Three refrigerated, unfixed, unfrozen, deidentified cadaveric specimens were obtained from the state anatomy board within the first 7 postmortem days. This cadaveric series was conducted in accordance with institutional review board approval (NA 00070589). Before intervention, the specimens underwent simulation CT imaging (Brilliance Big Bore CT [Royal Philips Electronics], 3-mm slices, 120 kVp, 300 mA, 60-cm field of view). All procedures were performed by interventional pulmonology and thoracic surgery specialists. Real-time endobronchial and esophageal ultrasound were used to confirm hydrogel placement, and images were digitally saved. After hydrogel implantation, repeat CT imaging simulation, T2-weighted MRI (MAGNETOM Espree 1.5T [Siemens Medical Solutions USA, Inc]; repetition time, 5.68 s; excitation pulse time, 82 ms; field of view, 30 cm; slices, 5.0 mm) fluid attenuated inversion recovery MRI sequences (repetition time, 9.0 s; excitement time, 120 milliseconds; inversion time 25.0 s; field of view, 22 cm; slices, 3.0 mm slices; anterior-posterior phase encoding), planar radiography, and cone beam CT imaging (Synergy [Elekta AB] linear accelerator, 120 kVp, 40 mA/frame, 40 ms/frame, 350° rotation, 410 × 120 × 410 matrix, 3-mm slices, M20 collimator) were performed.