title: Assessment of trabecular and cortical architecture and mechanical competence of bone by high-resolution peripheral computed tomography: comparison with transiliac bone biopsy.
abstract: We compared microarchitecture and mechanical competence parameters measured by high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite-element analysis of radius and tibia to those measured by histomorphometry, micro-CT, and finite-element analysis of transiliac bone biopsies. Correlations were weak to moderate between parameters measured on biopsies and scans.
  
  
  BACKGROUND
  HR-pQCT is a new imaging technique that assesses trabecular and cortical bone microarchitecture of the radius and tibia in vivo. The purpose of this study was to determine the extent to which microarchitectural variables measured by HR-pQCT reflect those measured by the "gold standard," transiliac bone biopsy.
  
  
  METHODS
  HR-pQCT scans (Xtreme CT, Scanco Medical AG) and iliac crest bone biopsies were performed in 54 subjects (aged 39 +/- 10 years). Biopsies were analyzed by 2D quantitative histomorphometry and 3D microcomputed tomography (microCT). Apparent Young's modulus, an estimate of mechanical competence or strength, was determined by micro-finite-element analysis (microFE) of biopsy microCT and HR-pQCT images.
  
  
  RESULTS
  The strongest correlations observed were between trabecular parameters (bone volume fraction, number, separation) measured by microCT of biopsies and HR-pQCT of the radius (R 0.365-0.522; P < 0.01). Cortical width of biopsies correlated with cortical thickness by HR-pQCT, but only at the tibia (R = 0.360, P < 0.01). Apparent Young's modulus calculated by microFE of biopsies correlated with that calculated for both radius (R = 0.442; P < 0.001) and tibia (R = 0.380; P < 0.001) HR-pQCT scans.
  
  
  CONCLUSIONS
  The associations between peripheral (HR-pQCT) and axial (transiliac biopsy) measures of microarchitecture and estimated mechanical competence are significant but modest.
authors.affiliation: Department of Medicine, PH8-864, Columbia University, College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA. ac1044@columbia.edu
authors.forename: A
authors.initials: A
authors.lastname: Cohen
authors.forename: D W
authors.initials: DW
authors.lastname: Dempster
authors.forename: R
authors.initials: R
authors.lastname: Müller
authors.forename: X E
authors.initials: XE
authors.lastname: Guo
authors.forename: T L
authors.initials: TL
authors.lastname: Nickolas
authors.forename: X S
authors.initials: XS
authors.lastname: Liu
authors.forename: X H
authors.initials: XH
authors.lastname: Zhang
authors.forename: A J
authors.initials: AJ
authors.lastname: Wirth
authors.forename: G H
authors.initials: GH
authors.lastname: van Lenthe
authors.forename: T
authors.initials: T
authors.lastname: Kohler
authors.forename: D J
authors.initials: DJ
authors.lastname: McMahon
authors.forename: H
authors.initials: H
authors.lastname: Zhou
authors.forename: M R
authors.initials: MR
authors.lastname: Rubin
authors.forename: J P
authors.initials: JP
authors.lastname: Bilezikian
authors.forename: J M
authors.initials: JM
authors.lastname: Lappe
authors.forename: R R
authors.initials: RR
authors.lastname: Recker
authors.forename: E
authors.initials: E
authors.lastname: Shane
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D015519:Bone Density / Q000502:physiology; D016022:Case-Control Studies; D055119:Elastic Modulus; D005260:Female; D006801:Humans; D007011:Hypoparathyroidism / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D011884:Radius / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D015203:Reproducibility of Results; D013977:Tibia / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D014057:Tomography, X-Ray Computed / Q000379:methods; D055114:X-Ray Microtomography / Q000379:methods; D055815:Young Adult