title: Microstructural parameters of bone evaluated using HR-pQCT correlate with the DXA-derived cortical index and the trabecular bone score in a cohort of randomly selected premenopausal women.
abstract: BACKGROUND
  Areal bone mineral density is predictive for fracture risk. Microstructural bone parameters evaluated at the appendicular skeleton by high-resolution peripheral quantitative computed tomography (HR-pQCT) display differences between healthy patients and fracture patients. With the simple geometry of the cortex at the distal tibial diaphysis, a cortical index of the tibia combining material and mechanical properties correlated highly with bone strength ex vivo. The trabecular bone score derived from the scan of the lumbar spine by dual-energy X-ray absorptiometry (DXA) correlated ex vivo with the micro architectural parameters. It is unknown if these microstructural correlations could be made in healthy premenopausal women.
  
  
  METHODS
  Randomly selected women between 20-40 years of age were examined by DXA and HR-pQCT at the standard regions of interest and at customized sub regions to focus on cortical and trabecular parameters of strength separately. For cortical strength, at the distal tibia the volumetric cortical index was calculated directly from HR-pQCT and the areal cortical index was derived from the DXA scan using a Canny threshold-based tool. For trabecular strength, the trabecular bone score was calculated based on the DXA scan of the lumbar spine and was compared with the corresponding parameters derived from the HR-pQCT measurements at radius and tibia.
  
  
  RESULTS
  Seventy-two healthy women were included (average age 33.8 years, average BMI 23.2 kg/m(2)). The areal cortical index correlated highly with the volumetric cortical index at the distal tibia (R  =  0.798). The trabecular bone score correlated moderately with the microstructural parameters of the trabecular bone.
  
  
  CONCLUSIONS
  This study in randomly selected premenopausal women demonstrated that microstructural parameters of the bone evaluated by HR-pQCT correlated with the DXA derived parameters of skeletal regions containing predominantly cortical or cancellous bone. Whether these indexes are suitable for better predictions of the fracture risk deserves further investigation.
authors.affiliation: Department of Osteoporosis, Inselspital, Berne University Hospital and University of Berne, Berne, Switzerland.
authors.forename: Albrecht W
authors.initials: AW
authors.lastname: Popp
authors.affiliation: Department of Osteoporosis, Inselspital, Berne University Hospital and University of Berne, Berne, Switzerland.
authors.forename: Helene
authors.initials: H
authors.lastname: Buffat
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Ursula
authors.initials: U
authors.lastname: Eberli
authors.affiliation: Department of Osteoporosis, Inselspital, Berne University Hospital and University of Berne, Berne, Switzerland.
authors.forename: Kurt
authors.initials: K
authors.lastname: Lippuner
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Manuela
authors.initials: M
authors.lastname: Ernst
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: R Geoff
authors.initials: RG
authors.lastname: Richards
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Stadelmann
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Windolf
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology*; D005260:Female; D050723:Fractures, Bone; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000648:ultrastructure*; D017697:Premenopause / Q000502:physiology; D011884:Radius / Q000000981:diagnostic imaging / Q000648:ultrastructure*; D012107:Research Design; D012306:Risk; D013977:Tibia / Q000000981:diagnostic imaging / Q000648:ultrastructure*; D014057:Tomography, X-Ray Computed