Background: It was known that the response of tumor cells to radiation is closely related
to tissue oxygen level and fractionated radiotherapy allows reoxygenation of hypoxic tumor
cells. Non-invasive mapping of tissue oxygen level may hold great importance in clinic.
Objective: The aim of this study is to evaluate the role of oxygen-enhanced MR imaging in the
detection of tissue oxygen levels between fractionated radiotherapy.
Methods: A cohort of 10 patients with brain metastasis was recruited. Quantitative oxygen enhanced
MR imaging was performed prior to, 30 minutes and 22 hours after first fractionated radiotherapy.
Results: The ΔR1 (the difference of longitudinal relaxivity between 100% oxygen breathing and air
breathing) increased in the ipsilateral tumor site and normal tissue by 242% and 152%, respectively,
30 minutes after first fractionated radiation compared to pre-radiation levels. Significant recovery
of ΔR1 in the contralateral normal tissue (p < 0.05) was observed 22 hours compared to 30
minutes after radiation levels.
Conclusion: R1-based oxygen-enhanced MR imaging may provide a sensitive endogenous marker
for oxygen changes in the brain tissue between fractionated radiotherapy.