Ultrasonic tissue characterization using a generalized Nakagami model.

The statistics of the backscattered ultrasonic echo from tissue have been described using Rayleigh, K, and Nakagami distributions. The Nakagami and K distributions, each with two parameters, can model the envelope reasonably well. However, a three-parameter distribution is likely to match the envelope of the backscattered echo much better than these two-parameter distributions. Starting with the Nakagami distribution and including an additional parameter to account for the tails of the density function, a generalized Nakagami distribution has been derived. Computer simulation of A-scans and analysis of data collected from tissue-mimicking phantoms show that the generalized Nakagami distribution fits the statistics of the echo of the envelope better than the Nakagami distribution. The parameters of the generalized Nakagami distribution appear to be far more sensitive to the scattering conditions than the parameters of the Nakagami distribution.