1. Adv Exp Med Biol. 2010;662:265-72.

Implantable resonators--a technique for repeated measurement of oxygen at
multiple deep sites with in vivo EPR.

Li H, Hou H, Sucheta A, Williams BB, Lariviere JP, Khan MN, Lesniewski PN, Gallez
B, Swartz HM.

EPR Center for Viable Systems, Department of Radiology, Dartmouth Medical School,
703, Vail, Hanover, NH 03755, USA.

EPR oximetry using implantable resonators allows measurements at much deeper
sites than are possible with surface resonators (> 80 vs. 10 mm) and achieves
greater sensitivity at any depth. We report here the development of an improved
technique that enables us to obtain the information from multiple sites and at a 
variety of depths. The measurements from the various sites are resolved using a
simple magnetic field gradient. In the rat brain multi-probe implanted resonators
measured pO(2) at several sites simultaneously for over 6 months under normoxic, 
hypoxic, and hyperoxic conditions. This technique also facilitates measurements
in moving parts of the animal such as the heart, because the orientation of the
paramagnetic material relative to the sensing loop is not altered by the motion. 
The measured response is fast, enabling measurements in real time of
physiological and pathological changes such as experimental cardiac ischemia in
the mouse heart. The technique also is quite useful for following changes in
tumor pO(2), including applications with simultaneous measurements in tumors and 
adjacent normal tissues.


PMID: 20204802 [PubMed - indexed for MEDLINE]