Wavelet entropy of Doppler ultrasound blood velocity flow waveforms distinguishes nitric oxide-modulated states

Christina E. Agnew, Paul K Hamilton, Aaron J. McCann, R. Canice McGivern, Gary E. McVeigh

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Wavelet entropy assesses the degree of order or disorder in signals and presents this complex information in a simple metric. Relative wavelet entropy assesses the similarity between the spectral distributions of two signals, again in a simple metric. Wavelet entropy is therefore potentially a very attractive tool for waveform analysis. The ability of this method to track the effects of pharmacologic modulation of vascular function on Doppler blood velocity waveforms was assessed. Waveforms were captured from ophthalmic arteries of 10 healthy subjects at baseline, after the administration of glyceryl trinitrate (GTN) and after two doses of N(G)-nitro-L-arginine-methyl ester (L-NAME) to produce vasodilation and vasoconstriction, respectively. Wavelet entropy had a tendency to decrease from baseline in response to GTN, but significantly increased after the administration of L-NAME (mean: 1.60 ± 0.07 after 0.25 mg/kg and 1.72 ± 0.13 after 0.5 mg/kg vs. 1.50 ± 0.10 at baseline, p < 0.05). Relative wavelet entropy had a spectral distribution from increasing doses of L-NAME comparable to baseline, 0.07 ± 0.04 and 0.08 ± 0.03, respectively, whereas GTN had the most dissimilar spectral distribution compared with baseline (0.17 ± 0.08, p = 0.002). Wavelet entropy can detect subtle changes in Doppler blood velocity waveform structure in response to nitric-oxide-mediated changes in arteriolar smooth muscle tone.

Original languageEnglish
Pages (from-to)1320-1327
Number of pages8
JournalUltrasound in Medicine & Biology
Issue number5
Publication statusPublished - May 2015

Bibliographical note

Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.


  • Adolescent
  • Adult
  • Blood Flow Velocity
  • Humans
  • Image Interpretation, Computer-Assisted
  • Male
  • NG-Nitroarginine Methyl Ester
  • Nitric Oxide
  • Nitroglycerin
  • Ophthalmic Artery
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Ultrasonography, Doppler
  • Vasoconstriction
  • Vasoconstrictor Agents
  • Vasodilation
  • Vasodilator Agents
  • Wavelet Analysis
  • Young Adult


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