Pulmonary MRA is an emerging technique to detect pulmonary embolism without the use of ionizing radiation. This technique is capable of achieving high quality angiograms in approximately 75% of the cases. However, a subset of patients fails the breathholding required for pulmonary MRA. To overcome this limitation, free-breathing ultrashort echo time (UTE) imaging of the pulmonary vasculature has been introduced recently. Due to the longer scan time of the free breathing UTE sequence, a blood pool contrast agent is beneficial in order to achieve constant high intravascular signal throughout the scan.
Ferumoxytol is a contrast agent that is increasingly used due to its excellent magnetic properties and the lack of gadolinium. Ferumoxytol is an effective blood pool contrast agent with an intravascular half-life of 14-15 hours.
The purpose of this study is to compare pulmonary MRA and UTE imaging with gadobenate dimeglumine and ferumoxytol in order to evaluate if a comparable image quality can be achieved with ferumoxytol.