Imaging Metabolic Processes to Predict Radiation Responses.

The aberrant vasculature in the tumor microenvironment creates hypoxic zones, poor perfusion, and high interstitial fluid pressure. Also, the tumor cell metabolic phenotype utilizes the aerobic glycolytic pathways for energy source and generation of cell mass. These physiologic and metabolic phenotypes in solid tumors are amenable for molecular imaging techniques to extract imaging biomarkers such as pO2 and enzyme kinetics reflecting glycolysis. The imaging biomarkers have value in diagnostic and prognostic purposes. Additionally, they can be used to guide choices for tailored treatment regimens. Electron paramagnetic resonance imaging for pO2 imaging and 13C magnetic resonance imaging with hyperpolarized 13C probes such as 13C-labeled pyruvate have shown significant potential in characterizing the tumor microenvironment physiologically and metabolically.