Correlation between Cobb Angle and Spinous Process Angle Measured from Ultrasound Data

Abstract

The correlation between the Cobb angle and spinous process angle (SPA) measured from ultrasound data was analyzed in this study. The three-dimensional (3D) spine model was reconstructed by using a freehand 3D ultrasound imaging system. With non-planar volume rendering, the Cobb angle and SPA were measured by manually detecting anatomical landmarks of the spine. A thoracic spinal phantom set in 24 different poses was used in the experiment. For each spinal curve, the Cobb angle and SPA were measured twice by three observers, respectively. Results showed that the correlation coefficients between these two measurements were 0.92 and 0.78 for the curves with two-dimensional (2D) and 3D deformity, respectively. Results indicate that the SPA has high correlation with the Cobb angle measured from ultrasound data, especially for the curves with 2D deformity. Therefore, SPA may be used as an alternative parameter to the Cobb angle for scoliosis assessment in an ultrasound imaging system.