PHASE-TO-AMPLITUDE/SLOPE MAPPING

• US 20130073262A1
• Filed: 04/27/2011
• Published: 03/21/2013
• Est. Priority Date: 06/04/2010
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Covitch, Adam Jacob, Klahr, Paul
• Granted Patent: US 9,265,452 B2
• Time in Patent Office: Days
• US Class Current: 702/189
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: A61B 6/527 using data from a motion artifact sensor
• CPC Class Codes: A61B 6/5288 involving retrospective matching to a physiological signal
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: G06F 17/00 Digital computing or data processing equipment or methods, specially adapted for specific functions information retrieval, database structures or file system structures therefor G06F16/00
• CPC Class Codes: G06F 2218/10 by analysing the shape of a waveform, e.g. extracting parameters relating to peaks

Abstract

A method includes obtaining a signal that includes a plurality of cycles and generating a map that maps motion phases to the signal based on both an amplitude and a slope of the signal. A system includes a processor that identifies a set of motion signal timestamps, for a plurality of motion cycles in a motion signal indicative of cyclic motion of a moving object, based on a predetermined motion phase of interest and a phase-to-amplitude/slope mapping, wherein the set of motion signal timestamps correspond to a common signal amplitude. A method include identifying a peak of a plurality of peaks in a motion cycle of a noisy cyclic signal having irregular periodicity, wherein the peak corresponds to a point lying between two points with amplitudes below a predetermined threshold, comparing points before and after the peak with the peak, and identifying the peak as a local maximum when the peak is greater than the points.

Claims

1. A method, comprising:

obtaining a signal that includes a plurality of cycles; and

generating a map that maps motion phases to the signal based on both an amplitude and a slope of the signal.

2. The method of claim 1, further comprising:

identifying a set of timestamps for the plurality of cycles for a predetermined phase of interest based on the map, wherein identified set of timestamps corresponds to a common signal amplitude; and

generating a signal indicative thereof.

3. The method of claim 1, wherein the signal is detected while imaging a moving object having recurring cyclic motion and a plurality of cycles corresponding to the recurring cyclic motion.

4. The method of claim 1, wherein the object is a subject and the signal is indicative of multiple breathing or cardiac cycles of the subject.

5. The method of claim 1, wherein a cycle has a descending amplitude region and an ascending region, and generating the map includes mapping one set phases to the descending amplitude region and mapping another set motion phases to the ascending region.

6. The method of claim 5, wherein the descending amplitude region corresponds to one of contraction or expansion of the object and the ascending amplitude region corresponds to the other of expansion or contraction of the object.

7. The method of claim 5, wherein the phases span from 0% to 99% over the cycle, and one set of phases ranges from 0% to 49% and another set of phases ranges from 50% to 99%.

8. The method of claim 1, further comprising:

identifying signal maxima and minima for the plurality of cycles;

determining a mean signal maximum and a mean signal minimum respectively based on the identified signal maxima and minima; and

mapping the phases to the amplitude of each cycle in a range spanning from a lesser of the mean signal maximum and the cycle maximum to a greater of the mean signal minimum and the cycle minimum.

9. The method of claim 1, further comprising:

identifying a maximum for an evaluation range within a cycle, wherein the maximum corresponds to a point lying between two points with amplitudes below a predetermined threshold;

comparing points in the evaluation range before and after the maximum with the maximum;

identifying the maximum as a local maximum for the evaluation range when the maximum is greater than the points; and

determining that the maximum is not the local maximum when the maximum is less than at least one of the points in the evaluation range.

10. The method of claim 9, further comprising:

de-identifying a maximum identified as a local maximum when the maxima are closer together than a predetermined remove maximum threshold; and

adding a maximum to the local maxima when the maxima are farther apart than a predetermined add maximum threshold.

11. A method, comprising:

mapping a first set of motion phases to a descending amplitude region of at least one motion cycle of a motion signal including a plurality of motion cycles; and

mapping a second set of motion phases to an ascending region of the at least one motion cycle.

12. A system, comprising:

a processor that identifies a set of motion signal timestamps, for a plurality of motion cycles in a motion signal indicative of cyclic motion of a moving object, based on a predetermined motion phase of interest and a phase-to-amplitude/slope mapping, wherein the set of motion signal timestamps correspond to a common signal amplitude.

13. The system of claim 12, further comprising:

a signal characteristic identifier that identifies signal maxima and minima for one or more cycles of the motion signal; and

a signal characteristic processor that determines a mean maximum and a mean minimum based on the identified maxima and minima.

14. The system of claim 13, wherein the signal characteristic identifier identifies a maximum for an evaluation range within a motion cycle as a point lying between two points with amplitudes below a maximum determining threshold, compares other points in the evaluation range before and after the maximum with the maximum;

and identifies the maximum as a local maximum for the evaluation range when the maximum is greater than the points.

15. The system of claim 13, further comprising:

a signal slope identifier that identifies a descending amplitude region and an ascending amplitude region for each cycle; and

a phase-to-amplitude/slope mapper that maps motion phases to the motion signal based on the mean maxima and minima and the descending and ascending amplitude regions.

16. The system of claim 15, further comprising:

a timestamp identifier that identifies timestamps of the motion signal that correspond to predetermined phase of interest and a common signal amplitude.

17. A method, comprising:

identifying a peak of a plurality of peaks in a motion cycle of a noisy cyclic signal having irregular periodicity, wherein the peak corresponds to a point lying between two points with amplitudes below a predetermined threshold;

comparing points before and after the peak with the peak; and

identifying the peak as a local maximum when the peak is greater than the points.

18. The method of claim 17, further comprising:

correcting, after identifying a plurality of local maxima, the spacing between the local maxima.

19. The method of claim 17, further comprising:

generating a map that maps motion phases to an amplitude of the motion signal based on the peak and a slope of each motion cycle.

20. The method of claim 17, further comprising:

identifying descending and ascending regions of the motion cycle, wherein one set of the phases is mapped to the descending region and another set of the phases is mapped to the ascending region.

21. The method of claim 20, further comprising:

identifying a set of motion signal timestamps for a plurality of motion cycles in the signal, wherein the timestamps are identified based on the map and correspond to predetermined phase of interest and a common signal amplitude.