An all-fiber-optic endoscopy platform for simultaneous OCT and fluorescence imaging

Abstract

We present an all-fiber-optically based endoscope platform for simultaneous optical coherence tomography (OCT) and fluorescence imaging. This design entails the use of double-clad fiber (DCF) in the endoscope for delivery of OCT source and fluorescence excitation light while collecting the backscattered OCT signal through the single-mode core and fluorescence emission through the large inner cladding of the DCF. Circumferential beam scanning was performed by rotating a 45° reflector using a miniature DC motor at the distal end of the endoscope. Additionally, a custom DCF coupler and a wavelength division multiplexer (WDM) were utilized to seamlessly integrate both imaging modalities to achieve an entirely fiber-optically based dual-modality imaging system. We demonstrated simultaneous intraluminal 3D OCT and 2D (surface) fluorescence imaging in ex vivo rabbit esophagus using the dual-modal endomicroscopy system. Structural morphologies (provided by OCT) and fluorophore distribution (provided by the fluorescence module) could be clearly visualized, suggesting the potential of the dual-modality system for future in vivo and clinical applications.

Circumferential optical coherence tomography angiography imaging of the swine esophagus using a micromotor balloon catheter

“…Due to their small size, precise alignment, centering and mounting were required for both components. A custom machined brass housing (Kroll Technologies, PA) housed and encapsulated the distal end components, which featured a three-strut design [35] with a ~20° circumferential extent for each strut to provide sufficient mechanical strength while achieving large (~300°) field of view (FOV). Individual struts were separated by 120° along the circumference.…”

A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography

“…Double-clad fiber (DCF) can also provide a common path for the two modalities that ensures co-registration. Additionally, DCF has relatively high AF collection efficiency due to the large inner cladding [33][34][35][36][37][38][39][40].…”

“…In the distal scanning case, the catheter commonly includes a stationary fiber and a distally located micromotor that actuates a rotating mirror [36,37]. However, using micromotors increases the overall catheter diameter and creates blind sectors due to wiring.…”

“…Commercially available WDMs with close input wavelengths ranges (635 nm/1310 nm) have been employed [33,36,40] albeit with a low AF excitation power transmission efficiency (~23%). Custom designed WDMs have shown enhanced blue AF excitation power efficiency (~60%) [37]. DCF couplers and (2 + 1):1 pump/signal DCF combiners have been proposed for splitting green AF emission from the back-scattered OCT light [30,[33][34][35][36]40] with 42% [35,40] and 20% [30,36] collection of AF emissions, respectively.…”

Optical coherence tomography – near infrared spectroscopy system and catheter for intravascular imaging

“…However, IVUS does not have the resolution to visualize important microstructures, such as thin fibrous caps and macrophage accumulations that are relevant to vulnerable plaque diagnosis. Furthermore, fluorescence imaging has been demonstrated as a complementary modality for OCT to provide additional information about molecular signatures [28][29][30][31][32][33]. Endogenous fluorescence imaging based on laser-induced fluorescence spectroscopy can also complement OCT and provide molecular information non-invasively [32,33].…”