کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5891774 | 1153280 | 2011 | 9 صفحه PDF | دانلود رایگان |
Serial reproducibility and reliability critically determine sensitivity to detect changes in response to intervention and provide a basis for sample size estimates. Here, we evaluated the performance of the MRI-based virtual bone biopsy in terms of 26 structural and mechanical parameters in the distal radius of 20 women in the age range of 50 to 75 years (mean = 62.0 years, S.D. = 8.1 years), representative of typical study populations in drug intervention trials and fracture studies. Subjects were examined three times at average intervals of 20.2 days (S.D. = 14.5 days) by MRI at 1.5 T field strength at a voxel size of 137 Ã 137 Ã 410 μm3. Methods involved prospective and retrospective 3D image registration and auto-focus motion correction. Analyses were performed from a central 5 Ã 5 Ã 5 mm3 cuboid subvolume and trabecular volume consisting of a 13 mm axial slab encompassing the entire medullary cavity. Whole-volume axial stiffness and sub-regional Young's and shear moduli were computed by finite-element analysis. Whole-volume-derived aggregate mean coefficient of variation of all structural parameters was 4.4% (range 1.8% to 7.7%) and 4.0% for axial stiffness; corresponding data in the subvolume were 6.5% (range 1.6% to 13.0%) for structural, and 5.5% (range 4.6% to 6.5%) for mechanical parameters. Aggregate ICC was 0.976 (range 0.947 to 0.986) and 0.992 for whole-volume-derived structural parameters and axial stiffness, and 0.946 (range 0.752 to 0.991) and 0.974 (range 0.965 to 0.978) for subvolume-derived structural and mechanical parameters, respectively. The strongest predictors of whole-volume axial stiffness were BV/TV, junction density, skeleton density and Tb.N (R2 0.79-0.87). The same parameters were also highly predictive of sub-regional axial modulus (R2 0.88-0.91). The data suggest that the method is suited for longitudinal assessment of the response to therapy. The underlying technology is portable and should be compatible with all general-purpose MRI scanners, which is appealing considering the very large installed base of this modality.
⺠The performance of MRI-based virtual bone biopsy was evaluated in the data from 20 women representative of osteoporosis study populations. ⺠Reproducibility and reliability of 26 structural and mechanical parameters in the distal radius were assessed. ⺠The work describes the methodology for minimization of reproducibility errors from subject motion and positioning. ⺠Expected errors of repeated imaging is in the range of 1-4%.
Journal: Bone - Volume 49, Issue 4, October 2011, Pages 895-903