A study on correction method of total acoustic power in presence of shielding in focused ultrasound treatment using acoustic radiation force imaging

Abstract

High-intensity focused ultrasound (HIFU) therapy is a noninvasive treatment for cancer. Prediction of the HIFU treatment region in advance by ultrasound imaging is important for the efficacy and safety of the treatment. Acoustic radiation force (ARF) imaging has been shown to be useful in estimating the heat distribution caused by HIFU. In this study, we investigated the effect of shielding on the estimated heat distribution when the propagation of HIFU is partially shielded by an object simulating ribs, imitating an actual clinical situation, and examined the correction method of HIFU output power using ARF imaging to obtain tissue coagulation equivalent to that without shielding. As a result, it was suggested that even with partial acoustic shielding, when the HIFU output power is adjusted so that the displacement induced by ARF is equal to that without shielding, almost the same coagulated region can be obtained as in the unshielded case.

Method for measuring time waveforms of minute sinusoidal displacements using continuous waves with a network analyzer

“…The viscoelastic properties of biological tissues play a pivotal role in diagnosing and detecting early stages of diseased tissues, leading to extensive research on measuring the elasticity and viscosity of tissues across various internal organs. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] To estimate viscoelastic parameters both locally and quantitatively, a method was developed employing dual amplitude-modulated acoustic radiation force to generate continuous sinusoidal displacements within a localized area of a specimen. [16][17][18][19] However, ensuring the safety of living tissues complicates stable displacement measurement due to the minuscule amplitude of displacement induced by ultrasonic excitation, typically only a few micrometers.…”