Monitoring of cycling hypoxia and angiogenesis in FaDu head and neck tumors using a side-firing sensor

… A mouse pulse oximeter (Mouse Ox, Starr Life Science Corp., Allison Park, PA) was also clamped
on to the left foot of the rat and the … the side-firing probe which is roughly about 1 cm in diameter
and thus is lower than the arterial blood saturation measured with the MouseOx. … Many studies have found that hypoxia, particularly cycling hypoxia (CH), can lead to enhanced tumor metastasis and resistance to radiation and chemotherapy. It was also reported that tumor total hemoglobin content (THb), which is directly related to tumor angiogenesis, can have significant impact on tumor’s response to radiation and neoadjuvant chemotherapy. There is a growing demand for technologies to measure tumor hypoxia and angiogenesis temporally in vivo. In this paper, a side-firing fiber optic sensor based on a multi-wavelength frequency-domain near infrared spectroscopy (FD-NIRS) instrument was used to quantify tumor oxygenation and hemoglobin concentrations in nude rats bearing human FaDu head and neck (H and N) tumors during normoxia and forced hyperoxia and cyclic hypoxia. Significant increase (with carbogen gas inhalation) or decrease (with reduced O2 supply) in tumor oxygenation was observed. The studies demonstrated the feasibility of the technology for longitudinal monitoring of H and N tumor’s response to therapy.