Quantitative evaluation der aortenklappenöffnungsfläche mit der dual-source-CT und korrelation mit der 2D-echokardiografie: Initiale ergebnisse

Purpose: To prospectively evaluate whether planimetric measurements of aortic valve area (AVA) with dual-source computed tomography (DSCT) correlate with measurements obtained by echocardiography and to correlate the amount of calcification of the aortic valve with AVA in a group of patients after aortic valve replacement. Materials and Method: 23 patients underwent dual-source computed tomography (DSCT) of the heart (Somatom Definition, Siemens Medical Solutions, Forchheim, Germany), without heart rate control (heart rate 52-113 beats/minute). All patients had undergone aortic valve replacement (homografts, mean time after surgery: 7 ± 3 years). The AVA of the transplanted aortic valve graft was measured planimetrically by means of DSCT and compared with echocardiography as a standard of reference, to exclude post-surgical restenosis of the valve. Maximum AVA in systole planimetrically measured with CT was compared with calculated AVA values determined with the continuity equation, using transvalvular pressure gradients. The amount of calcification of the aortic valve was quantified and correlated (Spearman's R) with the AVA. To assess intra- and inter-reader reproducibility, the DCST data was re-analyzed by two readers 4 weeks after the initial review. Results: All DSCT datasets were of diagnostic image quality concerning valve depiction. The mean AVA as measured by DSCT was 2.7 ± 0.9 cm² compared to 1.8 ± 0.5 cm² by echocardiography (p < 0.05). The planimetric evaluation of the CT data as compared to results of echocardiography showed a significant correlation of the results (Pearson's correlation coefficient R = 0.78, p < 0.001). Intra- and inter-reader reproducibility was good with intra-class correlation coefficients of 0.86 and 0.81, respectively (p < 0.001). There was a significant negative correlation between the amount of aortic valve calcification and AVA as measured by echocardiography (R = -0.42; p < 0.05) and as measured by DSCT (R = -0.67; p = 0.001). Conclusion: First experience indicates that DSCT is able to assess aortic valve opening area with high image quality and good intra- and inter-reader reproducibility in subjects after aortic valve replacement. The negative correlation between AVA and the amount of aortic valve calcification suggests that calcification is a possible risk factor for restenosis in subjects with aortic valve replacement.