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. 2025 Aug 23;167(1):227. doi: 10.1007/s00701-025-06645-x

Table 2.

Performance metrics of the keypoint region-based convolutional neural network (KR-CNN) including external and internal validation for automated measurement of thoracic Cobb angles in the validation cohort of patients undergoing long-segment posterior spinal fusion for adolescent idiopathic scoliosis correction

Model MAE ± SD (95% CI) MedAE (IQR; 95% CI) MSE SMAPE ICC GT
KR-CNN Resnet 50 (Current Study, External Validation) 2.22 ± 2.04 (1.06 to 3.39) 1.47 (0.73–2.97; 0.89 to 3.15) 9.1 4.29 0.98
KR-CNN Resnet 50 (Current Study, Internal Validation) 1.78 ± 1.61 (1.12 to 2.44) 1.21 (0.65–2.43; 0.81 to 2.74) 6.84 3.67 0.99
Landmark Net 13.85 — — 38.87 —
Angle Net 9.36 — — 23.91 —
AEC-Net 4.90 — — 23.59 —
Vertebra Landmark Detection — — — 10.81 —
Auto-CA — — — 5.27 —
VLTENet 2.51 — — 5.44 —
RegNet 2.92 — — 6.87
MVE-Net 7.81 24.94
Seg4Reg — — — 21.71 —
ScolioVis — — — 8.97 —
Minimum bounding rectangle — — — — 0.97

ICC Intraclass correlation coefficient, GT ground truth, IQR interquartile range, MAE Mean absolute error, MedAE Median absolute error, MSE Mean squared error, KR-CNN Keypoint Region-based convolutional neural network, Resnet 50 residual network 50, SD Standard deviation, SMAPE Symmetric mean absolute percentage error