title: USPIO-enhanced MR angiography of arteriovenous fistulas in patients with renal failure.
abstract: OBJECTIVE
  To determine the feasibility of using ferumoxytol-enhanced magnetic resonance (MR) angiography to depict the vasculature of hemodialysis fistulas and improve image quality compared with nonenhanced time-of-flight (TOF) MR angiography.
  
  
  METHODS
  The study was institutional review board approved and was in compliance with HIPAA regulations. All participants provided written informed consent. TOF and first-pass ferumoxytol-enhanced MR angiography were performed in 10 patients with upper extremity autogenous fistulas. Ferumoxytol was administered as a bolus solution containing 430 μmol of elemental iron. A qualitative comparison was performed on maximum intensity projection images. Lumen depiction was evaluated by using a five-point scale. The uniformity of intraluminal signal intensity was measured as the ratio between the mean signal intensity of the entirety of the imaged fistula and its standard deviation. The contrast-to-noise ratio (CNR) between intraluminal signal and adjacent tissue was evaluated as a function of image acquisition time. Lumen depiction scores, luminal signal heterogeneity, and CNR efficiency were compared between TOF and ferumoxytol-enhanced MR angiography by using a Wilcoxon-Mann-Whitney test.
  
  
  RESULTS
  Flow artifacts were greatly reduced by the use of ferumoxytol-enhanced MR angiography. Ferumoxytol-enhanced MR angiography had significantly better performance than TOF MR angiography as measured with the following: lumen depiction scores in all segments (mean, 4.7±0.1 [standard error of the mean]; vs 3.0±0.3 for arterial inflow, 4.1±0.3 vs 1.9±0.3 for arterial outflow, 3.7±0.3 vs 1.8±0.2 for anastomosis, and 4.5±0.2 vs 2.1±0.2 for venous outflow; P<.001), intraluminal signal homogeneity (0.3±0.02 vs 0.4±0.06, P=.005), and CNR efficiency in the venous outflow (5.1±0.6 vs 2.5±0.4, P=.01).
  
  
  CONCLUSIONS
  This study demonstrates the feasibility of using ferumoxytol-enhanced MR angiography in imaging hemodialysis fistulas with consistently superior image quality compared with nonenhanced TOF MR angiography.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California San Francisco, 4150 Clement St, Box 411D, San Francisco, CA 94121, USA. monica.sigovan1@gmail.com
authors.forename: Monica
authors.initials: M
authors.lastname: Sigovan
authors.forename: Warren
authors.initials: W
authors.lastname: Gasper
authors.forename: Hugh F
authors.initials: HF
authors.lastname: Alley
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Owens
authors.forename: David
authors.initials: D
authors.lastname: Saloner
mesh_terms: D000714:Anastomosis, Surgical; D001163:Arteriovenous Anastomosis / Q000473:pathology*; D003287:Contrast Media; D003911:Dextrans; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D058185:Magnetite Nanoparticles; D008297:Male; D051437:Renal Insufficiency / Q000473:pathology* / Q000601:surgery*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; C097921:ferumoxtran-10