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Calcified Tissue International

, Volume 62, Issue 6, pp 512–518 | Cite as

Evaluation of Bone Mineral Density Using Three-Dimensional Solid State Phosphorus-31 NMR Projection Imaging

  • Y.  Wu
  • J. L.  Ackerman
  • D. A.  Chesler
  • J.  Li
  • R. M.  Neer
  • J.  Wang
  • M. J.  Glimcher

Abstract.

A solid state magnetic resonance imaging technique is used to measure true three-dimensional mineral density of synthetic hydroxyapatite phantoms and specimens of bone ex vivo. The phosphorus-31 free induction decay at 2.0 T magnetic field strength is sampled following application of a short, hard radiofrequency excitation pulse in the presence of a fixed amplitude magnetic field gradient. Multiple gradient directions covering the unit sphere are used in an efficient spherical polar to Cartesian interpolation and Fourier transform projection reconstruction scheme to image the three-dimensional distribution of phosphorus within the specimen. Using 3–6 Gauss/cm magnetic field gradients, a spatial resolution of 0.2 cm over a field of view of 10 cm is achieved in an imaging time of 20–35 minutes. Comparison of solid state magnetic resonance imaging with dual energy X-ray absorptiometry (DXA), gravimetric analysis, and chemical analysis of calcium and phosphorus demonstrates good quantitative accuracy. Direct measurement of bone mineral by solid state magnetic resonance opens up the possibility of imaging variations in mineral composition as well as density. Advantages of the solid state magnetic resonance technique include avoidance of ionizing radiation; direct measurement of a constituent of the mineral without reliance on assumptions about, or models of, tissue composition; the absence of shielding, beam hardening, or multiple scattering artifacts; and its three-dimensional character. Disadvantages include longer measurement times and lower spatial resolution than DXA and computed tomography, and the inability to scan large areas of the body in a single measurement, although spatial resolution is sufficient to resolve cortical from trabecular bone for the purpose of measuring bone mineral density.

Key words: Densitometry — Bone mineral content — Hydroxyapatite — MRI. 

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Copyright information

© Springer-Verlag New York Inc. 1998

Authors and Affiliations

  • Y.  Wu
    • 1
  • J. L.  Ackerman
    • 1
  • D. A.  Chesler
    • 2
  • J.  Li
    • 3
  • R. M.  Neer
    • 3
  • J.  Wang
    • 1
  • M. J.  Glimcher
    • 1
  1. 1.Laboratory for the Study of Skeletal Disorders and Rehabilitation, Department of Orthopaedic Surgery, Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USAUS
  2. 2.Biomaterials Laboratory, NMR Center, Room 2301, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 149 13th Street, Charlestown, Massachusetts 02129, USAUS
  3. 3.Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School Boston, Massachusetts 02114, USAUS

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