# US 10,311,603 B2 · Correcting positron emission tomography image attenuation

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- Number: US 10,311,603 B2
- Document ID: US10311603B2
- Status: Granted
- Kind: B2
- Application number: 15/809,939
- Filed: 2017-11-10
- Published: 2018-05-17
- Granted: 2019-06-04
- Earliest claimed: 2016-11-11
- Assignees: Shenyang Neusoft Medical Systems Co., Ltd.
- Applicants: Shenyang Neusoft Medical Systems Co., Ltd.
- Inventors: Yunda Li; Yue Liu
- Web page: https://patentgrep.com/patent/US10311603B2

## CPC

- G06T 12/10: Image preprocessing, e.g. calibration, positioning of sources or scatter correction
- A61B 5/0035: {adapted for acquisition of images from more than one imaging mode, e.g. combining MRI and optical tomography}
- A61B 5/055: involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
- A61B 6/037: {Emission tomography}
- A61B 6/5235: {combining images from the same or different ionising radiation imaging techniques, e.g. PET and CT}
- G06T 5/50: using two or more images, e.g. averaging or subtraction
- G06T 7/11: Region-based segmentation
- G06T 7/30: Determination of transform parameters for the alignment of images, i.e. image registration
- G06T 12/00: Tomographic reconstruction from projections
- G06V 10/751: {Comparing pixel values or logical combinations thereof, or feature values having positional relevance, e.g. template matching}
- A61B 6/032: {Transmission computed tomography [CT]}
- A61B 6/5205: {involving processing of raw data to produce diagnostic data}
- A61B 2576/00: Medical imaging apparatus involving image processing or analysis (A61B1/00009, A61B6/52 and A61B8/52 take precedence)
- G06T 2207/10081: Computed x-ray tomography [CT]
- G06T 2207/10084: Hybrid tomography; Concurrent acquisition with multiple different tomographic modalities
- G06T 2207/10088: Magnetic resonance imaging [MRI]
- G06T 2207/10104: Positron emission tomography [PET]
- G06T 2207/20128: Atlas-based segmentation
- G16H 30/40: for processing medical images, e.g. editing
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA

## Abstract

Method of correcting PET image attenuation and PET/MRI devices are provided. In one aspect, an MRI image of a subject is segmented to obtain respective MRI sub-images corresponding to attenuation units of the subject, respective pseudo CT sub-images corresponding to the MRI sub-images are obtained based on an MRI-CT atlas, the respective pseudo CT sub-images corresponding to the MRI sub-images are spliced to obtain a pseudo CT image corresponding to the MRI image, and attenuation correction is performed for a PET image of the subject according to the pseudo CT image, wherein the PET image and the MRI image are obtained through a same scan process for the subject.

## Claims

### Claim 1

A method of correcting Positron Emission Tomography (PET) image attenuation, comprising:
segmenting an MRI image of a subject to obtain respective MRI sub-images corresponding to attenuation units of the subject;
for each MRI sub-image, obtaining pseudo CT sub-images corresponding to the MRI sub-images based on an MRI-CT atlas, wherein,
the pseudo CT sub-image is obtained by selecting a plurality of CT template sub-images present in the MRI-CT atlas that corresponds to a plurality of MRI template sub-images in the MRI-CT atlas matched to the MRI sub-image, and
the plurality of MRI template sub-images is matched to the MRI sub-image by a matching relationship comprising shape factors and intensity weight factors;
splicing the respective pseudo CT sub-images to obtain a pseudo CT image; and
performing attenuation correction for a PET image of the subject according to the pseudo CT image, wherein the PET image and the MRI image are obtained through a same scan process for the subject.

### Claim 2 (depends on 1)

The method of claim 1, wherein for each MRI sub-image obtaining the pseudo CT sub-images corresponding to the MRI sub-images based on the MRI-CT atlas comprises:
obtaining the plurality of MRI template sub-images associated with the attenuation unit corresponding to the MRI sub-image from an MRI template set in the MRI-CT atlas;
obtaining the matching relationship between the plurality of MRI template sub-images and the MRI sub-image, wherein
the matching relationship comprises respective weighting coefficients for the MRI template sub-images based on image intensity and image shape such that a weight sum of the plurality of MRI template sub-images is matched with the MRI sub-image; and
the matching relationship is calculated with formula (1):
M
patient
i
=
∑
k
=
1
K
⁢
t
k
⁢
T
ik
⁡
(
M
template
ik
)
,
(
1
)
wherein
tk represents the intensity weight factor of the k-th MRI template sub-image,
Tik represents the shape factor of the k-th MRI template sub-image,
Mpatienti represents the MRI sub-image i,
Mtemplateik template represents the k-th MRI template sub-image corresponding to the MRI sub-image i, and
K represents a number of the plurality of MRI template sub-image;
obtaining the plurality of CT template sub-images corresponding to the plurality of MRI template sub-images from a CT template set in the MRI-CT atlas; and
obtaining the pseudo CT sub-image corresponding to the MRI sub-image according to the plurality of CT template sub-images and the matching relationship.

### Claim 3 (depends on 1)

The method of claim 1, wherein splicing the respective pseudo CT sub-images comprises:
placing the respective pseudo CT sub-images into border images for the attenuation units corresponding to the respective pseudo CT sub-images.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
performing smoothing correction for respective adjacent borders of attenuation units in adjacent pseudo CT sub-images.

### Claim 5 (depends on 1)

The method of claim 1, wherein the attenuation unit is an organ tissue of the subject.

### Claim 6

A PET/MRI device, comprising:
a processor, and
a non-transitory machine-readable storage medium storing machine executable instructions which are executable by the processor to:
segment an MRI image of a subject to obtain respective MRI sub-images corresponding to attenuation units of the subject;
for each MRI sub-image, obtain a pseudo CT sub-images corresponding to the MRI sub-images based on an MRI-CT atlas, wherein;
the pseudo CT sub-image is obtained by selecting a plurality of CT template sub-images present in the MRI-CT atlas that corresponds to a plurality of MRI template sub-images in the MRI-CT atlas matched to the MRI sub-image, and
the plurality of MRI template sub-images is matched to the MRI sub-image by a matching relationship comprising shape factors and intensity weight factors;
splice the respective pseudo CT sub-images to obtain a pseudo CT image; and
perform attenuation correction for a PET image of the subject according to the pseudo CT image, wherein the PET image and the MRI image are obtained through a same scan process for the subject.

### Claim 7 (depends on 6)

The device of claim 6, wherein the processor is caused by the machine-executable instructions to:
obtain, for each of the MRI sub-images, the plurality of MRI template sub-images associated with the attenuation unit corresponding to the MRI sub-image from an MRI template set in the MRI-CT atlas;
obtain the matching relationship between the plurality of MRI template sub-images and the MRI sub-image, wherein
the matching relationship comprises respective weighting coefficients for the MRI template sub-images based on image intensity and image shape in a way that a weight sum of the plurality of MRI template sub-images is matched with the MRI sub-image; and
the matching relationship is calculated with formula (1):
M
patient
i
=
∑
k
=
1
K
⁢
t
k
⁢
T
ik
⁡
(
M
template
ik
)
,
(
1
)
wherein
tk represents the intensity weight factor of the k-th MRI template sub-image,
Tik represents the shape factor of the k-th MRI template sub-image,
Mpatienti represents the MRI sub-image i,
Mtemplateik represents the k-th MRI template sub-image corresponding to the MRI sub-image i, and
K represents a number of the plurality of MRI template sub-image;
obtain the plurality of CT template sub-images corresponding to the plurality of MRI template sub-images from a CT template set in the MRI-CT atlas; and
obtain the pseudo CT sub-image corresponding to the MRI sub-image according to the plurality of CT template sub-images and the matching relationship.

### Claim 8 (depends on 6)

The device of claim 6, wherein the processor is caused by the machine-executable instructions to:
place the respective pseudo CT sub-images into border images for the attenuation units corresponding to the respective pseudo CT sub-images.

### Claim 9 (depends on 6)

The device of claim 6, wherein the processor is caused by the machine-executable instructions to:
perform smoothing correction for respective adjacent borders of attenuation units in adjacent pseudo CT sub-images.

### Claim 10 (depends on 6)

The device of claim 6, wherein the attenuation unit is an organ tissue of the subject.