title: Issues in GRE & SE magnetic resonance imaging to probe tumor oxygenation.
abstract: Tumor oxygenation determines the efficacy of radiotherapy, but there is no non-invasive way to image this parameter. Since gradient recalled echo (GRE) images are sensitive to blood deoxyhaemoglobin concentration ([dHb]) they could have a role in assessing tumor oxygenation. In brain, linear relationships have been demonstrated between brain tissue R2* relaxation rate and tissue [dHb] or oxygen saturation, but in tumors, vascular and tissue heterogeneity, and the presence of simultaneous oxidative and glycolytic metabolism, complicate the analysis. We have studied the effects of vascular challenge in a rat prolactinoma tumor model by MR imaging and spectroscopy and comment on the implications of these results for calibrating GRE images for blood or tissue pO2.
authors.affiliation: Cancer Research, UK Biomedical Magnetic Resonance Research Group, Dept. Biochemistry and Immunology, St. George's Hospital Medical School, London, SW17 ORE, England.
authors.forename: Franklyn A
authors.initials: FA
authors.lastname: Howe
authors.forename: Simon P
authors.initials: SP
authors.lastname: Robinson
authors.forename: Loreta M
authors.initials: LM
authors.lastname: Rodrigues
authors.forename: Marion
authors.initials: M
authors.lastname: Stubbs
authors.forename: John R
authors.initials: JR
authors.lastname: Griffiths
mesh_terms: D000818:Animals; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009369:Neoplasms / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D015175:Prolactinoma / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D010100:Oxygen