Hepatobiliary scanning with 99mTc-pyridoxylidene glutamate. A retrospective study investigating the criteria for differentiation between intrahepatic and extrahepatic obstruction.

In 70 99mTc-pyridoxylidene glutamate (PG) studies with verified diagnoses, the following scan patterns were found. (1) Normal: within 30 min of PG injection the scan reveals the liver, hepatic ducts, common bile duct, gallbladder and flow to the intestine; after 2 h the liver had a higher concentration of activity than the hepatic ducts or the common bile duct. (2) Complete extrahepatic obstruction: no hepatic excretion to the intestine is observed 18-24 h after PG injection, nor is activity observed in the hepatic ducts, common bile duct and gallbladder. (3) Incomplete extrahepatic obstruction: intestinal activity is observed within 18-24 h of PG injection; after 2 h the concentration of activity in the hepatic ducts or the common bile duct exceeds that in the liver (regardless whether activity is or is not demonstrated in the gallbladder). (4) No extrahepatic obstruction: serum bilirubin normal or increased; intestinal activity is observed within 18-24 h after PG injection, and activity is demonstrable during this period somewhere in the hepatic ducts, the common bile duct or the gallbladder; after 2 h the concentration of biliary activity should not exceed that in the liver. (5) If excretion to the intestine is observed within 18-24 h of PG injection without demonstrable activity in the hepatic ducts, common bile duct or gallbladder, then it is impossible to differentiate between (3) and (4).