Quantification of mitral regurgitation on cardiac computed tomography: comparison with qualitative and quantitative echocardiographic parameters.

PURPOSE: To assess whether cardiac computed tomographic angiography (CCTA) can quantify the severity of chronic mitral regurgitation (MR) compared to qualitative and quantitative echocardiographic parameters.

MATERIALS AND METHODS: Cardiac computed tomographic angiography was performed in 23 patients (mean ± SD age, 63 ± 16 years; range, 24-86 years) with MR and 20 patients without MR (controls) as determined by transthoracic echocardiography. Multiphasic reconstructions (20 data sets reconstructed at 5% increments of the electrocardiographic gated R-R interval) were used to analyze the mitral valve. Using CCTA planimetry, 2 readers measured the regurgitant mitral orifice area (CCTA ROA) during systole. A qualitative echocardiographic assessment of severity of MR was made by visual assessment of the length of the regurgitant jet. Quantitative echocardiographic measurements included the vena contracta, proximal isovelocity surface area, regurgitant volume, and estimated regurgitant orifice (ERO). Comparisons were performed using the independent t test, and correlations were assessed using the Spearman rank test.

RESULTS: All controls and the patients with MR were correctly identified by CCTA. For patients with mild, moderate, or severe MR, mean ± SD EROs were 0.16 ± 0.03, 0.31 ± 0.08, and 0.52 ± 0.03 cm² (P < 0.0001) compared with mean ± SD CCTA ROAs 0.09 ± 0.05, 0.30 ± 0.04, and 0.97 ± 0.26 cm² (P < 0.0001), respectively. When echocardiographic measurements were graded qualitatively as mild, moderate, or severe, strong correlations were seen with CCTA ROA (R = 0.89; P < 0.001). When echocardiographic measurements were graded quantitatively, the vena contracta and the ERO showed modest correlations with CCTA ROA (0.48 and 0.50; P < 0.05 for both). Neither the proximal isovelocity surface area nor the regurgitant volume demonstrated significant correlations with CCTA ROA.

CONCLUSIONS: Single-source 64-slice CCTA provides a strong agreement with qualitative echocardiographic parameters but only a moderate correlation with quantitative echocardiographic parameters of chronic MR. Cardiac computed tomographic angiography slightly overestimates mild MR while slightly underestimating severe MR.