Cardiovascular magnetic resonance imaging for valvular heart disease: technique and validation.

Over the last half century, clinicians have employed several means to advance our knowledge of the causes and consequences of valvular heart disease. Invasive cardiac catheterization provided valuable information about hemodynamics, 2-dimensional (2D) echocardiography (echo) allowed direct visualization of the valvular apparatus and cardiac chambers, and Doppler echocardiography afforded a noninvasive tool for assessing hemodynamics and disease severity. Echocardiography is now the standard tool for initial assessment and longitudinal evaluation of patients with valvular heart disease; however, echocardiography is limited in patients with poor acoustic windows and may be more operator dependent than other modalities, particularly for quantitation of disease severity. In the last 20 years, cardiovascular magnetic resonance (CMR) has emerged as an alternative noninvasive modality without ionizing radiation that is applicable to patients with valvular heart disease. CMR provides images of valve anatomy and allows quantitative evaluation of stenosis and regurgitation. CMR can also discern the consequences of the valvular lesion, including the effects of ventricular volume or pressure overload and alterations in systolic function. The purpose of the present review is to summarize the general principles of CMR and validate CMR as a tool for evaluation of valvular heart disease. CMR uses a variety of pulse sequences to assess valvular heart disease (Table 1). A pulse sequence is a combination of transmitted radiofrequency pulses and magnetic gradients in the presence of a strong external magnetic field, from which a series of received radiofrequency pulses or “echoes” are obtained and processed into an image.1,2 View this table: Table 1. CMR Pulse Sequences for Valvular Heart Disease ### Anatomy CMR has the potential to visualize all parts of the valve (leaflets, chordae tendineae, and papillary muscles) throughout the entire cardiac cycle. Congenitally abnormal valve leaflets (bicuspid), aberrant papillary muscles or aberrant chordal attachments (parachute mitral valve), leaflet thickening, presence and extent of calcification, …