Complicated cholecystitis: the complementary roles of sonography and computed tomography.

Acute cholecystitis is a common cause of abdominal pain in the Western world. Unless treated promptly, patients with acute cholecystitis may develop complications such as gangrenous, perforated, or emphysematous cholecystitis. Because of the increased morbidity and mortality of complicated cholecystitis, early diagnosis and treatment are essential for optimal patient care. Nevertheless, complicated cholecystitis may pose significant challenges with cross-sectional imaging, including sonography and computed tomography (CT). Interpreting radiologists should be familiar with the spectrum of sonographic findings seen with complicated cholecystitis and as well as understand the complementary role of CT. Worrisome imaging findings for complicated cholecystitis include intraluminal findings (sloughed mucosa, hemorrhage, abnormal gas), gallbladder wall abnormalities (striations, asymmetric wall thickening, abnormal gas, loss of sonoreflectivity and contrast enhancement), and pericholecystic changes (echogenic fat, pericholecystic fluid, abscess formation). Finally, diagnosis of complicated cholecystitis by sonography and CT can guide alternative treatments including minimally invasive percutaneous and endoscopic options.