What’s New In Gastrointestinal Imaging – November 2021
Correlation of gastrointestinal perforation location and amount of free air and ascites on CT imaging – Drakopoulos D, Arcon J, Freitag P, El-Ashmawy M, Lourens S, Beldi G, Obmann VC, Ebner L, Huber AT, Christe A. Abdominal Radiology 2021 46:4536-4547
This article aims to localize a hollow viscus perforation by analyzing the volume of free air and ascites. First, the authors present the clinical scenarios in which free air and fluid may be present, and the imaging techniques used to attempt to localize the site of perforation. This retrospective study looked at 172 patients with a gastrointestinal perforation confirmed surgically, and volume of free air and ascites measured by 4 radiologists and semiautomated software. The authors found that significantly more ascites is associated with upper GI perforation, with an average of 333 mL, as opposed to lower GI, which produced an average of 100 mL of ascites. Stomach, descending colon, and sigmoid colon were associated with larger volumes of free air. The authors present an algorithm to localizing perforation. The first branch point is volume of free air >185 mL, then volume of ascites to indicate the likely site of perforation. The authors conclude that their two-step process using volume of air and ascites, interpreting radiologists can increase confidence in localizing GI perforation to the upper, middle or lower GI tract.
The CT scout view: complementary value added to abdominal CT interpretation. Lee MH, Luber MG, Mellnick VM, Menias CO, Bhalla S, Pickhardt PJ. Abdominal Radiology 2021. 46:5021-5036
This article gives an interesting perspective to the scout image. The authors state using the scout can add potentially life-changing information to the scan, such as an unsuspected cancer of the lung bases not included on the full CT. The authors begin by discussing that the scout is acquired to prescribe the start and end locations of the scan range, and identify anatomic landmarks, and follow by arguing that the medicolegal standard of care is that radiologists should review any image submitted for interpretation, including the scout. The authors state that while most findings from the scout will be seen on the CT images, up to 2% of scout images may have findings not included in the CT field of view. Additionally, hyperdense foreign bodies, including retained surgical instruments may be easily seen on scout images. The authors give the example that the scout can give a better idea of a metallic foreign body, which may be obscured by streak artifact on CT. The article gives many imaging correlates to findings that may be better evaluated with assistance from the scout image, as well as pitfalls of the scout.
Diagnostic utility of computed tomography in patients presenting to the emergency department with unintended weight loss. Rao S, Kikano EG, Smith DA, Tirumani SH, Ramaiya NH. Emergency Radiology (2021) 28: 771-779.
This article published in the Journal of Emergency Radiology discusses imaging of a challenging presenting complaint, unintended weight loss, defined as 5% of body weight over at least six months. The authors present a retrospective case cohort of 133 patients. Of these 133, 92 underwent abdomen/pelvis CT, 22 underwent full chest, abdomen, pelvis CT, and the others had single CTs of the chest, abdomen, or pelvis. The most common CT finding in these patients was a non-malignant GI condition (31%), most commonly chronic pancreatitis. This was followed by any type of malignancy (23%), the most common primaries were lung, colon, and pancreatic. The authors state they were able to find a cause on CT for unintended weight loss in 48% of patients. Notably, significant associations with a positive CT scan were found with both elevated WBC count and physical exam abnormalities.
CT for lymph node staging of Colon cancer: not only size but also location and number of lymph node count. Hong EK, Landolfi F, Castagnoli F, Park SJ, Boot J, Van den Berg J, Lee JM, Beets-Tan R. Abdominal Radiology (2021) 46:4096-4105
This article aims to predict lymph node status in patients with colon cancer using imaging features on CT. The authors begin with a discussion of current colon cancer staging and treatment, and highlight that there is currently no accurate radiologic criteria for lymph node involvement in colon cancer. A retrospective cohort of 317 patients with colon cancer who underwent primary surgical treatment were assessed with CT with IV contrast for lymph node location, size, cluster, attenuation, shape, internal heterogeneity, and margins and compared to histological lymph node status. Lymph node largest short diameter (with a cut-off of 7.95 mm) and internal heterogeneity were found to have the most significant association with malignant status. Total number of lymph nodes, number of lymph nodes in peritumoral area and number of lymph nodes along mesenteric vessels also showed significant association with malignant status of lymph nodes in colon cancer. The authors in this study found no significant association between a short/long axis ratio of lymph node of 0.8 or higher, as has been proposed by previous studies.
Approach to Cystic Lesions in the Abdomen and Pelvis, with Radiologic-Pathologic Correlation. Yacoub JH, Clark JA, Paal EE, Manning MA. Radiographics 2021; 41: 1368-1386
This paper focuses on imaging characteristics of cystic lesions of the gastrointestinal tract, mesentery and peritoneum and highlights features that can aid in diagnosis of these lesions. The authors highlight key features of cyst contents, locularity, wall thickness, internal complexity and enhancement. The authors begin by separating cysts into three categories: true cysts, cystic neoplasms, and cystic appearing lesions, and providing detailed imaging characteristics of each category. Detail is then provided on the utility and shortcomings of each imaging modality in the diagnosis of cysts. The bulk of the paper describes cystic lesions and provides important imaging features to help radiologists gain familiarity with the possible lesions as well as common mimics of cystic lesions. The manuscript provides many high quality images of these lesions. The paper concludes with a discussion of management for cystic lesions of the GI tract and abdomen.
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