Integrated mechanical and structural features for photoacoustic characterization of atherosclerosis using a quasi-continuous laser.

We present a novel integrated mechanical and structural photoacoustic imaging (IMS-PAI) for atherosclerosis characterization. A quasi-continuous laser with pulse width of 22 ns and repetition frequency of 25 KHz was used to realize simultaneous acquisition of PA phase and temporal intensity. An algorithm utilizing sound propagation model in conjunction with temporal PA intensity was developed and applied to correct the phase deviation caused by uneven tissue surface. Integration of en-face mechanical and in-depth structural PA imaging was verified by a tissue-mimicking phantom. Moreover, complementary visualization of en-face viscoelasticity distribution and in-depth structural anatomy of an atherosclerotic tissue was achieved, which was consistent with the histology. The results demonstrated the IMS-PAI has an attractive synergy in comprehensive atherosclerosis characterization.