Eugene Kim1, Paul T. Winnard, Jr. 2, 3, Venu Raman2, 3, Zaver M. Bhujwalla2, 3, Arvind P. Pathak2, 3
1The Whitaker Biomedical Engineering Institute, Johns Hopkins University, Baltimore, MD, United States; 2The Johns Hopkins University in vivo Cellular and Molecular Imaging Center Program; 3The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University
Hypoxia profoundly affects the tumor microenvironment, aggressiveness and invasiveness, and response to therapy. Here, we investigated how carbogen (95% O2/5% CO2) breathing effects oxygenation in hypoxic tumor regions by employing a unique combination of BOLD MRI and molecular imaging of a hypoxia-inducible fluorescent human breast cancer model. Our results showed heterogeneous MR-measured ΔR2* responses to carbogen in hypoxic regions identified by a fluorescent HIF-1 reporter in orthotopic tumors. The response was significantly greater in one tumor than the other, suggesting that carbogen breathing may alleviate hypoxia but with high intra- and inter-tumor variability.
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