[Evaluation of pediatric adenoid hypertrophy based on CBCT and lateral cephalograms with multiple regression analysis].

Objective: To investigate the correlations and regression models among adenoid-nasopharynx measurement indices (the linear ratio A/N, the two-dimensional area ratio 2D_A/N, and the three-dimensional volume ratio 3D_A/N), to evaluate the feasibility of predicting three-dimensional parameters from two-dimensional measurements. Methods: This cross-sectional study analysed 4 307 CBCT scans and lateral nasopharyngeal radiographs from 4-12-year-old children (July 2023-January 2025). Children with acute infection, major systemic disease, craniofacial anomalies, prior maxillofacial surgery, poor-quality images, or no consent were excluded. 3D_A/N was defined as adenoid volume/(adenoid+airway volume); 2D_A/N as adenoid area/total area; and linear A/N as adenoid thickness/nasopharyngeal thickness. Pearson correlation and multiple linear regression were used to quantify 2D-to-3D agreement, and independent-sample t-tests were employed to compare age, sex and seasonal subgroups. Results: (1) Significant sex-related differences in adenoid hypertrophy were detected at ages 5, 8, 9 and 11 years. In the 5-year-old group, females had significantly higher 3D_A/N and 2D_A/N values than males (3D_A/N: 0.76±0.10 vs. 0.74±0.10, t=-1.99, P=0.047; 2D_A/N: 0.66±0.10 vs. 0.64±0.09, t=-2.71, P=0.007). In the 8-year-old group, males exhibited significantly higher A/N and 3D_A/N values than females (A/N: 0.64±0.06 vs. 0.63±0.06, t=4.49, P<0.001; 3D_A/N: 0.66±0.12 vs. 0.64±0.12, t=2.00, P=0.046). In the 9-year-old group, males showed significantly higher 3D_A/N values than females (0.65±0.11 vs. 0.63±0.12, t=2.46, P=0.014). In the 11-year-old group, males had significantly higher A/N values than females (0.62±0.06 vs. 0.59±0.05, t=4.79, P<0.001). (2) The linear A/N ratio correlated moderately with 3D_A/N (r=0.82), whereas, 2D_A/N showed an excellent correlation (r=0.97); multiple regression confirmed 2D_A/N as the principal predictor of 3D_A/N. (3) Seasonal analysis revealed markedly greater adenoid hypertrophy in winter than in summer for children aged 4-9 years, while, no seasonal difference was found in the 10-12 year group; overall, winter hypertrophy was most pronounced in younger children. Conclusion: 2D_A/N demonstrates a marked advantage in predicting 3D_A/N. When combined with A/N and age factors, it can effectively model changes in the 3D volume ratio of the adenoid, underscoring the clinical value of lateral cephalometric measurements for evaluating adenoid hypertrophy in children. Moreover, adenoid hypertrophy is influenced by age, sex and seasonal factors.