title: Qualification of a noninvasive magnetic resonance imaging biomarker to assess tumor oxygenation.
abstract: OBJECTIVE
  Although hypoxia has been long recognized as a crucial factor impairing tumor response in many therapeutic schemes, atraumatic and reliable methods of individually quantifying tumor oxygenation are still lacking in day-to-day clinical practice. The aim of this work was to investigate the potentially quantitative properties of our recently described noninvasive magnetic resonance (MR) technique "MOBILE" (mapping of oxygen by imaging lipids relaxation enhancement) and to qualify this endogenous contrast as a tumor hypoxia marker.
  
  
  METHODS
  The "MOBILE" technique, which assesses the longitudinal MR relaxation rate, R1, of lipid protons, was benchmarked with the parent technique which assesses the global (or water) R1, in response to a hyperoxic challenge (carbogen breathing) and to a hypoxic challenge (combretastatin A4) in MDA-MB-231 xenografts and in NT2 mammary tumors. Electron paramagnetic resonance (EPR) oximetry was used to quantitatively assess the tumor pO2 in matching tumors longitudinally.
  
  
  CONCLUSIONS
  Our study evidenced that (i) positive and negative changes in tumor oxygenation can be detected using MOBILE; (ii) a change in the R1 of lipids is positively correlated with a change in the tumor pO2 (P = 0.0217, r = 0.5097); (iii) measured lipid R1 values are positively correlated with absolute pO2 values in both tumor models (P = 0.0275, r = 0.3726); and (iv) changes in the R1 of lipids are more sensitive than changes in the global R1. As this technique presents unique translational properties, it seems promising for the individual longitudinal monitoring of tumor oxygenation in a clinical setting.
authors.affiliation: Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Florence
authors.initials: F
authors.lastname: Colliez
authors.affiliation: Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Marie-Aline
authors.initials: MA
authors.lastname: Neveu
authors.affiliation: Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Julie
authors.initials: J
authors.lastname: Magat
authors.affiliation: Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Thanh Trang
authors.initials: TT
authors.lastname: Cao Pham
authors.affiliation: Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Bernard
authors.initials: B
authors.lastname: Gallez
authors.affiliation: Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium benedicte.jordan@uclouvain.be.
authors.forename: Bénédicte F
authors.initials: BF
authors.lastname: Jordan
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000737:chemistry* / Q000378:metabolism*; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008279:Magnetic Resonance Imaging / Q000379:methods; D051379:Mice; D008819:Mice, Nude; D009369:Neoplasms / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D008055:Lipids; D010100:Oxygen