(417) Radiographic Quantification of Tracheal Autografts

Introduction: Tracheal defects ultimately require tissue replacement for adequate reconstruction. We previously demonstrated the use of partially decellularized tracheal grafts to support regeneration of tracheal neotissue, however there is increased graft calcification in vivo. To distinguish graft versus surgical causes of cartilage calcification, we used a rabbit model of tracheal autograft and performed surveillance imaging of the graft in vivo. We hypothesize that tracheal autografts maintain patency and that grafts would demonstrate higher calcification at 3 and 6 months compared to native trachea.

Methods: Four male New Zealand White Rabbits underwent tracheal autograft. Briefly, a ~1 cm segment of trachea was resected and reimplanted. Three dimensional (3D) fluoroscopy was performed on days 0, 90 and 180. Three-dimensional reconstructions of the graft were created to calculate the average luminal area and quantify the Hounsfield units (HU) normalized by host. At endpoint (6 months), grafts were explanted and ex vivo imaging was performed using microCT and compared to native trachea (nonsurgical controls).

Results: All animals survived to endpoint without signs of respiratory distress. Grafts remained patent throughout the time points (90d: 28.9 ± 2.06 mm2; p=0.9771); 180d: 29.22 ± 2.09 mm2; p=0.9088) and equivalent to host airway dimensions (90d: 30.28 mm2 ± 0.78; 180d: 29.79 mm2 ± 2.07; p=0.691). There was an increase in autograft calcification seen with microCT at 180 days (2245 mm2 ±83.87) which was not observed in adjacent host trachea (1971mm2 ± 69.25; p< 0.05) or nonsurgical controls (2126 mm2 ± 76.71; p< 0.05).

Conclusions: Surgical management of the trachea results in an increase in graft calcification, which appears to increase over time. Orthotopic tracheal replacement does not result in changes in graft area after surgery. This suggests that calcification is part of the wound healing and remodeling of tracheal implantation. The impact of calcification on graft mechanics and graft viability remains unclear and will be explored in further studies.