Measurement of Ultrasound Coronal Angle as a Non-Radiological Alternative to Cobb Angle in School-Based Screening for Adolescent Scoliosis: Assessment of Accuracy, Validity, and Feasibility

Objective To evaluate the accuracy, validity, and feasibility of the ultrasound coronal angle (UCA) measured by a portable three-dimensional ultrasound imaging device as a non-radiological alternative to the Cobb angle in school-based screening for adolescent scoliosis. Methods A cross-sectional study was conducted in multiple regions of Gansu Province, China, from December 2024 to June 2025, involving 168 suspected adolescent scoliosis patients. A portable 3D ultrasound system (Scolioscan® Air) was used to obtain coronal plane images of the spine and measure the UCA. Concurrently, full-spine X-ray radiographs were taken to measure the Cobb angle. Measurement reliability was analyzed using intra-class correlation coefficient (ICC), mean absolute difference (MAD), and standard error of measurement (SEM). The correlation and agreement between UCA and Cobb angle were examined using Pearson correlation analysis, linear regression, and Bland-Altman analysis. Practical feasibility was assessed by comparing the measurement times of both methods. Results UCA showed a high correlation with the Cobb angle (r = 0.949, P  < 0.001), with a mean absolute difference of 2.1° and an SEM of 1.9°. UCA measurement demonstrated excellent intra-rater reliability (ICC = 0.899) and inter-operator consistency. The acquisition time for UCA was significantly shorter than for X-ray examination (7.2 ± 2.6 min vs. 37.5 ± 4.7 min, P  < 0.001), representing an efficiency improvement of approximately 79.2%. Conclusion The ultrasound coronal angle exhibits good reliability, validity, and time efficiency in school-based screening for adolescent scoliosis, and can serve as a radiation-free preliminary screening tool suitable for large-scale population screening.