Adolescent idiopathic scoliosis (AIS) has a prevalence of 1%-3%, with over one million patients in China, predominantly female. Currently, there is a lack of effective and safe diagnostic tools beyond X-ray.

This study aimed to evaluate the efficacy of rastertereography (RST) in diagnosing AIS in adolescents and to assess the validity and reliability of spinal sagittal and transverse parameter measurements.

Data from 70 adolescents with suspected AIS treated at Wangjing Hospital of China Academy of Chinese Medical Sciences in 2023 were randomly selected, including biplanar X-ray, angle of trunk rotation (ATR), and RST measurements. To evaluate the validity of spinal angles provided by RST, Cobb angle, thoracic kyphosis (TK) (T₁-T₁₂), lumbar lordosis (LL) (L₁-L₅), and vertebral rotation angle (ROT) measured by RST were compared with X-ray and manual measurements. Pearson correlation and intraclass correlation coefficient (ICC) consistency tests were performed to validate the diagnostic efficacy of RST. Receiver operating characteristic (ROC) curve analysis with area under the curve (AUC) was employed to describe the diagnostic capability of RST-measured spinal parameters for AIS (defined as Cobb angle≥10°), and Youden's index was used to determine optimal cutoff values (sensitivity and specificity).

The Cobb angle measured by RST was smaller than that by X-ray (t=3.056, P=0.003), with a correlation coefficient of 0.724 and good reliability (ICC=0.710). RST-measured TK was smaller than X-ray values (t=1.511, P=0.135), with a moderate correlation (r=0.538 8, ICC=0.520). RST-measured LL was smaller than X-ray values (t=2.700, P=0.008), with moderate correlation (r=0.595 6, ICC=0.589). RST-measured ROT was significantly greater than ATR (t=3.627, P<0.001), with moderate correlation (r=0.639 0, ICC=0.626). The AUC for RST-measured Cobb angle in diagnosing AIS was 0.895 (95%CI=0.815-0.975), with an optimal cutoff of 8.5° (sensitivity=0.769, specificity=0.889). The AUC for RST-measured ROT was 0.697 (95%CI=0.550-0.844), cutoff=3.75° (sensitivity=0.692, specificity=0.667). ATR had an AUC of 0.638 (95%CI=0.486-0.790), cutoff=2.50° (sensitivity=0.673, specificity=0.566).

Compared with X-ray, RST demonstrated moderate reliability in measuring spinal parameters. Given its operational simplicity, RST may be considered for large-scale early screening in adolescent populations, though cost-effectiveness analyses against traditional methods are warranted.