A First Time Proposal on 36-45 Tesla up to 100 Tesla NMR Microimaging With Spectroscopy Experiment Using a Series-Connected Hybrid Magnet: Lessons From Comparison of 21 Tesla vs 36 Tesla Biological NMR experiments

Abstract

The possible use of  Series-Connected Hybrid magnet DC power driven magnet operable at 36 Tesla was explored for NMR spectroscopy and NMR microimaging. The combined superconducting outsert and resistive insert connected in series minimize the high frequency fluctuations observed at 21 Tesla magnetic field resistive magnets. Another effect of field inhomogeneity at 21 Tesla field was improved by current-density-grading among various resistive coils. For it, conventional shims and combined resistive and ferromagnetic shims were fixed in a space of 48 mm magnet bore with 42 mm outer probe diameter. With above design of 36 Tesla NMR magnet, field maps corrected the field instabilities and better shimming up to 1 ppm homogeneity over a volume of interest 1 cubic cm. The ultrahigh field 900 MHz using PARAVISION console was suitable for spatial resolution of 35 micron imaging for excised brain, kidney, heart, skin organs. The ultrahigh 1.5 GHz using a AVANCE NEO console was suitable for possible microimaging and NMR spectroscopy at 1.5 GHz 1H frequency or 50% increased field strength over 21 Tesla 900 MHz or 0.9 GHz above the highest superconducting magnets available presently. The three NMR probes are equipped with rf coil to regulate the magnetic field within 0.2 ppm using an external 7Li lock sample doped with paramagnetic MnCl2. Possibilities of high resolution Magic Angle Spinning NMR spectroscopy of biopsy and microimaging at 21 Tesla and 36 Tesla experiments are exciting at ultra-high magnetic fields.