The radiographic appearances of the gas-filled gallbladder with intramural gas are quite different from normal gas-filled structures, e.g. the adjacent hepatic flexure. The differential diagnosis for curvilinear lucency as seen in this case is pneumatosis.
On ultrasound, intramural gas of emphysematous cholecystitis produced dirty shadowing. The differential diagnosis is porcelain gallbladder, where shadowing is usually dense.