Iron oxide contrast media improve MR-imaging of the portal venous system - An experimental study.

Purpose: The aim was to demonstrate that intravenous superparamagnetic iron oxide contrast agents improve the delineation of the portal venous system. Material and methods: The portal Venous system of 8 minipigs was demonstrated by a FLASH 2-D MRA-sequence. Scans were acquired before and after intravenous administration of 70 and 20 mu mol/kg of a superparamagnetic iron oxide contrast agent (SHU 555 A). Signal intensities were measured in the portal Vein and hepatic parenchymal and contrast-to-noise ratios were calculated. Results: Following a cumulative dose of 10 mu mol iron oxide, hepatic parenchymal signal intensity decreased to 67 +/- 6%, following 20 mu mol to 29 +/- 4%, and following 40 mu mol to 13 +/- 2% of control (p < 0.0001). These effects improved the contrast-to-noise ratio of the portal Vein (469 +/- 114%, 858 +/- 243%, and 957 +/- 272% of control in the left portaI vein main branch, p = 0.02). Conclusion: A decrease in hepatic parenchymal signal due to a magnetic susceptibility effect accounts for an improvement of portal Venous conspicuity following intravenous administration of iron oxide contrast medium.