Bioluminescent Endoscopic Imaging: Technical Requirements of the Chemistry and Camera System

Objective: Bioluminescent chemistry can be infused as an angiography media and by developing endoscopic techniques for bioluminescent imaging (BLI) we have previously demonstrated sensitive visualization of anatomic structures, including the biliary tree and vascular beds. In nature bioluminescence is light produced by a chemical reaction within a living organism. In BLI applications, a luciferin (the substrate coelenterazine) when combined with a luciferases (protein or enzyme) in the presence of oxygen produces visible light at the 480 nm wavelength. In this study we describe and define the chemistry of the bioluminescent coelenterazine-luciferase system and the technical specifications required of a scientific grade cooled CCD camera adapted for laparoscopic use by coupling to a standard Hopkins rod-lens. Methods: a human umbilical cord model was developed to allow multiple, easily repeated and standardized infusions of bioluminescent chemistry titrations in a dark laparoscopic training box. The chemistry of the renilla luciferase, gaussia luciferase and coelentrazine (BioLume, Inc.) is described. The range and ability of the camera to capture bioluminescent images was assessed. The exposure time, gain and pixel bin settings were varied using the software controls of a scientific grade CCD camera (Diagnostic Instruments, Inc.). The image processing software post capture was evaluated. In addition, umbilical cord tissue was assessed by standard fluoroscopic angiography and frozen section measurement of the specimens. Results: titrations of the bioluminescent chemistry determined the concentrations required for excellent imaging. Static image capture at longer exposure times but with relatively low gain and no pixel binning allows excellent anatomic visualization and definition. Dynamic imaging using a sequential image series benefits from shorter exposure times, high gain and increased bin settings. Post imaging processing with the camera software allows rapid adjustment of image intensity to maximize the image quality. Conclusions: Endoscopic bioluminescent imaging is a completely new way of instantly and directly imaging precarious anatomy in real time. The images obtained in this bench model define the technical requirements of endoscopic BLI and demonstrate the utility of this imaging technology.

Session: Podium Presentation

Program Number: S059

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