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Diffusion‐based MR methods for bone structure and evolution
Author(s) -
Sigmund E.E.,
Cho H.,
Chen P.,
Byrnes S.,
Song Y.Q.,
Guo X.E.,
Brown T. R.
Publication year - 2008
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21281
Subject(s) - diffusion , spins , nuclear magnetic resonance , characterization (materials science) , field (mathematics) , pulse sequence , densitometry , magnetic field , field strength , chemistry , materials science , physics , optics , condensed matter physics , mathematics , nanotechnology , quantum mechanics , pure mathematics , thermodynamics
Abstract A new approach to MR trabecular bone characterization is presented. This method probes the diffusion of spins through internal magnetic field gradients due to the susceptibility contrast between the bone and water (or marrow) phases. The resulting spin magnetization decay encodes properties of the underlying structure. This method, termed decay due to diffusion in the internal field (DDIF), is well established as a probe of pore size and structure. In the present work its application is shown for in vitro experiments on excised bovine tibiae samples. A comparison with pulsed field gradient (PFG) measurement of restricted diffusion shows a strong correlation of DDIF with the surface‐to‐volume ratio (SVR) of bones. Calculation of the internal magnetic field within the bone structure also supports this interpretation. These NMR measurements compare well with the image analysis from microscopic computed tomography (μCT). The SVR is not accessible in the clinically standard densitometry measurements, and provides vital information on bone strength and therefore on its fracture risk. The DDIF and PFG methods derive this information from a straightforward pulse sequence that does not employ either high applied field gradients or microimaging, and thus may have clinical potential. Magn Reson Med 59:28–39, 2008. © 2007 Wiley‐Liss, Inc.