Patent ID: 8904871

Claim:
A method of detecting a macrophage or foam cell in a tissue sample comprising: providing a contrast agent to a tissue sample, wherein the contrast agent comprises a metallic nanoparticles; exposing at least a portion of the tissue sample to a first level of thermal energy and to electromagnetic radiation and so as to generate a first acoustic signal; detecting the first acoustic signal; determining an amplitude of the first acoustic signal; exposing at least a portion of the tissue sample to a second level of thermal energy and to electromagnetic radiation so as to generate a second acoustic signal; detecting the second acoustic signal; determining the amplitude of the second acoustic signal; and correlating the amplitude of the first acoustic signal and the amplitude of the second acoustic signal with the presence or absence of a macrophage or foam cell in the tissue sample, wherein the acoustic signal amplitude change relative to level of thermal energy indicates the presence or absence of a macrophage or foam cell in the tissue sample.