Differential structured illumination microendoscopy for in vivo imaging of molecular contrast agents

Significance Advances in molecular-targeted optical imaging probes offer the opportunity to identify and monitor pathophysiologic processes; to achieve this promise, there is an important need to develop devices capable of imaging probes in vivo at the cellular level. The challenge is to build devices that overcome the many optical and mechanical challenges associated with imaging soft tissue inside the body. Fiber optic microendoscopy has shown promise for in vivo imaging, but image contrast in highly scattering tissue is severely limited by out-of-focus light. In this paper, we demonstrate differential structured illumination microendoscopy (DSIMe) to image molecular contrast agents in vivo. We demonstrate improved image contrast of DSIMe when imaging patients with cervical adenocarcinoma in situ to detect atypia associated with neoplasia. Fiber optic microendoscopy has shown promise for visualization of molecular contrast agents used to study disease in vivo. However, fiber optic microendoscopes have limited optical sectioning capability, and image contrast is limited by out-of-focus light generated in highly scattering tissue. Optical sectioning techniques have been used in microendoscopes to remove out-of-focus light but reduce imaging speed or rely on bulky optical elements that prevent in vivo imaging. Here, we present differential structured illumination microendoscopy (DSIMe), a fiber optic system that can perform structured illumination in real time for optical sectioning without any opto-mechanical components attached to the distal tip of the fiber bundle. We demonstrate the use of DSIMe during in vivo fluorescence imaging in patients undergoing surgery for cervical adenocarcinoma in situ. Images acquired using DSIMe show greater contrast than standard microendoscopy, improving the ability to detect cellular atypia associated with neoplasia.