title: Stenosis detection in forearm hemodialysis arteriovenous fistulae by multiphase contrast-enhanced magnetic resonance angiography: preliminary experience.
abstract: OBJECTIVE
  To assess the feasibility and accuracy of multiphase contrast-enhanced magnetic resonance angiography (CE-MRA) in patients with dysfunctioning hemodialysis arteriovenous fistulae (AVF), using digital subtraction angiography (DSA) as the standard of reference.
  
  
  METHODS
  Fifteen patients with dysfunctioning AVF (eight radiocephalic and seven graft AVF) underwent CE-MRA. Dysfunction was defined as a flow decline of more than 25% in 1 month measured by dilutional flow measurements. CE-MRA was performed during injection of 35 mL of gadolinium-DTPA. The CE-MRA sequence consisted of a time-resolved series of 10 scans, each lasting approximately 10 seconds. The technical parameters were TR/TE/FA/voxel = 5.4/1.6/40/3.1 mm(3), and a rectangular surface reception coil was used. All patients were scheduled to undergo DSA at which an intervention was carried out when a stenosis >or=50% was seen. Two observers, unaware of each other's findings and the findings at DSA, quantified the number and degree of stenosis in the failing AVF. Image quality for CE-MRA and DSA was scored on a 3-point scale. The diagnostic performance of CE-MRA was analyzed with receiver-operator characteristic (ROC) analysis.
  
  
  RESULTS
  CE-MRA and DSA examinations were performed without side effects in all 15 patients. Image quality was scored significantly better on CE-MRA (observer 1: CE-MRA, 2.0; DSA, 1.3; P =.001; observer 2: CE-MRA, 2.0; DSA, 1.4; P =.002). Interobserver agreement for detection of >or=50% stenosis was 0.81 (95% confidence interval (CI) = 0.71-0.92) for CE-MRA and 0.69 (95% CI = 0.55-0.84) for DSA. ROC analysis revealed a mean area under the curve of 0.78. On the patient level, at the >or=50% threshold, mean sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 100% (95% CI = 69%-100%), 10% (95% CI = 0%-78%), 70% (95% CI = 38%-92%), and 100% (95% CI = 50%-100%), respectively. At the >or=75% threshold, mean sensitivity, specificity, PPV, and NPV were 75% (95% CI = 20%-99%), 78% (95% CI = 39%-98%), 55% (95% CI = 12%-96%), and 89% (95% CI = 52%-100%), respectively.
  
  
  CONCLUSIONS
  CE-MRA is a useful diagnostic tool for detecting stenoses in flow-declined hemodialysis AVF prior to interventional DSA.
authors.affiliation: Department of Radiology, Maastricht University Hospital and Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands.
authors.forename: R Nils
authors.initials: RN
authors.lastname: Planken
authors.forename: Jan H M
authors.initials: JH
authors.lastname: Tordoir
authors.forename: Ruben
authors.initials: R
authors.lastname: Dammers
authors.forename: Michiel W
authors.initials: MW
authors.lastname: de Haan
authors.forename: T Khiam
authors.initials: TK
authors.lastname: Oei
authors.forename: Freek M
authors.initials: FM
authors.lastname: van der Sande
authors.forename: Jos M A
authors.initials: JM
authors.lastname: van Engelshoven
authors.forename: Tim
authors.initials: T
authors.lastname: Leiner
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction; D001164:Arteriovenous Fistula / Q000473:pathology*; D001166:Arteriovenous Shunt, Surgical / Q000009:adverse effects*; D003251:Constriction, Pathologic / Q000175:diagnosis / Q000473:pathology; D003287:Contrast Media; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D006435:Renal Dialysis / Q000009:adverse effects*
chemical_list: D003287:Contrast Media