Faculty Bibliography

Computed tomography (CT) plays an important role in the evaluation of patients presenting to the emergency department with a suspected spontaneous gastrointestinal tract (GIT) perforation. Prospective identification of the site of perforation helps the emergency department physician plan the appropriate treatment in a potentially unstable patient. The purpose of this pictorial essay is to review the CT approach a radiologist should take when evaluating the patient with suspected perforation in the emergent setting. A series of patients presenting to the emergency department with surgically proven GIT perforations were retrospectively reviewed, and key images were obtained. For the purposes of this review, the anatomy of the abdominal cavity in relation to sites of GIT perforation will be discussed. CT findings of perforation will be described, including free intraperitoneal/extraperitoneal air, bowel wall discontinuity, and localized inflammatory changes. The use of a bone window setting to increase the free air conspicuity will be emphasized. The mimics of pneumoperitoneum will be demonstrated, including pneumothorax, pneumomediastinum, and venous air. Using a systematic approach, CT can precisely determine the presence and site of a gastrointestinal perforation in a majority of patients. This greatly assists the surgeon in planning the correct surgical approach.

Mesenteric abnormalities are often incidentally discovered on cross-sectional imaging performed during daily clinical practice. Findings can range from the vague "misty mesentery" to solid masses, and the possible etiologic causes encompass a wide spectrum of underlying pathologies including infectious, inflammatory, and neoplastic processes. Unfortunately, the clinical and imaging findings are often non-specific and may overlap. This article discusses the various diseases that result in mesenteric abnormalities. It provides a framework to non-invasively differentiate these entities, when possible.

The ampulla of Vater is an important anatomic landmark where the common bile duct and main pancreatic duct converge in the major duodenal papilla. Imaging evaluation of the ampulla and periampullary region poses a unique diagnostic challenge to radiologists because of the region's complex and variable anatomy and the variety of lesions that can occur. Lesions intrinsic to the ampulla and involved segment of the biliary tree can be neoplastic, inflammatory, or congenital. Neoplastic lesions include ampullary adenocarcinomas and adenomas, which often are difficult to differentiate, as well as pancreatic or duodenal adenocarcinomas, pancreatic neuroendocrine tumors, and cholangiocarcinomas. Ultrasonography (US), computed tomography, magnetic resonance (MR) imaging, and MR cholangiopancreatography are commonly used to evaluate this region. Endoscopic retrograde cholangiopancreatography or endoscopic US examination may be necessary for more definitive evaluation. Periampullary conditions in the duodenum that may secondarily involve the ampulla include neoplasms, duodenitis, duodenal diverticula, and Brunner's gland hyperplasia or hamartomas. Because these lesions can exhibit a wide overlap of imaging features and subtle or nonspecific imaging findings, diagnosis is made on the basis of patient age, clinical history, and imaging and laboratory findings. Given the complexity of imaging evaluation of the ampulla and periampullary region, it is essential for radiologists to understand the variety of lesions that can occur and recognize their imaging characteristics.

The discovery of an incidental adrenal mass (adrenal incidentaloma) continues to rise with the increasing use of cross-sectional imaging. Although most adrenal lesions are benign and asymptomatic, radiologists should guide evaluation of these lesions, whether benign or malignant. This article reviews the various imaging techniques used to evaluate adrenal masses and their relative strengths and weaknesses. It focuses on the most prevalent adrenal pathologies and their typical imaging characteristics, and concludes with a brief discussion of developing techniques, including diffusion-weighted imaging and dual-energy CT.