Improving high-intensity focused ultrasound beam imaging via a backscattering suppression algorithm

In an ultrasound-guided high-intensity focused ultrasound (HIFU) device, a HIFU focal error may be observed in an ultrasound pulse-echo image due to the difference between the HIFU and imaging beam aberrations occurring in the heterogeneous propagative medium, which was verified by simulating the ultrasound beams passing through an abdominal wall. The HIFU focal error could reduce the accuracy of targeting the HIFU focal spot at a tumor. To measure the focal error, HIFU beam imaging based on backscattered wave reconstruction can be used; however, its image qualities deteriorate due to inhomogeneous backscattering. Hence, we proposed a novel backscattering suppression algorithm based on an inverse problem approach to retrieve HIFU beam components. The proposed algorithm was validated in ex vivo experiments in conjunction with focal spot shifts and beam width variations, demonstrating the clear improvement of HIFU beam imaging quality. (C) 2017 The Japan Society of Applied Physics