Case: 45-year-old female with rapidly progress- ing heart failure. Cardiac magnetic resonance imaging: Cine images, steady state free precession (top) and delayed hyperenhancement (bottom). Diagnosis: Amyloidosis—ven- tricular hypertrophy (top image, right arrow), thickened intra-atrial septum (top image, left arrow), and diffuse delayed hyperenhancement (bottom image). 

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... imaging methods to assess myocardial viability: (1) it can show the transmural extent of nonviable myocardium; (2) it has superior spatial resolution; (3) it can assess normal myocardial wall thickness; and (4) it can show contractility reserve with dobutamine. Administration of a gadolinium-based contrast agent is typically used to assess tissue fibrosis via cMRI technique of delayed hyperenhancement (DHE). The gadolinium is injected, and after approximately 10–15 minutes of ‘‘wash-out’’ period, the areas with fibrotic tissue appear white on DHE images due to the slower wash-out of contrast. Thus , white is fibrosis or inflammation , and black is normal tissue . DHE has been validated with ex vivo pathology specimens in dogs who underwent infarction of a specific coronary distribution. 5 This technique was then correlated in the clinical arena in a study by Kim et al, wherein 50 patients with left ventricular dysfunction underwent pre-revascularization cMRI with gadolinium injection. 6 Notably, the degree of hyperenhancement was inversely related to the improvement in post-revascu- larization contractility. Seventy-eight percent of patients identified as completely viable by contrast- enhanced MRI had an improvement in contractility after revascularization. On the other hand, of the patients labeled as nonviable by cMRI, less than 8% had an improvement in contractility (Figure 8). 6 Ischemic heart disease may represent one of the most common dilemmas facing the cardiologist, but nonischemic cardiomyopathy represents one of the most frustrating. Though certain forms of nonischemic cardiomyopathy are readily diagnosed by echocardiography, many other forms have required biopsy or autopsy tissue diagnosis to determine their etiology. Cardiac MRI is unique in offering a noninvasive evaluation of tissue composition and, thus, the opportunity to determine the etiology of many less common forms of cardiomyopathy without endomyocardial biopsy. Identification of a patient’s cause of cardiomyopathy carries with it important differences in therapy and prognosis. The specific pattern of DHE and/or the presence of fatty infiltration of the myocardium is used in the diagnosis of cardiomyopathies, such as myocarditis, hypertrophic cardiomyopathy, amyloidosis, and arrhythmogenic right ventricular dysplasia. 7 Myocarditis represents another area in which cMRI offers a significant improvement in diagnostic imaging options. Traditionally, myocarditis is diagnosed via its clinical manifestations: typically a viral syndrome, another infectious, or autoimmune etiology associated with the development of chest pain, heart failure, or arrhythmia. 8 Autopsy studies have demonstrated myocarditis in up to 12% of young patients presenting with sudden cardiac death, emphasizing the importance of appropriate diagnosis and treatment. 9 Endomyocardial biopsy has previously been the gold standard for diagnosis, but it is not only invasive but also highly insensitive, with only 10–25% of patients with clinically diagnosed myocarditis demonstrating histological findings of the disease. 10 Some of this discrepancy is undoubtedly related to clinical misdiagnosis, but the epicardial distribution of inflammatory cells (tissue unobtainable by intracardiac biopsy) may account for a significant proportion of false-negative biopsies. Myocarditis on cMRI shows a very characteristic DHE of the epicardium, most prominently of the lateral wall (Figure 9). 11 Given the importance of appropriate diagnosis and of ruling out other etiologies, such as acute ischemic events, that present with similar symptoms and laboratory findings, cMRI offers a unique and as yet underutilized imaging modality for confirming this diagnosis. In a study of patients presenting with chest pain, elevated troponin values, and normal coronary angiography who underwent subsequent cMRI, more than 30% demonstrated findings consistent with myocarditis, emphasizing the probability that this disease is likely under diagnosed because of the lack of sensitive modalities capable of providing antemortem diagnosis. 12 Cardiac amyloidosis, an infiltrative cardiomyopathy, carries an extremely poor prognosis, with a median survival of 13 months. Confirmatory diagnosis has historically been obtained through endomyocardial biopsy, which carries a sensitivity of 55%. 13 Several studies have reported a characteristic diffuse hyperenhancement pattern on cMRI, typically more prominent in the subendocardium. When compared to endomyocardial biopsy performed in patients with restrictive cardiomyopathy, cMRI had a positive predictive valve of 92% and a negative predictive valve of 85%. 14 In addition, cMRI provides prognostic data on patients with amyloidosis. Patients with diffuse DHE of the myocardium have a significantly worse outcome compared to those with amyloidosis without DHE. The difference in median survival was 144 days with DHE vs. 600 days for those with no evidence of hyperenhancement (Figure 10). 15 For the assessment of hypertrophic cardiomyopathy, cMRI determines the involved area and degree of myocardial hypertrophy, as well as the extent of myocardial fibrosis with DHE. A characteristic pattern of DHE is observed in the mid-myocardium at the junction of the interventricular septum and right ventricular free wall. This pattern of DHE has been correlated with pathologic specimens and has now been shown to correlate with increased incidence of ventricular arrhythmias. These findings are clinically important, as the amount/location of hypertrophy and presence of DHE has been associated with an increased risk of sudden cardiac death. 16 The diagnosis of ARVD is based on the presence of major and minor criteria encompassing structural, histological, electrocardiographic, arrhythmic, and genetic factors proposed by the ARVD Task Force in 1994. 10 Abnormalities in the right ventricular structure and function constitute some of the diagnostic criteria for ARVD: fatty infiltration of the myocardium, free wall aneurysms, right ventricular enlargement, and DHE. Cardiac MRI allows multi- planar evaluation of the right ventricle, enabling accurate morphologic and functional assessment without any geometric assumptions. Intramyocardial fat accumulation is a pathologic hallmark of ARVD, and cMRI has excellent tissue characterization capa- bility, particularly for fatty tissue. The ability to provide tissue characterization as well as to visualize right ventricular function makes MRI suitable for diagnosis of this disease. 17 The diagnosis of intracardiac tumors can be challenging in the absence of autopsy or intraopera- tive tissue. Cardiac MRI offers several advantages over echocardiography in better classifying the nature of an intracardiac mass. Through a series of imaging algorithms, cMRI can not only define the location of a mass with the high degree of spatial resolution, but also demonstrate perfusion characteristics, enhancement patterns, mobility, hemodynamic effects, and the tissue composition. Previously, we illustrated the utility of black blood and perfusion imaging by cMRI in evaluating cardiac tumors (Figure 7). The black blood images help delineate the location of the tumor and potential pericardial and extra-pericardial extension. Perfusion imaging establishes the structure’s vascularity. A technique known as fat suppression provides additional insight into tissue composition (Figure 11). 18 Echocardiography is the primary modality for the assessment and follow-up of valvular heart disease. However, cMRI can provide similar information: defining valvular anatomy and quantifying regurgitation volumes, peak gradients, chamber volumes, and ejection fraction. The pulse sequence primarily used involves cine images by steady state free precession and velocity encoding contrast (VENC) imaging. The cine images define the valve anatomy, visualize the regurgitation or stenotic jet, and quantify the ventricular volumes and function. The VENC pulse sequence is used to measure the velocity and volume of blood flow. This technology has been instrumental in the evaluation of chronic aortic, mitral, and tricuspid regurgitation (Figures 12). 19 These techniques give great insight into the optimum timing of mitral valve repair or replacement as it is able to accurately and reproducibly quantitate the regurgitation fraction, the ejection fraction, and the ventricular volumes. After echocardiography, cMRI is the primary imaging modality used in the evaluation of congenital heart disease, as it does not expose children and young adults to radiation and can provide both anatomic and physiological information in preopera- evaluation of congenital heart disease not only relies on the above evaluation, but also calculation of cardiac shunts. MRI relies on the use of VENC imaging to calculate Qp:Qs and saturation pulses to allow for visualization of the shunt. The calculation of shunt fraction by MRI has been validated with angiography. 20 Cardiac MRI is also used to evaluate for anomalous origin of coronary arteries by allowing visualization of the proximal coronary arteries without gadolinium (Figures 13). One of the greatest advantages of cMRI is its safety, with no reported short- or long-term ill effects from the magnet. 21 As opposed to CT, which relies on x-ray frequency radiation, cMRI relies on the applica- tion of radiofrequency (RF) pulses within a strong magnetic field. Because no high-energy radiation is involved, no genetic effects or carcinogenic potential are known. 22 Cardiac MRI thus shares with ultrasound an inherent safety advantage over x-ray techniques. The corollary is that iodine-based agents are not used for imaging and, thus, are not a concern for patients undergoing cMRI scanning. However, there are two concerns a physician must be aware of when ordering a cMRI. First, the magnetic field interacts with ferromagnetic materials (potential for movement) and electronic circuits ...