Beyond X-Rays: exploring correlation with surface topography measurements for safer scoliosis surveillance

Abstract

The management of adolescent idiopathic scoliosis (AIS) generally involves the repeated acquisition of full-spine radiographs, which leads to an increased risk of developing cancer due to cumulative radiation exposure. For this reason, several non-radiating techniques, such as surface topography (ST) are being investigated. In this study, 3D ST scans of 10 female AIS patients and their corresponding full-spine radiographs were obtained to study the correlation between measurements in both modalities, as well as the reliability of ST metrics. Specifically, the Cobb angle, coronal balance and pelvic obliquity were measured in the plain X-rays, while Root Mean Square (RMS), Posterior Trunk Symmetry Index (POTSI) and Horizontal Plane Deformity Index (DHOPI) were calculated in the ST volumes. All ST measurements achieved intra-observer correlation coefficients exceeding 0.89, demonstrating high reliability. Significant correlations were found between ST metrics and the main curve Cobb angle (0.83 for RMS, 0.87 for POTSI, and 0.76 for DHOPI), indicating strong agreement with the gold standard. However, correlations with coronal balance and pelvic obliquity were not statistically significant (p-value > 0.05). These findings suggest that ST holds great potential for quantifying spinal deformity, potentially reducing the dependence with radiographs. Even though ST cannot yet replace X-ray evaluation entirely, a combined approach could help reduce radiation exposure in the management of AIS patients.