Comparison of two blood pool contrast agents for 0.5-T MR angiography: experimental study in rabbits

To evaluate two experimental blood pool agents for potential use in equilibrium phase abdominal magnetic resonance (MR) angiography.

MR imaging at 0.5 T was performed in 37 rabbits before and after intravenous injection of a gadolinium-based blood pool contrast agent (SH L 643 A), superparamagnetic iron oxide blood pool agent (SH U 555 C), or gadopentetate dimeglumine. T1-weighted fast spoiled gradient-echo images from the renal arteries to below the iliac bifurcation were obtained. The aorta-to-tissue signal difference-to-noise ratio (SDNR) was measured over time.

Both blood pool agents yielded excellent demonstration of the rabbit abdominal aorta. At a dose of 0.1 mmol/kg, both provided a statistically significant increase in aorta-to-tissue SDNR in comparison with that achieved with gadopentetate dimeglumine (200% increase for SH L 643 A, 95% increase for SH U 555 C; P < .05). A 0.1 mmol/kg dose of SH L 643 A provided a 24% increase in SDNR relative to the increase with a 0.37 mmol/kg dose of gadopentetate dimeglumine. Time-dependent enhancement properties of the blood pool agents differed due to differences in elimination method.

Both blood pool agents were found to be promising contrast agents for 0.5-T MR angiography; however, their clinical applicability warrants further investigation. The gadolinium-based agent had several advantages over the iron oxide compound, including less T2* dephasing, lack of susceptibility artifacts, and fast renal elimination.