System and integrated catheter for real-time intravascular ultrasound and photoacoustic imaging

Combined intravascular ultrasound and photoacoustic imaging (IVUS/IVPA) is an emerging modality for the improved characterization of atherosclerotic plaques including anatomical features of the imaged vessel and tissue composition. Encouraging initial demonstrations of the technique, however, have been limited by slow catheter rotation and data acquisition rates on the order of several seconds per frame, with off-line image processing. Herein, we present both a system and an integrated catheter capable of real-time IVUS/IVPA imaging with online image processing and display of both IVUS and IVPA images. The integrated IVUS/IVPA catheter is fully contained within a 1 mm outer diameter torque cable with the electrical signals transmitted at the proximal end using a slip ring rotary joint. Additional components include a pulsed laser operating at 10 kHz pulse repetition frequency, motor and servo drive, an ultrasound pulser/receiver, and a 200 MHz digitizer coupled to a system capable of real-time IVUS/IVPA imaging. The system performance was validated on a vessel-mimicking phantom with an embedded coronary stent intended to provide IVPA contrast within content of an IVUS image.