<prompt> Features suggestive of Acute cholecystitis on CT abdomen are all ExceptPericholecystic fluidPresence of gallstonesContratcted gall bladderAir in the gallbladder wall  <response>: Diagnostic criteria for acute cholecystitis on CT includemajor criteriagallstonesthickened gallbladder wallpericholecystic fluid collectionssubserosal oedemaminor criteriagallbladder distentionsludgeContraction of the gallbladder is sen in cholelithiasis, not acute cholecystitis. 