Iosulamide, an experimental cholangiographic agent recently being evaluated for hepatic contrast enhancement in computed tomography, has been investigated in the rat for the differential enhancement between the liver and three histologically different experimental
tumors (a well differentiated mammary
adenocarcinoma, a poorly differentiated colon
carcinoma, and a
hepatoma). After
intravenous injection of
iosulamide in dosages of 140 and 280 mg
iodine per kg,
iodine concentrations were determined in blood, liver and
tumors at 1, 5, 10, and 30 minutes, using x-ray energy spectrometry. Compared with the surrounding liver parenchyma, the
iodine concentrations were generally higher in the
breast carcinoma. With respect to the liver,
iodine concentrations varied greatly in the colon
carcinoma and
hepatoma. The
iodine washout from all three
tumors was relatively slow. Since the distribution volume of cholangiographic
contrast agents includes both vascular and interstitial space, the relatively high and prolonged
iosulamide accumulation in
tumors can be explained by a relatively large interstitial compartment, which is apparently characteristic of neoplastic lesions. This, together with the modest
iodine concentrations found in the liver, suggests that
iosulamide is of little use in computed tomography for the differential enhancement of liver and hepatic
tumors.