title: Evaluation of factors influencing arterial Doppler waveforms in anin vitroflow phantom.
abstract: OBJECTIVE
  The aim of this study was to investigate factors that influence arterial Doppler waveforms in anin vitrophantom to provide a more accurate and comprehensive explanation of the Doppler signal.
  
  
  METHODS
  A flow model was created using a pulsatile artificial heart, rubber or polyethylene tubes, a water tank, and a glass tube. Spectral Doppler tracings were obtained in multiple combinations of compliance, resistance, and pulse rate. Peak systolic velocity, minimum diastolic velocity, resistive index (RI), pulsatility index, early systolic acceleration time, and acceleration index were measured. On the basis of these measurements, the influences of the variables on the Doppler waveforms were analyzed.
  
  
  RESULTS
  With increasing distal resistance, the RI increased in a relatively linear relationship. With increasing proximal resistance, the RI decreased. The pulsus tardus and parvus phenomenon was observed with a small acceleration index in the model with a higher grade of stenosis. An increase in the distal resistance masked the pulsus tardus and parvus phenomenon by increasing the acceleration index. Although this phenomenon occurred independently of compliance, changes in the compliance of proximal or distal tubes caused significant changes in the Doppler waveform. There was a reverse relationship between the RI and the pulse rate.
  
  
  CONCLUSIONS
  Resistance and compliance can alter the Doppler waveforms independently. The pulse rate is an extrinsic factor that also influences the RI. The compliance and distal resistance, as well as proximal resistance, influence the pulsus tardus and parvus phenomenon.
authors: Department of Radiology, SMG-SNU Boramae Medical Center, Seoul National University College of Medicine, Seoul, Korea.
authors: Chang Kyu
authors: 0000-0003-4922-5107
authors: CK
authors: Sung
authors: Department of Radiology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
authors: Kyoung Ho
authors: 0000-0001-6045-765X
authors: KH
authors: Lee
authors: Department of Radiology and the Institute of Radiation Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors: Seung Hyup
authors: 0000-0002-9339-5907
authors: SH
authors: Kim
keywords: Phantoms, imaging; Renal artery; Ultrasonography, Doppler