupts electrical conduction providing regions that support reentrant ventricular arrhythmias. Recent studies have shown that increased MRI scar in both prior infarction and nonischemic cardiomyopathy patients is associated with arrhythmogenesis, worsening heart failure, and cardiac mortality. This review will focus on the emerging role of MRI to quantify scar and predict arrhythmogenesis in patients with prior infarction and with nonischemic cardiomyopathies—including idiopathic, hypertrophic, Fabry's disease, myocarditis, Chagas' disease, and sarcoidosis. Furthermore, this review will discuss the potential role of the 12-lead electrocardiographic Selvester QRS scoring system to quantify myocardial scar and predict arrhythmogenesis in prior infarct and nonischemic cardiomyopathy patients.     

Imaging Heart Failure: Current and Future Applications

A variety of cardiac imaging tests are used to help manage patients with heart failure (HF). This article reviews current and future HF applications for the major noninvasive imaging modalities: transthoracic echocardiography (TTE), single-photon emission computed tomography (SPECT), positron emission tomography (PET), cardiovascular magnetic resonance (CMR), and computed tomography (CT). TTE is the primary imaging test used in the evaluation of patients with HF, given its widespread availability and reliability in assessing cardiac structure and function. Recent developments in myocardial strain, 3-dimensional TTE, and echo contrast appear to offer superior diagnostic and prognostic information. SPECT imaging is a common method employed to detect ischemia and viability in patients with HF; however, PET offers higher diagnostic accuracy for both. Ongoing study of sympathetic and molecular imaging techniques may enable early disease detection, better risk stratification, and ultimately targeted treatment interventions. CMR provides high-quality information on cardiac structure and function and allows the characterization of myocardial tissue. Myocardial late gadolinium enhancement allows the determination of HF etiology and may predict patient outcomes and treatment response. Cardiac CT has become a reliable means for detecting coronary artery disease, and recent advances have enabled concurrent myocardial function, perfusion, and scar analyses. Overall, available imaging methods provide reliable measures of cardiac performance in HF, and recent advances will allow detection of subclinical disease. More data are needed demonstrating the specific clinical value of imaging methods and particularly subclinical disease detection in large-scale, clinical settings.     

Cardiovascular Magnetic Resonance of Myocarditis

Within the past decade, cardiovascular magnetic resonance (CMR) imaging has led to unprecedented growth in our understanding of myocarditis. From what began as a diagnostic tool for assessing ventricular function, CMR has transitioned into visualizing changes that occur in myocardial tissue during inflammation, including edema, hyperemia/inflammation, and fibrosis. In terms of research applications, the entire spectrum ranging from subclinical to fulminant myocarditis can be visualized, as well as unmasking myocarditis from other cardiomyopathies. The impact of CMR in clinical applications is best exemplified by recent findings demonstrating that CMR is a leading diagnostic tool and may perhaps even be the method of choice for establishing a diagnosis of myocarditis in Germany. With the advent of an International Consensus Group on Cardiovascular Magnetic Resonance in Myocarditis and large-scale multicenter registries on CMR-based visualization of myocarditis, further advances aimed at improving clinical decision making and guiding patient therapy are expected.     

CMR in Evaluating Valvular Heart Disease: Diagnosis,Severity, and Outcomes

Cardiac magnetic resonance (CMR) is a versatile imaging tool that brings much to the assessment of valvular heart disease. Although it is best known for myocardial imaging (even in valve disease), it provides excellent assessment of all 4 heart valves, with some distinct advantages, including a free choice of image planes and accurate flow and volumetric quantification. These allow the severity of each valve lesion to be characterized, in addition to optimal visualization of the surrounding outflow tracts and vessels, to deliver a comprehensive package. It can assess each valve lesion separately (in multiple valve disease) and is not affected by hemodynamic status. The accurate quantitation of regurgitant lesions and the ability to characterize myocardial changes also provides an ability to predict future clinical outcomes in asymptomatic patients. This review outlines how CMR can be used in cardiac valve disease to compliment echocardiography and enhance the patient assessment. It covers the main CMR methods used, their strengths and limitations, and the optimal way to apply them to evaluate valve disease.     

Delayed enhancement cardiovascular magnetic resonance assessment of non-ischaemic cardiomyopathies.

Non-ischaemic cardiomyopathies (NICMs) are chronic, progressive myocardial diseases with distinct patterns of morphological, functional, and electrophysiological changes. In the setting of cardiomyopathy (CM), determining the exact aetiology is important because the aetiology is directly related to treatment and patient survival. Determining the exact aetiology, however, can be difficult using currently available imaging techniques, such as echocardiography, radionuclide imaging or X-ray coronary angiography, since overlap of features between CMs may be encountered. Cardiovascular magnetic resonance (CMR) imaging has recently emerged as a new non-invasive imaging modality capable of providing high-resolution images of the heart in any desired plane. Delayed contrast enhanced CMR (DE-CMR) can be used for non-invasive tissue characterization and may hold promise in differentiating ischaemic from NICMs, as the typical pattern of hyperenhancement can be classified as 'ischaemic-type' or 'non-ischaemic type' on the basis of pathophysiology of ischaemia. This article reviews the potential of DE-CMR to distinguish between ischaemic and NICM as well as to differentiate non-ischaemic aetiologies. Rather than simply describing various hyperenhancement patterns that may occur in different disease states, our goal will be (i) to provide an overall imaging approach for the diagnosis of CM and (ii) to demonstrate how this approach is based on the underlying relationships between contrast enhancement and myocardial pathophysiology.     

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.     

Impact of cardiac magnetic resonance imaging in nonischemic cardiomyopathies

Non-ischemic cardiomyopathies include a wide spectrum of disease states afflicting the heart, whether a primary process or secondary to a systemic condition. Cardiac magnetic resonance imaging(CMR) has established itself as an important imaging modality in the evaluation of non-ischemic cardiomyopathies. CMR is useful in the diagnosis of cardiomyopathy, quantification of ventricular function, establishing etiology, determining prognosis and risk stratification. Technical advances and extensive research over the last decade have resulted in the accumulation of a tremendous amount of data with regards to the utility of CMR in these cardiomyopathies. In this article, we review CMR findings of various non-ischemic cardiomyopathies and focus on current literature investigating the clinical impact of CMR on risk stratification, treatment, and prognosis.     

Assessment of myocardial ischemia and viability using cardiac magnetic resonance

In the past decade, cardiac magnetic resonance (CMR) has evolved dramatically. Its clinical applications are now a major tool in the diagnosis and prognostic assessment of patients with ischemic heart disease. CMR can be used for detection and quantification of ischemia and for viability assessment using different techniques that are now well validated. Scar can be easily detected using contrast enhancement (late gadolinium enhancement). Ischemia detection is usually achieved with stress CMR techniques, whereas prediction for the recovery of function (detection of dysfunctional but viable myocardial segments) can be deduced from scar and stress imaging. Although determination of which approach is better may depend on the population group, the major advantage of CMR is the ability to integrate different information about anatomy, wall motion, myocardial perfusion, and tissue characterization in a single comprehensive examination.