title: Use of multi-coil parallel-gap resonators for co-registration EPR/NMR imaging.
abstract: This article reports experimental investigations on the use of RF resonators for continuous-wave electron paramagnetic resonance (cw-EPR) and proton nuclear magnetic resonance (NMR) imaging. We developed a composite resonator system with multi-coil parallel-gap resonators for co-registration EPR/NMR imaging. The resonance frequencies of each resonator were 21.8MHz for NMR and 670MHz for EPR. A smaller resonator (22mm in diameter) for use in EPR was placed coaxially in a larger resonator (40mm in diameter) for use in NMR. RF magnetic fields in the composite resonator system were visualized by measuring a homogeneous 4-hydroxy-2,2,6,6-tetramethyl-piperidinooxy (4-hydroxy-TEMPO) solution in a test tube. A phantom of five tubes containing distilled water and 4-hydroxy-TEMPO solution was also measured to demonstrate the potential usefulness of this composite resonator system in biomedical science. An image of unpaired electrons was obtained for 4-hydroxy-TEMPO in three tubes, and was successfully mapped on the proton image for five tubes. Technical problems in the implementation of a composite resonator system are discussed with regard to co-registration EPR/NMR imaging for animal experiments.
authors.affiliation: Department of Electrical Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan.
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Kawada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hirata
authors.forename: Hirodata
authors.initials: H
authors.lastname: Fujii
mesh_terms: D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation* / Q000379:methods; D008280:Magnetics / Q000295:instrumentation*; D019047:Phantoms, Imaging; D013382:Subtraction Technique / Q000295:instrumentation*; D018511:Systems Integration; D014159:Transducers