Tissue pO{sub 2} of Orthotopic 9L and C6 Gliomas and Tumor-Specific Response to Radiotherapy and Hyperoxygenation
- EPR Center for Viable Systems, Dartmouth Medical School, Hanover, NH (United States)
- Department of Medicine, Section of Radiation Oncology, Dartmouth-Hitchcock Medical Center, Lebanon, NH (United States)
Purpose: Tumor hypoxia is a well-known therapeutic problem; however, a lack of methods for repeated measurements of glioma partial pressure of oxygen (pO{sub 2}) limits the ability to optimize the therapeutic approaches. We report the effects of 9.3 Gy of radiation and carbogen inhalation on orthotopic 9L and C6 gliomas and on the contralateral brain pO{sub 2} in rats using a new and potentially widely useful method, multisite in vivo electron paramagnetic resonance oximetry. Methods and Materials: Intracerebral 9L and C6 tumors were established in the left hemisphere of syngeneic rats, and electron paramagnetic resonance oximetry was successfully used for repeated tissue pO{sub 2} measurements after 9.3 Gy of radiation and during carbogen breathing for 5 consecutive days. Results: Intracerebral 9L gliomas had a pO{sub 2} of 30-32 mm Hg and C6 gliomas were relatively hypoxic, with a pO{sub 2} of 12-14 mm Hg (p < 0.05). The tissue pO{sub 2} of the contralateral brain was 40-45 mm Hg in rats with either 9L or C6 gliomas. Irradiation resulted in a significant increase in pO{sub 2} of the 9L gliomas only. A significant increase in the pO{sub 2} of the 9L and C6 gliomas was observed in rats breathing carbogen, but this effect decreased during 5 days of repeated experiments in the 9L gliomas. Conclusion: These results highlight the tumor-specific effect of radiation (9.3.Gy) on tissue pO{sub 2} and the different responses to carbogen inhalation. The ability of electron paramagnetic resonance oximetry to provide direct repeated measurements of tissue pO{sub 2} could have a vital role in understanding the dynamics of hypoxia during therapy that could then be optimized by scheduling doses at times of improved tumor oxygenation.
- OSTI ID:
- 21172642
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 3 Vol. 73; ISSN IOBPD3; ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
Similar Records
Monitoring Tumor Response to Carbogen Breathing by Oxygen-Sensitive Magnetic Resonance Parameters to Predict the Outcome of Radiation Therapy: A Preclinical Study
Evaluation and Immunohistochemical Qualification of Carbogen-Induced ΔR{sub 2}* as a Noninvasive Imaging Biomarker of Improved Tumor Oxygenation