Assessing the microarchitecture and microenvironment of cancer in vivo by photoacoustic imaging techniques

Abstract

Majority of current studies on photoacoustic (PA) imaging are focused on the total signal magnitudes as the reflection of the macroscopic optical absorption by specific chemical contents at single or multiple optical wavelengths. Our recent research has demonstrated that the frequency domain power distribution of radio-frequency PA signals contains the microscopic information of the optically absorbing materials in biological samples. In this research, I will present our recent development of quantitative PA methods for in vivo evaluation of histological microarchitectures of biological tissues as well as potential clinical applications of these methods such as the assessment of prostate cancer aggressiveness. In addition, powered by our recently developed polyacrylamide hydrogel nanoparticles containing a variety of functional contrast agents, multi-wavelength PA imaging plus spectral unmixing technique can enable quantitative mapping of the chemical and metabolic properties in cancer microenvironments, such as tissue oxygenation, pH level, and ion concentrations. Imaging of these chemical makeups of an entire tumor in vivo, non-invasively, with high sensitivity and high spatial resolution can shed new light to the understanding of cancer onset, progress, and responses to therapies.