Near-Infrared Spectroscopy and Imaging of Tumor Vascular Oxygenation

This chapter elaborates the near-infrared spectroscopy and imaging of tumor vascular oxygenation. A large number of investigations have been conducted in both laboratory and clinical settings to noninvasively monitor tissue vascular oxygenation using near-infrared (NIR) spectroscopy and imaging. The NIR studies of the brain include detection of brain injury or trauma, determination of cerebrovascular hemodynamics and oxygenation, and functional brain imaging in response to a variety of neurologic activations. The elevated oxygenation process is completely reversible upon returning air breathing, but still present 10 to 20 min after the baseline inhalation in many cases. The high reproducibility of results suggests that one can apply repeated interventions to explore the efficacy of interventions designed to alter tumor vascular oxygenation. It is found that a combination of well-perfused and poorly perfused mechanisms in tumor vasculature will result in the coexistence of two time constants. It is found that the concentration changes in oxygenated hemoglobin measured from both breast and prostate tumors often display a very prompt rise, followed by a gradual persistence throughout the intervention.