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Abstract #4829

Evaluation and Immunohistochemical Qualification of Carbogen-Induced δR2* as a Non-Invasive Imaging Biomarker of Improved Tumour Oxygenation

Lauren CJ Baker1, Jessica K.R. Boult1, Yann Jamin1, Lesley D. McPhail1, Simon Walker-Samuel1, Jake S. Burrell1, Margaret Ashcroft2, Franklyn A. Howe3, John R. Griffiths4, James A. Raleigh5, Albert J. van der Kogel6, Simon P. Robinson1

1The Institute of Cancer Research, Sutton, Surrey, United Kingdom; 2University College London, London, United Kingdom; 3St. George's, University of London, London, United Kingdom; 4Cambridge Cancer Institute, Cambridge, United Kingdom; 5University of North Carolina, Chapel Hill, United States; 6University of Nijmegen Medical Centre, Nijmegen, Netherlands

The transverse relaxation rate R2* (s-1) of GH3 prolactinomas was quantified whilst the host breathed air and subsequently carbogen (95%O2/5%CO2), and the data compared with quantitative immunohistochemical analysis of uptake of two hypoxia markers, CCI-103F, administered whilst the host breathed air, and pimonidazole, administered during subseqent carbogen breathing, within the same tumour. A significant reduction in R2* with carbogen breathing was associated with a significant reduction in pimonidazole staining, providing further validation of carbogen-induced δR2* as a non-invasive imaging biomarker of increased tumour oxygenation.