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. CO
2 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
Endoscopy_UCTN_Code_TTT_1AR_2AB
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