The accumulation of
diatrizoate and two new low osmolality
contrast agents,
iopamidol and
ioxaglate, was investigated in three experimental
tumors (a well differentiated mammary
adenocarcinoma, a poorly differentiated colon
carcinoma, and a
hepatoma) in the rat. All three
tumors were implanted into the liver 12 to 14 days prior to
intravenous injection of the
contrast agents in a dose of 300 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. Ratios between
tumor iodine and blood
iodine concentrations increased more with time with
diatrizoate than either
iopamidol or
ioxaglate and were at 30 minutes significantly greater for
diatrizoate than the other two agents. This suggests that the contrast medium efflux from the vascular compartment into the extravascular compartment of all
tumors is greater for
diatrizoate than either
iopamidol or
ioxaglate. Although it is known from clinical experience that the differential enhancement between hypodense hepatic
tumors and liver parenchyma decreases rapidly with time after contrast administration, this investigation suggests that the substitution of
diatrizoate by either
iopamidol or
ioxaglate should not affect appreciably the contrast enhancement in this condition in dynamic CT completed within the first minutes after contrast administration. In a later phase, after contrast administration, however, both
iopamidol and
ioxaglate should conceal hypodense hepatic
tumors less than
diatrizoate.