title: Time-resolved, high-resolution contrast-enhanced MR angiography of dialysis shunts using the CENTRA keyhole technique with parallel imaging.
abstract: OBJECTIVE
  To evaluate the use of a dynamic keyhole magnetic resonance angiography (MRA) sequence combined with sensitivity encoding (SENSE) for hemodialysis shunts, because surveillance with conventional contrast-enhanced MRA (CE-MRA) is limited by its low temporal resolution, resulting in arteriovenous overlay.
  
  
  METHODS
  A total of 12 patients with Brescia-Cimino shunts were investigated prospectively using the new technique. During the contrast passage (gadoterate, Gd-DOTA) a series of five to nine dynamic central k-space measurements (10% for upper-arm shunt, 25% for lower-arm shunt) followed by a full reference data set were acquired. The outer k-space data of the single reference scan were used to complete the dynamic data sets.
  
  
  RESULTS
  All studies were diagnostic (17 stenoses, three aneurysms) without complications. The acquisition times for a single dynamic scan of the upper- and lower-arm shunts were 2.2 and 3.2 seconds, respectively, while the reference scan needed 13 and 22.4 seconds, respectively. The dynamic angiograms allowed the differentiation of arterial and venous filling despite a mean peak delay time of only 4.2 seconds in the shoulder region. Image quality qualified in consensus by two experienced readers was rated "good" in 19 cases and "intermediate" in five cases with high mean values for signal-to-noise ratios (SNRs) and contrast-to-noise-ratios (CNRs).
  
  
  CONCLUSIONS
  We have successfully implemented a fast, dynamic, CE-MRA technique with CE timing robust angiography (CENTRA) keyhole and SENSE in clinical routine. High spatial and temporal resolution improve the diagnostics of dialysis shunts and allow the assessment of detailed, dynamic, four-dimensional (4D) information.
authors.affiliation: MR-Research Group, Institute of Radiology, Cantonal Hospital, Winterthur, Switzerland, and Department of Radiology and MicroTherapy, University Witten-Herdecke, Germany. katja@mende.ch
authors.forename: Katja A
authors.initials: KA
authors.lastname: Mende
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Froehlich
authors.forename: Constantin
authors.initials: C
authors.lastname: von Weymarn
authors.forename: Romhild
authors.initials: R
authors.lastname: Hoogeveen
authors.forename: Thomas
authors.initials: T
authors.lastname: Kistler
authors.forename: Christoph L
authors.initials: CL
authors.lastname: Zollikofer
authors.forename: Klaus U
authors.initials: KU
authors.lastname: Wentz
mesh_terms: D000328:Adult; D000368:Aged; D001132:Arm; D001166:Arteriovenous Shunt, Surgical; D003287:Contrast Media; D005260:Female; D006083:Graft Occlusion, Vascular / Q000175:diagnosis*; D006571:Heterocyclic Compounds; D006801:Humans; D007091:Image Processing, Computer-Assisted; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009942:Organometallic Compounds; D011446:Prospective Studies; D006435:Renal Dialysis
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate