Validation of Single C-Arm Fluoroscopic Technique for Measuring In Vivo Abdominal Wall Deformation

Abstract

Hernia meshes significantly reduce the recurrence rates in hernia repair. It is known that they affect the abdominal wall postimplantation, yet the understanding of in vivo mechanics in the mesh placement area is lacking. We established a single C-arm biplane fluoroscopic system to study strains at the interface between the mesh and repaired abdominal tissues. We aimed to validate this system for future porcine hernia repair studies. Custom matlab programs were written to correct for pincushion distortion, and direct linear transformation (DLT) reconstructed objects in 3D. Using a custom biplane-trough setup, image sets were acquired throughout the calibrated volume to evaluate a radio-opaque test piece with known distances between adjacent beads. Distances were measured postprocessing and compared to known measurements. Repeatability testing was conducted by taking image sets of the test piece in a fixed location to determine system movement. The error in areal stretch tracking was evaluated by imaging a square plate with fixed radio-opaque beads and using matlab programs to compare the measured areal stretch to known bead positions. Minor differences between measured and known distances in the test piece were not statistically different, and the system yielded a 0.01 mm bias in the XY plane and a precision of 0.61 mm. The measured areal stretch was 0.996, which was not significantly different than the expected value of 1. In addition, preliminary stretch data for a hernia mesh in a porcine model demonstrated technique feasibility to measure in vivo porcine abdominal mechanics.