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

PURPOSE: To evaluate two experimental blood pool agents for potential use i n equilibrium phase abdominal magnetic resonance (MR) angiography. MATERIALS AND METHODS: MR imaging at 0.5 T was performed in 37 rabbits befo re and after intravenous injection of a gadolinium-based blood pool contras t agent (SH L 643 A), superparamagnetic iron oxide blood pool agent (SH U 5 55 C), or gadopentetate dimeglumine. T1-weighted fast spoiled gradient-echo images from the renal arteries to below the iliac bifurcation were obtaine d. The aorta-to-tissue signal difference-to-noise ratio (SDNR) was measured over time. RESULTS: Both blood pool agents yielded excellent demonstration of the rabb it abdominal aorta. At a dose of 0.1 mmol/kg, both provided a statistically significant increase in aorta-to-tissue DNR in comparison with that achiev ed with gadopentetate dimeglumine (200% increase for SH L 643 A, 95% increa se 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 gad opentetate dimeglumine. Time-dependent enhancement properties of the blood pool agents differed due to differences in elimination method. CONCLUSION: Both blood pool agents were found to be promising contrast agen ts for 0.5-T MR angiography; however, their clinical applicability warrants further investigation. The gadolinium-based agent had several advantages o ver the iron oxide compound, including less T2* dephasing, lack of suscepti bility artifacts, and fast renal elimination.