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Abstract #0038

Mapping Water Exchange in Rat Tumour Xenografts: Using Multiple Flip Angles During Late-Uptake Stages Contrast Agent Injection

MAGNA25Colleen Bailey1, 2, Firas Moosvi1, 2, Greg J. Stanisz1, 2

1Medical Biophysics, University of Toronto, Toronto, ON, Canada; 2Imaging Research, Sunnybrook Health Sciences Centre, Toronto, ON, Canada

Intra-to-extracellular water exchange has been shown to increase during apoptotic cell death In Vitro. To map exchange in vivo, four flip angles were used during the late near-constant stages of uptake following three separate injections of Gd-DTPA-BMA in rat tumour xenografts. High extracellular water fraction corresponded to low cellularity on H&E. Regions of low water exchange were negative on TUNEL staining, while regions of high water exchange were positive, indicating apoptosis. High water exchange was observed even in cases where cells had not cleared and water fraction did not yet show a change.