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Abstract #1089

Quantitative T1 & T2* Assessment of VX2 Tumour Oxygenation in Response to Hyperoxia & Hypercapnia: Comparison with Invasive Measures & DCE-MRI

Jeff D. Winter1,2, Margarete K. Akens3, Hai-Ling Margaret Margaret Cheng1,4

1Physiology & Experimental Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; 2Research & Development, IMRIS, Winnipeg, Manitoba, Canada; 3Orthopaedic Surgery, Sunnybrook Health Sciences, Toronto, Ontario, Canada; 4Medical Biophysics, University of Toronto, Toronto, Ontario, Canada

Hypoxic tumour regions exhibit reduced radiotherapy responses. One strategy to improve tumour O2 levels is through breathing 100 % O2 or carbogen gases. This study characterized T1 and T2* responses to 100 % O2, and carbogen (with three CO2 concentrations) in a VX2 tumour model in comparison to quantitative DCE and invasive pO2 and perfusion measurements. We observed consistent T1 decrease and T2* increases (relative to air) for all gas challenges. Invasive measures demonstrated substantial pO2 increases and moderate perfusion increases for all gas challenges. Study results suggest similar tumour oxygenation may be achieved with or without a CO2 component.