A prototype liver-specific contrast medium for CT: preclinical evaluation of gadoxetic acid disodium, or Gd-EOB-DTPA.

Abstract

The suitability of the hepatobiliary contrast medium gadoxetic acid disodium, or Gd-EOB-DTPA, for liver enhancement at computed tomography (CT) was studied. CT attenuation levels at 120 kV were measured in samples of increasing concentrations of gadolinium (gadoxetic acid disodium) or iodine (iopromide) in aqueous solutions in vitro. In dogs, CT attenuation in the liver was measured up to 90 minutes after a single intravenous injection of 0.3, 0.5, and 0.7 mmol Gd/kg gadoxetic acid disodium (three dogs per dose group). In addition, three VX2 tumor-bearing rabbits were examined (0.7 mmol Gd/kg). In vitro, the CT attenuation of gadolinium is 40% higher than that of iodine if calculated per milligram of gadolinium and iodine, respectively. In dogs, the median net increase in liver enhancement was 25, 33, and 43 HU with a dose of 0.3, 0.5, and 0.7 mmol Gd/kg, respectively. The gallbladder and bile ducts became clearly visible. In rabbits, liver enhancement of 25 HU provided improved visualization of the unenhanced tumor. Because of the higher CT attenuation of gadolinium compared with iodine and because of its liver-specific uptake, gadoxetic acid disodium is a contrast medium that may improve diagnosis of pathologic liver conditions at CT.