Photoacoustic Imaging: An Emerging Optical Modality in Diagnostic and Theranostic Medicine

Abstract

Photoacoustic imaging, also referred to optoacoustic imaging, is an emerging optical imaging technique that is capable of providing both structural and functional optical information of tissues up to several centimeters deep with scalable ultrasound resolution. The combination of ultrasound spatial resolution and intrinsic rich optical contrast in cancer / inflammatory tissues allow photoacoustic imaging a promising early detection tool in diagnostic medicine. At the same time, the availability of various optical absorbing nanostructures extensively studied in targeted drug delivery extends the capability of photoacoustic imaging to theranostic medicine, where functionalized nanostructures provide photoacoustic imaging contrast and targeting moieties / drug carrier for targeted drug delivery. In this paper, we provide a review of the photoacoustic imaging technique for studies in diagnostic and theranostic medicine. The technical consideration for photoacoustic imaging systems and reconstruction algorithms of structural / quantitative photoacoustic imaging have been introduced. A review of the photoacoustic imaging in breast cancer detection and osteoarthritis evaluation is included in the section of photoacoustic applications in diagnostic medicine, where patient subjects have been already recruited and photoacoustically evaluated. At the end of this paper, a brief review of optical controlled drug release and photoacoustic evaluation is presented as a view to the effort of combining laser induced photoacoustic imaging with laser controlled drug delivery / release in theranostic medicine.