Overhauser enhanced magnetic resonance imaging for tumor oximetry: coregistration of tumor anatomy and tissue oxygen concentration.

Abstract

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.

• Authors: Murali C Krishna, Sean English, Kenichi Yamada, John Yoo, Ramachandran Murugesan, Nallathamby Devasahayam, John A Cook, Klaes Golman, Jan Henrik Ardenkjaer-Larsen, Sankaran Subramanian, James B Mitchell
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 99 Issue 4 Pg. 2216-21 (Feb 19 2002) ISSN: 0027-8424 [Print] United States
• PMID: 11854518 (Publication Type: Journal Article)

Chemical References

• Contrast Media
• Oxygen

Topics

• Algorithms
• Animals
• Contrast Media (pharmacology)
• Dose-Response Relationship, Drug
• Female
• Hypoxia
• Image Processing, Computer-Assisted
• Magnetic Resonance Imaging (methods)
• Mice
• Mice, Inbred C3H
• Neoplasm Transplantation
• Neoplasms (diagnosis, metabolism)
• Oxygen (metabolism)
• Oxygen Consumption