Optofluidic needle probe integrating targeted delivery of fluid with optical coherence tomography imaging

We present an optofluidic optical coherence tomography (OCT) needle probe capable of modifying the local optical properties of tissue to improve needle-probe imaging performance. The side-viewing probe comprises an all-fiber-optic design encased in a hypodermic needle (outer diameter 720 μm) and integrates a coaxial fluid-filled channel, terminated by an outlet adjacent to the imaging window, allowing focal injection of fluid to a target tissue. This is the first fully integrated OCT needle probe design to incorporate fluid injection into the imaging mechanism. The utility of this probe is demonstrated in air-filled sheep lungs, where injection of small quantities of saline is shown, by local refractive index matching, to greatly improve image penetration through multiple layers of alveoli. 3D OCT images are correlated against histology, showing improvement in the capability to image lung structures such as bronchioles and blood vessels.