Prospects for sub-micron solid state nuclear magnetic resonance imaging with low-temperature dynamic nuclear polarization.
We evaluate the feasibility of (1)H nuclear magnetic resonance (NMR) imaging with sub-micron voxel dimensions using a combination of low temperatures and dynamic nuclear polarization (DNP). Experiments are performed on nitroxide-doped glycerol-water at 9.4 T and temperatures below 40 K, using a 30 mW tunable microwave source for DNP. With DNP at 7 K, a 0.5 microL sample yields a (1)H NMR signal-to-noise ratio of 770 in two scans with pulsed spin-lock detection and after 80 db signal attenuation. With reasonable extrapolations, we infer that (1)H NMR signals from 1 microm(3) voxel volumes should be readily detectable, and voxels as small as 0.03 microm(3) may eventually be detectable. Through homonuclear decoupling with a frequency-switched Lee-Goldburg spin echo technique, we obtain 830 Hz (1)H NMR linewidths at low temperatures, implying that pulsed field gradients equal to 0.4 G/d or less would be required during spatial encoding dimensions of an imaging sequence, where d is the resolution in each dimension.
Thurber
Kent R
KR
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 5, Room 112, Bethesda, Maryland 20892-0520, USA.
Tycko
Robert
R
D003080:Cold Temperature; D003497:Cyclic N-Oxides / Q000737:chemistry; D005990:Glycerol / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D014867:Water / Q000737:chemistry
D003497:Cyclic N-Oxides; D014867:Water; D005990:Glycerol; C003959:TEMPO
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