Reliability, validity, and precision of an active stereophotogrammetry system for three-dimensional evaluation of the human torso

To determine the reliability, stability, validity and precision of a stereophotogrammetry (SP) system for use in quantifying the complex three-dimensional 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 23.5 cm2 for surface area and 32 mL for volume. These results demonstrate 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.