Photoacoustic Imaging: Principles and Applications

Photoacoustic (PA) imaging is an emerging imaging technology with potential for preclinical biomedical research and clinical applications. PA imaging, which relies on the generation of broadband acoustic waves via the absorption of intensity-modulated light in tissue, offers the combination of strong optical contrast and high spatial resolution provided by ultrasound. For excitation wavelengths in the visible and near-infrared region, image contrast is predominately due to hemoglobin. Exogenous contrast agents, such as dyes or genetically expressed absorbers, can be used to obtain targeted molecular contrast. Over the past decade, PA imaging has rapidly evolved into different microscopy and tomography modalities, while novel methodologies have led to a variety of exciting applications. This chapter explains the basic principles of PA imaging and its implementation in the different modalities and provides examples of applications to morphological, functional, and molecular imaging. Furthermore, the challenge of recovering quantitative information from PA image data sets is described.