Influence of patient axial malpositioning on the trueness and precision of pelvic parameters obtained from 3D reconstructions based on biplanar radiographs

Bachir Ghostine , Christophe Sauret (1, 2) , Ayman Assi (2) , Ziad Bakouny , Nour Khalil , Wafa Skalli (2, 3, 1) , Ismat Ghanem (4)

1 Institut de Biomecanique Humaine Georges Charpak
2 LBM - Laboratoire de biomécanique
3 I2M - Institut de Mécanique et d'Ingénierie de Bordeaux
4 USJ - Université Saint-Joseph de Beyrouth

Objectives: Radiographs are often performed to assess pelvic and hip parameters, but results depend upon correct pelvis positioning. Three-dimensional (3D) reconstruction from biplanar-radiographs should provide parameters that are less sensitive to pelvic orientation, but this remained to be evaluated. Methods: Computerized-tomographic scans of six patients were used both as a reference and for generating simulated frontal and lateral radiographs. These simulated radiographs were generated while introducing axial rotations of the pelvis ranging from 0° to 20°. Simulated biplanar-radiographs were utilized by four operators, three times each, to perform pelvic 3D-reconstructions. These reconstructions were used to assess the trueness, precision and global uncertainty of radiological pelvic and hip parameters for each position. Results: In the neutral position, global uncertainty ranged between ± 2° for pelvic tilt and ± 9° for acetabular posterior sector angle and was mainly related to precision errors (ranging from 1.5° to 7°). With increasing axial rotation, global uncertainty increased and ranged between ± 5° for pelvic tilt and ± 11° for pelvic incidence, sacral slope and acetabular anterior sector angle, mainly due to precision errors. Conclusion: Radiological parameters obtained from 3D-reconstructions, based on biplanar-radiographs, are less sensitive to axial rotation compared to plain radiographs. However, the axial rotation should nonetheless not exceed 10°.

Domaines: Biomécanique [physics.med-ph]

Bachir Ghostine, Christophe Sauret, Ayman Assi, Ziad Bakouny, Nour Khalil, et al.. Influence of patient axial malpositioning on the trueness and precision of pelvic parameters obtained from 3D reconstructions based on biplanar radiographs. European Radiology, 2016, 27 (3), pp.1295-1302. ⟨10.1007/s00330-016-4452-x⟩. ⟨hal-02197220⟩