3D reconstruction of the spine from biplanar X-rays using parametric models based on transversal and longitudinal inferences

Abstract 

Reconstruction methods from biplanar X-rays provide 3D analysis of spinal deformities for patients in standing position with a low radiation dose. However, such methods require an important reconstruction time and there is a clinical need for fast and accurate techniques. This study proposes and evaluates a novel reconstruction method of the spine from biplanar X-rays. The approach uses parametric models based on longitudinal and transversal inferences.

A first reconstruction level, dedicated to routine clinical use, allows to get a fast estimate (reconstruction time: 2min 30s) of the 3D reconstruction and accurate clinical measurements. The clinical measurements precision (evaluated on asymptomatic subjects, moderate and severe scolioses) was between 1.2° and 5.6°.

For a more accurate 3D reconstruction (complex pathologies or research purposes), a second reconstruction level can be obtained within a reduced reconstruction time (10min) with a fine adjustment of the 3D models. The mean shape accuracy in comparison with CT-scan was 1.0mm. The 3D reconstruction method precision was 1.8mm for the vertebrae position and between 2.3° and 3.9° for the orientation.

With a reduced reconstruction time, an improved accuracy and precision and a method proposing two reconstruction levels, this approach is efficient for both clinical routine uses and research purposes.

Keywords: Biplanar X-rays, Spine, Scoliosis, 3D reconstruction, Longitudinal and transversal inferences