Right ventricular strain analysis from three‐dimensional echocardiography by using temporally diffeomorphic motion estimation

Abstract

Purpose: Quantitative analysis of right ventricle (RV) motion is important for study of the mechanism of congenital and acquired diseases. Unlike left ventricle (LV), motion estimation of RV is more difficult because of its complex shape and thin myocardium. Although attempts of finite element models on MR images and speckle tracking on echocardiography have shown promising results on RV strain analysis, these methods can be improved since the temporal smoothness of the motion is not considered. Methods: The authors have proposed a temporally diffeomorphic motion estimation method in which a spatiotemporal transformation is estimated by optimization of a registration energy functional of the velocity field in their earlier work. The proposed motion estimation method is a fully automatic process for general image sequences. The authors apply the method by combining with a semiautomatic myocardium segmentation method to the RV strain analysis of three-dimensional (3D) echocardiographic sequences of five open-chest pigs under different steady states. Results: The authors compare the peak two-point strains derived by their method with those estimated from the sonomicrometry, the results show that they have high correlation. The motion of the right ventricular free wall is studied by using segmental strains. The baseline sequence results show that the segmental strains in their methods are consistent with results obtained by other image modalities such as MRI. The image sequences of pacing steady states show that segments with the largest strain variation coincide with the pacing sites. Conclusions: The high correlation of the peak two-point strains of their method and sonomicrometry under different steady states demonstrates that their RV motion estimation has high accuracy. The closeness of the segmental strain of their method to those from MRI shows the feasibility of their method in the study of RV function by using 3D echocardiography. The strain analysis of the pacing steady states shows the potential utility of their method in study on RV diseases. C 2014 American Association of Physicists in Medicine. [http://dx

Regularization-Free Strain Mapping in Three Dimensions, With Application to Cardiac Ultrasound

“…In 2D, such motion and deformation is impossible to track in the absence of additional information such as a rigorous model of behavior or images from additional cameras. In 3D, the reduced resolution in the out-of-plane direction leads to reduced resolution in displacements in that direction, and in general, leads to increased error in strain estimation when gradients of these displacement fields are taken to estimate strains [3,4,7,8,[12][13][14][15][16][17][18][19][20][21][22][23]29,30]. By eliminating the need for these numerical derivatives, the current method eliminates this latter source of error.…”

“…Even advanced regularization techniques, such as diffeomorphic smoothing [12,13], hyperelastic warping [14][15][16], or finite element based methods [8,[17][18][19], have limitations. These either do not warp reference volumes when searching for their counterparts in deformed imaged volumes [12,13]; require imposition of strain compatibility upon averaged fields [7]; or require imposition of an assumed material model [8,[13][14][15][16][19][20][21]. Overcoming all of these limitations currently requires post hoc regularization that tends to mask strain concentrations [6,8,22,23].…”