Photoacoustic and Ultrasound Imaging with Nanosized Contrast Agents

Molecular imaging has attracted great attention in biomedicine in the last few decades as a valuable tool for personalized medicine. This chapter mainly discusses principles of photoacoustic (PA) imaging with a short overview of nanosized PA contrast agents. It describes the following topics of photoacoustic tomography (PAT): (i) basic principles of PAT, (ii) two types of PAT modalities (i.e., inverse algorithm-based PACT and raster scanning-based PAM), (iii) intrinsic contrasts for morphological and functional PAT, and (iv) exogenous contrasts for PAT. Although many contrast agents manipulated by nanotechnology have been investigated and the results were promising in preclinical PA applications, so far, any nanostructures have not been approved by the FDA, which is a key hurdle for clinical translation. The key criterion for the clinical agent must be biodegradability and biocompatibility.