title: ECG-gated nonenhanced 3D steady-state free precession MR angiography in assessment of transplant renal arteries: comparison with DSA.
abstract: OBJECTIVE
  To evaluate noncontrast material-enhanced steady-state free precession (SSFP) magnetic resonance (MR) angiography in the assessment of transplant renal arteries (RAs) by using digital subtraction angiography (DSA) as the reference standard.
  
  
  METHODS
  This prospective study was approved by the institutional review board; written informed consent was obtained from all participants. In 20 renal allograft recipients scheduled for DSA, the transplant RAs were assessed with electrocardiographically gated nonenhanced SSFP MR angiography performed at 1.5 T; the degree of stenosis was compared with that of DSA. Subjective image quality for SSFP MR angiography was assessed independently by two radiologists on a four-point scale (from 1, nondiagnostic to 4, excellent) in four predefined segments (I, the iliac artery; II, the main transplant artery; III, segmental branches; and IV, parenchymal branches). Sensitivity, specificity, and accuracy of SSFP MR angiography for the detection of relevant (> or =50%) transplant RA stenosis (TRAS) were calculated on a per-artery basis.
  
  
  RESULTS
  One patient was excluded because SSFP MR angiography failed to adequately visualize the allograft vasculature owing to low cardiac output. The mean image quality assessed by both readers was 3.98 +/- 0.16 (standard deviation), 3.5 +/- 0.68, 2.71 +/- 1.12 and 2.03 +/- 1.09 for segments I, II, III, and IV, respectively (kappa = 0.80). DSA helped identify eight relevant (> or =50%) stenoses in six transplant RAs. Kinking of the transplant artery without relevant stenosis was found in seven patients. The degree of stenosis was overestimated in three patients by using SSFP MR angiography. As compared with DSA, the sensitivity, specificity, and accuracy of SSFP MR angiography to help detect relevant TRAS were 100% (six of six), 88% (14 of 16), and 91% (20 of 22), respectively.
  
  
  CONCLUSIONS
  Nonenhanced SSFP MR angiography is a reliable alternative imaging technique for the assessment of transplant RAs in patients for whom contrast-enhanced MR angiography is contraindicated.
authors.affiliation: Institute of Radiology, University Hospital Düsseldorf, Moorenstr 5, 40225 Düsseldorf, Germany. rotemshlomo@yahoo.de
authors.forename: Rotem S
authors.initials: RS
authors.lastname: Lanzman
authors.forename: Adina
authors.initials: A
authors.lastname: Voiculescu
authors.forename: Clemens
authors.initials: C
authors.lastname: Walther
authors.forename: Adrian
authors.initials: A
authors.lastname: Ringelstein
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Bi
authors.forename: Peter
authors.initials: P
authors.lastname: Schmitt
authors.forename: Sonja-Marie
authors.initials: SM
authors.lastname: Freitag
authors.forename: Sora
authors.initials: S
authors.lastname: Won
authors.forename: Axel
authors.initials: A
authors.lastname: Scherer
authors.forename: Dirk
authors.initials: D
authors.lastname: Blondin
mesh_terms: D000328:Adult; D015901:Angiography, Digital Subtraction; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007668:Kidney / Q000098:blood supply* / Q000000981:diagnostic imaging; D016030:Kidney Transplantation; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012077:Renal Artery; D012078:Renal Artery Obstruction / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D014184:Transplantation, Homologous; D014463:Ultrasonography