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Abstract #2794

Intrinsic Susceptibility Contrast (R2*) in the Evaluation of Tumour Oxygenation at Baseline and in Response to Neoadjuvant Chemotherapy in Breast Cancer

Sonia P. Li1, N J. Taylor2, J J. Stirling2, Mei-Lin W. Ah-See1, Mark J. Beresford1, David J. Collins3, James A. d'Arcy3, Andreas Makris1, Anwar R. Padhani2

1Mount Vernon Hospital, Northwood, Middlesex HA6 2RN, United Kingdom; 2Paul Strickland Scanner Centre, Mount Vernon Hospital, Northwood, Middlesex HA6 2RN, United Kingdom; 3CR-UK Clinical MR Research Group, Royal Marsden Hospital, Sutton, Surrey, SM2 5PT, United Kingdom

R2* has potential to provide information about tumour oxygenation but is underexplored in breast cancer. Here, primary carcinomas were imaged with multiparametric MRI before and after 2 cycles of neoadjuvant chemotherapy. Correlations between R2* and kinetic parameters were investigated. R2* as a predictor of pathological benefit was compared with DCE/DSC-MRI parameters. Significant inverse correlations between R2* and blood flow/volume in untreated cancers confirm that R2* reflects blood oxygenation; however this relationship disappears after treatment. Increases in R2* in responders suggest that cancers become more hypoxic with successful treatment. R2* was a relatively poor response predictor compared with some DCE and DSC-MRI parameters.