Ultrasonic Method and Apparatus for Measuring or Detecting Flow Behavior of a Non-Sinusoidal Periodicity

• US 20090018449A1
• Filed: 01/29/2007
• Published: 01/15/2009
• Est. Priority Date: 02/03/2006
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Raju, Balasundara I.
• Application Number:
  US12/161,983
• Publication Number:
  US 20090018449A1
• Time in Patent Office: Days
• US Class Current: 600/455
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: A61B 8/5269 involving detection or reduction of artifacts for image enhancement algorithms G06T5/00
• CPC Class Codes: A61B 8/543 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting

Abstract

A method and apparatus for automated detection of a general, non-sinusoidal type of periodicity in ultrasound Doppler signals from pulsatile blood flow is described. The method computes a pulsation index, which is a sum of the normalized powers of the fundamental and several harmonic components in the frequency spectrum of the banded Doppler signal. A weighting function may be applied to the power from each harmonic component in order to suppress contributions due to spurious peaks, as in the case when pulsatile flow is absent.

Claims

1. An ultrasonic method for detecting and/or measuring pulsatile flow comprising:

acquiring ultrasonic Doppler signal information from a flow site;

determining from the Doppler signal information a power spectrum within a specific frequency band;

identifying fundamental and harmonic peaks of the power spectrum;

determining the power in bands including the identified fundamental and harmonic peaks; and

determining a measure of pulsatility from the power in the bands.

2. The method of claim 1, wherein identifying further comprises identifying a fundamental and a plurality of harmonic peaks of the power spectrum.

3. The method of claim 2, wherein identifying further comprises identifying a fundamental and four harmonic peaks of the power spectrum.

4. The method of claim 1, wherein determining the power further comprises calculating the normalized power in each band including a fundamental or harmonic peak.

6. The method of claim 1, further comprising weighting the power in the bands as a function of noise.

7. The method of claim 6, wherein weighting the power in the bands further comprises weighting the power in the bands with a sigmoidal weighting function.

8. The method of claim 1, wherein determining a measure of pulsatility comprises combining the power in the bands to form a pulsation index.

9. The method of claim 8, further comprising comparing the pulsation index with a threshold.

10. The method of claim 1, further comprising determining a measure of noise from the spectrum between the peaks.

11. The method of claim 10, further comprising normalizing the measure of noise to total spectral power.

12. A defibrillator comprising:

a pair of electrodes;

a shock delivery circuit coupled to the electrodes;

an ultrasonic Doppler transducer;

a Doppler processor, coupled to the Doppler transducer, which operates to produce a Doppler spectrum;

a peak detector operable to detect a fundamental and at least one harmonic peak in the Doppler spectrum;

a pulsatility processor, responsive to the detected peaks, which acts to produce a measure of pulsatility from the Doppler power in the vicinity of the detected peaks.

13. The defibrillator of claim 12, further comprising an ECG signal processor coupled to the electrodes and to the shock delivery circuit.

14. The defibrillator of claim 12, further comprising a Doppler signal transmitter coupled to the Doppler transducer.

15. The defibrillator of claim 12, wherein the Doppler processor further comprises means for producing a banded Doppler signal.

16. The defibrillator of claim 12, further comprising a noise detector operable to immunize the pulsatility processor against the effect of noise.