  Imaging airway tissue, optical coherence tomography (OCT) provides
cross-sectional images of tissue structures, shows cilia movement and mucus
secretion, but does not provide sufficient contrast to differentiate individual
cells. By using fast sequences of microscopic resolution OCT (mOCT) images, OCT
can picture small signal fluctuations (dynamic) OCT and overcomes the lack in
contrast caused by speckle noise. In this way, OCT visualizes airway morphology
on a cellular level and allows to track the dynamic behavior of immune cells,
as well as mucus transport and secretion. Here, we demonstrate that mOCT, by
using temporal tissue fluctuation as contrast (dynamic OCT), provides the
possibility to study physiological and pathological tissue processes in vivo.
