Room: Davidson Ballroom B
Purpose: To develop, calibrate, and implement a portable imaging system used with boron nanoparticles to image hypoxia within murine tumors.
Methods: Boron nanoparticles (BNP) are ratiometric indicators of oxygen tension. They emit stable blue fluorescence and oxygen-quenched green phosphorescence when stimulated by UV light. The ratio of fluorescence to phosphorescence is dependent on the surrounding oxygenation, allowing for the BNP to be employed as an in-vivo probe for hypoxia. A portable imaging system was developed - utilizing a Raspberry Pi, white and UV LEDs, and a modified Pi Camera for macro photography. Tumors were grown within dorsal window chambers installed on mice. In-vitro imaging of nanoparticles with fixed and measured oxygenation was performed for calibration. Imaging was performed on restrained mice inhaling varied oxygen concentrations while anesthetized and awake. Calibration data along with Parallel Factor Analysis was used to produce oxygen concentration maps.
Results: Within individual oxygen maps, spatial variation of oxygen concentration was observed - with tumor regions containing lower levels. Increasing inhaled oxygen concentration raised in-vivo oxygenation, while decreasing inhaled oxygen concentration lowered in-vivo oxygenation. Comparison between oxygen maps produced while mice were anesthetized and awake showed the outcome that anesthesia lowers tissue oxygenation.
Conclusion: Utilization of the developed portable imaging system enables hypoxia imaging to be performed without the skewing biological effects of anesthesia. Acquisition of accurate hypoxia data is imperative, given the mounting importance of functional imaging's prospective contributions to diagnostic and therapeutic applications. Future plans include 1) optimization of a ballast system to allow for imaging of non-restrained mice during longer time intervals 2) implementation of the portable imaging system within combinative hyperthermia and immunotherapy studies 3) development of an implantable sensor system suitable for clinical translation.