Technetium-99m-pyridoxylideneglutamate: a new hepatobiliary radiopharmaceutical. II. Clinical aspects

Technetium-99m-pyridoxylideneglutamate (99mTc-PG) is a nontoxic radiopharmaceutical that was found to undergo rapid biliary excretion in normal humans. The biliary tree and gallbladder were seen within 10-15 min of injection and by 20 min marked accumulation of radioactivity was noted in the gallbladder and gastrointestinal tract. Of ten "control" volunteers, seven had normal 99mTc-PG-cholescintigrams. In the remaining three, the gallbladder was not visualized. Gallbladder disease was not excluded in these three subjects. Of 24 patients referred for investigation of right upper quadrant abdominal pain, 13 proved to have gallbladder disease. All seven patients with acute cholecystitis and one of four patients with chronic cholecystitis had nonvisualization of the gallbladder on the cholescintigram whereas five patients with chronic cholecystitis or cholesterolosis had normal cholescintigrams. Six of the eight patients with nonvisualization of the gallbladder on cholescintigram had contrast radiologic studies (oral cholecystogram or intravenous cholangiogram or both), and in all six, nonvisualization of the gallbladder was also reported on the contrast study. cholescintigraphy was found to be greatly inferior to contrast radiologic studies in the detection of gallbladder stones. Eleven patients had complete extrahepatic biliary obstruction and this diagnosis was correctly made in all 11 by the cholescintigram. Fourteen patients had incomplete extrahepatic biliary obstruction. The correct diagnosis was made on the cholescintigram in seven but in the remaining seven it was not possible to distinguish between incomplete extrahepatic biliary obstruction and hepatocellular disease. Malignant lesions (carcinomas of head of pancreas, gallbladder, common bile duct or ampulla of Vater) were the cause of obstruction in 10 of the 25 patients with complete or incomplete obstruction and the diagnosis of obstruction due to malignancy was correctly made in 8 of these 10 by means of a scintigraphic equivalent to Courvoisier's sing. Finally, 11 patients had hepatocellular disease and a nonspecific pattern consistent with either imcomplete biliary obstruction or hepatocellular disease was observed on the cholescintigram in all 11. The 99mTc-PG cholescintigram is suggested for a role complementary to that of contrast radiologic studies in the preoperative investigation of patients with possible surgical disease of the biliary tract. Contrast radiologic techniques are advocated as being more appropriate in the nonjaundiced patient with suspected gallbladder disease whereas the 99mTc-PG cholescintigram is advocated as being more appropriate in the patient with jaundice. The value of the 99mTc-PG cholescintigram lies in the confidence with which complete extrahepatic biliary obstruction can be diagnosed. The "scintigraphic Courvoisier's sign" seems a useful indicator of malignant obstruction.