Performance of a Fourier-based program for three-dimensional reconstruction of the mitral annulus on application to sparse, noisy data.

Objectives: We investigated the accuracy of mitral annular reconstruction from noisy, sparse data typical of three-dimensional (3D) transthoracic echocardiograms.

Background: Our Fourier-based method for reconstructing the annulus from dense, accurate 3D transesophageal echo (TEE) data has been validated in vitro with four harmonics in the x, y, and z coordinates (4,4,4).

Methods: Thirteen mitral annuli were reconstructed from 'complete' 3D TEE data using four harmonics (4,4,4) and used to measure area, eccentricity. height, perimeter, and interpeak and intervalley distances; these were the 'true values'. To simulate transthoracic echo data, the TEE data sets were reduced evenly and unevenly (randomly). The complete and reduced data sets were used to reconstruct the annuli using three sets of fitting parameters: (4,4,4), (1,1,3), and (1,1,4). The resulting size and shape measurements were compared with true values.

Results: Regardless of the fitting parameters used, area, 2D perimeter, and 3D perimeter measurements were more accurate using reconstructions from evenly-reduced than randomly-reduced data sets (p < 0.006), and depended significantly on both data density (p < 0.015 for all) and data distribution (p < 0.02 for all). Perimeter, height, and eccentricity of the reconstructed annuli were more accurately measured using four harmonics (4,4,4).

Conclusions: Mitral annuli can be reconstructed from sparse, noisy data using the (4,4,4) fit if at least 25 points are obtained from evenly distributed imaging planes. These results suggest that detailed analysis of mitral annular size and shape can be made accurately from 3D transthoracic echocardiograms.