A Symmetry-Based Method for the Determination of Vertebral Rotation in 3D

Abstract

Abstract. In the past, a number of methods were proposed for quantitative assessment of vertebral rotation from three-dimensional (3D) images. However, these methods were based on manual identification of distinctive anatomical landmarks, required manual determination of cross-sections from 3D images, and measured only axial vertebral rotation instead of the rotation in 3D. In this paper, we propose an automated method for quantitative assessment of vertebral rotation in 3D that is based on finding the planes of vertebral symmetry by matching image intensity gradients on both sides of each plane. The method was evaluated on 28 images of normal and pathological vertebrae, obtained by computed tomography (CT) and magnetic resonance (MR). For each vertebra, final angle displacements of 200 initial angle displacements, uniformly distributed within 30• from manually obtained reference angles, were obtained. The results show that by the proposed method, vertebral rotation can be successfully estimated in 3D with an average accuracy of 1.0• and precision of 0.5• .

Analysis of Four Manual and a Computerized Method for Measuring Axial Vertebral Rotation in Computed Tomography Images

“…The reported intermethod variability between their symmetry ratio algorithm and the method of Aaro and Dahlborn 9 and Ho et al 10 were 3.3 degrees and 3.4 degrees SD, respectively. The symmetry of the whole vertebral structure in 3D was proposed by Vrtovec et al, 6 who reported accuracy of 0.5 degrees and precision of 0.3 degrees after comparing each computerized AVR measurement to a single manually identified line that best described the symmetry of vertebral anatomic structures. The computerized method does, however, not search for a perfect (idealized) symmetry, but instead for the maximal available symmetry, which makes it applicable to normal as well as pathologic vertebrae.…”

“…Computerized methods do not suffer from these limitations and may yield accurate AVR results in images acquired by computed tomography (CT). [3][4][5][6] However, computerized methods also require manual identification of multiple anatomic landmarks or neglect the sagittal and coronal inclinations of vertebrae, which may result in inaccurate measurements. 7,8 The accuracy and reliability of computerized methods have not been thoroughly investigated yet.…”

“…The purpose of this study is to analyze, compare and evaluate different manual 8 -11 and a computerized method 6 for measuring AVR in CT images of normal and pathologic (scoliotic) vertebrae. Using each method, multiple observers performed multiple AVR measurements, which allowed the estimation of intraobserver, interobserver, and intermethod variabilities.…”

Variability of Manual and Computerized Methods for Measuring Coronal Vertebral Inclination in Computed Tomography Images

“…The computerized measurements were based on a method that determines the sagittal, coronal and axial angle of vertebral rotation in 3D images from the inclination of the planes of maximal symmetry (Vrtovec et al, 2008), which divide the vertebral body into symmetrical left and right, anterior and posterior, and cephalic and caudal halves (Fig. 2).…”

Automatic measurement of axial vertebral rotation in 3D vertebral models

“…With the increase of measurement methods, different comparisons of measurement methods appeared [7,8], in which the advantages and disadvantages of various algorithms were analyzed and the direction was pointed out for the new algorithm. Vrtovec et al [9] assessed vertebral rotation quantitatively by proposing an automated method in terms of finding the planes of vertebral symmetry. Wong et al [10] achieved the measurement vertebral rotation using 3D ultrasound method and validate the feasibility of this method.…”