Investigation of initial value dependence in the statistical analysis of ultrasonic scattered echoes for the non-invasive estimation of temperature distribution in biological tissue

In the present study, the variation of the Nakagami shape parameter m of the probability distribution of amplitudes of ultrasonic echoes from soft tissue due to a temperature increase is shown to exhibit initial m-value dependence. The change of the Nakagami shape parameter m due to the temperature rise increased with increasing the initial m-value. In order to measure the temperature distribution in soft tissue, we propose a parameter that indicates the absolute values of ratio changes of m values with the multiplying factor varying as a function of the initial m-value. In the hot-scale images indicating the absolute values of ratio changes of m values with the consideration of the initial m-value dependence, the temperature distribution in soft tissue was visualized clearly. (C) 2019 The Japan Society of Applied Physics