Influence of proton T1 on oxymetry using Overhauser enhanced magnetic resonance imaging.
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.
Matsumoto
Shingo
S
Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA.
Utsumi
Hideo
H
Aravalluvan
Thirumaran
T
Matsumoto
Ken-Ichiro
K
Matsumoto
Atsuko
A
Devasahayam
Nallathamby
N
Sowers
Anastasia L
AL
Mitchell
James B
JB
Subramanian
Sankaran
S
Krishna
Murali C
MC
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
D014408:Biomarkers, Tumor; D003287:Contrast Media; D006575:Heterocyclic Compounds, 3-Ring; C495909:Oxo63; D011522:Protons; D019786:Gadolinium DTPA; D010100:Oxygen