title: Influence of proton T1 on oxymetry using Overhauser enhanced magnetic resonance imaging.
abstract: In Overhauser enhanced magnetic resonance imaging (OMRI) for in vivo measurement of oxygen partial pressure (pO2), a paramagnetic contrast agent is introduced to enhance the proton signal through dynamic nuclear polarization. A uniform proton T1 is generally assumed for the entire region of interest for the computation of pO2 using OMRI. It is demonstrated here, by both phantom and in vivo (mice) imaging, that such an assumption may cause erroneous estimate of pO2. A direct estimate of pixel-wise T1 is hampered by the poor native MR intensities, owing to the very low Zeeman field (15-20 mT) in OMRI. To circumvent this problem, a simple method for the pixel-wise mapping of proton T1 using the OMRI scanner is described. A proton T1 image of a slice through the center of an SCC tumor in a mouse clearly shows a range of T1 distribution (0.2 approximately 1.6 s). Computation of pO2 images using pixel-wise T1 values promises oximetry with minimal artifacts by OMRI.
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA.
authors.forename: Shingo
authors.initials: S
authors.lastname: Matsumoto
authors.forename: Hideo
authors.initials: H
authors.lastname: Utsumi
authors.forename: Thirumaran
authors.initials: T
authors.lastname: Aravalluvan
authors.forename: Ken-Ichiro
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Atsuko
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Nallathamby
authors.initials: N
authors.lastname: Devasahayam
authors.forename: Anastasia L
authors.initials: AL
authors.lastname: Sowers
authors.forename: James B
authors.initials: JB
authors.lastname: Mitchell
authors.forename: Sankaran
authors.initials: S
authors.lastname: Subramanian
authors.forename: Murali C
authors.initials: MC
authors.lastname: Krishna
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D019786:Gadolinium DTPA / Q000493:pharmacokinetics; D006575:Heterocyclic Compounds, 3-Ring / Q000493:pharmacokinetics; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D051379:Mice; D008809:Mice, Inbred C3H; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000378:metabolism*; D019047:Phantoms, Imaging; D011522:Protons
chemical_list: D014408:Biomarkers, Tumor; D003287:Contrast Media; D006575:Heterocyclic Compounds, 3-Ring; C495909:Oxo63; D011522:Protons; D019786:Gadolinium DTPA; D010100:Oxygen