High frame rate video mosaicking microendoscope to image large regions of intact tissue with subcellular resolution

Abstract

High-resolution microendoscopy (HRME) is a low-cost strategy to acquire images of intact tissue with subcellular resolution at frame rates ranging from 11 to 18 fps. Current HRME imaging strategies are limited by the small microendoscope field of view (∼0.5 mm2); multiple images must be acquired and reliably registered to assess large regions of clinical interest. Image mosaics have been assembled from co-registered frames of video acquired as a microendoscope is slowly moved across the tissue surface, but the slow frame rate of previous HRME systems made this approach impractical for acquiring quality mosaicked images from large regions of interest. Here, we present a novel video mosaicking microendoscope incorporating a high frame rate CMOS sensor and optical probe holder to enable high-speed, high quality interrogation of large tissue regions of interest. Microendoscopy videos acquired at >90 fps are assembled into an image mosaic. We assessed registration accuracy and image sharpness across the mosaic for images acquired with a handheld probe over a range of translational speeds. This high frame rate video mosaicking microendoscope enables in vivo probe translation at >15 millimeters per second while preserving high image quality and accurate mosaicking, increasing the size of the region of interest that can be interrogated at high resolution from 0.5 mm2 to >30 mm2. Real-time deployment of this high-frame rate system is demonstrated in vivo and source code made publicly available.

Multiscale Optical Imaging with Real Time Projection of Cancer Risk and Biopsy Guidance Maps for Early Oral Cancer Diagnosis and Treatment

“…The high frame rate of the microscope and the large percentage of overlap between subsequent frames enables detection of subtle changes in cellular morphology at the surface of the epithelium. We have previously shown that this high frame rate combined with image analysis techniques can effectively increase the eld of view of the microscope through the generation of high-quality mosaics 27 . While these large mosaics can be used to directly visualize large areas of the epithelium, previous implementations were unable to provide diagnostic guidance based on these generated mosaics.…”

“…Mosaic Generation. High resolution mosaics were generated using a previously described approach 27 . Brie y, the region of the image corresponding to the active area of the ber bundle is identi ed and all frames are downsampled to remove the ber bundle pattern from the image.…”

“…The Active Biopsy Guidance System (ABGS) consists of two optical subsystems controlled through a single user interface: (1) a camera and projector capable of white light and auto uorescence image acquisition and real time projection of visible risk maps on the tissue surface and (2) a microscope with a ber optic probe that can directly image nuclear morphology 27 . The ABGS and its associated software are designed to guide a clinician through wide eld and high-resolution imaging to determine if and where a biopsy is needed for early detection of oral cancer and its precursors.…”

“…These systems use a ber-optic probe to image the super cial oral epithelium with sub-cellular resolution, albeit with a limited eld of view. Recent advances in video mosaicking allow larger image mosaics to be created in real-time, effectively increasing the eld of view [27][28][29] .…”

Multimodal optical imaging with real-time projection of cancer risk and biopsy guidance maps for early oral cancer diagnosis and treatment

“…The ABGS consists of two subsystems controlled through a single user interface: (1) a camera and projector for white light (WL) and AF image acquisition and real-time projection of visible risk maps and (2) a microscope with a fiber optic probe to image nuclear morphology. 21 The ABGS is designed to guide a clinician through widefield and microscopic imaging to determine if and where a biopsy is needed for early detection of oral cancer and its precursors. Figure 1(a) shows a photograph of the ABGS system; the camera and projector are assembled and housed in a 3D-printed enclosure and mounted on a portable articulated arm.…”