An improved spectral width Doppler method for estimating Doppler angles in flows with existence of velocity gradients

Po Lei Lee, Yi Hong Chou, Jen Chuen Hsieh, Huihua Kenny Chiang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Doppler angle (i.e., beam-to-flow angle) is an important parameter for quantitative flow measurements. With known Doppler angles, volumetric flows can be obtained by the mean flow velocity times the cross-section area of the vessel. The differences or changes between prestenotic and poststenotic volumetric flows have been quantified as an indicator for assessing the clinical severity of the stenosis. Therefore, several research groups have dedicated themselves to developing user-independent methods to determine automatically the Doppler angle. Nevertheless, most of these methods were developed for narrow ultrasound beam measurements. For small vessels, where the beam width is a significant fraction of the diameter of the vessel, the effect of velocity gradients plays an important role and should not be ignored in the Doppler angle estimations. Accordingly, this paper is concerned with a method for improving the estimation of Doppler angles from spectral width Doppler (SWD) method, but correcting for velocity-gradient broadening that may arise when the beam has a nonzero width. In our method, Doppler angles were firstly calculated by SWD and then were corrected by an artificial neural network (ANN) method to neutralize the contribution of velocity gradient broadening (VGB). This SWD and ANN conjoint method has been successfully applied to estimate Doppler angles from 50° to 80° for constant flows in 10 mm, 4 mm and 1 mm diameter tubes, whose mean flow velocities were 15.3, 19.9 and 25.5 cm/s, respectively, and the achieved mean absolute errors of the estimated Doppler angles were 1.46°, 1.01° and 1.3°. (E-mail:

Original languageEnglish
Pages (from-to)1229-1245
Number of pages17
JournalUltrasound in Medicine and Biology
Issue number8
StatePublished - Aug 2006


  • Artificial neural networks
  • Doppler ultrasound
  • Spectral-width Doppler
  • Velocity-gradient broadening


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