Tissue motion analysis medical diagnostic ultrasound system and method

• US 6,527,717 B1
• Filed: 06/30/2000
• Issued: 03/04/2003
• Est. Priority Date: 03/10/2000
• Status: Expired due to Term

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Acuson Corporation (Siemens AG)
• Inventors: Schlesinger, Randall L., Jackson, John I., Allison, John W.
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): Jain, Ruby
• Application Number:
  US09/608,235
• Time in Patent Office: 977 Days
• Field of Search: 600/437, 600/441, 600/438, 348/443, 382/128, 128/916
• US Class Current: 600/437
• CPC Class Codes: A61B 8/0883 for diagnosis of the heart
• CPC Class Codes: A61B 8/485 involving measuring strain or elastic properties
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: A61B 8/5276 due to motion
• CPC Class Codes: A61B 8/543 involving acquisition triggered by a physiological signal
• CPC Class Codes: G01S 15/8979 Combined Doppler and pulse-echo imaging systems
• CPC Class Codes: Y10S 128/916 Ultrasound 3-D imaging

Abstract

Accurate tissue motion systems and methods are provided. Motion of the ultrasound transducer is accounted for in estimates at tissue motion. Correcting for transducer motion better isolates localized tissue contractions or expansions, such as motion of the myocardial muscle or fibers. Accurate motion estimation is also provided by determining an angle of motion from the ultrasound data. The angle of motion is used to adjust velocity estimates, providing two-dimensional velocity vectors (i.e. motion estimates comprising motion in at least two dimensions). Movement of tissue is determined by correlating speckle or a feature represented by two different sets of ultrasound data obtained at different times. Additional aspects include tracking the location of a tissue of interest. A characteristic of strain, such as the strain rate or strain, is calculated for the tracked tissue of interest. Ultrasound data associated with different positions relative to the transducer are selected as a function of the tracking and used to determine the characteristic of strain. Motion estimates corrected for transducer motion may also be used to determine a strain or strain rate. In yet another aspect, motion estimates are generated with data from an intra-cardiac transducer array. The characteristic of strain is determined from the motion estimates. Other aspects discussed above may be used with an intra-cardiac transducer array, providing accurate motion analysis based on imaging from within the heart.

Claims

1. A method for providing motion estimates of a target with an ultrasound system, the method comprising the acts of:

(a) determining with a motion processor a first motion angle from ultrasound data as a function of speckle or a feature;

(b) estimating a first velocity magnitude with the motion processor as a function of ultrasound data; and

(c) determining a second velocity magnitude responsive to the motion angle and the first velocity magnitude.

2. The method of claim 1 further comprising:

(d) measuring motion of a transducer array with an electromagnetic position sensor; and

(e) altering one of the first and second velocity magnitudes as a function of the measured motion of (d).

3. The method of claim 1 wherein (a) comprises determining the first motion angle as a function of speckle represented by the ultrasound data.

4. The method of claim 1 wherein (a) comprises determining the first motion angle as a function of the feature of the target represented by the ultrasound data.

5. The method of claim 1 wherein the target comprises tissue and (a) comprises determining the first motion angle of the tissue.

6. The method of claim 1 further comprising:

(d) determining a second motion angle corresponding to motion along an elevation axis;

wherein (c) comprises determining the second velocity magnitude as a function of the second motion angle, the first motion angle and the first velocity magnitude.

7. The method of claim 1 further comprising:

(d) estimating a third velocity magnitude as a function of the speckle or feature; and

(e) comparing the first motion angle to a close to orthogonal threshold;

wherein (c) comprises determining the second velocity magnitude as a function of the third velocity magnitude in response to (e).

8. The method of claim 1 wherein (c) comprises dividing the first velocity magnitude by a cosine of the first motion angle.

9. The method of claim 1 wherein (a) comprises determining the first motion angle as a function of the speckle or feature represented by coherent ultrasound data.

10. The method of claim 1 further comprising:

(d) calculating a characteristic of strain as a function of the second velocity magnitude.

11. The method of claim 1 further comprising:

(d) performing (a), (b) and (c) for each of a plurality of local regions within a scanned region of the target.

12. A method for providing motion estimates of a target tissue with an ultrasound system, the method comprising the acts of:

(a) determining with a processor at least first and second motion angles for at least first and second local regions, respectively, as a function of ultrasound data, the first local region a different region than the second local region; and

(b) adjusting at least first and second tissue motion estimates for the at least first and second local regions, respectively, as a function of the at least first and second motion angles, respectively.

13. The method of claim 12 further comprising:

(c) determining a characteristic of tissue strain as a function of the at least first and second tissue motion estimates.

14. A method for providing motion estimates of a target with an ultrasound system, the method comprising the acts of:

(a) measuring a velocity vector representing at least two-dimensions as a function of ultrasound data; and

(b) calculating a characteristic of strain as a function of the velocity vector.

15. The method of claim 14 wherein (a) comprises determining the velocity vector as a function of speckle or a feature of the target represented by the ultrasound data.

16. The method of claim 14 wherein (a) comprises measuring a velocity vector representing three-dimensions.

17. The method of claim 14 wherein (b) comprises calculating a maximum velocity strain.

18. The method of claim 14 further comprising:

(c) performing (a) for a plurality of locations;

wherein (b) comprises calculating the characteristic of strain as a function of the velocity vector for at least two of the plurality of locations.

19. The method of claim 18 further comprising:

(d) adjusting a Doppler velocity estimate as a function of a tracking velocity estimate.

20. The method of claim 18 further comprising:

(d) tracking the at least two of the plurality of locations as a function of time;

wherein (b) comprises calculating strain as a function of the velocity vector for the at least two of the plurality of locations as a function of time with ultrasound data selected as a function of (d).

21. The method of claim 18 further comprising:

(c) determining a time in a heart cycle; and

(d) calculating strain as a function of (c) and (b) where the characteristic of strain comprises a strain rate.

22. A medical diagnostic ultrasound system for providing motion estimates of a target, the system comprising:

a motion processor for measuring a velocity vector representing at least two-dimensions as a function of ultrasound data; and

a strain processor for calculating a characteristic of strain as a function of the velocity vector.