Experimental evaluation of superparamagnetic iron oxide nanoparticles for pulmonary MR angiography

Purpose: Initial experimental results of contrast-enhanced pulmonary MR angiography using the new superparamagnetic iron oxide blood pool agent FeO-BPA. Method: Pulmonary MRA was performed in 7 domestic pigs using a cardiac-triggered coronal T-1-weighted FFE-Sequence before and up to 90 minutes after contrast injection obtained on a 1.5 T magnet with a standard gra dient equipment. A dose of 4 mg Fe/kg bodyweight was used for MRA. The images were qualitatively assessed and compared with X-ray i.v.-DSA. Results: The injection of FeO-BPA allows the acquisition of unsaturated in-plane images of the pulmonary vascular tree down to the first: order subsegmental branches including vessel diameters of approximately 1.5 mm. In the normal non-occluded vasculature, no signal void is seen in the T-E range of 2.8-5.5 ms secondary to exceeding susceptibility effects which are caused by the iron oxide accumulation. Even 90 minutes after injection of FeO-BPA, assessment of the pulmonary vasculature is still satisfactory. Conclusions: In the animal experiment, the use of the blood pool agent FeO-BPA provides detailed pulmonary angiograms even on a magnet with a conventional gradient system. The major advantage is the comfortable diagnostic window of > 1.5 hours which also portends its utility for future MR-guided pulmonary interventions.