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Gastrointestinal Imaging

E2346. MDCT Imaging of Acute Biliary Inflammation and the Gamut of Secondary Complications

Spain J,  Rheinboldt M. Henry Ford Hospital, Detroit, MI

Address correspondence to M. Rheinboldt (mrheinbold@yahoo.com)

Background Information: Though ultrasound is the modality of choice for the initial workup of suspected biliary disease, MDCT imaging is frequently the first if not only study employed in the evaluation of patients presenting to the emergency department with abdominal pain. Indeed, in the subset of these patients over 60 years of age, MDCT is employed in over 30% of cases, 10% of which are ultimately diagnosed with biliary disease. Familiarity with the gamut of potential imaging findings facilitates a timely and accurate diagnosis, minimizes redundant supplementary imaging studies, and expedites patient care.

Educational Goals/Teaching Points: The goal of this exhibit is to illustrate MDCT findings in acute simple and complicated cholecystitis, including emphysematous, gangrenous, and hemorrhagic cholecystitis. Additionally, we will illustrate secondary complications, including gallbladder perforation, gallstone ileus, choledocholithiasis, ascending cholangitis, Mirizzi syndrome, and recurrent pyogenic cholangitis. We will review MDCT protocols for optimization of biliary imaging and discuss CT performance statistics for detection of early biliary inflammation, obstruction, and cholelithiasis.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: CT features of acute cholecystitis include wall thickening greater than 3 mm, pericholecystic fluid, hydrops as defined by distention greater than 5 cm in short axis or 8 cm in long axis, subserosal edema, and inflammatory stranding. Other described features include the tensile fundus sign, adjacent hepatic hyperemia, and mucosal hyperemia of the gallbladder and cystic duct. The tensile fundus sign denotes loss of flattening of the gallbladder fundus by the overlying abdominal wall due to increased endoluminal pressure in the setting of early inflammation. Gallstones are variable in their imaging appearance, dependent upon the internal cholesterol content. True cholesterol stones, as depicted, will contain greater than 70% cholesterol as opposed to pigmented calculi, composed of primarily calcium bilirubinate with only a small fraction of cholesterol. At 140 kVp, MDCT has a sensitivity of approximately 80% for cholelithiasis, diminishing with decreasing tube voltage. Gangrenous cholecystitis has an increasing prevalence with age and comorbidities such as diabetes. CT features include the presence of endoluminal or intramural gas, absent mural enhancement, pericholecystic abscesses, and intraluminal membranes secondary to mucosal sloughing. Adjacent hepatic hyperemia and striated mural appearance are less definitive findings. Due to mural friability, the conversion rate from laparoscopic to open resection is threefold higher than in routine cases.

Conclusion: Although ultrasound is the imaging modality of choice for the initial evaluation of biliary disease, MDCT imaging is not infrequently the first if not only examination performed in the workup of these patients, presenting with oftentimes vague or non-contributory symptomatology. Familiarity with the gamut of imaging features and potential complications allows the imaging specialist to make a timely and accurate diagnosis and expedite appropriate patient care.