Intravascular Photoacoustic Viscoelasticity Imaging

Plaque rupture drives acute cardiovascular events and originates from a mechanical imbalance between fibrous cap integrity and lipid core loading. This process reflects the coupled elastic and viscous behavior of plaque components, and viscoelasticity therefore serves as a biomechanical marker for stability assessment. In this study, an intravascular photoacoustic viscoelasticity imaging (IVPAVEI) method was developed for the quantification of the plaque viscosity–elasticity ratio through phase delay analysis between the photoacoustic signal and laser pulse. A miniature probe with a diameter of 1.1 mm was integrated into the IVPAVEI system, rendering it suitable for intravascular applications. The capacity of the system to discriminate tissues with distinct viscoelastic properties was validated by resolution experiments in phantom. In situ evaluations were performed on rabbit aortic plaques, and IVPAVEI captured subtle viscoelastic changes before overt morphological lesions emerged. This minimally invasive approach thus enables the early detection of atherosclerotic plaques and holds potential for identifying lesions with high progression risk in future clinical practice.