# US 11,304,678 B2 · Systems, methods, and apparatuses for confidence mapping of shear wave imaging

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- Number: US 11,304,678 B2
- Document ID: US11304678B2
- Status: Granted
- Kind: B2
- Application number: 16/476,785
- Filed: 2018-01-09
- Published: 2019-11-28
- Granted: 2022-04-19
- Earliest claimed: 2017-01-10
- Assignees: Koninklijke Philips N.V.
- Applicants: Koninklijke Philips N.V.
- Inventors: Ji Cao; Lars Jonas Olsson; Vijay Thakur Shamdasani; David Wesley Clark; Hua Xie; Jean-Luc Francois-Marie Robert; Alexey Viktorovich Cherepakhin; Bruce Adrian Kincy
- Web page: https://patentgrep.com/patent/US11304678B2

## CPC

- A61B 8/085: {for locating body or organic structures, e.g. tumours, calculi, blood vessels, nodules}
- A61B 8/463: {characterised by displaying multiple images or images and diagnostic data on one display}
- A61B 8/0858: {involving measuring tissue layers, e.g. skin, interfaces}
- A61B 8/14: Echotomography
- A61B 8/483: {involving the acquisition of a 3D volume of data}
- A61B 8/485: {involving measuring strain or elastic properties}
- A61B 8/5207: {involving processing of raw data to produce diagnostic data, e.g. for generating an image}
- A61B 8/5253: {combining overlapping images, e.g. spatial compounding}
- A61B 8/5269: {involving detection or reduction of artifacts}
- A61B 8/5276: {due to motion}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

Systems, methods, and apparatuses for confidence mapping of shear wave measurements are disclosed. Confidence maps of shear wave image measurements may be generated from one or more confidence factors. Masking of graphical overlays of tissue stiffness values, based at least in part on the confidence map is disclosed. The confidence map and/or masked graphical overlays of tissue stiffness values may be superimposed on ultrasound images and provided on a display.

## Claims

### Claim 1

An ultrasound imaging system comprising:
an ultrasound imaging device configured to generate shear wave signals responsive to shear wave tracking echoes received by an ultrasound probe communicatively coupled to the ultrasound imaging device; and
a processor integral with or communicatively coupled to the ultrasound imaging device, wherein the processor includes:
a shear wave processor configured to calculate tissue stiffness values based, at least in part, on the shear wave signals;
an image processor configured to generate an ultrasound image including a graphical overlay of tissue stiffness values for one or more pixels within a region of interest, and
a confidence map generator configured to calculate a plurality of confidence factors for each of a plurality of pixels of the ultrasound image, and calculate a confidence value for each of the pixels based on the plurality of confidence factors, wherein each confidence value has a value between 0 and 1;
wherein the ultrasound image is configured to provide, based on the calculated confidence values, an indication of reliability of the tissue stiffness values within the region of interest, and
wherein calculating the confidence value for each of the plurality of pixels comprises comparing the plurality of confidence factors and selecting a minimum confidence factor as the confidence value.

### Claim 2 (depends on 1)

The ultrasound imaging system of claim 1, wherein the image processor is further configured to generate a masked graphical overlay of tissue stiffness values, wherein tissue stiffness values having a confidence value below a threshold value are masked out.

### Claim 3 (depends on 2)

The ultrasound imaging system of claim 2, wherein the threshold value is set by a user.

### Claim 4 (depends on 2)

The ultrasound imaging system of claim 2, further comprising a display communicatively coupled to the image processor, wherein, responsive to the image processor, the display is configured to display concurrently:
the image with the masked graphical overlay of tissue stiffness values superimposed; and
the image with a confidence map superimposed, wherein the confidence map is based, at least in part, on the confidence values.

### Claim 5 (depends on 2)

The ultrasound imaging system of claim 2, wherein the ultrasound imaging system prevents collection of tissue stiffness values where the confidence values are below the threshold value.

### Claim 6 (depends on 1)

The ultrasound imaging system of claim 1, wherein the tissue stiffness values are represented by different colors in the graphical overlay.

### Claim 7 (depends on 1)

The ultrasound imaging system of claim 1, wherein the confidence factor is one of signal-to-noise ratio, motion detection, displacement amplitude, a range estimate of expected tissue stiffness values, or energy ratio, the energy ratio corresponding to a ratio of the energy of a noise-filtered shear wave signal to the energy of the corresponding unfiltered shear wave signal.

### Claim 8 (depends on 7)

The ultrasound imaging system of claim 7, wherein the range estimate is set by a user.

### Claim 9 (depends on 7)

The ultrasound imaging system of claim 7, wherein motion detection includes at least one of flash and flow.

### Claim 10 (depends on 1)

The ultrasound imaging system of claim 1, wherein the ultrasound probe is further configured to perform B-mode imaging.

### Claim 11

A method comprising:
acquiring a shear wave image with an ultrasound probe of an ultrasound imaging system;
calculating, with at least one processor of the ultrasound imaging system, a tissue stiffness value for each pixel in the shear wave image;
calculating, with the at least one processor a plurality of confidence factors for each of the plurality of pixels, wherein each confidence value has a value between 0 and 1;
determining, with the at least one processor, a confidence value for each of the plurality of pixels based, at least in part, on the corresponding plurality of confidence factors, wherein the confidence values correspond to confidence in tissue stiffness values;
generating, with the at least one processor a confidence map based, at least in part, on the confidence values, wherein calculating the confidence value for each of the plurality of pixels comprises comparing the plurality of confidence factors and selecting a minimum confidence factor as the confidence value; and
displaying the confidence map on a display of the ultrasound imaging system.

### Claim 12 (depends on 11)

The method of claim 11, wherein each of the plurality of confidence factors is weighted.

### Claim 13 (depends on 11)

The method of claim 11, wherein a subset of the plurality of confidence factors are compared to determine the confidence values.

### Claim 14 (depends on 13)

The method of claim 13, wherein the subset of the plurality of confidence factors is selected by a user.

### Claim 15 (depends on 11)

The method of claim 11, wherein the confidence map represents different confidence values with different colors.