New methods of
ultrasound imaging are presented that provide images with reduced
reverberation noise and images of
nonlinear scattering and propagation parameters of the object, and
estimation of corrections for wave front aberrations produced by spatial variations in the
ultrasound propagation velocity. The methods are based on
processing of the received
signal from transmitted
dual frequency band
ultrasound pulse complexes with overlapping high and
low frequency pulses. The
high frequency pulse is used for the image reconstruction and the
low frequency pulse is used to manipulate the
nonlinear scattering and / or propagation properties of the
high frequency pulse. A 1st method uses the scattered
signal from a single dual band pulse complex for filtering in the fast time (depth time) to provide a
signal with suppression of
reverberation noise and with 1st
harmonic sensitivity and increased spatial resolution. In other methods two or more dual band pulse complexes are transmitted where the frequency and / or the phase and / or the amplitude of the
low frequency pulse vary for each transmitted pulse complex. Through filtering in the
pulse number coordinate and corrections of nonlinear propagation delays and optionally also amplitudes, a linear back scattering signal with suppressed pulse
reverberation noise, a nonlinear back scattering signal, and quantitative
nonlinear scattering and
forward propagation parameters are extracted. The reverberation suppressed signals are further useful for
estimation of corrections of wave front aberrations, and especially useful with broad transmit beams for multiple parallel receive beams. Approximate estimates of aberration corrections are given. The nonlinear signal is useful for imaging of differences in tissue properties, such as micro-calcifications, in-growth of
fibrous tissue or foam cells, or micro gas bubbles as found with decompression or injected as ultrasound contrast agent.