Isolated Mitral Regurgitation: Quantitative Assessment with 64-Section Multidetector CT-Comparison with MR Imaging and Echocardiography

Purpose: To evaluate the accuracy of 64-section multidetector computed tomography (CT) for the assessment of the severity of isolated mitral regurgitation by measuring ventricular volumetrics compared with those at magnetic resonance (MR) imaging and echocardiography. Materials and Methods: This study was approved by an institutional review board; patient informed consent was obtained. Forty-nine patients (22 men, 27 women; mean age, 39 years +/- 11 [standard deviation]) with isolated mitral regurgitation underwent retrospective electrocardiographically (ECG) gated 64-section CT, echocardiography, and MR imaging for the assessment of the severity of mitral regurgitation. Stroke volumes of the left and right ventricles were measured at 64-section CT and MR imaging. With these measurements, regurgitant volumes (RVs) and regurgitant fractions (RFs) were calculated and compared. The agreement between CT and MR imaging was tested by using linear regression and Bland-Altman analyses. RFs were compared with corresponding echocardiographic grades (grades I-IV) based on the absolute area of the regurgitation jet and in relation to the size of the left atrium by using Spearman rank order correlation and a weighted kappa test. Results: No significant differences were found in calculated RV and RF between 64-section CT and MR imaging (P = .56 and .87, respectively; paired t test). Regression analysis showed that 64-section CT correlated well with MR imaging for the measurement of RV (r = 0.89; 95% confidence interval [CI]: 0.81, 0.94) and for calculating the RF (r = 0.91; 95% CI: 0.84, 0.95). Bland-Altman analysis showed no significant differences in RV (bias, -1.0 mL) and RF (bias, 0.2%) between 64-section CT and MR imaging. The severity of regurgitation estimated by using echocardiography correlated well with that estimated by using 64-section CT (r = 0.95; 95% CI: 0.92, 0.97) and MR imaging (r = 0.94; 95% CI: 0.91, 0.96). Conclusion: ECG-gated 64-section CT helps provide quantitative information with high accuracy for determining the severity of isolated mitral regurgitation. (C) RSNA, 2009