P3A-6 The Effect of Including Fiber Orientation in Simulated 3D Ultrasound Images of the Heart

We have examined the effect of muscle fiber orientation on simulated ultrasound images. In ultrasound simulation studies, the myocardium is usually modeled as a cloud of uncorrelated point scatterers. This approach successfully generates a fully developed speckle pattern, but it does not reproduce any effects of image anisotropy which is seen in vivo. We hypothesize that some of these effects are caused by the varying orientation of myocardium muscle fibers relative to the ultrasonic beam. Images of the septal wall of a pig heart were obtained in vitro, and the dominating fiber direction in each layer was found from the backscattered signal. A segment of the heart muscle was then modeled as a grid of point scatterers correlated in the direction of the muscle fibers, as determined experimentally. Ultrasound images of this model were simulated by using a k-space based convolution approach. The simulated images showed a line of increased intensity where the fiber direction was nearly perpendicular to the beam direction, similar to the experimental results. We conclude that inclusion of the orientation of the muscle fibers is important, in order to generate realistic ultrasound images