E1350. Sleuthing the Stomach on CT: A Case-Based Review of Inflammatory Disorders and Their Neoplastic Mimics
  1. Edward Lawrence; Department of Radiology, UW-Madison School of Medicine and Public Health
  2. Meg Lubner; Department of Radiology, UW-Madison School of Medicine and Public Health
  3. Perry Pickhardt; Department of Radiology, UW-Madison School of Medicine and Public Health
  4. Michael Hartung; Department of Radiology, UW-Madison School of Medicine and Public Health
The stomach and duodenum are a common source of upper abdominal pain, for which CT is commonly used as a first step in evaluation. Issues with variable luminal distention and overlapping findings can make confident evaluation difficult for the interpreting radiologist. However, there are key findings for peptic ulcer disease, neoplastic, and non-neoplastic conditions that the radiologist can identify which offer important value-added and may significantly impact patient management and outcomes. The purpose of this exhibit is to review the relevant anatomy, discuss technical/interpretive factors that can improve diagnostic yield, and present a case-based review of benign inflammatory conditions of the upper tract as well as important neoplastic and non-neoplastic mimics.

Educational Goals / Teaching Points
1. Review relevant anatomy and how finding location, especially air or oral contrast, may point to the underlying etiology or source 2. Review a collection of cases, both neoplastic and inflammatory, with emphasis on key findings and interpretation tips 3. Develop differentiating criteria for distinguishing benign from malignant gastric or duodenal thickening

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
1. Evidence of acute inflammation and corresponding symptoms may suggest gastritis or duodenitis. While uncommon, emphysematous gastritis is important to accurately diagnose. 2. The location of extraluminal fluid (including intraperitoneal versus retroperitoneal) and air often directs the radiologist to the location of perforation. Focal air near the duodenum, even if only tiny locules, is highly suspicious for the site of perforation. Peritonitis from leaking gastric contents can potentially mislead the radiologist to suggest a colonic source of perforation. 3. Oral contrast is often helpful for detection of the site of perforation/leak. If the contrast redistributes in the extraluminal fluid it may only be apparent as an abnormally elevated fluid attenuation on delayed or repeated examinations. 4. Benign versus malignant wall thickening can be difficult to differentiate. Lower attenuation (suggestive of edema) or continued presence of mural stratification would suggest benign inflammation. Higher attenuation or enhancement can indicate the presence of infiltrative tumor. 5. The most challenging neoplastic mimics are lymphoma, adenocarcinoma (especially linitis plastica), and neuroendocrine tumor.

CT can assist with the evaluation and diagnosis of both benign and malignant conditions of the stomach and duodenum. The location of extraluminal fluid, air, and even oral contrast can aid the radiologist to detect the site of perforation/ulceration. Wall thickening with higher attenuation and loss of mural stratification is more worrisome for possible malignancy.