title: Dixon-based fat-free MR-angiography compared to first pass and steady-state high-resolution MR-angiography using a blood pool contrast agent.
abstract: BACKGROUND
  Compared to standard arterial-only first-pass MR-angiography (FPMRA), imaging during the equilibrium phase of a blood pool contrast agent (steady state) has been shown to provide higher image quality and better stenosis grading. Homogenous Dixon fat-suppression promises to increase contrast by suppression of fat adjacent to vessels. This study was performed to compare diagnostic image quality and vessel-to-background contrasts in equilibrium phase Dixon-based fat-free MRA (DFSMRA) of run-off vessels to FPMRA imaging and equilibrium phase T1-weighted non-fat-suppressed ultra-high resolution MRA (SSMRA).
  
  
  METHODS
  In a prospective, intra-individual comparative study, 17 patients with known or suspected peripheral arterial occlusive disease (PAOD; 11 men, mean age 65.6±18.1 [23-89] years) received FPMRA, DFSMRA, and SSMRA at 1.5 Tesla using a clinical whole body MRI scanner. All sequences were performed within the same session applying a single dose of a blood pool contrast agent (gadofosveset trisodium) that was injected during acquisition of FPMRA. The diagnostic image quality of the run-off vessels was evaluated on a 3-point scale. Quantitative analysis consisted of contrast-ratio (CR) measurements of vascular lumen signals compared to signals of adjacent muscle and fat.
  
  
  RESULTS
  The average image quality of vessel visualization was rated highest in SSMRA (mean 1.34±0.41), followed by standard FPMRA (mean 1.15±0.33) and DFSMRA (mean 0.99±0.61). Image quality was rated similarly high in the thighs and pelvic region, whereas small vessels in the lower legs and in the feet were best visualized by SSMRA. CR of vascular lumen compared to adjacent fatty tissue was 2.7 times higher in DFSMRA compared to SSMRA, whereas CR of vascular lumen to muscle was 1.3 times higher in SSMRA.
  
  
  CONCLUSIONS
  Vessel to fat contrast is strongly increased in DFSMRA compared to T1-weighted ultra-high resolution non-fat suppressed SSMRA, whereas vessel to muscle contrast is decreased in DFSMRA. Given the current technical limitations of DFSMRA, possible benefits are outweighed by advantages of first-pass imaging regarding arterial selectivity as well as advantages of SSMRA with respect to spatial resolution.
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany.
authors.forename: Rami
authors.initials: R
authors.lastname: Homsi
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany; Phillips Healthcare, Veenpluis 4, 5684 PC Best, Netherlands.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gieseke
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany.
authors.forename: Guido M
authors.initials: GM
authors.lastname: Kukuk
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Träber
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany; Center for Radiology, Neuroradiology, Sonography and Nuclear Medicine, Krankenhaus der Barmherzigen Brueder, Nordallee 1, 54292 Trier, Germany.
authors.forename: Winfried A
authors.initials: WA
authors.lastname: Willinek
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany.
authors.forename: Hans H
authors.initials: HH
authors.lastname: Schild
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany. Electronic address: dariusch.hadizadeh@ukb.uni-bonn.de.
authors.forename: Dariusch R
authors.initials: DR
authors.lastname: Hadizadeh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001157:Arterial Occlusive Diseases / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D005682:Gadolinium; D006801:Humans; D007089:Image Enhancement; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D009942:Organometallic Compounds; D010388:Pelvis / Q000098:blood supply / Q000473:pathology; D058729:Peripheral Arterial Disease / Q000473:pathology*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013848:Thigh / Q000098:blood supply / Q000473:pathology; D055815:Young Adult
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D005682:Gadolinium; C109932:gadofosveset trisodium
keywords: Blood pool contrast agent; Contrast-ratio; Dixon; MRA; Steady state