Vital dye enhanced fluorescence imaging. VFI Consists of high resolution epithelial imaging with exogenous topical fluorescent contrast to highlight glandular morphology and delineate neoplasia in the distal esophagus. In setting up, connect the digital visual interface cable between the monitor and the DVI splitter.
To set the monitor to DVI press the input button below the screen until DVI appears. The laser diode is found within the silver metal box and the power switch is located inside. On the outside, there is a knob to adjust the voltage to turn the laser diode on, pull the handle towards the voltage knob.
A yellow light will appear to indicate that the laser diode is on before the VFI portion of the study can be performed. Set up a sterile area from where the assistant can work to secure the filter and cap on the endoscope. Lay out two Kim wipes overlapping one another.
The filter can be placed on top of this platform. Also, make the cap ready for use. Before the patient is in the endoscopy suite, informed and consent must be obtained.
Please note that informed consent was obtained for each patient in this study and that this research has been performed in compliance with all institutional, national and international guidelines for human welfare. After completing the standard white light imaging spray the pro flavin dye over the tissue of interest. Typically only one to five ccs of pro flavin is necessary while the pro flavin is being sprayed.
Turn on the laser dde upon removing the endoscope after completion of the white light study, clean the tip with Kim wipes in an effort to adequately remove debris and mucus clean several centimeters along all sides of the endoscope tip. After cleaning, the outer set of gloves should be taken off and discarded with the Kim wipes to prevent contamination of the filter. Now with the endoscopist keeping the tip vertical, the assistant can put on the filter.
Notice that the assistant uses the cylindrical protuberance on the filter and guides it into the socket located on the endoscope tip, holding the filter in place. The assistant slides the cap over the filter and pushes it down over the tip of the endoscope. Make sure the cap is secured and pushed completely on with the edges flush with the endoscope.
When finished, the lip of the cap should be slightly extended over the tip of the endoscope. Lastly, make sure the filter is still in place and flush with the tip of the endoscope. With a laser diode on the tissue should have a green fluorescence and one canned pan over the tissue of interest.
This video depicts classic Barrett's esophagus with no dysplasia surrounded on the borders by normal squamous epithelium. In static image, notice the flatter squamous tissue, which is peripherally located and indicated by the blue arrows. A homogenous area of dull fluorescence is present with no glandular architecture By comparison in moving to the centrally located Barrett's tissue, glandular structures can be defined as green fluorescence surrounding a darker lumen.
Although some glands are elongated, there is little distortion between adjacent glands as the width of the glands is similar and the edges are clearly defined. In addition, the glands in the lumen are evenly spaced with no clumping or crowding present. Finally, the green arrows indicate a circular green line surrounding the squamous tissue.
This outline is artifact resulting from the cap of the endoscope. This second video depicts a centrally located adenocarcinoma in video. The mass is more apparent yet in static image.
Notice first, the cancer within the red oval and the complete obliteration of glandular architecture with luminal absence. This obliteration can be further appreciated when comparing it to the tissue indicated by the blue oval, which possesses some glandular framework on the left. The gray rectangle highlights squamous epithelium, which can be better appreciated in the video when the endoscope pans over it in its entirety.
The squamous tissue is a flat, homogenous area of dull fluorescence with no glandular architecture. To remove the cap and filter, use Kim wipes and firmly pull the cap off. The cap can be discarded, but the filter must be cleaned.
To clean the filter, fill a cup with side X enough to completely submerge the filter. Before submerging the filter, remove any large debris that may be caught on it to finish cleaning. Dry the filter with Kim wipes and res submerge it into a new cup filled with water.
Currently, benign metaplasia can be indistinguishable from high grade dysplasia and adenocarcinoma in the distal esophagus. However, by highlighting a tissue's glandular morphology, VFI provides distinct features to differentiate these tissue types, thereby improving surveillance of Barrett's esophagus and the diagnosis of neoplasia in the distal esophagus. Although an improvement VFI cannot resolve cellular dysplasia a feature that is possible with micro endoscopy, confocal.
Micro endoscopy provides surface tomography of the esophageal mucosa to identify cellular patterns of non neoplastic and neoplastic tissue. In this confocal image of normal Barrs epithelium, note the appearance of cylindrical regular cells and the presence of a brush border. In confocal imaging, the most important feature of Barrett's epithelium is the presence of goblet cells, which present as dark central spots in the epithelium because of mucin within the goblet cells.
High resolution micro endoscopy, also known as HRME, is a more novel technology that also aims to differentiate neoplastic from non neoplastic tissue on a cellular level. In a static HRME image, the nuclei illuminate bright white and cellular features such as nuclear to cytoplasmic ratio and spacing can be appreciated. These microscopic technologies are limited by their field of view and therefore are better classification tools rather than surveillance tools.
The future of endoscopic screening for Barrett's dysplasia will likely involve a combination approach of wide field surveillance technology such as VFI, along with a cellular classification technology such as micro endoscopy.
