Cameron M. Lee

Scanning fiber endoscopy with highly flexible, 1-mm catheterscopes for wide-field, full-color imaging

In modern endoscopy, wide field of view and full color are considered necessary for navigating inside the body, inspecting tissue for disease and guiding interventions such as biopsy or surgery. Current flexible endoscope technologies suffer from reduced resolution when device diameter shrinks. Endoscopic procedures today, using coherent fiber-bundle technology on the scale of 1 mm, are performed with such poor image quality that the clinicians vision meets the criteria for legal blindness. Here, we review a new and versatile scanning fiber-imaging technology and describe its implementation for ultrathin and flexible endoscopy. This scanning fiber endoscope (SFE) or catheterscope enables high-quality, laser-based, video imaging for ultrathin clinical applications, while also providing new options for in vivo biological research of subsurface tissue and high resolution fluorescence imaging.

Targeted detection of murine colonic dysplasia in vivo with flexible multispectral scanning fiber endoscopy

Gastrointestinal cancers are heterogeneous and can overexpress several protein targets that can be imaged simultaneously on endoscopy using multiple molecular probes. We aim to demonstrate a multispectral scanning fiber endoscope for wide-field fluorescence detection of colonic dysplasia. Excitation at 440, 532, and 635 nm is delivered into a single spiral scanning fiber, and fluorescence is collected by a ring of light-collecting optical fibers placed around the instrument periphery. Specific-binding peptides are selected with phage display technology using the CPC;Apc mouse model of spontaneous colonic dysplasia. Validation of peptide specificity is performed on flow cytometry and in vivo endoscopy. The peptides KCCFPAQ, AKPGYLS, and LTTHYKL are selected and labeled with 7-diethylaminocoumarin-3-carboxylic acid (DEAC), 5-carboxytetramethylrhodamine (TAMRA), and CF633, respectively. Separate droplets of KCCFPAQ-DEAC, AKPGYLS-TAMRA, and LTTHYKL-CF633 are distinguished at concentrations of 100 and 1 μM. Separate application of the fluorescent-labeled peptides demonstrate specific binding to colonic adenomas. The average target/background ratios are 1.71 ± 0.19 and 1.67 ± 0.12 for KCCFPAQ-DEAC and AKPGYLS-TAMRA, respectively. Administration of these two peptides together results in distinct binding patterns in the blue and green channels. Specific binding of two or more peptides can be distinguished in vivo using a novel multispectral endoscope to localize colonic dysplasia on real-time wide-field imaging.

Tethered Capsule Endoscopy, A Low-Cost and High-Performance Alternative Technology for the Screening of Esophageal Cancer and Barrett's Esophagus

Esophageal cancer is currently the fastest growing cancer in the United States. To help combat the recent rise in morbidity, our laboratory has developed a low-cost tethered capsule endoscope system (TCE) aimed at improving early detection of esophageal cancer. The TCE contains a resonant fiberoptic laser scanner (1.6 mm O.D.) which fits into 6.4-mm easy-to-swallow capsule at the distal tip. The tethered portion contains a single mode optical fiber multiplexed to three laser diodes at the proximal end. This design offers two main advantages over current endoscope technology. First, because of its small size, the TCE can be swallowed with minimal patient discomfort, thereby obviating sedation. Second, by imaging via directed laser light, the TCE is strategically positioned to employ several burgeoning laser-based diagnostic technologies, such as narrow-band, hyperspectral, and fluorescence imaging. It is believed that the combination of such imaging techniques with novel biomarkers of dysplasia will greatly assist in identifying precancerous conditions such as Barretts esophagus (BE). As the probe is swallowed, the fiber scanner captures high resolution, wide-field color images of the gastroesophageal junction (500 lines at 0.05-mm resolution) currently at 15-Hz frame rate. Video images are recorded as the capsule is slowly retracted by its tether. Accompanying software generates panoramic images from the video output by mosaicing individual frames to aid in pattern recognition. This initial report describes the rationale for the unique TCE system design, results from preliminary testing in vitro and in vivo, and discussion on the merits of this new platform technology as a basis for developing a low-cost screening program for esophageal cancer.

Multispectral endoscopic imaging of colorectal dysplasia in vivo

Light provides a broad range of colors in the visible and near-infrared (400–900 nm) spectrum that can be used to transmit information about molecular expression in normal and diseased tissues. The absorbance spectrum of hemoglobin, the primary chromophore in tissue, is shown in Fig. 1A. Genetic changes that occur in cancer transformation can be heterogeneous, and several signaling pathways may be activated concurrently.1 Moreover, molecular activity levels may vary between individual patients, at different time points, and within the tumor. Thus, a single genetic mutation is unlikely to characterize most disease processes over a general population. Unfortunately, most endoscopic imaging methods are sensitive to only one molecular parameter.2 Thus, a methodology that can image multiple molecular targets simultaneously is better suited to address the heterogeneity of cancer and achieve disease detection with high sensitivity and specificity desired for efficient surveillance. In addition, these multiplexed strategies can potentially visualize the interactions between signaling pathways and allow for better understanding of disease pathogenesis on a systems level. Figure 1 A) The visible and near-infrared spectrum of light provides a broad range of colors to generate molecular images from digestive tract mucosa that can be collected with a B) 1.6 mm diameter multispectral scanning fiber endoscope. C) Excitation is delivered ... Recently, significant progress has been made in advancing new methods of endoscopic imaging to target disease in the digestive tract, including the development of novel instruments and specific contrast agents.3 In this video journal, we aim to demonstrate the application of a novel, multispectral endoscope that uses a scanning fiber to image multiple targets at the same time. Fluorescence imaging can be achieved with high target-to-background ratios, and allow us to see the different target expression patterns in an Apc-mutation dependent mouse model of spontaneous colorectal adenomas using multiple peptides as targeting ligands.4

Low-cost wearable low-vision aid using a handmade retinal light-scanning microdisplay

The Wearable Low Vision Aid (WLVA) is a portable system that uses machine vision to track potential walking hazards for the visually impaired. A scanning fiber display couples a laser diode to a vibrating optical fiber that projects a virtual image onto the retina to display warning icons that the visually impaired can recognize. Initial low-vision subject testing has given promising results for this low-cost assistive device.

57.1: Near‐to‐Eye Display using Scanning Fiber Display Engine

: A novel near-to-eye display has been demonstrated, using a scanning fiber as the image source. Light is relayed from remote sources to the scanner via singlemode optical fiber. As a replacement for conventional LCD image sources, the fiber scanner reduces weight and power consumption, and enables a water-immersible display.

Efficient image segmentation of walking hazards using IR illumination in wearable low vision

Pulsed IR illumination is used to segment near obstacles and hazards from the background from incoming video to a wearable low vision aid that displays icons.

Wide field fluorescence imaging in narrow passageways using scanning fiber endoscope technology

An ultrathin scanning fiber endoscope (SFE) has been developed for high resolution imaging of regions in the body that are commonly inaccessible. The SFE produces 500 line color images at 30 Hz frame rate while maintaining a 1.2-1.7 mm outer diameter. The distal tip of the SFE houses a 9 mm rigid scan engine attached to a highly flexible tether (minimum bend radius < 8 mm) comprised of optical fibers and electrical wires within a protective sheath. Unlike other ultrathin technologies, the unique characteristics of this system have allowed the SFE to navigate narrow passages without sacrificing image quality. To date, the SFE has been used for in vivo imaging of the bile duct, esophagus and peripheral airways. In this study, the standard SFE operation was tailored to capture wide field fluorescence images and spectra. Green (523 nm) and blue (440 nm) lasers were used as illumination sources, while the white balance gain values were adjusted to accentuate red fluorescence signal. To demonstrate wide field fluorescence imaging of small lumens, the SFE was inserted into a phantom model of a human pancreatobiliary tract and navigated to a custom fluorescent target. Both wide field fluorescence and standard color images of the target were captured to demonstrate multimodal imaging.

P-251L: Late-News Poster: Miniature Wide-Throw-Angle Scanning Fiber Projection Display

Advances in mobile devices have enabled internet access and viewing of images and video, but small screens constrain the experience. We have developed a novel scanning fiber optical projector that is 1.07 mm in diameter and 13 mm long, and can project images at up to a 100° throw angle.

Evaluation of a novel, ultrathin, tip-bending endoscope in a synthetic force-sensing pancreas with comparison to medical guide wires

Purpose Direct visualization of pancreatic ductal tissue is critical for early diagnosis of pancreatic diseases and for guiding therapeutic interventions. A novel, ultrathin (5 Fr) scanning fiber endoscope (SFE) with tip-bending capability has been developed specifically to achieve high resolution imaging as a pancreatoscope during endoscopic retrograde cholangiopancreatography (ERCP). This device has potential to dramatically improve both diagnostic and therapeutic capabilities during ERCP by providing direct video feedback and tool guidance to clinicians. Methods Invasiveness of the new tip-bending SFE was evaluated by a performance comparison to ERCP guide wires, which are routinely inserted into the pancreatic duct during ERCP. An in vitro test model with four force sensors embedded in a synthetic pancreas was designed to detect and compare the insertion forces for 0.89 mm and 0.53 mm diameter guide wires as well as the 1.7 mm diameter SFE. Insertions were performed through the working channel of a therapeutic duodenoscope for the two types of guide wires and using a statistically similar direct insertion method for comparison to the SFE. Results Analysis of the forces detected by the sensors showed the smaller diameter 0.53 mm wire produced significantly less average and maximum forces during insertion than the larger diameter 0.89 mm wire. With the use of tip-bending and optical visualization, the 1.7 mm diameter SFE produced significantly less average force during insertion than the 0.89 mm wire at every sensor, despite its larger size. It was further shown that the use of tip-bending with the SFE significantly reduced the forces at all sensors, compared to insertions when tip-bending was not used. Conclusion Combining high quality video imaging with two-axis tip-bending allows a larger diameter guide wire-style device to be inserted into the pancreatic duct during ERCP with improved capacity to perform diagnostics and therapy.