Semi-automatic ultrasound curve angle measurement for adolescent idiopathic scoliosis

De Yang, Timothy Tin Yan Lee, Kelly Ka Lee Lai, Tsz Ping Lam, Winnie Chiu Wing Chu, René Marten Castelein, Jack Chun Yiu Cheng, Yong Ping Zheng

Research output: Journal article publicationJournal articleAcademic researchpeer-review

5 Citations (Scopus)


Purpose: Using X-ray to evaluate adolescent idiopathic scoliosis (AIS) conditions is the clinical gold standard, with potential radiation hazards. 3D ultrasound has demonstrated its validity and reliability of estimating X-ray Cobb angle (XCA) using spinous process angle (SPA), which can be automatically measured. While angle measurement with ultrasound using spine transverse process-related landmarks (UCA) shows better agreed with XCA, its automatic measurement is challenging and not available yet. This research aimed to analyze and measure scoliotic angles through a novel semi-automatic UCA method. Methods: 100 AIS subjects (age: 15.0 ± 1.9 years, gender: 19 M and 81 F, Cobb: 25.5 ± 9.6°) underwent both 3D ultrasound and X-ray scanning on the same day. Scoliotic angles with XCA and UCA methods were measured manually; and transverse process-related features were identified/drawn for the semi-automatic UCA method. The semi-automatic method measured the spinal curvature with pairs of thoracic transverse processes and lumbar lumps in respective regions. Results: The new semi-automatic UCA method showed excellent correlations with manual XCA (R2 = 0.815: thoracic angles R2 = 0.857, lumbar angles R2 = 0.787); and excellent correlations with manual UCA (R2 = 0.866: thoracic angles R2 = 0.921, lumbar angles R2 = 0.780). The Bland–Altman plot also showed a good agreement against manual UCA/XCA. The MADs of semi-automatic UCA against XCA were less than 5°, which is clinically insignificant. Conclusion: The semi-automatic UCA method had demonstrated the possibilities of estimating manual XCA and UCA. Further advancement in image processing to detect the vertebral landmarks in ultrasound images could help building a fully automated measurement method. Level of evidence: Level III.

Original languageEnglish
Pages (from-to)351-359
Number of pages9
JournalSpine Deformity
Issue number2
Publication statusPublished - Mar 2022


  • 3D ultrasound
  • AIS
  • Cobb
  • Scoliotic angles
  • Transverse process

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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