Nonlinear photoacoustic imaging dedicated to thermal-nonlinearity characterization [Early Posting]
We proposed a nonlinear photoacoustic (PA) technique as a new imaging contrast mechanism for tissue thermal-nonlinearity characterization. When a sine-modulated Gaussian temperature field is introduced by a laser beam, in view of the temperature dependence of the thermal diffusivity, nonlinear PA effect occurs which leads to the production of second-harmonic (SHPA) signals. By extracting the fundamental frequency photoacoustic (FFPA) and SHPA signal amplitudes of samples through lock-in technique, a parameter that only reflects nonlinear thermal diffusivity characteristics of the sample then can be obtained. The feasibility of the technique for thermal-nonlinearity characterization has been studied on phantom samples. In vitro biological tissues have been studied by this method to demonstrate its medical imaging capability, prefiguring great potential of this new method in medical imaging applications.
作者单位：South China Normal University
South China Normal University
Shi Yujiao,zhang zhenhui. Nonlinear photoacoustic imaging dedicated to thermal-nonlinearity characterization[J].Chinese Optics Letters,2021,19(7):07.