Steering angle varied pattern for ultrasound imaging with a two-dimensional array

• US 20050131298A1
• Filed: 12/10/2003
• Published: 06/16/2005
• Est. Priority Date: 12/10/2003
• Status: Active Grant

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Inventors: Cai, Anming He
• Granted Patent: US 7,833,163 B2
• Time in Patent Office: Days
• US Class Current: 600/447
• CPC Class Codes: G01S 15/8925 the array being a two-dimensional transducer configuration, i.e. matrix or orthogonal linear arrays
• CPC Class Codes: G01S 7/52047 for elimination of side lobes or of grating lobes; for increasing resolving power

Abstract

Methods and systems for varying a pattern as a function of steering angle for medical imaging with a multidimensional array are provided. Transmit waveform, delay, phase or apodization patterns in addition to delays, phases or apodization for focusing are used with a multidimensional array. By applying a periodic variation perpendicular to the steering direction, the effects of grating lobes due to the variation may be reduced. Along the steering direction, additional offsets are not provided, but may be provided. This different or non-existent offsets provide less grating lobe clutter. The transmit aperture is adjusted to be parallel to a direction of steering of non-normal transmit scan line or scan lines. The variation pattern is selected to result in enhancement or isolation of one or more frequency bands from one or more other frequency bands, such as isolation of second harmonic information from fundamental transmit frequency information.

Claims

1. A method for varying a pattern as a function of steering angle for medical imaging with a multi-dimensional array, the method comprising:

(a) setting an azimuth axis of a transmit aperture of the multidimensional array of N×

M transducer elements, where N and M are both greater than 1, as substantially parallel with a first steering vector on a face of the array of transducer elements;

(b) applying an alternating pattern substantially perpendicular to the steering vector, the alternating pattern being a variation of one of;

waveform, delay, phase, apodization and combinations thereof along an elevation axis.

2. The method of claim 1 wherein (b) comprises applying the alternating pattern by variation across scan lines, each of the scan lines associated with a substantially same steering vector direction and in a same scan plane.

3. The method of claim 1 wherein (b) comprises applying the alternating pattern by variation across elements for a scan line, the scan line associated with the steering vector.

4. The method of claim 1 wherein (b) comprises variation in addition to focusing profiles.

5. The method of claim 4 wherein (b) comprises applying variation that is periodic.

6. The method of claim 1 further comprising:

(c) applying focusing profiles free of variation in any one of;

delay, phase and apodization in addition to focusing profiles along the azimuth axis.

7. The method of claim 1 wherein (b) comprises applying the variation as a delay variation to one of unipolar and bipolar transmit waveforms.

8. The method of claim 1 wherein (b) comprises applying the variation as a phase variation to sinusoidal transmit waveforms.

9. The method of claim 1 wherein (b) comprises applying the variation as an apodization including positive and negative apodization variation.

10. The method of claim 1 further comprising:

(c) performing (a) and (b) for each of a plurality of scan planes spaced along the elevation axis.

21. The method of claim 1 where in (b) comprises applying the variation as waveform variation.

11. A system for varying a pattern as a function of steering angle for medical imaging with a multi-dimensional array, the system comprising:

the multi-dimensional array having N×

M transducer elements wherein N and M are both greater than 1;

a transmit beamformer operable to set an azimuth axis of a transmit aperture on the multi-dimensional array as substantially parallel with a first steering vector on a face of the multi-dimensional array, and operable to apply an alternating pattern substantially perpendicular to the steering vector, the alternating pattern being a variation of one of;

waveform, delay, phase, apodization and combinations thereof.

12. The system of claim 11 wherein the transmit beamformer is operable to apply the alternating pattern by variation across scan lines, each of the scan lines associated with a substantially same steering vector direction and in a same scan plane.

13. The system of claim 11 wherein the transmit beamformer is operable to apply the alternating pattern by variation across elements for a scan line, the scan line associated with the steering vector.

14. The system of claim 11 wherein the transmit beamformer is operable to apply periodic variation in addition to focusing profiles.

15. The system of claim 11 wherein the transmit beamformer is operable to apply focusing profiles free of variation in any one of:

waveform, delay, phase and apodization in addition to focusing profiles along the azimuth axis.

16. A method for varying a pattern as a function of steering angle for medical imaging with a multi-dimensional array, the method comprising:

(a) applying a periodic pattern of offsets along a first profile for focusing along a first axis substantially perpendicular to an intersection of a scan line vector with a multi-dimensional transducer; and

(b) applying a second profile for focusing substantially free of offsets along a second axis substantially parallel with the intersection.

17. The method of claim 16 wherein (b) comprises setting an azimuth axis of a transmit aperture of the multidimensional transducer as substantially parallel with the intersection and wherein (a) comprises applying the periodic pattern being a variation of one of:

delay, phase, apodization and combinations thereof along an elevation axis substantially perpendicular with the intersection.

18. The method of claim 16 wherein (a) comprises applying the periodic pattern along the first profile, the first profile representing variation of one of:

waveform, phase, delay, apodization and combinations thereof across a plurality of scan lines, each of the plurality of scan lines associated with a substantially same scan line vector direction.

19. The method of claim 16 wherein (a) comprises applying the alternating pattern by variation across elements for a scan line, the first profile being for the scan line.

20. The method of claim 16 further comprising:

(c) isolating echo information at a first frequency band in response to (a); and

(d) reducing echo information at a second frequency band in response to (a), the second frequency band different than the first frequency band.