Simulation study on practical choices for B / A measurement by the generalized finite amplitude insert-substitution method

The measurement of the parameter of nonlinearity B/A of tissues and liquids has potential to aid medical diagnosis. Therefore, accurate B/A measurement stays a relevant task. The finite amplitude insert-substitution (FAIS) method estimates B/A of biological tissues based on the measured 2nd harmonic in two configurations, (1) when only the reference medium is between the acoustic source and receiver, and (2) when the studied sample is inserted in the acoustic path with the reference medium. The generalised FAIS (gFAIS) has been previously proposed with the advantage of measuring B/A of liquids as well as ex-vivo tissues and allowing freedom in sample positioning. This simulations study validates the gFAIS method and provides insight into the practical choices for the setup that allow for an accurate measurement. Source and receiver size, distance between the source and the receiver and sample positioning have been studied on the subject of their effect on the measurement error for a homogeneous (modelling liquid) and a heterogeneous (modelling tissue) sample. Since B/A estimation also requires the measurement of the attenuation coefficients at the fundamental and 2nd harmonic frequnecy, practical choices for these measurements have also been studied.