title: Voxel-based modeling and quantification of the proximal femur using inter-subject registration of quantitative CT images.
abstract: We have developed a general framework which employs quantitative computed tomography (QCT) imaging and inter-subject image registration to model the three-dimensional structure of the hip, with the goal of quantifying changes in the spatial distribution of bone as it is affected by aging, drug treatment or mechanical unloading. We have adapted rigid and non-rigid inter-subject registration techniques to transform groups of hip QCT scans into a common reference space and to construct composite proximal femoral models. We have applied this technique to a longitudinal study of 16 astronauts who on average, incurred high losses of hip bone density during spaceflights of 4-6 months on the International Space Station (ISS). We compared the pre-flight and post-flight composite hip models, and observed the gradients of the bone loss distribution. We performed paired t-tests, on a voxel by voxel basis, corrected for multiple comparisons using false discovery rate (FDR), and observed regions inside the proximal femur that showed the most significant bone loss. To validate our registration algorithm, we selected the 16 pre-flight scans and manually marked 4 landmarks for each scan. After registration, the average distance between the mapped landmarks and the corresponding landmarks in the target scan was 2.56 mm. The average error due to manual landmark identification was 1.70 mm.
authors: Department of Radiology, University of California San Francisco, San Francisco, CA 94143, USA. wenjun.li@radiology.ucsf.edu
authors: Wenjun
authors: W
authors: Li
authors: Irina
authors: I
authors: Kezele
authors: D Louis
authors: DL
authors: Collins
authors: Alex
authors: A
authors: Zijdenbos
authors: Joyce
authors: J
authors: Keyak
authors: John
authors: J
authors: Kornak
authors: Alain
authors: A
authors: Koyama
authors: Isra
authors: I
authors: Saeed
authors: Adrian
authors: A
authors: Leblanc
authors: Tamara
authors: T
authors: Harris
authors: Ying
authors: Y
authors: Lu
authors: Thomas
authors: T
authors: Lang
mesh_terms: D015519:Bone Density; D005270:Femur Head / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D006801:Humans; D008953:Models, Anatomic; D014057:Tomography, X-Ray Computed
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