# US 8,771,190 B2 · Methods and apparatus for ultrasound imaging

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- Number: US 8,771,190 B2
- Document ID: US8771190B2
- Status: Granted
- Kind: B2
- Application number: 11/926,206
- Filed: 2007-10-29
- Published: 2008-10-02
- Granted: 2014-07-08
- Earliest claimed: 2007-03-29
- Assignees: Hitachi Aloka Medical, Ltd.
- Applicants: Tadashi Tamura
- Inventors: Tadashi Tamura
- Web page: https://patentgrep.com/patent/US8771190B2

## CPC

- G01S 7/52033: {Gain control of receivers (for seismic signals G01V1/245)}
- A61B 8/06: Measuring blood flow
- A61B 8/13: Tomography (A61B8/10, A61B8/12 take precedence)
- G01S 15/8981: {Discriminating between fixed and moving objects or between objects moving at different speeds, e.g. wall clutter filter}
- G01S 7/52077: {with means for elimination of unwanted signals, e.g. noise or interference}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

Blood flow information is used to reduce noise manifest in blood vessel ultrasound B-mode images. A blood flow signal is obtained by a flow detector. After wall filtering, only the flow signal power in the blood vessel lumen remains, while signal power from stationary tissue region is suppressed. The flow signal component is used to calculate a flow component parameter that is used to generate a gain control signal α that reduces noise in a B-mode image.

## Claims

### Claim 1

A method for suppressing ultrasound clutter noise comprising:
generating a B-mode image based on first ultrasound signals returned from blood vessels;
generating Doppler signals based on second ultrasound signals returned from the blood vessels;
determining a normalized amplitude a, a normalized power a2 and a normalized power raised to a power ab(i), where the ith component b(i) is a real number, based on the Doppler signals;
multiplying the normalized amplitude a, normalized power a2 and normalized power raised to a power ab(i), with a corresponding weight d1, d2 and di, where d1, d2 and the ith component di are real numbers;
summing together the weighted normalized amplitude d1a, normalized power d2a2 and normalized power raised to a power diab(i) to determine a combined flow component parameter
d
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generating a gain control signal α based on the combined flow component parameter; and
applying a gain to the B-mode image based on the gain control signal α to generate a second B-mode image, wherein the second B-mode image exhibits less clutter noise than the first B-mode image.

### Claim 2 (depends on 1)

The method according to claim 1 further comprising:
high-pass filtering the Doppler signals to determine the normalized amplitude a and the normalized power a2.

### Claim 3 (depends on 1)

The method according to claim 1 wherein the gain control signal α is a predetermined curve response based on the combined flow component parameter.

### Claim 4

A method for suppressing ultrasound clutter noise comprising:
generating a B-mode image based on first ultrasound signals returned from blood vessels;
generating RF signals based on second ultrasound signals returned from the blood vessels;
determining a normalized amplitude a, a normalized power a2 and a normalized power raised to a power ab(i), where the ith component b(i) is a real number, based on the RF signals;
multiplying the normalized amplitude a, normalized power a2 and normalized power raised to a power ab(i), with a corresponding weight d1, d2 and di, where d1, d2 and the ith component di are real numbers;
summing together the weighted normalized amplitude d1a , normalized power d2a2 and normalized power raised to a power diab(i) to determine a combined flow component parameter
d
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generating a gain control signal α based on the combined flow component parameter; and
applying a gain to the B-mode image based on the gain control signal αto generate a second B-mode image wherein the second B-mode image exhibits less clutter noise than the first B-mode image.

### Claim 5 (depends on 4)

The method according to claim 4 further comprising:
high-pass filtering the RF signals to determine the normalized amplitude a and the normalized power a2.

### Claim 6 (depends on 4)

The method according to claim 4 wherein the gain control signal α is a predetermined curve response based on the combined flow component parameter.

### Claim 7

A system for suppressing ultrasound clutter noise comprising:
a transmitter to transmit ultrasound signals to blood vessels;
a receiver configured to receive first ultrasound image signals and second ultrasound image signals from the blood vessels;
a B-mode image processor coupled to the receiver and configured to output a B-mode image based on the first ultrasound image signals;
a Doppler flow detector coupled to the receiver, configured to:
determine a normalized amplitude a, a normalized power a2 and a normalized power raised to a power ab(i), where the ith component b(i) is a real number, based on the second ultrasound signals;
multiply the normalized amplitude a, normalized power a2 and normalized power raised to a power ab(i) , with a corresponding weight d1and d2, where d1, d2 and the ith component di are real numbers; and
sum together the weighted normalized amplitude d1 a, normalized power d2a2 and normalized power raised to a power diab(i) to determine a combined flow component parameter
d
1
⁢
a
+
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a gain control generator coupled to the Doppler flow detector and configured to generate a gain control signal α based on the combined flow component parameter; and
a signal combiner coupled to the gain control generator and the B-mode image processor, the signal combiner configured to apply a gain to the B-mode image based on the gain control signal α to generate a second B-mode image wherein the second B-mode image exhibits less clutter noise than the first B-mode image.

### Claim 8 (depends on 7)

The system according to claim 7 wherein the gain control signal α is a predetermined curve response based on the combined flow component parameter.

### Claim 9

A system for suppressing ultrasound clutter noise comprising:
a transmitter to transmit ultrasound signals to blood vessels;
a receiver configured to receive first ultrasound image signals and second ultrasound signals from the blood vessels;
a B-mode image processor coupled to the receiver and configured to output a B-mode image based on the first ultrasound signals;
an RF flow detector coupled to the receiver, the flow detector configured to:
determine a normalized amplitude a, a normalized power a2 and a normalized power raised to a power ab(i), where the ith component b(i) is a real number, based on the second ultrasound signals;
multiply the normalized amplitude a, normalized power a2 and normalized power raised to a power ab(i) , with a corresponding weight d1, d2 and diwhere di, d2 and the ith component di are real numbers; and
sum together the weighted normalized amplitude d1a, normalized power d2a2 and normalized power raised to a power diab(i) to determine a combined flow component parameter
d
1
⁢
a
+
d
2
⁢
a
2
+
∑
i
⁢
d
i
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a
b
⁡
(
i
)
a gain control generator coupled to the RF flow detector and configured to generate a gain control signal α based on the combined flow component parameter; and
a signal combiner coupled to the gain control generator and the B-mode image processor, the signal combiner configured to apply gain to the B-mode image based on the gain control signal α to generate a second B-mode image wherein the second B-mode image exhibits less clutter noise than the first B-mode image.

### Claim 10 (depends on 9)

The system according to claim 9 wherein the gain control signal α is a predetermined curve response based on the combined flow component parameter.