Mean scatterer spacing estimation using wavelet spectrum [ultrasonic biological tissue characterization applications]

Mean scatterer spacing (MSS) has been proven as an effective method for characterizing biological tissue structures, especially for live tissue. Periodogram, correlogram, cepstrum and spectral autocorrelation (SAC) are the major techniques proposed for MSS estimation. However, due to the interferences of diffusive scattering echo, it is difficult to estimate the MSS of the regular (quasi-periodic) scatterers. Robust techniques, such as the SAC method. which can tolerate the diffusive speckle interference are preferred. A newly developed periodicity detection technique, known as the periodic wavelet transform (PWT) is proposed for MSS estimation here. The wavelet spectrum is defined as the PWT over scale space. The wavelet approach provides a unique framework for the MSS estimation problem.