Evaluation of focal defects on technetium-99m sulfur colloid scans with new hepatobiliary agents.

In 3,600 patients evaluated with technetium-99m sulfur colloid for metastatic liver disease, 40 had equivocal scans due to a solitary defect in the interior margin of the right lobe. In these patients, the authors differentiated the gallbladder fossa from a metastatic focus using one of two new hepatobiliary agents: technetium-99m labeled pyridoxylideneglutamate and paraisopropylacetanilido iminodiacetic acid. In 31 patients, the focal defect filled with radioactive bile, showing that the solitary defect in the radiocolloid scan was a prominent gallbladder fossa. On laparoscopic biopsy, eight of nine patients whose focal defects were not due to the gallbladder were found to have metastatic disease. The ninth patient had carcinoma of the gallbladder. The need for laparoscopic biopsy was obviated in a majority (78%) of the patients by identifying the gallbladder fossa.