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Abstract #3173

Difference in Early Intratumoral Changes Induced by Single Dose and Fractionated Radiotherapy in Rat Rhabdomyosarcoma Measured with Diffusion- and Perfusion-Weighted Magnetic Resonance Imaging

Peeters R, Chen F, Hermans R, De Keyzer F, Eckelmans J, Vandecaveye V, Landuyt W, Hamaekers P, Ni Y, Nuyts S, Bosmans H
University Hospitals Leuven

Early intratumoral changes after single-dose or fractionated irradiation were examined using DW- and DCE-MRI in rat rhabdomyosarcoma. Either a single-dose of 8Gy or a fraction of 3Gy daily (5 days) was given. The tumors treated with single-dose irradiation showed perfusion decrease, no diffusion differences and growth delay of 12 days. The fractionated radiotherapy tumors showed stronger perfusion decrease and strong diffusion increase, translated in an 18-day growth delay. DW-MRI and DCE-MRI indicate perfusion decrease in single-dose radiotherapy, but limited necrosis formation and tumor growth delay. Fractionated radiotherapy resulted in similar perfusion decreases, but more intratumoral necrosis and longer growth delay.