Introduction

Whereas MR angiography has been widely used for more than two decades, the rapid proliferation of CT angiography has underscored the advantages in speed and practicality of modern CTA when compared to contrast enhanced MR angiography (CEMRA). Beyond challenges in workflow, the relatively long magnet time associated with conventional MR techniques serves to discourage patients with even modest levels of claustrophobia. Furthermore, recent controversies surrounding the safety of gadolinium based contrast agents (GBCA) has added further uncertainty in the cost-benefit balance point of conventional CEMRA. We hypothesize that with the use of ferumoxytol (Feraheme, AMAG Pharmaceuticals), comprehensive vascular imaging of the thorax, abdomen and pelvis can be performed in as little as 5 minutes within the magnet bore, sufficient to reassure all but the most claustrophobic patients and greatly improving workflow and throughput.

Methods

In this HIPAA-compliant and IRB-approved study, all patients expressed reluctance to undergo the MR examination due to claustrophobia, but agreed to a trial of up to 10 minutes in the scanner bore. Following localizer sequences, breath held, high-resolution 3-D ferumoxytol enhanced MR angiography (FEMRA) was carried out in one (n=1) or two (n=12) overlapping stations on a 3.0T MR system (Magnetom TIM Trio or Magnetom Skyra, Siemens Medical Solutions) or a 1.5T MRI system (Magnetom TIM Avanto, Siemens Medical Solutions). Acquisition time for each station was 16-20 seconds and voxel dimensions were on the order of 1 mm x 1.2 mm x 1.3 mm. Overlapping stations were composed into one large field of view study using vendor software (Image Compose, Siemens). The total scanning time was measured from the beginning of localizer image acquisition to the end of the ultimate FEMRA acquisition. Scanner tuning and coil adjustment routines preceded localizer acquisition. Patient-specific machine shimming was not performed and the default shim settings were employed to minimize adjustment time.

Results

Thirteen examinations were carried out in 12 claustrophobic patients (age 11 to 84 years, 6 females) with renal failure (n=11) or hemorrhagic hereditary telangiectasia (n=1), who underwent IV infusion of 4 mg /kg of ferumoxytol (AMAG Pharmaceuticals, Waltham, MA) outside the magnet bore. All examinations were completed successfully without adverse events. The imaging indications included central venous occlusion (n=8), aortic stenosis (n=2), central arterial occlusion (n=1), or hereditary hemorrhagic telangiectasia (n=1). The average scanning time was 6.44 minutes (range 4.16 to 10.10 minutes) including tune up time which was less than one minute. All scans were considered of high diagnostic quality and supported full visualization of arterial and venous anatomy from the neck to the thighs.

Conclusion

Comprehensive vascular imaging of the thorax, abdomen and pelvis can be completed in as little as 5 minutes in the scanner bore using focused MR angiographic image acquisition, following infusion of ferumoxytol. The implications for imaging of claustrophobic patients and for patient throughput are profound.

Acknowledgements

No acknowledgement found.

References

1. Dewey M, Schink T,Dewey CF. Claustrophobia during magnetic resonance imaging: cohort study in over 55,000 patients. J Magn Reson Imaging. 2007;26:1322-7