Evaluation of the Severity of Mitral Regurgitation by the Use of Signal Void in Magnetic Resonance Imaging

Background: The study was designed to evaluate the severity of mitral regurgitation by cardiac magnetic resonance imaging (MRI). We proposed a new measurement of signal void by MRI and tried to define threshold values for the severity of regurgitation with different sequences. Methods: Twenty‐one patients with mitral regurgitation were evaluated by echocardiography and MRI. We measured the length, width, and the area of jet flow void from long‐axis and four‐chamber views. The regurgitant area was measured with TrueFISP, FLASH sequences, and phase images by tracing the signal‐void area in left atrium parallel to mitral annulus. This new parameter for grading of the severity of mitral regurgitation by cine MRI was called regurgitant area from short axis (RAFSA). Results: All methods (EROA, vena contracta) were correlated for determining the regurgitation severity (P < 0.01). There was a correlation between EROA by echocardiography and RAFSA by MRI with the TrueFISP, FLASH sequences, and phase images (P < 0.01). Stepwise regression analysis revealed that EROA was significantly correlated with RAFSA by phase images (P < 0.001). After regression analysis, threshold values of RAFSA by phase imaging were calculated and found to be 0.27 cm² and 0.92 cm² between mild, moderate, and severe mitral regurgitations (100% sensitivity, 67% specificity, and 100% sensitivity, 78% specificity, respectively) (P < 0.01, P < 0.05). Conclusions: MRI is an alternative method for evaluating mitral regurgitation. Our study suggests a new parameter, RAFSA by cine MRI, to grade the severity of mitral regurgitation and provides threshold values in order to define mild, moderate, and severe regurgitations. (ECHOCARDIOGRAPHY, Volume **, ***********)