ARRS 2022 Abstracts

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E1068. Dual Energy for Bowel Pathology: A Beginners Guide
Authors
  1. Madison Kocher; Medical University of South Carolina
  2. Jeffrey Waltz; Medical University of South Carolina
  3. Jordan Chamberlin; Medical University of South Carolina
  4. Shaun Hinen; Medical University of South Carolina
  5. Mark Kovacs; Medical University of South Carolina
  6. Andrew Hardie; Medical University of South Carolina
Background
Dual-energy CT (DECT) is particularly helpful in the identification of intravenous (IV) and parenterally administered iodinated contrast material, which is advantageous for diagnosing bowel pathology. A previous study demonstrated the utility of DECT in increasing diagnostic confidence and reducing unnecessary follow-up examinations. The purpose of this project is to highlight key DECT reconstructions and their application to specific bowel pathologies that are easier to recognize and diagnose with the use of DECT.

Educational Goals / Teaching Points
The goals of this exhibit are to review DECT applications with oral iodinated contrast material, specially bowel leak and bowel fistulas; review DECT applications with IV iodinated contrast material, specifically active gastrointestinal bleeding and bowel ischemia; and avoid DECT imaging pitfalls.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
DECT allows for the reconstruction of postprocessed images, of which a standard set of reconstructions including a virtual unenhanced image, iodine map, iodine map superimposed on the virtual unenhanced image, and a single-energy 120-kVp-equivalent are helpful for rapid access and interpretation. The iodine overlay should be one of the key reconstructions utilized by a radiology resident. All interpretation must be with the caveat that simultaneous administration of oral and IV iodinated contrast material may confound interpretation and should be considered when protocoling. Initially, the 120-kVp-equivalent should be viewed as in routine CT assessment. In the case of gastrointestinal bleed with the administration of IV contrast material, intraluminal hyperdense material should be cross-referenced with the iodine overlay, whereas ischemic bowel can be confirmed without IV contrast material in the bowel wall. The use of an oral contrast agent is helpful in confirming the presence of iodine in extraluminal places such as in leak and fistula. An absence of iodine in an area of hyperdensity can help in ruling out bleed or leak in favor of suture material or old hematoma. All of these findings can be definitively diagnosed with correlation of the presence or absence of an IV or oral contrast agent.

Conclusion
With the use of DECT, several reconstructions can be made to help in the diagnosis of bowel pathology. The presence or absence of both IV and orally administered iodinated contrast medium can be especially advantageous when evaluating for gastrointestinal bleed, ischemia, enteric leak, and fistula formation in addition to other numerous bowel pathologies.