The interpretation of ultrasound imaging is essentially visual and qualitative, so there are important inter and intra-observer variations. Quantification methods aim at decreasing this dependency. Among those, the quantification of the Mean Scatterer Spacing (MSS) can be useful to detect changes in the microstructure of quasi-periodic tissues, such as liver or spleen. This study evaluated the following methods of spectral estimation for calculating the MSS (without requiring operator intervention): BURG, WIENER and MUSIC. The aim is to compare their potential for automatic estimation of MSS from ultrasonic scattering signals. Initially, the evaluation has been carried out using 10,000 simulated signals, with the aim of studying the behavior of the methods using a model in which the variables of interest can be controlled. Then, the methods have been applied to real signals of nylon phantoms immersed in water. The BURG method could not estimate the spacing of US phantom signals, presenting results similar to the other methods only for simulated signals. The WIENER method for the simulated signals was in second place in terms of percentage of success, when considering signals from the phantoms. The subspace method MUSIC had the best performance from all three methods.
Average spacing; Ultrasonic scatterers; Spectral estimation; Periodic media
