A number of methods were proposed to measure sagittal vertebral inclination (SVI) in lateral radiographic projections in the form of spinal curvature or segmental angulation. A systematic analysis of the manual and computerized measurements in sagittal computed tomography (CT) cross-sections has not been performed yet. In this study, SVI was systematically evaluated for 28 vertebrae in CT images by three observers using six manual and two computerized measurements. Manual measurements were obtained in sagittal cross-sections by manually identifying the vertebral body corners, which defined the lines of SVI (superior and inferior tangents, anterior and posterior tangents, mid-endplate and mid-wall lines) against reference horizontal or vertical lines. Computerized measurements were obtained by manually identifying the vertebral centroids, which initialized an automated method that evaluated SVI by searching for the planes of maximal symmetry of vertebral bodies in two dimensions (2D) and in three dimensions (3D). The mid-wall lines proved to be the most reproducible and reliable manual measurements (1.0 degree and 1.4 degrees standard deviation, SD). The computerized measurements in 3D were more reproducible and reliable (0.9 degrees and 1.3 degrees SD) and also most consistent with the mid-wall lines (2.1 degrees SD and 1.7 degrees mean absolute difference, MAD). In terms of speed and operator-friendliness, the computerized measurements may represent an adequate alternative to manual measurements.
COBISS.SI-ID: 8373332
Accurate and objective evaluation of vertebral deformations is of significant importance in clinical diagnostics and therapy of pathological conditions affecting the spine. Although modern clinical practice is focused on three-dimensional (3D) computed tomography (CT) and magnetic resonance (MR) imaging techniques, the established methods for evaluation of vertebral deformations are limited to measuring deformations in two-dimensional (2D) x-ray images. In this paper, we propose a method for quantitative description of vertebral body deformations by efficient modelling and segmentation of vertebral bodies in 3D. The deformations are evaluated from the parameters of a 3D superquadric model, which is initialized as an elliptical cylinder and then gradually deformed by introducing transformations that yield a more detailed representation of the vertebral body shape. After modelling the vertebral body shape with 25 clinically meaningful parameters and the vertebral body pose with six rigid body parameters, the 3D model is aligned to the observed vertebral body in the 3D image. The performance of the method was evaluated on 75 vertebrae from CT and 75 vertebrae from T2-weighted MR spine images, extracted from the thoracolumbar part of normal and pathological spines. The results show that the proposed method can be used for 3D segmentation of vertebral bodies in CT and MR images, as the proposed 3D model is able to describe both normal and pathological vertebral body deformations. The method may therefore be used for initialization of whole vertebra segmentation or for quantitative measurement of vertebral body deformations.
COBISS.SI-ID: 8805716