Development of a combined intravascular ultrasound and photoacoustic imaging system

Abstract

Intravascular ultrasound (IVUS) imaging has emerged as an imaging technique to evaluate coronary artery diseases including vulnerable plaques. However, in addition to the morphological characteristics provided by IVUS imaging, there is a need for functional imaging capability that could identify the composition of vulnerable plaques. Intravascular photoacoustic (IVPA) imaging, in conjunction with clinically available IVUS imaging, may be such a technique allowing vulnerable plaque characterization and differentiation. We have developed an integrated intravascular ultrasound and photoacoustic imaging system to visualize clinically relevant structural and functional properties of the coronary arteries. The performance of the combined IVUS and IVPA imaging system was evaluated through images of arterial phantoms. Experiments were performed using high frequency IVUS imaging catheters operating at 20 MHz, 30 MHz and 40 MHz. The IVPA imaging was successful in highlighting inclusions based on differential optical absorption while these lesions did not have sufficient contrast in the IVUS images. Finally, initial IVUS and IVPA imaging studies were performed on ex vivo samples of a rabbit artery using the 40 MHz IVUS imaging catheter. Results of the above studies demonstrate the feasibility of combining intravascular ultrasound and photoacoustic imaging and suggest clinical utility of the developed imaging system in interventional cardiology.