Magnetic resonance imaging of liver metastases: experimental comparison of anionic and conventional superparamagnetic iron oxide particles with a hepatobiliary contrast medium during dynamic and uptake phases.

OBJECTIVES

To assess the contrast-enhancing effects of citrate-coated superparamagnetic iron oxide particles (VSOP-C184) in a rat liver tumor model using dynamic and delayed magnetic resonance imaging in comparison to carboxydextran-coated particles (ferucarbotran) and a hepatobiliary contrast medium (gadobenate dimeglumine).

MATERIALS AND METHODS

A total of 32 male rats with liver tumors (CC-531 colorectal carcinoma) were examined at 1.5 T with a T1-weighted dynamic series (3D gradient echo sequence) and T1-weighted and T2*-weighted images (2D gradient echo sequences) before and 15 and 90 minutes after injection. VSOP-C184 was investigated at doses of 0.015, 0.045, and 0.06 mmol Fe/kg, ferucarbotran at 0.015 mmol Fe/kg, and gadobenate dimeglumine at 0.025, 0.05, and 0.1 mmol Gd/kg. Liver-tumor contrast-to-noise ratio (CNR) was calculated and statistically compared.

RESULTS

T1-weighted dynamic images: VSOP-C184 has significantly higher CNR values at a dose of 0,015 mmol Fe/kg than ferucarbotran at the same dose (P = 0.001). VSOP-C184 produces a significantly higher CNR at a dose of 0.045 mmol Fe/kg than gadobenate dimeglumine at a dose of 0.05 mmol Gd/kg (P = 0.019). At a dose of 0.06 mmol Fe/kg, the CNR for VSOP-C184 is significantly lower than that of gadobenate dimeglumine (0.1 mmol Gd/kg) (P = 0.005).T2-weighted delayed images: CNR values of VSOP-C184 are similar to those of ferucarbotran and are significantly higher than those of gadobenate dimeglumine (P < 0.05).

CONCLUSIONS

On T1-weighted magnetic resonance imaging of liver tumors VSOP-C184 produces a high contrast comparable to that of a hepatobiliary contrast medium in addition to its contrast-enhancing effect in T2-weighted imaging.