Digital subtraction imaging with carbon dioxide and liquid contrast in the biliary and pancreatic ducts

Digital subtraction imaging (DSI) is used to enhance visualization [1] [2] [3]. By subtracting a precontrast image from a postcontrast image, DSI identifies anatomical structures while minimizing interference from surrounding tissues. It enhances the evaluation of biliary and pancreatic ducts by removing background structures and improving image clarity. This report presents two cases demonstrating the utility of CO₂ digital subtraction cholangiography (CDDSC) and contrast digital subtraction pancreatography (CDSP) in clinical practice. An Ultimax-i DREX-U180 (Canon) was used to acquire the DSI sequences. Case 1 involves a 66-year-old woman with hilar cholangiocarcinoma. To evaluate biliary anatomy, CDDSC was performed via an endoscopic nasobiliary drainage tube with CO₂ infusion at a controlled rate of 1 mL/s. CO₂ allows clear visualization of separate intrahepatic ducts, which is challenging with traditional liquid contrast agents ([Fig. 1]). Rapid absorption of CO₂ by the body reduces the risk of postprocedural complications such as cholangitis. This technique successfully delineated tumor-induced strictures, enabling precise assessment of biliary obstruction and facilitating effective treatment planning. Case 2 is a 71-year-old woman evaluated for pancreatic duct stenosis. CDSP was performed using an endoscopic nasopancreatic drainage tube, with amidotrizoic acid infused at 0.4 mL/s. Vertebral interference was effectively removed, and visualization of the pancreatic body and branch ducts was enhanced ([Fig. 2]). Improved image clarity enabled a detailed assessment of the stenotic segment, potentially allowing differentiation between benign and malignant changes. The total radiation dose was 9.4 mGy in Case 1 and 8.5 mGy in Case 2. Both cases highlight the advantages of DSI ([Video 1]). CDDSC is a safer alternative to biliary imaging, reducing procedural complications while providing high-resolution images. Similarly, CDSP improves pancreatic duct evaluation by overcoming anatomical challenges and enhancing diagnostic accuracy. These imaging techniques are safer, more effective, and a substantial progress in the evaluation of ductal systems.

Fig. 1 a Radiograph obtained 3 seconds after the infusion of CO₂ at 1 mL/s via an ENBD tube during digital subtraction imaging. b A radiograph showing the same image as (a), but with inverted black-and-white contrast. c Radiograph obtained 6 seconds after the infusion of amidotrizoic acid at 1 mL/s via an ENBD tube. Abbreviation: ENBD, endoscopic nasobiliary drainage.

Fig. 2 a Radiograph obtained 3 seconds after the infusion of amidotrizoic acid at 0.4 mL/s during digital subtraction pancreatography. b Radiograph obtained 3 seconds after the infusion of amidotrizoic acid at 0.4 mL/s without digital subtraction imaging.

This video demonstrates the application of digital subtraction imaging (DSI) for enhanced visualization of biliary and pancreatic ducts. CO₂ was infused at 1 mL/s via an endoscopic nasobiliary drainage (ENBD) tube, effectively contrasting the hilar bile ducts due to its diffusibility and rapid absorption. Subsequently, an iodinated contrast agent was infused at the same rate, which provided less immediate visualization due to higher viscosity. For pancreatic imaging, the iodinated contrast agent was infused at 0.4 mL/s via an endoscopic nasopancreatic drainage (ENPD) tube. DSI subtracted overlapping vertebral structures, enabling clearer visualization of branch pancreatic ducts in the pancreatic body. These results highlight the potential of DSI in achieving precise and detailed imaging for biliary and pancreatic evaluations.Video 1

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Conflict of Interest

The authors declare that they have no conflict of interest.

• References

• 1 Haug RM, McCabe M, Gomez JM. et al. ERCP with carbon dioxide cholangiography using digital subtraction imaging is comparable to iodinated contrast cholangiography for detection of choledocholithiasis: A pilot study. Gastrointest Endosc 2020; 91: AB105
• 2 Modic MT, Weinstein MA, Chilcote WA. et al. Digital subtraction angiography of the intracranial vascular system: Comparative study in 55 patients. AJR Am J Neuroradiol 1981; 2: 527-534
• 3 Maruyama A, Kobayashi M, Takeshima H. et al. Carbon dioxide digital subtraction enterography for route identification in post-Roux-en-Y biliary interventions. Endoscopy 2025; 57: E153-E154

Publication History

Article published online:
09 May 2025