Higher order nonlinear ultrasound propagation in tissue-simulation study

Nonlinear wave propagation in tissue has been simulated using typical propagation parameters for liver. The results indicate that the amplitude level of higher order harmonics can exceed the level of the second harmonic component. In that case detection of the higher order components can be achieved with increased signal to noise ratio due to the fact that the amplitude of the 3^rd order component can be higher than the 2^nd harmonic and the fact that the 3^rd order mixing component falls into the middle of the transducer bandwidth. Odd order harmonic components are of particular interest since they create spectral mixing products at the fundamental frequency. Therefore, transmission and reception can operate around the same center frequency.