Wichmann, Julian L. ; Booz, Christian ; Wesarg, Stefan ; Bauer, Ralf W. ; Kerl, J. Matthias ; Fischer, Sebastian ; Lehnert, Thomas ; Vogl, Thomas J. ; Khan, M. Fawad ; Kafchitsas, Konstantinos (2015)
Quantitative Dual-energy CT for Phantomless Evaluation of Cancellous Bone Mineral Density of the Vertebral Pedicle: Correlation with Pedicle Screw Pull-out Strength.
In: European Radiology, 25 (6)
doi: 10.1007/s00330-014-3529-7
Article, Bibliographie

Abstract

Objectives: To evaluate quantitative dual-energy computed tomography (DECT) for phantomless analysis of cancellous bone mineral density (BMD) of vertebral pedicles and to assess the correlation with pedicle screw pull-out strength. Methods: Twenty-nine thoracic and lumbar vertebrae from cadaver specimens were examined with DECT. Using dedicated post-processing software, a pedicle screw vector was mapped (R1, intrapedicular segment of the pedicle vector; R2, intermediate segment; R3, intracorporal segment; global, all segments) and BMD was calculated. To invasively evaluate pedicle stability, pedicle screws were drilled through both pedicles and left pedicle screw pull-out strength was measured. Resulting values were correlated using the paired t test and Pearson's linear correlation. Results: Average pedicle screw vector BMD (R1, 0.232 g/cm3; R2, 0.166 g/cm3; R3, 0.173 g/cm3; global, 0.236 g/cm3) showed significant differences between R1-R2 (P<0.002) and R1-R3 (P<0.034) segments while comparison of R2-R3 did not reach significance (P>0.668). Average screw pull-out strength (639.2 N) showed a far stronger correlation with R1 (r=0.80; P<0.0001) than global BMD (r=0.42; P=0.025), R2 (r=0.37; P=0.048) and R3 (r=0.33; P=0.078) segments. Conclusions: Quantitative DECT allows for phantomless BMD assessment of the vertebral pedicle. BMD of the intrapedicular segment shows a significantly stronger correlation with pedicle screw pull-out strength than other segments.

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