Free of speckle ultrasonic imaging of soft tissue with account of second harmonic signal

Abstract

The Born approximation deconvolved inverse scattering imaging technique is an alternative to the conventional pulse-echo method. This novel technique deconvolves the incident pulse from the reflected pulse, and uses the resulting impulse response to produce an image of the acoustic impedance distribution. It is applicable mainly to structures that resemble a layered medium. The images captured by this method prove to have improved resolution and are free of speckle. With this method one can use ultrasound of lower frequencies than would be required by the pulse-echo method to achieve the same resolution. To provide further improvement of images the second harmonic signals can be employed. Here we describe the deconvolved inverse scattering imaging technique with account of the second harmonic signal. For this purpose the hybrid transducer by Krautkramer Branson Co., which consists of a cylindrical 5 MHz transducer wrapped in an annulus-shaped 2.5 MHz transducer, has been used. The phantom and soft tissue were imaged and in both cases the account of the second harmonic reflection data provides an improvement of the image quality.