Valvular Disease

Methods: Magnetic Resonance Imaging of cardiac valves requires state of the art equipement such as a 1.5 or 3 Tesla magnet and a surface coil. Three principal sequences are required [1]: 1) Black blood, 2) cine steady state free precession (CineSSFP), and 3) phase contrast velocity encoded cine (VENCine). Black blood images are obtained by preparation of a fast spin echo sequences with a nonselective 180° pulse followed by a slice selective 180° pulse (double inversion recovery). Such preparation can be used for T1, T2, and PD weighted images. CineSSFP are used for assessment of valvular and myocardial motion. Temporal resolution is typically 50ms for a segmented breath hold sequence but may be further shortened by means of parallel imaging or non-breath hold sequences, if required. VENCine is an excellent tool for quantification of flow volume and velocity. It allows absolute quantification, since phase shift is proportional to the velocity of a moving spin in linear field gradients. Volume measurements are important to assess the regurgitant fraction of an incompetent valve, velocity measurement are used to assess degree of stenosis relying on the modified Bernoulli equation similarly to echocardiography.