Journal article
Overhauser enhanced magnetic resonance imaging for tumor oximetry: coregistration of tumor anatomy and tissue oxygen concentration
Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA. murali@helix.nih.gov1
An efficient noninvasive method for in vivo imaging of tumor oxygenation by using a low-field magnetic resonance scanner and a paramagnetic contrast agent is described. The methodology is based on Overhauser enhanced magnetic resonance imaging (OMRI), a functional imaging technique. OMRI experiments were performed on tumor-bearing mice (squamous cell carcinoma) by i.v. administration of the contrast agent Oxo63 (a highly derivatized triarylmethyl radical) at nontoxic doses in the range of 2-7 mmol/kg either as a bolus or as a continuous infusion.
Spatially resolved pO(2) (oxygen concentration) images from OMRI experiments of tumor-bearing mice exhibited heterogeneous oxygenation profiles and revealed regions of hypoxia in tumors (<10 mmHg; 1 mmHg = 133 Pa). Oxygenation of tumors was enhanced on carbogen (95% O(2)/5% CO(2)) inhalation. The pO(2) measurements from OMRI were found to be in agreement with those obtained by independent polarographic measurements using a pO(2) Eppendorf electrode.
This work illustrates that anatomically coregistered pO(2) maps of tumors can be readily obtained by combining the good anatomical resolution of water proton-based MRI, and the superior pO(2) sensitivity of EPR. OMRI affords the opportunity to perform noninvasive and repeated pO(2) measurements of the same animal with useful spatial (approximately 1 mm) and temporal (2 min) resolution, making this method a powerful imaging modality for small animal research to understand tumor physiology and potentially for human applications.
Language: | English |
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Publisher: | The National Academy of Sciences |
Year: | 2002 |
Pages: | 2216-21 |
ISSN: | 10916490 and 00278424 |
Types: | Journal article |
DOI: | 10.1073/pnas.042671399 |