Stereo photogrammetry soft tissue imaging

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Abstract

In preparation to begin study of human subjects with dysmorphology of the trunk, the technical capabilities of a commercially available stereophotogrammetry system have been assessed. We performed a study to determine the reliability, stability, validity and precision of a stereophotogrammetry (SP) system for use in quantifying the complex three-dimensional (3D) structure of the human torso. We performed assessments of the system using images of geometric solids and a human-form mannequin. Analysis of geometric solids revealed excellent intra- and interrater reliability of the system for linear, surface area and volume measurements (r > 0.99, P < 0.001). Overall, no significant difference was found between SP and manual measurements (F = 4.23, P > 0.06). The system exhibited excellent stability in images of the mannequin over time (r > 0.99). The limit of precision (error > 5%) of the system to detect objects on the surface of the mannequin was estimated at an object size of 23.5cm2 for surface area and 32mL for volume. These results demonstrated the capability of SP of the torso to be used as a reliable, stable and valid measure of torso morphology to be applied as a clinical outcome tool in studies of bony and soft tissue pathologies such as scoliosis, rib deformities, obesity or edema. A materials transfer agreement with the University of Alberta, Canada has been completed to share software developed to analyze the images obtained with the stereophotogrammetry system. A human subjects protocol to initiate study of stereophotogrammetry as an outcome measure in scoliosis, chest deformities and truncal obesity was approved by the NIDCR IRB. Enrollment and data gathering on the first phase of the study, analysis of healthy volunteers has been completed. Analysis of data obtained in this phase of the study almost complete. Accrual of subjects with scoliosis and/or rib deformities will begin soon. Subsequent to that accrual and analysis, the information gained will be applied to accrual and analysis of persons with truncal obesity.