Phosphorus-31 magnetic resonance imaging of hydroxyapatite: a model for bone imaging.
One-dimensional 31P nuclear magnetic resonance images (projections) of synthetic calcium hydroxyapatite, Ca10(OH)2(PO4)6, have been obtained for samples on the order of 0.5 to 1.0 cm in linear extent at 7.4 T magnetic field strength. Because of the solid state nature of these samples, short 31P spin-spin relaxation times under 1 ms occur, necessitating echo times of 1 ms and phase-encoding magnetic field gradient pulses shorter than 500 microseconds. Optimal projection quality and shortest acquisition times result from pulsed gradient phase-encoding of the spatial dimension, using a compensating gradient pulse to cancel the distorting effects of gradient waveform transients. The exceedingly long 31P spin-lattice relaxation times could lead to potentially intolerable image acquisition times; these have been reduced with a flipback pulse technique. In addition to holding great potential as a novel research tool in the study of biomineralization of those organisms containing calcium phosphate solid phases, these methods should be of general utility in the multinuclear imaging of a wide variety of solids of interest in biophysics and materials science.
Ackerman
J L
JL
Department of Radiology, Massachusetts General Hospital, Charlestown.
Raleigh
D P
DP
Glimcher
M J
MJ
D001842:Bone and Bones / Q000378:metabolism*; D017886:Durapatite; D006801:Humans; D006882:Hydroxyapatites; D009682:Magnetic Resonance Spectroscopy; D008903:Minerals / Q000378:metabolism; D008954:Models, Biological
D006882:Hydroxyapatites; D008903:Minerals; D017886:Durapatite