First-pass contrast-enhanced magnetic resonance angiography in humans using ferumoxytol, a novel ultrasmall superparamagnetic iron oxide (USPIO)-based blood pool agent

Abstract

Purpose: To evaluate the feasibility of first-pass contrast-enhanced magnetic resonance angiography (MRA) using ferumoxytol in humans. Materials and Methods: First-pass and equilibrium phase MRA were performed using ferumoxytol in one healthy volunteer and 11 patients with a fast three-dimensional spoiled gradient recalled (SPGR) pulse sequence. The examined vessels included carotid arteries, thoracic aorta, abdominal aorta, and peripheral arteries. A dose of either 71.6 μmol Fe/kg (n = 9), or 35.8 μmol Fe/kg (n = 3) was used. Based on a phantom study, the agent with initial concentration of 537.2 μmol Fe/mL was diluted by either four-fold (134.3 μmol Fe/mL) or eight-fold (67.1 μmol Fe/mL) for first-pass MRA. Results: All subjects completed their studies without adverse events. First-pass MRA showed selective arterial enhancement, with both arterial and venous enhancement on delayed acquisitions. Selective venous enhancement could be obtained by subtraction of arterial phase images from equilibrium phase images. The findings in ferumoxytol MRA were consistent with the results of original vascular tests. Conclusion: Our preliminary experience supports the feasibility of first-pass MRA with ferumoxytol. Satisfactory arterial enhancement during first-pass imaging is obtained with injection of diluted contrast agent. With ferumoxytol, arteries and veins can be selectively depicted in a single exam.