Affiliations: Department of Radiology, Weill Medical College of
Cornell University, New York, NY 10022, USA | Advanced Magnetics, Inc., Cambridge, MA, USA
Note: [] Corresponding author: Martin R. Prince, 416 East 55th Street,
New York, NY 10022, USA. Tel.: +1 212 746 6801; Fax: +1 212 752 8908; E-mail:
map2008@med.cornell.edu
Abstract: Purpose: To evaluate the imaging potential of ferumoxytol, a new
superparamagnetic iron oxide colloidal blood pool contrast agent. Materials and Methods: Magnetic resonance (MR) imaging at 1.5 Tesla
was performed before and after intravenous injection of ferumoxytol using
escalating doses of 0.4, 0.8, 1.2 and 1.6 mg Fe/kg for a total of 4 mg Fe/kg in
five subjects imaged with 3D MR Angiography (MRA) of the trifurcation after
each dose. In five subjects cardiac cine MRI was performed pre and post 4.0 mg
Fe/kg. Image quality was assessed by measuring signal to-noise ratio (SNR) and
contrast-to-noise ratio (CNR) in the vascular structures. Pre- and post-dose
urine and blood tests as well as EKG/vital sign monitoring were performed to
evaluate safety and blood samples were collected for T1 relaxivity
measurements. Results: Cumulative doses of 0, 0.4, 1.2, 2.4 and 4 mg Fe/kg yielded
mean SNR in the arteries of 10, 16, 39, 57 and 69 respectively indicating that
the higher doses produced higher SNR on 3D vascular images. Similarly aorta SNR
on 2D time-of-flight increased from 11.8 without Fe to 15.4 post Fe (p =
0.004) indicating improved image quality on MRA sequences optimized for use
without contrast. At 4 mg Fe/kg there was a substantial T1 shortening measured
in the blood from 1990 ± 573 ms to 80 ± 42 ms (p < 0.0001),
corresponding to the increased SNR. Images of large vascular structures
including cardiac chambers, aorta, and pulmonary arteries were excellent post
ferumoxytol but images of smaller arteries of the trifurcation were difficult
to evaluate due to enhancement of the overlapping veins. No serious adverse
events occurred. Conclusion: The new superparamagnetic iron oxide colloid ferumoxytol
is a promising blood pool agent especially for cardiac, aorta and pulmonary
imaging.
Keywords: magnetic resonance angiography, contrast media, iron oxide, cardiac imaging, aorta
