Optical coherence tomography and confocal fluorescence microscopy as a combined method for studying morphological changes in lung dynamics

Abstract

Acute lung injury (ALI) is a severe pulmonary disease leading to hypoxemia accompanied by a reduced compliance and partial edema of the lung. Most of the patients have to be ventilated to compensate for the lack of oxygen. The treatment is strongly connected with ventilator induced lung injury (VILI), which is believed to introduce further stress to the lung and changes in its elastic performance. A thorough understanding of the organs micro-structure is crucial to gain more insight into the course of the disease. Due to backscattering of near-infrared light, detailed description of lung morphology can be obtained using optical coherence tomography (OCT), a non-invasive, non-contact, high resolution and fast three-dimensional imaging technique. One of its drawbacks lies in the non-specificity of light distribution in relation to defined substances, like elastic biomolecules. Using fluorescence detection, these chemical components can be visualized by introducing specifically binding fluorophores. This study presents a combined setup for studying alveolar compliance depending on volume changes and elastic fiber distributions. Simultaneously acquired OCT and confocal fluorescence images allow an entire view into morphological rearrangements during ventilation for an ex vivo mouse model using continuous pulmonary airway pressure at different values.