Scintigraphic variations of normal biliary physiology.

We studied 115 healthy adult volunteers, fasting overnight, to establish the normal scintigraphic variability. Five Tc-99m IDA agents with liver excretion half-times ranging from 18 to 108 min were used. The time of appearance of the common bile duct correlated directly with the liver's excretion half-time. The appearance of the gallbladder and the small intestine were independent of the excretion half-time and showed a reciprocal relationship suggesting a major role for the sphincter of Oddi. In 22% of the subjects, the sphincter tonus was tight enough to divert all of the hepatic bile into the gallbladder, allowing none into the intestine. All of such subjects showed normal dynamic response to intravenous cholecystokinin. The pattern of the bile drainage from the two lobes differed, resulting in asymmetry of the right and left hepatic ducts. It is concluded that the selection of a Tc-99m IDA agent should be based on the clinical problem at hand and that a clinician's understanding of the scintigraphic variability in normal subjects is critical before attempting diagnosis.