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Adolescent idiopathic scoliosis (AIS) is a prevalent musculoskeletal disorder that causes abnormal spinal deformities. The early screening of children and adolescents is crucial to identify and prevent the further progression of AIS. In clinical examinations, scoliometers are often used to noninvasively estimate the primary Cobb angle, and optical 3D scanning systems have also emerged as alternative noninvasive approaches for this purpose. The recent advances in low-cost 3D scanners have led to their use in several studies to estimate the primary Cobb angle or even internal spinal alignment. However, none of these studies demonstrate whether such a low-cost scanner satisfies the minimal requirements for capturing the relevant deformities of the human back. To practically quantify the minimal required spatial resolution and camera resolution to capture the geometry and shape of the deformities of the human back, we used multiple 3D scanning methodologies and systems. The results from an evaluation of 30 captures of AIS patients and 76 captures of healthy subjects showed that the minimal required spatial resolution is between 2 mm and 5 mm, depending on the chosen error tolerance. Therefore, a minimal camera resolution of 640 × 480 pixels is recommended for use in future studies. [ABSTRACT FROM AUTHOR]

Adolescent idiopathic scoliosis (AIS) is a prevalent musculoskeletal disorder that causes abnormal spinal deformities. The early screening of children and adolescents is crucial to identify and prevent the further progression of AIS. In clinical examinations, scoliometers are often used to noninvasively estimate the primary Cobb angle, and optical 3D scanning systems have also emerged as alternative noninvasive approaches for this purpose. The recent advances in low-cost 3D scanners have led to their use in several studies to estimate the primary Cobb angle or even internal spinal alignment. However, none of these studies demonstrate whether such a low-cost scanner satisfies the minimal requirements for capturing the relevant deformities of the human back. To practically quantify the minimal required spatial resolution and camera resolution to capture the geometry and shape of the deformities of the human back, we used multiple 3D scanning methodologies and systems. The results from an evaluation of 30 captures of AIS patients and 76 captures of healthy subjects showed that the minimal required spatial resolution is between 2 mm and 5 mm, depending on the chosen error tolerance. Therefore, a minimal camera resolution of 640 × 480 pixels is recommended for use in future studies.

This paper analyse and compare the methods to detect and represent the human symmetry line. In the last years, the development of 3D scanners has allowed to replace the traditional techniques (marking based methods) with modern methodologies that, starting from a 3D valid discrete geometric model of the back, perform the posture and vertebral column detection based on a complex processing of the acquired data. The purpose of the paper is a critical discussion of the state of the art in order to highlight real potentialities and limitations of the most important methodologies proposed for human symmetry line detection. [ABSTRACT FROM AUTHOR]

Background: The main objective of the present method was to automatically obtain a spatial curve of the thoracic and lumbar spine based on a 3D shape measurement of a human torso with developed scoliosis. Manual determination of the spine curve, which was based on palpation of the thoracic and lumbar spinous processes, was found to be an appropriate way to validate the method. Therefore a new, noninvasive, optical 3D method for human torso evaluation in medical practice is introduced. Methods: Twenty-four patients with confirmed clinical diagnosis of scoliosis were scanned using a specially developed 3D laser profilometer. The measuring principle of the system is based on laser triangulation with onelaser-plane illumination. The measurement took approximately 10 seconds at 700 mm of the longitudinal translation along the back. The single point measurement accuracy was 0.1 mm. Computer analysis of the measured surface returned two 3D curves. The first curve was determined by manual marking (manual curve), and the second was determined by detecting surface curvature extremes (automatic curve). The manual and automatic curve comparison was given as the root mean square deviation (RMSD) for each patient. The intra-operator study involved assessing 20 successive measurements of the same person, and the inter-operator study involved assessing measurements from 8 operators. Results: The results obtained for the 24 patients showed that the typical RMSD between the manual and automatic curve was 5.0 mm in the frontal plane and 1.0 mm in the sagittal plane, which is a good result compared with palpatory accuracy (9.8 mm). The intra-operator repeatability of the presented method in the frontal and sagittal planes was 0.45 mm and 0.06 mm, respectively. The inter-operator repeatability assessment shows that that the presented method is invariant to the operator of the computer program with the presented method. Conclusions: The main novelty of the presented paper is the development of a new, non-contact method that provides a quick, precise and non-invasive way to determine the spatial spine curve for patients with developed scoliosis and the validation of the presented method using the palpation of the spinous processes, where no harmful ionizing radiation is present. [ABSTRACT FROM AUTHOR]

The methods forsymmetry linedetection presented in the literature are typically suited to analyse symmetric upright postures, both standing and seated. The proposed method focuses on thesymmetry linedetection in subjects assuming asymmetric postures in which this line falls far outside the sagittal plane. The proposed approach evaluates thesymmetry lineby means of an autoregressive process in order to determine the set of planes suited to slice the back coherently with its geometric spatial configuration. The method is analysed assuming the cutaneous marking as reference and it is compared with a previous one, also developed by these authors. Results are analysed and critically discussed. [ABSTRACT FROM AUTHOR]

In this work, a new technique for symmetry line detection for non-erected postures, which can not be investigated with the other methods presented in the literature, is proposed. It evaluates the symmetry line by means an adaptive process in which a first attempt is modified step by step until the solution converges to the best estimation. The method here proposed is validated by analysing four different non-erected postures in which the spine does not lie onto sagittal plane, by the comparison with the traditional approach to symmetry line detection, having as reference the cutaneous marking. Results are analysed and critically discussed. [ABSTRACT FROM AUTHOR]

In this work, a new technique for symmetry line detection for asymmetric postures, which can not be investigated with the other methods presented in the literature, is proposed. It evaluates the symmetry line by means an adaptive process in which a first attempt is modified step by step until the solution converges to the best estimation. The method here proposed is validated by analysing four different asymmetric postures in which the spine lies far outside the sagittal plane, having as reference the cutaneous marking. Results are analysed and critically discussed. [ABSTRACT FROM AUTHOR]

Abstract: Objective. The objective of the present study is to improve the accuracy and reliability of the spinal midline reconstructions in scoliosis from back shape data. Design. An active shape model which covers the variety of scoliotic curves with a minimum of adjustable parameters is designed for the reconstruction of the spinal midline based on rasterstereographic back surface measurements. Background. To reduce the number of X-rays needed for patients with a scoliosis, an automatic method was developed for the reconstruction of spinal deformities from back shape data. Methods. 264 digital X-rays of 264 patients with scoliosis were used as a training set. By examining the statistics of the vertebral body centres a point distribution model was derived. The model is used as a basis to reconstruct the spinal midline from back shape data (active shape model). Results. 478 rasterstereographs of 114 scoliotic patients have been evaluated with this new procedure and with an existing procedure. Both procedures deliver a three-dimensional curve of the spinal midline. The frontal projections of these spinal midlines are compared with the vertebral centres of the corresponding 478 X-rays. The active shape model improved the results as compared to the existing procedure from σ x =3.4mm to σ x =3.0mm. Conclusion. The use of the active shape model improves the overall accuracy of the spinal midline reconstructions in scoliosis from back shape data. Relevance. Improvements to the accuracy and the reliability of the three-dimensional spinal reconstruction based on back shape data, can lead to an additional reduction of X-rays for patients with a scoliosis. [Copyright &y& Elsevier]

To reduce the amount of radiographs needed for patients with a scoliosis, a radiation-free method based on topographic images of the back was developed. An active contour model simulating spinal stiffness has been applied to video rasterstereographic (VRS) data. The aim of the present study is (a) to evaluate the applicability of active contours to improve the accuracy and the reliability of the three-dimensional (3D) spinal midline reconstruction from back surface data and (b) to design a more robust method to detect the spinal midline.To evaluate the reliability and accuracy, the active contour-based method is compared to a conventional procedure, which has been specifically developed for scoliosis; both methods produce a 3D curve of the spinal midline. The frontal projections and surface rotations of these spinal midlines are compared; r.m.s. deviations of 0.9 mm between the frontal curves and 0.4° between the surface rotations were obtained. Applying the active contour-based method does therefore not result in a substantial difference in accuracy to the conventional procedure.As a conclusion the active contour method is a valuable mathematical method that can accurately reconstruct the spinal midline based on back surface data. In addition, the method can be applied to various postures. [Copyright &y& Elsevier]

Objective. To determine the accuracy of rasterstereographic three-dimensional back surface analysis and reconstruction of the spine in idiopathic scoliosis treated by posterior correction and fusion.Design. Prospective imaging study of 25 patients with idiopathic scoliosis who underwent posterior correction and fusion and were followed for one year.Background. In an earlier study published in this journal rasterstereography has proved to be an accurate imaging modality for quantifying the changes in the three-dimensional shape of the spine and posterior rib cage after anterior correction and fusion. Goal of the present study was to determine the accuracy for the more common posterior correction and fusion with attention paid to the presence of the posterior implants and scarring.Methods. Twenty-five patients with idiopathic scoliosis with maximum Cobb angles of 78° were examined by rasterstereography and radiography. Seventy-one anterior–posterior radiographs were digitised. Twenty-four were preoperative and 47 postoperative radiographs. Rasterstereographic and radiographic curves were compared by best-fit superimposition. Root-mean-square differences were calculated as parameters of accuracy.Results. The accuracy of rasterstereography in severe idiopathic scoliosis with Cobb angles between 48° and 78° was satisfactory with root-mean-square differences of 5.8 mm for the lateral deviation and 4.8° for vertebral rotation. Following posterior correction the accuracy was good. The root-mean-square difference was 4.5 mm for the lateral deviation and 4.3° for vertebral rotation.Conclusion. The accuracy obtained for posteriorly-operated scolioses between 50° and 80° was similar to the findings for scolioses operated via anterior approach, as well as those with curves up to 50° Cobb angle. Therefore rasterstereography can be used postoperatively to reduce the number of radiographs and radiation exposure. Additionally, the method provides an objective quantification of the postoperative improvement in the cosmesis of the back shape.RelevanceIn the treatment of severe idiopathic scoliosis rasterstereography provides both a considerable reduction of X-rays and an objective documentation of the cosmesis before after scoliosis surgery. [Copyright &y& Elsevier]