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Title: A reliability and validity study for Scolioscan : a radiation-free scoliosis assessment system using 3D ultrasound imaging
Authors: Zheng, YP 
Lee, TY
Lai, KL
Yip, BHK
Zhou, G
Jiang, W
Cheung, CWJ 
Wong, MS 
Cheng, JCY
Lam, TP
Issue Date: 2016
Source: Scoliosis and spinal disorders, 2016, v. 11, 13, p. 1-15
Abstract: Background: Radiographic evaluation for patients with scoliosis using Cobb method is the current gold standard, but radiography has radiation hazards. Several groups have recently demonstrated the feasibility of using 3D ultrasound for the evaluation of scoliosis. Ultrasound imaging is radiation-free, comparatively more accessible, and inexpensive. However, a reliable and valid 3D ultrasound system ready for clinical scoliosis assessment has not yet been reported. Scolioscan is a newly developed system targeted for scoliosis assessment in clinics by using coronal images of spine generated by a 3D ultrasound volume projection imaging method. The aim of this study is to test the reliability of spine deformity measurement of Scolioscan and its validity compared to the gold standard Cobb angle measurements from radiography in adolescent idiopathic scoliosis (AIS) patients.
Methods: Prospective study divided into two stages: 1) Investigation of intra-and inter-reliability between two operators for acquiring images using Scolioscan and among three raters for measuring spinal curves from those images; 2) Correlation between the Cobb angle obtained from radiography by a medical doctor and the spine curve angle obtained using Scolioscan (Scolioscan angle). The raters for ultrasound images and the doctors for evaluating radiographic images were mutually blinded. The two stages of tests involved 20 (80 % females, total of 26 angles, age of 16.4 +/- 2.7 years, and Cobb angle of 27.6 +/- 11.8 degrees) and 49 (69 % female, 73 angles, 15.8 +/- 2.7 years and 24.8 +/- 9.7 degrees) AIS patients, respectively. Intra-class correlation coefficients (ICC) and Bland-Altman plots and root-mean-square differences (RMS) were employed to determine correlations, which interpreted based on defined criteria.
Results: We demonstrated a very good intra-rater and intra-operator reliability for Scolioscan angle measurement with ICC larger than 0.94 and 0.88, respectively. Very good inter-rater and inter-operator reliability was also demonstrated, with both ICC larger than 0.87. For the thoracic deformity measurement, the RMS were 2.5 and 3.3 degrees in the intra-and inter-operator tests, and 1.5 and 3.6 degrees in the intra-and inter-rater tests, respectively. The RMS differences were 3.1, 3.1, 1. 6, 3.7 degrees in the intra-and inter-operator and intra-and inter-rater tests, respectively, for the lumbar angle measurement. Moderate to strong correlations (R-2 > 0.72) were observed between the Scolioscan angles and Cobb angles for both the thoracic and lumbar regions. It was noted that the Scolioscan angle slightly underestimated the spinal deformity in comparison with Cobb angle, and an overall regression equation y = 1.1797x (R-2 = 0.76) could be used to translate the Scolioscan angle (x) to Cobb angle (y) for this group of patients. The RMS difference between Scolioscan angle and Cobb angle was 4.7 and 6.2 degrees, with and without the correlation using the overall regression equation.
Conclusions: We showed that Scolioscan is reliable for measuring coronal deformity for patients with AIS and appears promising in screening large numbers of patients, for progress monitoring, and evaluation of treatment outcomes. Due to it being radiation-free and relatively low-cost, Scolioscan has potential to be widely implemented and may contribute to reducing radiation dose during serial monitoring.
Keywords: Scoliosis
Cobb angle
3D ultrasound
Volume projection imaging
Publisher: BioMed Central
Journal: Scoliosis and spinal disorders 
ISSN: 2397-1789
DOI: 10.1186/s13013-016-0074-y
Rights: © 2016 Zheng et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.
The following publication Zheng, Y. P., Lee, T. Y., Lai, K. L., Yip, B. H. K., Zhou, G., Jiang, W., … Lam, T. P. (2016). A reliability and validity study for Scolioscan : a radiation-free scoliosis assessment system using 3D ultrasound imaging. Scoliosis and Spinal Disorders, 11, 13, 1-15 is available at
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