Phantom gallbladder. A variant of the rim sign.

Nonvisualization of the gallbladder is the primary finding in cholescintigraphy for acute cholecystitis. Recent investigators have described a useful secondary finding of increased pericholecystic hepatic activity (PCHA). A case of acute cholecystitis is presented in which the PCHA was round in configuration and appeared in the first 5 minutes of the study.