Performance Evaluation of Compound Plane-Wave Imaging Combined with the Generalized Coherence Factor

Abstract

Compound plane-wave imaging (CPWI) is a widely used and investigated imaging technique in medical ultrasound because it provides high quality ultrafast imaging for recent applications such as elastography. CPWI can be either coherent to provide high resolution and reduce sidelobe, or incoherent to provide high speckle homogeneity. To further improve imaging quality, coherence-based factors are used for weighting the output of ultrasound beamformers. This work studied the effects of the number of compounded frames and the step between these frames on the imaging quality produced by coherent and incoherent CPWI in the presence of the generalized coherence factor (GCF). The quality of the produced images of two different RF datasets was assessed in two different scenarios, in addition to conducting cyst phantom simulations. Results showed that the amount of image contrast improved by GCF increased, while the amount of resolution improved by GCF decreased, with the increase in step between frames. The same results were obtained in both types of CPWI. On the other hand, increasing the number of frames had almost no effect on the amounts of improvement provided by GCF. When CPWI is used in ultrafast imaging, it is important to monitor frame rates as well as imaging quality; these two factors are, respectively, inversely and directly proportional to the number of compounding frames. Therefore, the results of this research provide guidelines for accurate angle selection for CPWI so that a trade-off between imaging quality and frame rate is achieved.