Abstract 13248: Intravascular Ultrasound-Guided Photoacoustic Imaging: From Visualization of Tissue Morphology to Cellular/Molecular Imaging of Atherosclerotic Plaque Composition
INTRODUCTION: Recently, we introduced combined intravascular ultrasound and photoacoustic (IVUS/IVPA) imaging as a modality capable of visualizing tissue morphology (e.g., presence/location of plaque) and cellular/molecular composition (e.g., lipid and active macrophages) of atherosclerotic plaques. HYPOTHESIS: IVUS/IVPA imaging can be translated to enable characterization of atherosclerotic plaques in vivo without flushing luminal blood.
Methods: An ultrasound pulser/receiver and a tunable nanosecond pulsed laser were interfaced with a custom built integrated IVUS/IVPA imaging catheter consisting of an IVUS transducer and a fiber optical light delivery system. A coronary stent deployed in a rabbit thoracic aorta was first imaged, utilizing high contrast between metal and tissue optical absorbance. Next, the aorta of an atherosclerotic rabbit was imaged with the catheter operating at 1720 nm wavelength, where the optical absorption of lipid is stronger than other vascular tissue. No flushing of luminal blood was performed.
RESULTS: Although IVUS imaging can depict the morphology of the vessel, it is IVPA imaging that was able to reliably image stent struts within the context of the IVUS image. In addition, IVPA imaging was capable of depth-resolved visualization of lipid within the atherosclerotic plaque. Furthermore, the high contrast imaging of both stent struts and lipid deposits was performed without flushing luminal blood.
Conclusions: Clinical IVUS/IVPA imaging requires an integrated IVUS/IVPA imaging catheter. Our studies indicate that design and fabrication of such a catheter is possible. Furthermore, real-time IVUS/IVPA imaging can be implemented using existing IVUS platforms augmented with a pulsed laser operating at desired wavelengths for high-contrast depth-resolved images of stent or lipid. Finally, using nanoparticle contrast agents, IVPA imaging of macrophages is possible, opening the door for concurrent monitored therapy.
- © 2013 by American Heart Association, Inc.