6G-3 Temperature Monitoring in Intravascular Photoacoustic Imaging

We previously demonstrated a method to perform simultaneous intravascular photoacoustic (IVPA) and ultrasound (IVUS) imaging using an IVUS imaging catheter. During photoacoustic imaging, the energy fluence of optical irradiation was maintained low to conform to laser safety standards for medical imaging applications. However, the maximum permissible exposure for intravascular imaging is not yet well established and it is essential to address general safety issues of IVPA imaging. Hence, there is a need to monitor the temperature dynamics following laser excitation in IVPA imaging to estimate the maximum temperature increase and to insure thermal safety. In this paper, we present an ultrasound technique to monitor the temporal behavior of temperature in a tissue mimicking phantom and in an excised sample of arterial tissue after either a single laser pulse or during multiple laser pulses. The results of our study suggest that it is possible to monitor temperature and insure safety during the combined intravascular ultrasound and photoacoustic imaging