title: Development of a Duplex Ultrasound Simulator and Preliminary Validation of Velocity Measurements in Carotid Artery Models.
abstract: OBJECTIVE
  Duplex ultrasound scanning with B-mode imaging and both color Doppler and Doppler spectral waveforms is relied upon for diagnosis of vascular pathology and selection of patients for further evaluation and treatment. In most duplex ultrasound applications, classification of disease severity is based primarily on alterations in blood flow velocities, particularly the peak systolic velocity (PSV) obtained from Doppler spectral waveforms. We developed a duplex ultrasound simulator for training and assessment of scanning skills.
  
  
  METHODS
  Duplex ultrasound cases were prepared from 2-dimensional (2D) images of normal and stenotic carotid arteries by reconstructing the common carotid, internal carotid, and external carotid arteries in 3 dimensions and computationally simulating blood flow velocity fields within the lumen. The simulator displays a 2D B-mode image corresponding to transducer position on a mannequin, overlaid by color coding of velocity data. A spectral waveform is generated according to examiner-defined settings (depth and size of the Doppler sample volume, beam steering, Doppler beam angle, and pulse repetition frequency or scale). The accuracy of the simulator was assessed by comparing the PSV measured from the spectral waveforms with the true PSV which was derived from the computational flow model based on the size and location of the sample volume within the artery.
  
  
  RESULTS
  Three expert examiners made a total of 36 carotid artery PSV measurements based on the simulated cases. The PSV measured by the examiners deviated from true PSV by 8% ± 5% (N = 36). The deviation in PSV did not differ significantly between artery segments, normal and stenotic arteries, or examiners.
  
  
  CONCLUSIONS
  To our knowledge, this is the first simulation of duplex ultrasound that can create and display real-time color Doppler images and Doppler spectral waveforms. The results demonstrate that an examiner can measure PSV from the spectral waveforms using the settings on the simulator with a mean absolute error in the velocity measurement of less than 10%. With the addition of cases with a range of pathologies, this duplex ultrasound simulator will be a useful tool for training health-care providers in vascular ultrasound applications and for assessing their skills in an objective and quantitative manner.
authors.affiliation: Division of Vascular Surgery, Department of Surgery, University of Washington, Seattle, WA, USA gzierler@u.washington.edu.
authors.forename: R Eugene
authors.initials: RE
authors.lastname: Zierler
authors.affiliation: Applied Physics Laboratory, University of Washington, Seattle, WA, USA.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Leotta
authors.affiliation: Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.
authors.forename: Kurt
authors.initials: K
authors.lastname: Sansom
authors.affiliation: Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.
authors.forename: Alberto
authors.initials: A
authors.lastname: Aliseda
authors.affiliation: Division of Cardiology, Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Anderson
authors.affiliation: Division of Cardiology, Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Florence H
authors.initials: FH
authors.lastname: Sheehan
mesh_terms: D001783:Blood Flow Velocity; D002309:Cardiology / Q000193:education*; D002342:Carotid Artery, External / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016022:Case-Control Studies; D002983:Clinical Competence; D003198:Computer Simulation; D003194:Computer-Assisted Instruction; D004501:Education, Medical / Q000379:methods*; D006801:Humans; D059032:Learning Curve; D008348:Manikins; D015588:Observer Variation; D011237:Predictive Value of Tests; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D018616:Ultrasonography, Doppler, Duplex
keywords: Doppler spectral waveform; carotid artery stenosis; color-Doppler; duplex ultrasound; medical simulation