PURPOSE: To prospectively compare mitral valve regurgitation fractions calculated at electron-beam computed tomography (CT) (Doppler echocardiography as reference standard) and to evaluate accuracy of electron-beam CT volume and flow measurements compared with magnetic resonance (MR) imaging results.
MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Volume and flow measurements were performed at electron-beam CT in 219 patient!. (197 men, 22 womdn; mean age, 61.5 years � 10.4 [standard deviation]), of whom 157 had known isolated mitral valve regurgitation. Regurgitation volume was calculated as the difference between lefl ventricular total and forward stroke volumes. Regurgitation fractions were compared with corresponding echo< ardiographic grades (grades 0-IV) by using Spearman rank correlation and a weighted k test. In 22 patients, CT volume and flow measurements were compared with MR results by using intraclass correlation.
RESULTS: Regurgitation Tractions at CT correlated well with echocardiographic grading (rank correlation coefficient, rs - 0.82; P < .05). Mean regurgitation fractions for echocardiographic grades 0,1, II, III, and IV were 3.1% � 6.2,12.7% i 9.9, 25.3% <- 12.3, 40.4% � 11.5, and 55.9% � 13.7, respectively. The most suitable thresholds for differentiating echocardiographic grades were ^calculated regurgilation fractions of 6%, 20%, 30%, and 44%; with these thresholds, individual echocardiographic grades were differentiated (grades 0 vs I�IV, 0 I vs II�IV, 0-11 vs III�IV, and 0 -III vs IV, respectively) with sensitivities of 89%, 87%, 86%, and 93% and specificities of 81%, 87%, 92%, and 91%, respectively. There was perfect agreement in classification of mitral valve insufficiency between electron-beam CT and echocardiography in 134r(61%) patients and a mismatch by one grade in 72 (33%) and by two grades in 13 (6%) (k = 0.84). Intraclass correlation coefficients between CT and MR imaging for total and forward stroke volumes and regurgilation volume and fraction were 0.88, 0.79, 0.93, and 0.89, respectively.
CONCLUSION: Electron-beam CT provides quantitative information on severity of mitral valve regurgitation, but semiquantitative classification of regurgilation showed mismatch between electron-beam CT and Doppler echocardiography by at least one grade in more than one-third of all patients.