Discrimination of gangrenous from uncomplicated acute cholecystitis: accuracy of CT findings.

In acute cholecystitis, the presence of gangrene is associated with higher morbidity and mortality and necessitates open surgical intervention rather than laparoscopic cholecystectomy. As Murphy's sign may be absent, gangrene may not be detected ultrasonographically. This retrospective study evaluated indications of acute gangrenous cholecystitis on computed tomography (CT) in 25 patients, who were proven as having acute cholecysitis surgically and pathologically within 3 days of pre-operative CT. The CT images were reviewed by two board-certified radiologists blind to the initial CT report. Acute gangrenous cholecystitis was significantly correlated with the CT signs of perfusion defect (PD) of the gallbladder wall (P = 0.02), pericholecystic stranding (PS) (P = 0.028), and no-gallstone condition (No-ST) (P = 0.026). The presence of PD was associated with acute gangrenous cholecystitis with a relatively high accuracy (80%), a sensitivity of 70.6%, a specificity of 100%, a positive predictive value (PPV) of 100%, and a negative predictive value (NPV) of 61.5%. The combination CT signs of PD or No-ST improved the accuracy for acute gangrenous cholecystitis to 92%, with a sensitivity, specificity, PPV, and NPV of 88.2%, 100%, 100%, and 80%, respectively. Other CT signs were highly specific for acute gangrenous cholecystitis but of low sensitivity, including mucosal hemorrhage, mucosal sloughing, wall irregularity, pericholecystic abscess, gas formation, and portal venous thrombosis. CT was found to accurately diagnose acute cholecystitis, with the presence of PD, PS, or No-ST significantly correlated with that of gangrenous change. Thus, CT is useful in the preoperative detection of acute gangrenous cholecystitis.