In situ 3D imaging of alveoli with a 30 gauge side-facing optical needle probe

In situ imaging of alveoli and small airways with optical coherence tomography (OCT) needle probes has significant potential in the study and clinical assessment of lung disease. We present the smallest reported OCT needle probe capable of acquiring 3D volumetric data. The side-facing needle probe comprises miniaturized focusing optics consisting of no-core and GRIN fibre, terminated with a reflection-coated, fibre tip beam deflector. The optics are encased within a 30-gauge (outer diameter 310 μm) needle, and interfaced to a spectral-domain OCT scanner. Multiple 3D-OCT data sets were acquired on preterm lamb lungs (excised) filled with amniotic fluid and saline. Results demonstrated the ability of such a probe to image individual alveoli and bronchioles, and enabled the rendering of 3D volumetric visualisations of the data. We observed notably less tissue distortion than in earlier work with larger 23 gauge needle probes.