1Radiology, University of Chicago, Chicago, IL, United States; 2Radiation & Cellular Oncology, University of Chicago, Chicago, IL, United States
Ionizing radiation is a staple for treating tumors. However, failure to cure tumors is thought to be due to an intrinsic tumor cell radioresistance and its microenvironment. DCE-MRI was used to characterize the response of two tumor cell lines one radioresistant and the other radiosensitive. A genetically modified adenoviral vector was used, which causes infected cells to produce tumor necrosis factor alpha (a potent antivascular agent), only when irradiated. The radioresistant tumors showed no significant changes in the rate transfer constant and fractional volume accessible to the contrast agent. However, the radiosensitive tumors showed significant reduction in both kinetic parameters.