Photoacoustic viscoelasticity imaging of thin-cap fibroatheromas: Implications for detecting vulnerable plaques

Viscoelasticity is a key mechanical property for assessing the vulnerability of atherosclerotic plaques. In this Letter, we propose photoacoustic viscoelasticity imaging (PAVEI) to provide morphological information on necrotic-core fibroatheromas together with correlative viscoelastic contrast. Gelatin–collagen mixtures with different concentrations were used to simulate fibroatheromas with distinct viscoelastic properties and to validate the sensitivity of PAVEI. Pilot experiments were further performed on ex vivo murine artery specimens from an apolipoprotein E-knockout mouse. Thin-cap fibroatheromas exhibited significantly greater photoacoustic time delays than other atherosclerotic lesions. These results demonstrate that PAVEI can provide valuable viscoelastic information for detecting vulnerable plaques and evaluating the risk of plaque rupture.