CT Findings for Detecting the Presence of Gangrenous Ischemia in Cholecystitis

OBJECTIVE: The objective of our study was to evaluate the diagnostic accuracy of CT in differentiating gangrenous cholecystitis from uncomplicated cholecystitis and healthy gallbladders. MATERIALS AND METHODS: We performed a retrospective review of 308 patients with histologically proven gangrenous cholecystitis who underwent preoperative CT 1 month before gallbladder removal over a 4-year period. Two readers who were blinded to the histologic diagnosis independently recorded CT features of and overall likelihood of gangrenous cholecystitis on a 5-point scale (1, definitely absent; 5, definitely present). Ratings were dichotomized such that a diagnosis was considered present at a rating of 4 or 5 and considered absent at lower ratings. Interobserver variability for individual CT findings was also assessed. RESULTS: Patients had gangrenous cholecystitis (n = 28), acute cholecystitis (n = 98), chronic cholecystitis (n = 118), or healthy gallbladders (n = 64). Multivariate analysis showed that CT findings of gallbladder distention greater than 4.0 cm (odds ratio [OR], 9.63; p < 0.01), mural striation (OR, 11.39; p < 0.01), and decreased mural enhancement (OR, 3.55; p < 0.05) independently predicted gangrenous cholecystitis. Using these CT features, the diagnosis of gangrenous cholecystitis was made with a specificity of 93.9% and 89.6% for readers 1 and 2, respectively, and accuracy of 90.9% and 87.0%, respectively. Good agreement was seen between the two readers with respect to gallbladder distention greater than 4.0 cm (κ = 0.77) and decreased mural enhancement (κ = 0.64). CONCLUSION: A markedly distended gallbladder associated with decreased wall enhancement is highly specific for gangrenous cholecystitis.