Radiation-induced lung injury using a pig model. Evaluation by high-resolution computed tomography.

Rationale and Objectives: To assess the early phase of radiation-induced lung injury using high-resolution computed tomography (CT) under experimental conditions and to perform precise CT-pathologic correlation.
Methods: Five Yorkshire pigs received a single dose of 12.5 Gy to the right lower lung. Computed tomographic images were obtained at 2-week intervals. The animals were killed after follow-up periods of 4-16 weeks. The lungs were removed, inflated, fixed, dried, and sliced corresponding to the CT sections. Computed tomography, specimen radiography, and histologic findings were correlated.
Results: Various CT findings were observed during the first 16 weeks, including ground-glass opacity, discrete consolidation, patchy consolidation, thickened interlobular septum, and bronchovascular bundle. Ground-glass opacity was associated with thickened alveolar wall and scattered tiny fibrotic foci. Thickened interlobular septum and bronchovascular bundle were the results of fibrosis adjacent to these structures. Discrete consolidation correlated with intraalveolar edema with hemorrhage and infiltration of inflammatory cells.
Conclusions: High-resolution CT correlated well with pathology of the lung due to radiation injury as verified by precise radiologic-pathologic correlation.