Super resolution in positron emission tomography imaging using ultrafast ultrasound imaging

Patent metadata

Field	Value
Publication number	US-11940578-B2
Application number	US-202117160866-A
Country	US
Kind code	B2
Filing date	Jan 28, 2021
Priority date	Jan 31, 2020
Publication date	Mar 26, 2024
Grant date	Mar 26, 2024

Abstract

An imaging method including:
a) acquiring N successive positron emission tomography (PET) low resolution images Γ i and simultaneously, N successive Ultrafast Ultrasound Imaging (UUI) images Ui of a moving object; b) determining from each UUI image Ui, the motion vector fields M i that corresponds to the spatio-temporal geometrical transformation of the motion of the object; c) obtaining a final estimated high resolution image H of the object by iterative determination of a high resolution image H n+1 obtained by applying several correction iterations to a current estimated high resolution image H n , n being the number of iterations, starting from an initial estimated high resolution image H 1 of the object, each correction iteration including at least: i) warping the estimated high resolution image H n using the motion vector fields M i to determine a set of low resolution reference images L n i ; ii) determining a differential image Di by difference between each PET image Γ i and the corresponding low resolution reference image L n i ; iii) warping back the differential images Di using the motion vector fields M i and averaging the N warped back differential images to obtain a high resolution differential image; iv) determining the high resolution image H n+1 by correcting the high resolution image H n using the high resolution differential image; d) applying the motion vector fields M i of each UUI image Ui to the final high resolution image H.

First claim

The invention claimed is:

1. An imaging method including:
a) acquiring N successive positron emission tomography (PET) low resolution images Γ i and simultaneously, N successive Ultrafast Ultrasound Imaging (UUI) images Ui of a moving object; b) determining from each UUI image Ui, the motion vector fields M i that corresponds to the spatio-temporal geometrical transformation of the motion of the object; c) obtaining a final estimated high resolution image H of the object by iterative determination of a high resolution image H n+1 obtained by applying several correction iterations to a current estimated high resolution image H n , n being the number of iterations, starting from an initial estimated high resolution image H 1 of the object, each correction iteration including at least:
i) warping said estimated high resolution image H n using the motion vector fields M i to determine a set of low resolution reference images L n i ;
ii) determining a differential image Di by difference between each PET image Γ i and the corresponding low resolution reference image L n i ;
iii) warping back said differential images Di using the motion vector fields M i and averaging the N warped back differential images to obtain a high resolution differential image;
iv) determining the high resolution image H n+1 by correcting said high resolution image H n using said high resolution differential image;
d) applying the motion vector fields M i of each UUI image Ui to said final high resolution image H.

2. The imaging method according to claim 1 , wherein the motion vector fields M i of b) are estimated by combination of both global and local image estimators by characterizing respectively intensity and local phase information obtained from two consecutive frames of the set of UUI images.

3. The imaging method according to claim 2 , wherein the motion vector fields M i are estimated according to the following equation:

M
i

=

1
2

[

(

I
R

-

I

T
i

)

⁢

∇

I
R



∇

I
R



2

+

(

I
R

-

I

T
i

)

2

+

(

θ
R

-

θ

T
i

)

⁢

∇

θ
R



∇

θ
R



2

+

(

θ
R

-

θ

T
i

)

2

]

wherein I T i and I R are defined as the image template (at frame i) and reference, respectively; ∇ is the gradient operator and θ T i and θ R are the local phases of the image template and reference, respectively.

4. The imaging method according to claim 2 , wherein the local phase θ(x,y) is obtained from the monogenic signal using quadrature filters, which are the combination of an even-symmetric band-pass filter and of two consecutive odd-symmetric filters applied to the even component of the signal according to the following equation:

θ
=

ta
⁢

n

-
1

(

I
e

(

F
01

⊗

I
e

)

2

+

Assignees

• Inst Nat Sante Rech Med
• Univ Paris
• Centre Nat Rech Scient
• Ecole Superieure Physique & Chimie Ind Ville De Paris
• Centre National De La Rech Scientifique—Cnrs

Inventors

• Tavitian Bertrand
• Tanter Mickaël
• Perez-Liva Mailyn
• Lopez Herraiz Joaquin
• Provost Jean

Classifications

• G06T12/30 Primary

  Image post-processing, e.g. metal artefact correction · CPC title

• G01T1/2985 Primary

  In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis); (using external radiation sources A61B6/02) · CPC title

• A61B6/5229

  combining image data of a patient, e.g. combining a functional image with an anatomical image · CPC title

• A61B6/5235

  combining images from the same or different ionising radiation imaging techniques, e.g. PET and CT · CPC title

• G06T2211/424

  Iterative · CPC title