Cardiac MRI in Diagnosis and Management

Abstract

Cardiac magnetic resonance imaging (CMR) is an essential tool for diagnosis, risk stratification, and treatment of patients with hypertrophic cardiomyopathy (HCM). CMR works by manipulating protons found in myocytes and contrast agents such as gadolinium, using magnetic pull to create and detect energy differences in order to obtain images. CMR is ideal for determining location and extent of hypertrophy, presence of membranes, distribution of fibrosis, as well as for identifying anatomy and physiology of the mitral valve, all of which are crucial for management of HCM and can be missed on standard echocardiography. This is especially true for areas of the heart that are difficult to evaluate on echocardiography, such as the apex and lateral wall, as well as atypical presentations, e.g., focal segmental hypertrophy. Additionally, CMR enables accurate assessment of ventricular volumes, mass, and function, which have diagnostic, as well as prognostic value. Magnetic resonance tagging and delayed enhancement with gadolinium contrast agents allow for strain and perfusion analysis, further increasing the utility of CMR to detect regional function and cardiac microvascular ischemia. Delayed enhancement may also improve risk stratification for sudden cardiac death. Limitations of CMR include difficulty to assess left ventricular outflow tract gradients and the ability to identify highly mobile structures on the mitral valve, although newer protocols and improved technology may be able to compensate for these deficits in the future.