Characterization of submucosal lesions using optical coherence tomography in the rabbit subglottis.

OBJECTIVE To evaluate the efficacy of optical coherence tomography in differentiating between several simulated subglottic lesions, using an ex vivo rabbit laryngotracheal model. DESIGN Laryngotracheal complexes were harvested from euthanized rabbits and divided into the following 4 groups: (1) control, (2) submucosal collagen injection (simulating scar formation), (3) dehydration and rehydration (simulating edema), and (4) repeated intubation trauma. The subglottic region was imaged using optical coherence tomography. Images were later correlated with conventional histologic findings. RESULTS The epithelium, basement membrane, lamina propria, perichondrium, and cartilage (cricoid and tracheal) were clearly imaged. In group 2, an increase in the thickness of the lamina propria was observed, in addition to a characteristic optical pattern of the injected collagen. Dehydration (in group 3) produced a visible reduction in the thickness of the lamina propria, while rehydration of the same specimen with distilled water revealed a significant increase in submucosal swelling. Repeated intubation (in group 4) resulted in tissue edema that was seen as wavy heterogeneous thickening of the lamina propria. Edema produced by repeated intubation or distilled water immersion was easily differentiated from native and collagen-injected tissues. CONCLUSION Optical coherence tomography successfully identifies the microstructure layers of the subglottis and can differentiate between edema and increased collagen deposition in the rabbit model.