Three-dimensional Imaging of subpleural Alveoli by Fourier Domain Optical Coherence Tomography

Abstract

Understanding alveolar mechanics is essential to improve artificial ventilation strategies and hence minimize ventilator associated lung injury. The investigation of alveolar geometry changes during ventilation was performed by intravital microscopy (IVM) and 3D Fourier domain optical coherence tomography (3D-OCT) in an in-vivo mouse model and in isolated, perfused and ventilated rabbit lungs. Air pocket size of individual alveoli was quantified in the en-face view. For both imaging techniques, IVM and 3D-OCT, subpleural air-pocket size was positively correlated with the applied airway pressure (endinspiratory pressure or continuous positive airway pressure, respectively). No alveolar recruitment/derecruitment was observed. We conclude that in the non-injured lung alveolar expansion rather than recruitment is the main mechanism of volume uptake. We demonstrated that OCT allows a 3D reconstruction of a single alveolus for several inspiratory pressure levels and consequently display a volume change of an alveolar structure in an in vivo situation. © 2009 Springer Berlin Heidelberg.