Ultrasound imaging apparatus

Patent metadata

Field	Value
Publication number	US-9754185-B2
Application number	US-201214342101-A
Country	US
Kind code	B2
Filing date	Aug 7, 2012
Priority date	Sep 15, 2011
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A weight value used for a beamforming process performed on received signals in an ultrasound imaging apparatus is obtained with a small amount of computations and with a high degree of precision, even when a method of adaptive signal processing is employed.
Multiple elements 401 receive ultrasound signals from a test subject, and the similarity operator 404 obtains the similarity between the received signals x(n). By using the similarity C(n) between the received signals obtained by the similarity operator 404 , the adaptive weight operator 407 computes the adaptive weight w(n) in association with the similarity. The beamforming operator 408 uses the adaptive weight w(n) and the received signal x(n) to generate a beamforming output. The imaging processor 108 uses the beamforming output to generate image data. By way of example, the similarity operator 404 performs computations of the similarity in the time direction.

First claim

What is claimed is:

1. An ultrasound imaging apparatus comprising,
a plurality of elements that receive ultrasound signals from a test subject, wherein the ultrasound signals is delayed by a first delay;
a similarity operator that obtains a similarity between the received ultrasound signals of the plurality of elements;
a matrix operator that, using the similarity as in input, calculates a spatial covariance matrix R(n) that represents a covariance matrix at a certain sample point n in a time direction;
an adaptive weight operator that calculates an adaptive weight associated with the similarity by using the spatial covariance matrix R(n);
a beamforming operator that generates a beamforming output by using the adaptive weight and the received ultrasound signals;
an image processor that generates image data by using the beamforming output; and
an extractor, placed between the similarity operator and the adaptive weight operator, that extracts a predetermined index value indicating characteristics of the similarity;
a second delay part, placed between the plurality of elements and the similarity operator, that delays each of the received ultrasound signals that are received by the plurality of elements based on the predetermined index value extracted by the extractor so as to align wave fronts,
wherein the similarity operator obtains the similarity of the received ultrasound signals that are delayed by the delay part, and
wherein the adaptive weight operator uses the received ultrasound signals delayed by the delay part to obtain the adaptive weight.

2. The ultrasound imaging apparatus according to claim 1 , wherein,
the similarity operator computes the similarity in the time direction.

3. The ultrasound imaging apparatus according to claim 1 , wherein,
the adaptive weight operator uses the similarity obtained by the similarity operator to perform an adaptive signal processing, thereby obtaining the adaptive weight.

4. The ultrasound imaging apparatus according to claim 1 , wherein,
the extractor is placed between the similarity operator and the adaptive weight operator, the extractor extracting the predetermined index value indicating characteristics of the similarity, and the adaptive weight operator uses the index value extracted by the extractor as the similarity.

5. The ultrasound imaging apparatus according to claim 3 , wherein,
the adaptive weight operator generates the spatial covariance matrix from the similarity between the received signals, and performs the adaptive signal processing to obtain the adaptive weight.

6. The ultrasound imaging apparatus according to claim 1 , wherein,
the multiple elements are placed side by side, and the similarity operator obtains the similarity between the received signals of two elements out of the multiple elements, one of the two elements being positioned a predetermined number of the elements away from the other element.

7. The ultrasound imaging apparatus according to claim 1 , wherein,
if the number of the adaptive weights obtained by the adaptive weight operator is less than the number of the received signals, the beamforming operator performs computations to allow the multiple received signals to degenerate in accordance with the number of the adaptive weights, and generate a beamforming output by using the received signal after degeneration and the adaptive weight.

8. The ultrasound imaging apparatus according to claim 1 , wherein,
the adaptive weight operator comprises,
a weight memory configured to store multiple-type combinations of a distribution of the similarity and a weight value, and
a weight estimator configured to select a combination of the distribution of the similarity and the weight value being stored in the weight memory, based on multiple distributions of the similarity received from the similarity operator, thereby enabling a selection from the weight values associated with the multiple distributions of the similarity received from the similarity operator.

9. The ultrasound imaging apparatus according to claim 1 , wherein,
the adaptive weight operator comprises a first operator and a second operator, wherein,
the first operator uses the similarity obtained by the similarity operator to perform the adaptive signal processing, and computes the adaptive weight, and
the second operator comprises,
a weight memory configured to store in advance, multiple-type combinations of a distribution of the similarity and a weight value, and
the weight estimator configured to select a combination of the distribution of the similarity and the weight value, being stored in the weight memory, based on multiple distributions of the similarity received from the similarity operator, and enabling a selection from the weight values associated with the multiple distributions of the similarity received from the similarity operator.

10. The ultrasound imaging apparatus according to claim 9 , further comprising,
a subtraction part configured to obtain a difference between a computation result of the first operator and a computation result of the second operator, and
a weight changer configured to change the weight value stored in the weight memory of the second operator, according to the difference obtained by the subtraction part.

11. The ultrasound imaging apparatus according to claim 9 , wherein,
the adaptive weight operator comprises at least one of;
a drive switching part configured to selectively drive the first operator or the second operator, and
an output switching part configured to selectively transfer to the image processor, an output from either of the first operator and the second operator.

12. The ultrasound imaging apparatus according to claim 11 , further comprising,
a timing controller configured to control switching timing of a drive switching part and an output switching part.

13. The ultrasound imaging apparatus according to claim 2 , further comprising,
a window-length adjuster configured to set any length of window in the time direction of the received signals, wherein,
the similarity operator obtains the similarity between the received signals, as to the received signals within the window set by the window-length adjuster.

14. The ultrasound imaging apparatus according to claim 4 , wherein,
the similarity is a function, and the index value being predetermined indicating the characteristics of the similarity is at least one of; an amplitude, a phase, a complex number using the amplitude and the phase, only a real part of the complex value, and only an imaginary part of the complex value.

15. The ultrasound imaging apparatus according to claim 4 , wherein,
the extractor comprises an index switching part for switching and extracting as the index value indicating the characteristics of the similarity, at least any one of; an amplitude, a phase, a complex number using the amplitude and the phase, only a real part of the complex value, and only an imaginary part of the complex value.

16. The ultrasound imaging apparatus according to claim 1 , wherein,
the similarity operator comprises,
a decimating operator configured to decimate the similarity being obtained in the time direction and output a result thereof.

Assignees

• Ikeda Teiichiro
• Azuma Takashi
• Masuzawa Hiroshi
• Hitachi Ltd

Inventors

• Ikeda Teiichiro
• Azuma Takashi
• Masuzawa Hiroshi

Classifications

• A61B8/5207 Primary

  involving processing of raw data to produce diagnostic data, e.g. for generating an image · CPC title

• H04N23/632

  for displaying or modifying preview images prior to image capturing, e.g. variety of image resolutions or capturing parameters · CPC title

• G01S15/8927

  using simultaneously or sequentially two or more subarrays or subapertures · CPC title

• A61B8/4405

  Device being mounted on a trolley · CPC title

• G01S7/52047

  for elimination of side lobes or of grating lobes; for increasing resolving power · CPC title