Modified Alderman-Grant resonator with high-power stability for proton electron double resonance imaging.
Proton-electron double resonance imaging (PEDRI) requires a dual EPR/NMR resonator. In order to saturate electron spins, long high-power RF EPR pulses are needed. Dissipated power causes resonator and sample heating, resulting in instability of the resonator frequency and coupling, which in turn causes a reduction in sensitivity. To overcome this problem, we designed, built, and tested a modified Alderman-Grant (MAG) resonator for in vivo and in vitro applications. We improved the temperature stability by using fused quartz in critical structural components of the resonator and employing a design that minimized moving parts. All of the components of the resonator and matching circuit, including coupling capacitors, were rigidly positioned on the surface of the quartz tube. Electrical coupling circuitry between the feeding cable and resonator was employed to provide independent coupling and tuning adjustments, which improved the ease and speed of operation. The equivalent schematic of the matching circuit is presented along with calculations of critical parameters. The resonator exhibits no frequency shift with 20 W of continuous power irradiation, and can handle intermittent power of 60 W for up to 3 min without detuning, enabling stable and reliable data acquisition for PEDRI of biological samples.
Petryakov
Sergey
S
Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, Columbus, Ohio 43210-1252, USA.
Samouilov
Alexandre
A
Roytenberg
Michael
M
Li
Haihong
H
Zweier
Jay L
JL
D017076:Computer-Aided Design; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers
D011522:Protons