title: Variation in duplex peak systolic velocity measurement in a multi-site vascular service.
abstract: OBJECTIVE
  Duplex US (DUS) is increasingly utilised as a first-line investigation for the assessment of carotid disease. For clinical decision-making, DUS assessment must be accurate and reproducible to ensure reliability. We aimed to investigate the variability in peak systolic velocity (PSV) measurement in a multi-site vascular network.
  
  
  METHODS
  DUS measurements of PSV were taken from continuous and pulsatile flow, generated by a high fidelity phantom, by 12 experienced vascular scientists across four hospitals. Participants were blinded to the actual PSV value (50 cm/s).
  
  
  RESULTS
  We observed an average error of 13.2% (± 8.3) and 11.6% (± 7.5) in PSV measurements taken from pulsatile and continuous waveforms, respectively. Measurements of PSV using the pulsatile waveform demonstrated statistically significant variation across all hospitals; ((hospital/mean) A 43.9 cm/s, B 61.7 cm/s, C 57.4 cm/s, D 47.7 cm/s, p=0.001). Further analysis demonstrated statistically significant variation in 4 instrumentation-related factors when measuring from a pulsatile waveform (Doppler angle, angle of insonation, velocity range, scale range).
  
  
  CONCLUSIONS
  We observed a significant level of error and variation in PSV measurements across four sites within our vascular network. Variation in instrumentation-related factors may be accountable for this. In light of the centralisation of vascular services, it is increasingly important to unify and implement scanning protocols in order to reduce error and inter-site variability.
authors.affiliation: Department of Vascular Surgery, Imperial College School of Medicine, UK pn106@imperial.ac.uk.
authors.forename: P
authors.initials: P
authors.lastname: Normahani
authors.affiliation: Department of Vascular Surgery, Imperial College School of Medicine, UK.
authors.forename: M
authors.initials: M
authors.lastname: Aslam
authors.affiliation: Department of Vascular Surgery, Imperial College School of Medicine, UK.
authors.forename: G
authors.initials: G
authors.lastname: Martin
authors.affiliation: Department of Vascular Surgery, Imperial College School of Medicine, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Standfield
authors.affiliation: Department of Vascular Surgery, Imperial College School of Medicine, UK.
authors.forename: U
authors.initials: U
authors.lastname: Jaffer
mesh_terms: D001783:Blood Flow Velocity; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D063177:Pulse Wave Analysis; D012720:Severity of Illness Index; D013599:Systole / Q000502:physiology*; D018615:Ultrasonography, Doppler, Color
keywords: carotid; diagnostics; duplex; ultrasound; vascular