Background: Standard modalities to assist in determining the extent of chest wall developmental deformities in patients include x-ray and computed tomography (CT). The purpose of this study is to describe an optical imaging technique that provides accurate cross-sectional images of the chest, and to compare these with standard CT-derived images of chest wall abnormalities.
Patients and methods: Ten patients (5 pectus excavatum and 5 pectus carinatum) underwent imaging that included limited CT and optical cross-sectional imaging. Severity indices of the deformity using the standard Haller index (HI) were calculated from CT scans. A similar severity measurement of deformity was derived from the outline of torso cross sections (ie, from skin to skin measurements) obtained from optical images. To assess the severity of carinatum defects, a modified pectus index was derived, which measures the anterior chest protrusion from the central chord of the chest cross section. We performed regression analyses, comparing the indices obtained from CT and optical imaging methodologies.
Results: Optical measures of cross-sectional deformities correlated well with standard HI (r2 = 0.94) and even better with the modified pectus index (r2 = 0.96). Adaptation of the HI for pectus carinatum deformity evaluation was effective, and consistent with the torso surface deformity measures.
Conclusions: Torso models from optical imaging offer 3-D images of the chest wall deformity with no radiation exposure. This preliminary study showed promising results for the use of torso surface measurement as an alternative index of pectus deformities; if validated in larger studies, these measures may be useful for following chest wall abnormalities, using repeated studies in patients.