Freehand three-dimensional ultrasound system for assessment of scoliosis

Background/Objective: Standing radiograph with Cobb's method is routinely used to diagnose scoliosis, a medical condition defined as a lateral spine curvature > 10 degrees with concordant vertebral rotation. However, radiation hazard and two-dimensional (2-D) viewing of 3-D anatomy restrict the application of radiograph in scoliosis examination. Methods: In this study, a freehand 3-D ultrasound system was developed for the radiation-free assessment of scoliosis. Bony landmarks of the spineweremanually extracted froma series of ultrasound images with their spatial information recorded to form a 3-D spine model for measuring its curvature. To validate its feasibility, in vivo measurements were conducted in 28 volunteers (age: 28.0 +/- 13.0 years, 9 males and 19 females). A significant linear correlation (R-2 = 0.86; p < 0.001) was found between the spine curvatures as measured by Cobb's method and the 3-D ultra sound imaging with transverse process andsuperior articular processas landmarks. Theintra-and interobserver tests indicated that the proposed method is repeatable. Results: The 3-D ultrasoundmethod using bony landmarks tended to underestimate the deformity, and a proper scaling is required. Nevertheless, this study demonstrated the feasibility of the freehand 3-D ultrasound system to assess scoliosis in the standing posture with the proposed methods and 3-D spine profile. Conclusion: Further studies are required to understand the variations that exist between the ultrasound and radiograph results with a larger number of volunteers, and to demonstrate its potential clinical applications formonitoring of scoliosis patients. Through further clinical trials and development, the reported 3-D ultrasound imaging system can potentially be used for scoliosis mass screening and frequent monitoring of progress and treatment outcome because of its radiationfree and easy accessibility feature. Copyright (C) 2015, The Authors. Published by Elsevier (Singapore) Pte Ltd. This is an open access article under the CC BY-NC-ND license.