title: High wall shear stress measured by magnetic resonance is a predictor of restenosis in the femoral-artery after balloon angioplasty.
abstract: OBJECTIVE
  Wall shear stress (WSS) has been implied in the pathogenesis of restenosis after percutaneous transluminal angioplasty (PTA). Aims of the present study were to calculate WSS in the superficial femoral artery (SFA) from magnetic resonance imaging (MRI) and from duplex sonography in healthy controls and in patients after PTA of the SFA to evaluate the predictive value of WSS for restenosis.
  
  
  METHODS
  WSS was assessed by calculating the slope of velocity profiles at the vessel wall from data obtained with velocity encoded cine MR and with duplex using the formula: Shear stress=4xblood viscosityxpeak blood velocity/internal diameter. Seventeen patients were studied 1 day after successful PTA of the SFA. Restenosis was determined by duplex ultrasound at the 6-months follow-up visit.
  
  
  RESULTS
  In healthy controls WSS values calculated from MRI and from duplex were similar (1.86+/-0.35 N/m2 vs 1.88+/-0.34 N/m2, n.s.). In patients the values obtained with duplex were higher than those obtained with MRI (4.1+/-2.3 N/m2 vs 2.4+/-1.2 N/m2, p=0.002). With both methods post-interventional WSS was higher in patients developing restenosis (duplex 5.4+/-2.2 N/m2, MRI 3.1+/-0.9 N/m2) than in those without restenosis (duplex 2.7+/-1.4 N/m2, MRI 1.5+/-0.7 N/m2) and was revealed to be an independent predictor of restenosis (p=0.03).
  
  
  CONCLUSIONS
  This is the first study demonstrating that increased post-interventional WSS in the SFA is predictive for restenosis. WSS values obtained with MRI and duplex were different in patients, however with both methods higher WSS was associated with restenosis.
authors.affiliation: Division of Angiology, University Hospital, Zurich. Switzerland. beatrice.amann@usz.ch
authors.forename: B R
authors.initials: BR
authors.lastname: Amann-Vesti
authors.forename: S
authors.initials: S
authors.lastname: Kozerke
authors.forename: E
authors.initials: E
authors.lastname: Krieger
authors.forename: P
authors.initials: P
authors.lastname: Boesiger
authors.forename: R
authors.initials: R
authors.lastname: Koppensteiner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000800:Angioplasty, Balloon; D001157:Arterial Occlusive Diseases / Q000503:physiopathology / Q000628:therapy*; D001783:Blood Flow Velocity; D005260:Female; D005263:Femoral Artery / Q000000981:diagnostic imaging / Q000473:pathology*; D005500:Follow-Up Studies; D006083:Graft Occlusion, Vascular / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D013314:Stress, Mechanical; D016896:Treatment Outcome; D018616:Ultrasonography, Doppler, Duplex