Magnetic resonance of calcified tissues

Laboratory for Structural NMR Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, United States. Electronic address: .
Journal of Magnetic Resonance (Impact Factor: 2.51). 01/2013; 229. DOI: 10.1016/j.jmr.2012.12.011
Source: PubMed


MRI of the human body is largely made possible by the favorable relaxation properties of protons of water and triacyl glycerides prevalent in soft tissues. Hard tissues - key among them bone - are generally less amenable to measurement with in vivo MR imaging techniques, not so much as a result of the lower proton density but rather due to the extremely short life-times of the proton signal in water bound to solid-like entities, typically collagen, or being trapped in micro-pores. Either mechanism can enhance T2 relaxation by up to three orders of magnitude relative to their soft-tissue counterparts. Detection of these protons requires solid-state techniques that have emerged in recent years and that promise to add a new dimension to the study of hard tissues. Alternative approaches to probe calcified tissues exploit their characteristic magnetic properties. Bone, teeth and extra-osseous calcium-containing biomaterials are unique in that they are more diamagnetic than all other tissues and thus yield information indirectly by virtue of the induced magnetic fields present in their vicinity. Progress has also been made in methods allowing very high-resolution structural imaging of trabecular and cortical bone relying on detection of the surrounding soft-tissues. This brief review, much of it drawn from work conducted in the author's laboratory, seeks to highlight opportunities with focus on early-stage developments for image-based assessment of structure, function, physiology and mechanics of calcified tissues in humans via liquid and solid-state approaches, including proton, deuteron and phosphorus NMR and MRI.

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    • "More recently, magnetic resonance microimaging (mMRI) methods have been developed and refined (Callaghan, 1995) to provide images characterized by a spatial resolution of approximately 100 mm or smaller. They have been particularly useful for investigating porous systems (Strange et al., 1993; Allen et al., 1997) and bones (De Santis et al., 2010; Wehrli, 2013). Specifically, mMRI techniques are able to retrieve high resolution information about the density, the mean diameter, and the distribution of microfeatures in porous systems. "
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    Journal of Human Evolution 05/2014; 74. DOI:10.1016/j.jhevol.2014.04.005 · 3.73 Impact Factor
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    • "A new potential surrogate marker for osteoporosis, the internal magnetic field gradient (IMFG), has recently been proposed [22] [23]. In cancellous bone, the susceptibility mismatch between the solid matrix and interstitial liquid marrow generates internal gradients at the interface between the bone and marrow [22] [23] [24] [25] [26] [27]. "
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