title: Fourier X-ray scattering radiography yields bone structural information.
abstract: OBJECTIVE
  To characterize certain aspects of the microscopic structures of cortical and trabecular bone by using Fourier x-ray scattering imaging.
  
  
  METHODS
  Protocols approved by the National Institutes of Health Animal Care and Use Committee were used to examine ex vivo the hind limb of a rat and the toe of a pig. The Fourier x-ray scattering imaging technique involves the use of a grid mask to modulate the cone beam and Fourier spectral filters to isolate the harmonic images. The technique yields attenuation, scattering, and phase-contrast (PC) images from a single exposure. In the rat tibia cortical bone, the scattering signals from two orthogonal grid orientations were compared by using Wilcoxon signed rank tests. In the pig toe, the heterogeneity of scattering and PC signals was compared between trabecular and compact bone regions of uniform attenuation by using F tests.
  
  
  RESULTS
  In cortical bone, the scattering signal was significantly higher (P < 10(-15)) when the grid was parallel to the periosteal surface. Trabecular bone, as compared with cortical bone, appeared highly heterogeneous on the scattering (P < 10(-34)) and PC (P < 10(-27)) images.
  
  
  CONCLUSIONS
  The ordered alignment of the mineralized collagen fibrils in compact bone was reflected in the anisotropic scattering signal in this bone. In trabecular bone, the porosity of the mineralized matrix accounted for the granular pattern seen on the scattering and PC images.
authors.affiliation: National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA. wenh@nhlbi.nih.gov
authors.forename: Han
authors.initials: H
authors.lastname: Wen
authors.forename: Eric E
authors.initials: EE
authors.lastname: Bennett
authors.forename: Monica M
authors.initials: MM
authors.lastname: Hegedus
authors.forename: Stanislas
authors.initials: S
authors.lastname: Rapacchi
mesh_terms: D000818:Animals; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging* / Q000648:ultrastructure*; D005583:Fourier Analysis; D011859:Radiography; D051381:Rats; D012542:Scattering, Radiation; D018709:Statistics, Nonparametric; D013552:Swine; D014965:X-Rays