A composite resonator assembly suitable for EPR/NMR coregistration imaging

Abstract

The development of a composite resonator assembly for electron paramagnetic resonance (EPR)/nuclear magnetic resonance (NMR) imaging and its first application to EPR/NMR coregistration imaging are described. Anatomic registration would be useful for the meaningful interpretation of images by EPR of free radical distributions in vivo. The composite resonator assembly consists of a parallel coil resonator, a field modulation coil for EPR imaging, and a solenoidal detection coil for NMR imaging. Radio-frequency (RF) shielding was used in addition for the EPR imaging. The homogeneity of the RF magnetic field of the EPR resonator was measured experimentally using a small-loop antenna; it was reasonably homogeneous along the long axis and in the radial plane. EPR and NMR images were obtained with both phantom and animal tests. The presence of the parallel coil resonator did not significantly affect NMR images. The superposition of the distribution of free radicals and protons was computed using three positional markers. The assembly performs the registration of two multimodal images. It is compatible with an orthogonal crossed-coil configuration for open-type clinical NMR imagers. © 2005 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 25B: 1–11, 2005