Influence of elevational motion on the degradation of 2D image frame matching

A clinically useful approach to forming extended field of view images has recently been developed. This method takes a sequence of 2D images acquired while the transducer is scanned in an azimuthal direction and determines inter frame translation and rotation based on image matching techniques. The image motion estimation techniques employed do not generally distinguish anatomically related features from inherent image speckle and hence speckle typically forms a significant component of the image information being tracked. Consequently, speckle decorrelation due to out of plane motion by the transducer may lead to significantly reduced image motion estimation accuracy and/or reliability. The impact of elevation motion is investigated here using simulated speckle images obtained by determining a 3D point spread function (PSF) that is then convolved with a 3D random scatterer target to obtain 2D speckle images.