Dual-Energy CT in Evaluation of the Acute Abdomen

Abstract

Evaluation of the nontraumatic acute abdomen with multidetector CT has long been accepted and validated as the reference standard in the acute setting. Dual-energy CT has emerged as a promising tool, with multiple clinical applications in abdominal imaging already demonstrated. With its ability to allow characterization of materials on the basis of their differential attenuation when imaged at two different energy levels, dual-energy CT can help identify the composition of internal body constituents. Therefore, it is possible to selectively identify iodine to assess the enhancement pattern of an organ, including the identification of hyperenhancement in cases of inflammatory processes, or ischemic changes secondary to vascular compromise. Quantification of iodine uptake with contrast material-enhanced dual-energy CT is also possible, and this quantification has been suggested to be useful in differentiating inflammatory from neoplastic conditions. Dual-energy CT can help determine the composition of gallstones and urolithiasis and can be used to accurately differentiate uric acid urinary calculi from non-uric acid urinary calculi. Moreover, dual-energy CT is capable of substantially reducing artifacts caused by metallic prostheses, to improve the imaging evaluation of abdominopelvic organs. The possibility of creating virtual nonenhanced images in the evaluation of acute aortic syndrome, gastrointestinal hemorrhage and is chemia, or pancreatic pathologic conditions substantially reduces the radiation dose delivered to the patient, by eliminating a true nonenhanced acquisition. Finally, by increasing the iodine conspicuity, contrast-enhanced dual-energy CT can render an area of free active extravasation or endoleak more visible, compared with conventional single-energy CT. This article reviews the basics of dual-energy CT and highlights its main clinical applications in evaluation of the nontraumatic acute abdomen. ©

Adhesive Small Bowel Obstruction: Predictive Radiology to Improve Patient Management

“…They found that the addition of unenhanced images increased the Youden index from 0.41 to 0.58 for one observer and from 0.42 to 0.61 for the other. Dualenergy CT is a recent technical improvement for assessing acute abdominal conditions (25). Dual-energy CT characterizes materials based on their differential attenuation when imaged at two different energy levels.…”

“…Thus, dual-energy CT can help identify the composition of materials inside the body. In patients with SBO, dual-energy CT may be able to help determine whether a high-attenuation area contains iodine (ie, is enhancing) or, instead, hemoglobin degradation products (Fig 2) (25). Dualenergy CT can provide virtual unenhanced images, thereby obviating an unenhanced acquisition (25).…”

“…In patients with SBO, dual-energy CT may be able to help determine whether a high-attenuation area contains iodine (ie, is enhancing) or, instead, hemoglobin degradation products (Fig 2) (25). Dualenergy CT can provide virtual unenhanced images, thereby obviating an unenhanced acquisition (25). Low-kiloelectron volt virtual monoenergetic imaging has been reported to improve confidence in assessing bowel wall enhancement in patients with acute SBO by increasing the attenuation difference between ischemic and nonischemic segments (26).…”

“…CT pitfalls.-Decreased bowel wall enhancement-the most specific sign of ischemia-may be difficult to identify with the portal venous acquisition. In late-stage ischemia complicating adhesive SBO, mural hyperattenuation due to intramural hemorrhage may mimic enhancement, making decreased bowel wall enhancement difficult to identify if unenhanced images are unavailable (24,25). Thus, obtaining both unenhanced and contrast-enhanced CT scans improves diagnostic accuracy, reader confidence, and interobserver agreement when assessing the decreased bowel wall enhancement sign (24).…”

How I do it – CT-Protokolle beim akuten Abdomen

“…ist in einer kürzlich durchgeführten Umfrage der Arbeitsgemeinschaft Gastrointestinal-und Abdominaldiagnostik der Deutschen Röntgengesellschaft gezeigt worden [6]. Der potenzielle Zugewinn der neusten CT-Weiterentwicklung in Form der Dual-Energy-CT (DECT) ist vielversprechend und Gegenstand aktueller Untersuchungen [7].…”