Rationale and objectives: To characterize an iodized oil emulsion for computed tomography (CT) imaging of experimental hepatic tumors in rat models.
Materials and methods: For characterizing the agents in normal rats, three rats were intravenously infused and imaged with clinical CT up to 1 week. Iopamidol solution was also used as controls (n = 3). For evaluating the feasibility of diagnosis of hepatic tumors, 12 rats were injected with C6 glial tumor cells into the liver 11, 9, 7, and 5 days before CT (n = 3 per day). After CT imaging, gross and histopathologic correlation of liver tumors with CT images were performed.
Results: CT numbers of aorta and inferior vena cava (IVC) increased immediately after injection of the emulsion and remained above 200 Hounsfield units for 1 hour (maximum: 295.67 +/- 27.65 in aorta and 347.07 +/- 10.58 in IVC). The mean attenuation in liver and spleen was relatively stable between 30 and 180 minutes (maximum: 188.84 +/- 18.70 in liver and 210.97 +/- 15.83 in spleen). All 20 tumors later confirmed by pathology were detected as hypodense lesions on CT (sensitivity: 100%; range, 2.0-16.4 mm). The mean enhancement ratios of liver at all time points were significantly higher than those of tumors (P < .05).
Conclusion: The hepatic enhancement achieved by the iodized oil emulsion is reticuloendothelial system-specific with the property of blood pool enhancement and longer lasting than that achievable with the current water soluble agents. Thus, this agent may offer significant advantages for diagnosis of hepatic metastases.