Numerical investigation on improving photoacoustic imaging contrast based on temperature difference effect in biological tissues

Abstract

Exploiting the variances in light absorption among different components of biological tissues and utilizing the light absorption coefficient as an imaging contrast, photoacoustic imaging achieves remarkable imaging resolution. Within the laser wavelength range commonly employed in photoacoustic imaging, biological tissue components like hemoglobin and melanin exhibit higher light absorption coefficients compared to other components. Consequently, these components generate stronger photoacoustic signals during the imaging process. However, this heightened signal strength obscures components of biological tissues with low light absorption coefficients, making it challenging to clearly visualize them in the resulting images. To address this limitation and enhance the visibility of low absorption coefficient components against a background of intense photoacoustic signals produced by high absorption coefficient components, we propose a method that utilizes low-intensity unfocused ultrasound to induce the temperature difference (TD) effect in biological tissues during photoacoustic imaging. By analyzing the disparities between the photoacoustic signals collected before and after introducing the TD effect, we establish a novel imaging parameter that improves the imaging contrast. To validate the feasibility and effectiveness of inducing photoacoustic effects in biological tissues, we conducted simulations using the finite element method, which yielded positive results. Subsequent simulations of photoacoustic imaging incorporating the TD effect demonstrated enhanced visualization of components with low light absorption coefficients in biological tissue. The method proposed in this paper is expected to provide a research idea for improving the photoacoustic imaging contrast of biological tissues.