Ultrasound Imaging: Correction of Geometric Distortions using Warping

Abstract

Ultrasound images suffer from inherent geometric distortions due to variations in sound speed within the body. Other distortions include missing surfaces parallel to the direction of the ultrasonic rays, intense speckle noise, acoustic shadows and resolution inconsistency. These artifacts depend on the positioning of the transducer relative to the scanned organs, and considerably degrade the quality of the images obtained. We introduce a new algorithm that combines ultrasound images taken from distant viewpoints using spatial warping and compounding to obtain a quality-enhanced image. The algorithm is iterative: in each iteration the B-Mode images are divided into blocks and a matching procedure is performed between blocks of the reference images. Individual pixels are translated based on inter-block interpolation, subject to physical and medical constraints. The resultant warped images are used as an input signal to the next iteration. The algorithm was implemented and tested in-vitro, demonstrating superior results compared to presently available methods. The results are presented and discussed.