Role of cardiovascular magnetic resonance in clinical cardiology

Nov 3 2011

Cardiovascular Magnetic Resonance (CMR) has undergone substantial development and offers important advantages compared with other well-established imaging modalities.  In the November/December issue of Progress in Cardiovascular Diseases, published by Elsevier, a series of articles on key topics in CMR will foster greater understanding of the rapidly expanding role of CMR in clinical cardiology.

 "Until a decade ago, CMR was considered mostly a research tool, and scans for clinical purpose were rare," stated guest editors Theodoros D. Karamitsos, MD, PhD, and Stefan Neubauer, MD, of the University of Oxford Centre for Clinical Magnetic Resonance Research and the Department of Cardiovascular Medicine, John Radcliffe Hospital, Oxford, UK.  "With technical advances in hardware and software, CMR is now considered a powerful tool to assess ventricular function, cardiac morphology, perfusion, viability and metabolism, as well as the vasculature.  All of this imaging is possible without the need for ionizing radiation, and with high resolution in three dimensions.  CMR is now a highly attractive first-line test for routine clinical indications such as the evaluation of ischemic heart disease and nonischemic cardiomyopathies."

"It is anticipated that CMR may still have its best years to come.  In the near future, the technique will become even more patient and user friendly, with simplified acquisition approaches, faster real-time scanning protocols, novel contrast agents that target specific molecules for diagnosis and treatment, and advanced tissue characterization that will further improve in vivo assessment of myocardial pathology," commented Dr. Karamitsos and Prof. Neubauer.

Key Points:

Cardiovascular Magnetic Resonance: A Powerful Diagnostic and Prognostic Tool in Modern Cardiology

Theodoros D. Karamitsos, Stefan Neubauer

CMR is a relatively new imaging technique that has developed progressively over the last three to four decades.  CMR's acceptance has been facilitated by its ability to acquire images faster, the introduction of steady-state free-precision sequences for cine imaging, the development of the late gadolinium enhancement technique to assess myocardial scarring and fibrosis, and the improvement of stress perfusion. 

Cardiovascular Magnetic Resonance: Physics and Terminology

Christopher T. Rodgers, Matthew D. Robson

The widespread availability of magnetic resonance imaging (MRI) equipment in hospitals demonstrates that magnetic resonance (MR) has extraordinary value in medicine. This primer provides an introduction to MRI and its application in cardiology. The authors summarize the essential physics underlying CMR, present a compact glossary of important terminology, and provide references as starting points for further study.

Assessment of Myocardial Ischemia with Cardiovascular Magnetic Resonance

Bobak Heydari, Michael Jerosch-Herold, Raymond Y. Kwong

The assessment of patients presenting with symptoms suspicious for myocardial ischemia remains one of the most common and challenging clinical scenarios faced by physicians.  CMR can provide comprehensive diagnostic and prognostic assessment of myocardial ischemia for patients presenting with chest pain, stable angina, or for myocardial viability. Stress CMR is a highly accurate and safe diagnostic modality that has widespread patient applicability and has proven advantageous for certain patient subgroups, including those with poor echocardiographic windows, baseline left ventricular dysfunction, and resting wall motion abnormalities.  This review covers techniques of ischemia assessment with CMR and compares CMR with other commonly used noninvasive modalities. 

Evaluation of Myocardial Viability With Cardiac Magnetic Resonance Imaging

Suchi Grovera, Govindarajan Srinivasana, Joseph B. Selvanayagam

The management of patients with ischemic cardiomyopathy and history of myocardial infarction critically depends on the assessment of left ventricular (LV) function and viability. All of the currently used imaging modalities for viability assessment have substantial limitations related to image quality, poor spatial resolution, and attenuation artifact. The authors discuss how CMR overcomes these limitations and established itself as a reliable alternative to echocardiography and nuclear techniques.

Late Gadolinium Enhancement CMR Predicts Adverse Cardiovascular Outcomes and Mortality in Patients With Coronary Artery Disease: Systematic Review and Meta-Analysis

Filip Zemrak, Steffen E. Petersen

CMR has a recognized role in diagnosing and monitoring coronary artery disease (CAD). Multiple studies have shown that CMR can predict adverse outcomes. The authors review contemporary available literature to establish the role of CMR with late gadolinium enhancement (LGE) in predicting mortality and major adverse cardiac events (MACEs) in patients with CAD. They found that the presence of LGE increases the hazards of death by more than 4 times and of MACE by almost four times. The size of LGE (per gram or percent) increases the hazards of death and MACE by 4% and 5%, respectively. The presence and size of LGE predict mortality and MACE in CAD.

The Role of Cardiovascular Magnetic Resonance in Patients With Acute Coronary Syndromes

Erica Dall′Armellina, Robin P. Choudhury

CMR imaging is a recognized technique for characterization of myocardial tissue in stable ischemic heart disease. In addition, CMR's ability to provide a more complete characterization of myocardial tissue and to distinguish scarred from viable myocardium suggest a further role for CMR in diagnosing and stratifying patients with chest pain/acute coronary syndromes (ACSs) at admission or in the early hours post revascularization.  The authors evaluate the potential clinical role of CMR in the acute setting, highlighting its advantages and limitations. 

Coronary Imaging With Cardiovascular Magnetic Resonance: Current State of the Art

Amedeo Chiribiri, Masaki Ishida, Eike Nagel, Rene M. Botnar

CMR allows noninvasive and radiation-free visualization of both the coronary arteries and veins, with the advantage of an integrated assessment of cardiac function, viability, perfusion, and anatomy. Moreover, magnetic resonance offers the possibility of coronary vessel wall imaging, therefore assessing the anatomy and pathology of the normal and diseased coronary vessels noninvasively. Coronary magnetic resonance angiography is challenging because of cardiac and respiratory motion and the small size and tortuous path of the coronary vessels.  The authors provide an update on current technical improvements in coronary magnetic resonance angiography, including how to optimize the acquisition protocols, and give an overview of its current clinical applications. 

The Current and Emerging Role of Cardiovascular Magnetic Resonance in the Diagnosis of Nonischemic Cardiomyopathies

Theodoros D. Karamitsos, Jane M. Francis, Stefan Neubauer

CMR allows an accurate and reproducible assessment of cardiovascular anatomy and ventricular function, and it also provides detailed myocardial tissue characterization. These unique capabilities make it particularly attractive for the initial assessment and longitudinal follow-up of patients with cardiomyopathies. This review presents the main CMR features of common nonischemic cardiomyopathies, with particular focus on the specific advantages of this imaging modality.

Cardiovascular Magnetic Resonance Imaging in Myocarditis

Helene Childs, Matthias G. Friedrich

Only 10% of patients with myocarditis have clinical symptoms.  Most are often left without a conclusive diagnosis, potentially subject to further myocardial injury.  This paper reviews how CMR is being used for noninvasive assessment of patients with suspected myocarditis, facilitating assessment of all forms of myocarditis and differentiation from other cardiomyopathies. A recent international consensus on three diagnostic criteria for CMR in the clinical setting is discussed. Although definite diagnosis of myocarditis remains challenging, the outcome of this disease necessitates further investigation with the objective of providing robust noninvasive tests.

The Role of Cardiovascular Magnetic Resonance in the Evaluation of Valve Disease

Theodoros D. Karamitsos, Saul G. Myerson

This review looks at the optimal use of CMR in the assessment of patients with valve disease and its advantages in key areas. Although it is usually used as an adjunct to echocardiography, the ability to image all parts of the heart (including difficult areas such as the RV and pulmonary valve) makes CMR an attractive "stand-alone" alternative.  CMR delivers optimal assessment in quantifying the severity of the valve lesion, determining etiology, and examining the consequences for the relevant ventricle. Additional information on great vessel anatomy and the presence of myocardial scar (infarction) or patchy fibrosis can also be clinically useful.

Assessment of Iron Overload with T2* Magnetic Resonance Imaging

Lisa J. Anderson

The author describes how T2* CMR emerged as the method of choice for the assessment of tissue iron deposition.  The ability to measure ventricular function plus T2* in the heart and liver during the same scan has revolutionized the understanding of iron storage disease and the management of the iron-loaded patient. The early findings using T2* CMR challenged conventional teachings, and both the technique and the findings were initially viewed with skepticism. However, after a decade of work in validating, calibrating, and expanding access to this method, it is now accepted as the method of choice for tissue iron assessment.

The Role of Cardiovascular Magnetic Resonance in Adults with Congenital Heart Disease

Philip J. Kilner

In this paper, the author discusses the role of CMR in the management of adults with congenital heart disease (ACHD), a patient group that is expanding as advances in pediatric cardiology and cardiac surgery have allowed most to survive into adulthood. Transthoracic echocardiography remains the first-line imaging modality in ACHD. However, CMR's ability to provide functional as well as anatomical information make it useful in the assessment and follow-up of adults after procedures such as repairs of tetralogy of Fallot, aortic coarctation, and transposition of the great arteries, and those with Fontan operations or with operated or unoperated complex malformations.   CMR in ACHD requires specific training and experience, and the author advocates that for more complex cases, CMR should be undertaken by specialists committed to long-term collaboration with the clinicians and surgeons managing the patients in a tertiary referral center. 

Assessment of Pericardial Diseases and Cardiac Masses with Cardiovascular Magnetic Resonance

Dana Dawson, Raad Mohiaddin

This review focuses on the state-of the- art application of cardiovascular magnetic resonance in assessing pericardial diseases and cardiac tumors, and differentiating these conditions from other cardiac and noncardiac diseases.  A number of imaging modalities are available for this task and each has its advantages and limitations.  CMR is a very well suited to visualize fine structures such as the pericardium or to provide detailed anatomical information and tissue characterization of cardiac masses..  However, the authors point out the technical issues that can compromise accurate image collection; these need to be understood and considered when images are acquired. 

Clinical Cardiac Magnetic Resonance Spectroscopy

Cameron J. Holloway, Joseph Suttie, Sairia Dass, Stefan Neubauer

Cardiac magnetic resonance spectroscopy (MRS) is a powerful noninvasive technique for the investigation of cardiac metabolism; in particular, myocardial energetics and lipidosis. Although currently used only in the research setting, with new technical developments cardiac MRS has the potential to substantially improve our understanding of cardiac diseases and provide clinical tools for assessment and therapeutic monitoring.  This paper provides an overview of human cardiac MRS methods and their application in cardiac disease.  Current technical limitations and future directions are also explored. 

Progress in Cardiovascular Diseases Editor-in-Chief, Henry Greenberg, MD, added that "this issue, with its own primer on CMR physics and terminology, is a wonderful compendium for the cardiology trainee, pulling together in one place the essential evidence for the role of CMR."

Source: Progress in Cardiovascular Diseases