Assessment of valvular heart disease by magnetic resonance imaging.

MRI has developed very rapidly and now provides anatomic and functional information in cases of valvular heart disease. MRI has several important attributes that make it advantageous for the evaluation of valvular heart disease. First, the natural contrast between flowing blood and surrounding cardiovascular structures provides sharp delineation of endocardial and epicardial borders without the need for contrast media. This feature in combination with the essential three-dimensional nature of this imaging technique allows precise quantification of cardiac volumes, function, and mass without the use of any assumed formulas or geometric models. Second, blood flow-sensitive GRE techniques are able to identify areas of turbulent flow caused by stenotic or regurgitant valves. With this technique regurgitant jets can be visualized and semiquantitative grading can be performed as with color Doppler. Third, recently developed velocity-encoded techniques permit measurements of blood flow velocities across stenotic native and prosthetic heart valves and retrograde flow caused by regurgitation. Moreover, the close interstudy reproducibility of measurements of cardiac dimensions and valvular regurgitation suggests a role in assessing the effect of therapeutic interventions.