Cardiac Magnetic Resonance in Non Ischemic Cardiomyopathy

Cardiac Magnetic Resonance Imaging in Non Ischemic Cardiomyopathy

Cardiac magnetic resonance imaging has been established as a promising three dimensional imaging modality with the ability to assess cardiac morphology, ventricular function, perfusion, viability and imaging characteristics of the surrounding vasculature without ionizing radiation. The accurate treatment of patients with cardiac disorders has created the need for accurate and reproducible measurements of cardiac chamber volumes and function. Cardiac magnetic resonance has the ability to provide this information as well as assess edema, perfusion, viability and vascular anatomy.

Nonischemic cardiomyopathy is considered as a variety of structural and functional myocardial disorders in which the myocardium is abnormal in the absence of diseases such as hypertension and coronary artery, valvular, and congenital heart diseases. Classification of cardiomyopathies is complex, with many available systems. The American Heart Association broadly divides them into primary and secondary types. The European Society of Cardiology classifies cardiomyopathies into several distinct morphologic and functional phenotypes, each of which can be further subclassified into familial and nonfamilial forms . There is an overlap between genetic and acquired cardiomyopathies, especially in the category of dilated cardiomyopathies. Cardiomyopathy has a prevalence of 0.02% of the population with annual death rates up to 25,000 in the United States. Nonischemic cardiomyopathy is more common in younger individuals and women. Although echocardiography is the simplest imaging technique used for screening, diagnosis and classification of cardiomyopathies on the basis of morphology, it is operator dependent , has no tissue characterization capabilities and limited field of view especially in obese/chronic obstructive pulmonary disease patients, influenced by acoustic window, is not adequate in the evaluation of the right ventricle or extra-cardiac associated chest manifestations where magnetic resonance is superior in this issue . Transesophageal echocardiography has a better acoustic window, but it is an invasive procedure. In comparison, cardiac multidetector computed tomography is less useful for the assessment of such cases currently because multidetector computed tomography involves radiation exposure and contrast medium- related problems and provides less information (ie, hemodynamic information, tissue characterization such as fibrosis) than magnetic resonance imaging does. Computed tomography would be more appropriate in specific requests to detect coronary calcification, exclude coronary artery disease and in those cases with contraindications for magnetic resonance imaging, such as a pacemaker. Cardiac magnetic resonance imaging has been established as the best three dimensional imaging modality with the ability to assess cardiac morphology, ventricular function, perfusion, viability and imaging characteristics of the surrounding vasculature without ionizing radiation. The accurate treatment of patients with cardiac disorders has created the need for accurate and reproducible measurements of cardiac chamber volumes and function. Cardiac magnetic resonance has the ability to provide this information as well as assess oedema, perfusion, viability and vascular anatomy. The high soft-tissue contrast, availability of a large field of view, multiplanar acquisition capability and lack of ionizing radiation are particularly appealing features of Cardiac magnetic resonance. There are certain technical challenges unique to cardiac magnetic resonance image as rapid and complex motion of the heart and pulsations of the surrounding great vessels. In addition, the effects of respiratory motion and systolic ventricular blood velocities up to 200 cm/s further complicate cardiac imaging. These challenges are generally solved by implementation of electrocardiography (cardiac) gating; navigator echo respiratory gating; breath-hold techniques; rapid, high-performance gradients; improved field homogeneity; and advanced pulse sequences. electrocardiography gating can be either prospective or retrospective. Several Cardiac magnetic resonance sequences are available for the evaluation of Nonischemic cardiomyopathy, each providing specific information. Depending on the clinical suspicion, the cardiac imager can add specific sequences to form a Cardiac magnetic resonance protocol tailored to that particular disease process. Delayed myocardial enhancement, being one of cardiac magnetic resonance imaging sequences, is not specific for myocardial infarction and can be used in many other cardiac diseases. Delayed enhancement in nonischemic myocardial disease generally, unlike in ischemic heart disease, has no particular coronary artery distribution and is often midwall rather than subendocardial or transmural . Moreover, in the acute phase, the first-pass perfusion study usually does not show any focal perfusion defect in nonischemic cardiomyopathy but instead may show normal results or early increased enhancement. Cardiac magnetic resonance has now established itself as a crucial imaging technique in the evaluation of several cardiomyopathies. It not only provides comprehensive information on structure and function, but also can perform tissue characterization, which helps in establishing the etiology of cardiomyopathy. Cardiac magnetic resonance is also useful in establishing the diagnosis, providing guidance for endomyocardial biopsy, accurate quantification of function, volumes, and fibrosis, prognostic determination, risk stratification, and monitoring response to therapy. One of the most important added points in in investigator(s) research is to assess extra cardiac chest manifestation in by one session of magnetic resonance imaging session with high accuracy and least cost. Echocardiography is the best available gold standard for cardiomyopathic patient as in multiple previous studies, so it well be done for each patient in investigator(s) study for comparison.

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