ESTIMATING THE MYOCARDIUM'S ANGLE OF THREE-DIMENSIONAL TRAJECTORY, USING THE TRACKING OF SEQUENTIAL TWO-DIMENSIONAL ECHOCARDIOGRAPHY IMAGES

BACKGROUND: In this study, the angle of the myocardium's trajectory in three dimensions (${\Phi}$) was estimated by simultaneous use of long-axis and short-axis views of left ventricle septum two-dimensional images. Then correlation of three-dimensional trajectory's angle with the rotation angle from the long (${\chi}$) and short (${\theta}$) axis views was estimated and compared at the three levels of base, mid and apex of the interventricular septum wall. METHODS: Two-dimensional echocardiography images of long- and short-axis views of 19 healthy men were recorded and analyzed. Using an electrocardiogram of each individual, the images of the two views were synchronized. The interventricular septum wall motion at the three levels of base, mid and apex were estimated, using a block matching algorithm throughout three cardiac cycles. Considering the defined system of coordinates and the position vectors in long and short-axis views, the 3-dimensional angle of the trajectory was calculated. RESULTS: Maxima of the ${\Phi}$, ${\theta}$, and ${\chi}$ angles were extracted at $16.33{\pm}3.01$, $10.61{\pm}3.38$, and $15.11{\pm}3.30$ degrees at base level, $22.77{\pm}4.95$, $7.78{\pm}2.96$, and $16.72{\pm}2.66$ degrees at mid level and $14.60{\pm}5.81$, $10.37{\pm}5.48$, and $8.79{\pm}3.32$ degrees at apex level, respectively, of the septum wall, respectively. This study shows significant correlation between the angle of 3-dimensional trajectory (${\Phi}$) with the angle in short axis view (${\theta}$) of the septum wall at the apex level; and also with the angle in long axis view (${\chi}$) of the septum wall at base and mid levels. CONCLUSION: Due to the motion of the wall of the left ventricle in three dimensions, and the non-isotropic structure of myofibers, the angle of 3-dimensional trajectory was estimated using the speckle tracking method of 2-dimentional echocardiography images.