Experimental validation of a nonlinear coded excitation method for contrast imaging

The amount of harmonics generated by a contrast agent bubble is mainly dependent on peak bubble wall excursion. As we have previously shown for a single bubble, using chirps as the excitation signal improves both the linear and the non-linear response. Computer simulations of contrast bubble clouds show an increase of 10-13 dB in response, comparing pulsed excitations with chirped excitations that have equal bandwidths and peak amplitudes. Experimental results from water tank measurements with SonoVue™ contrast agent are in agreement with computer simulations showing better signal to noise ratio and an increase of ∼12 dB in second harmonic between pulse and chirp.