Bile layering: a cause for false-positive cholescintiscans

A number of /sup 99m/Tc-labeled pharmaceuticals have been introduced recently for evaluation and diagnosis of hepatobiliary disease. Pyridoxylidene glutamate (PG) and iminodiacetic acid derivatives have evolved as the most useful agents due to excellent biliary excretion with rapid visualization of the gallbladder and the biliary ducts. These radiopharmaceuticals offer substantial advantages over /sup 131/I-rose bengal. In our experience of over 80 patients evaluated for various hepatobiliary disorders with /sup 99m/Tc PG or paraisopropyl acetanilidoiminodiacetic acid (PIPIDA), two patients had early cholescintigrams suggestive of intraluminal defects. These were not confirmed on delayed imaging. The cholescintigrams in these two patients were similar and suggested bile layering. Although demonstration of this phenomenon by oral cholecystography and intravenous cholangiography has been reported, we found no description of bile layering with radiopharmaceuticals.