Sensitivity enhancement of remotely coupled NMR detectors using wirelessly powered parametric amplification
Article first published online: 13 JAN 2012
Copyright © 2012 Wiley Periodicals, Inc.
Magnetic Resonance in Medicine
Volume 68, Issue 3, pages 989–996, September 2012
How to Cite
Qian, C., Murphy-Boesch, J., Dodd, S. and Koretsky, A. (2012), Sensitivity enhancement of remotely coupled NMR detectors using wirelessly powered parametric amplification. Magn Reson Med, 68: 989–996. doi: 10.1002/mrm.23274
- Issue published online: 23 AUG 2012
- Article first published online: 13 JAN 2012
- Manuscript Accepted: 5 OCT 2011
- Manuscript Revised: 2 OCT 2011
- Manuscript Received: 3 MAY 2011
- NINDS (Intramural Research Program)
- parametric amplifier;
A completely wireless detection coil with an integrated parametric amplifier has been constructed to provide local amplification and transmission of MR signals. The sample coil is one element of a parametric amplifier using a zero-bias diode that mixes the weak MR signal with a strong pump signal that is obtained from an inductively coupled external loop. The NMR sample coil develops current gain via reduction in the effective coil resistance. Higher gain can be obtained by adjusting the level of the pumping power closer to the oscillation threshold, but the gain is ultimately constrained by the bandwidth requirement of MRI experiments. A feasibility study here shows that on a NaCl/D2O phantom, 23Na signals with 20 dB of gain can be readily obtained with a concomitant bandwidth of 144 kHz. This gain is high enough that the integrated coil with parametric amplifier, which is coupled inductively to external loops, can provide sensitivity approaching that of direct wire connection. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.