Endoscopic retrograde cholangiography (ERC) with balloon-equipped endoscopy is used for treating biliary diseases in patients with altered gastrointestinal anatomy. Carbon dioxide enterography is commonly used during ERC for route selection at the anastomotic branch, as it allows noninvasively visualizing intestinal pathways [1]
[2]. However, route identification accuracy may be compromised in cases with excessive intestinal gas, where overlapping shadows obscure the anatomy. Digital subtraction imaging (DSI) is a radiological technique widely used to enhance visualization. By subtracting a pre-contrast image from a post-contrast image, DSI allows for clear identification of vascular and anatomical structures while minimizing interference from surrounding tissues [3]. When applied to carbon dioxide enterography, this technique is termed carbon dioxide digital subtraction enterography. To acquire DSI sequences, we used the Ultimax-i DREX-U180 (Canon, Tokyo, Japan). In ERC, DSI can improve the effectiveness of carbon dioxide enterography, particularly in challenging cases involving excessive intestinal gas. This report highlights the successful use of carbon dioxide digital subtraction enterography in overcoming the limitations of traditional imaging and enabling better visualization.
A 77-year-old man with a history of total gastrectomy and Roux-en-Y reconstruction presented
with abdominal pain. Drip infusion cholangiography-computed tomography revealed common bile duct
stones ([Fig. 1]). The patient was scheduled to undergo ERC with a single-balloon endoscope (SIF-H290S;
Olympus, Tokyo, Japan) to facilitate stone removal. Carbon dioxide enterography alone failed to
clearly delineate the route to the blind end owing to overlapping intestinal gas shadows.
Therefore, DSI was also performed, enhancing the visualization of the anastomotic branch and
enabling clear identification of the correct route ([Fig. 2], [Video 1]).
Fig. 1 Imaging findings of a patient with common bile duct stones. a
Coronal section of the drip infusion cholangiography-computed tomography showing a round
filling defect in the common bile duct, consistent with a bile duct stone. b Three-dimensional reconstruction of the bile duct, providing detailed
visualization of the stone's location and surrounding anatomy.
Fig. 2 Comparison of carbon dioxide enterography and carbon dioxide digital subtraction enterography. a The route is obscured by overlapping intestinal gas in carbon dioxide enterography. b In carbon dioxide digital subtraction enterography, subtraction of the vertebral bodies and intestinal gas enhances route visualization, providing a clear view.
This video demonstrates the application of carbon dioxide enterography combined with digital subtraction imaging for route identification in a patient with post-Roux-en-Y reconstruction. The anastomotic branch was initially unclear because of the overlapping intestinal gas shadows. After digital subtraction imaging was applied, the route to the blind end became clearly visible, facilitating precise navigation and successful common bile duct stone extraction.Video 1
Carbon dioxide enterography is a valuable tool for route selection during ERC. However, its efficacy may be limited in cases of excessive intestinal gas. Combining DSI and carbon dioxide enterography enhanced route visibility. By eliminating background noise generated by overlapping gas shadows, this combination can improve route selection and procedural outcomes.
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