Title : Non-radiologic measurement and 3-D surface imaging techniques for pectus deformity severity assessment and monitoring: A scoping review of diagnostic approaches, clinical applications, and implications for bracing
Abstract:
Pectus Excavatum (PE) and Pectus Carinatum (PC) are the most common congenital deformities of the anterior chest wall. Accurate, non-invasive assessment methods are essential for diagnosis, treatment planning, and monitoring especially in children undergoing orthotic bracing. Conventional radiologic techniques such as CT and MRI provide detailed anatomical data but present limitations, including radiation exposure, cost, and limited feasibility for routine follow-up.
This scoping review explores the expanding use of non-radiologic methods particularly 3D surface imaging and anthropometric approaches for assessing the severity of PE and PC. The review aims to map the literature on diagnostic indices derived from optical surface data and evaluate their clinical application, correlation with radiologic benchmarks, and potential for use in bracing.
A systematic search of Scopus and PubMed (up to June 2025) was conducted, including English-language studies focused on external, non-radiologic assessment methods such as 3D optical scanning, photogrammetry, and linear or volumetric index derivation. Commonly cited indices included the External Correction Index (XCI), Correction Index 3D (CI3D), External Haller Index (EHI), Hebal-Malas Index (HMI), Optical Index (OI), and Surface Lengths Pectus Index (SLPI), among others.
Findings revealed strong correlations between several surface-based indices and traditional CT-derived metrics, with many studies reporting r-values above 0.80. Certain indices showed particular promise for tracking progress during bracing and informing clinical decision-making. Despite the growing body of evidence, methodological heterogeneity, limited sample sizes, and varied technologies restricted cross-study comparisons. Most studies focused on pediatric populations and involved custom-built or commercial 3D scanning systems.
Although this review did not include a formal quality appraisal or meta-analysis, the findings suggest that surface-based assessments offer a safe, repeatable, and clinically useful alternative for pectus evaluation. Broader adoption will require standardised protocols and larger validation studies. Still, these techniques present a compelling option for radiation-free monitoring in conservative orthotic care settings.
