# US 10,769,820 B2 · System and method for model-based reconstruction of quantitative images

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- Number: US 10,769,820 B2
- Document ID: US10769820B2
- Status: Granted
- Kind: B2
- Application number: 15/032,938
- Filed: 2014-10-22
- Published: 2016-09-01
- Granted: 2020-09-08
- Earliest claimed: 2013-10-30
- Assignees: Mayo Foundation for Medical Education and Research
- Applicants: Mayo Foundation for Medical Education and Research
- Inventors: Joshua D. Trzasko; Armando Manduca
- Web page: https://patentgrep.com/patent/US10769820B2

## CPC

- G06T 12/00: Tomographic reconstruction from projections
- A61B 5/743: {Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots}
- G01R 33/5608: {Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels (image data processing or generation, in general G06T)}
- G06T 7/0012: {Biomedical image inspection}
- G06T 7/0016: {involving temporal comparison}
- G06T 2207/10076: 4D tomography; Time-sequential 3D tomography
- G06T 2207/10088: Magnetic resonance imaging [MRI]
- G06T 2207/10092: Diffusion tensor magnetic resonance imaging [DTI]
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

A system and method for estimating a physiological parameter from data acquired with a medical imaging system includes acquiring data with the medical imaging system. A physiological parameter is estimated from the acquired data using an iterative estimation in which a model of the medical imaging system is decoupled from a physics-based model of the acquired data.

## Claims

### Claim 1

A system for generating medical images comprising:
a communications connection configured to receive image data acquired from a subject using a medical imaging system;
a processor configured to receive the image data and to:
a) estimate a physiological parameter from the image data by inputting the image data to an estimation model comprising a model of the medical imaging system that is decoupled from a physics-based model of the image data, generating output as the estimate of the physiological parameter, wherein the physics-based model comprises a nonlinear signal model functional that models the image data such that the image data have a nonlinear dependence on at least one parameter of the physics-based signal model, and the model of the medical imaging system is actively decoupled from the physics-based model by applying a multi-level splitting routine to the model of the medical imaging system and the physics-based model;
b) iteratively minimize a cost function that includes the model of the medical imaging system and the physics-based model of the acquired data to quantify the physiological parameter of the subject from the image data; and
c) reconstruct a set of medical images of the subject from the image data at least including the physiological parameter of the subject.

### Claim 2 (depends on 1)

The system of claim 1 wherein the model of the medical imaging system is a large-scale system operator that describes data acquisition using the medical imaging system.

### Claim 3 (depends on 2)

The system of claim 2 wherein the medical imaging system is a magnetic resonance imaging (MRI) system and the model of the medical imaging system includes a Fourier transform.

### Claim 4 (depends on 1)

The system of claim 1 wherein to estimate the physiological parameter the processor is further caused to apply the multi-level splitting routine in order to prospectively enable the use of a dimensionality reduction strategy to reduce overall complexity of the estimation due to non-uniqueness of data.

### Claim 5 (depends on 1)

The system of claim 1 wherein to estimate the physiological parameter the processor is further caused to form separable nonlinear least squares problems.

### Claim 6 (depends on 1)

The system of claim 1 wherein to iteratively minimize the cost function, the processor is further caused to control an influence of ancillary parameters, f, that are not associated with the physiological parameter.

### Claim 7 (depends on 6)

The system of claim 6 wherein to control an influence of ancillary parameters, f, the processor is further caused to marginalize f out of estimations by constructing a specific alternating direction method of multipliers (“ADMM”) paradigm.

### Claim 8 (depends on 7)

The system of claim 7 wherein to iteratively minimize the cost function, the processor is further caused to solve a linear system of:
∇
u
_
⁢
J
AL
=
⁢
A
*
⁡
(
A
⁢
u
^
-
g
)
+
μ
u
⁡
(
u
^
-
v
-
η
u
)
=
0
⁢
⇓
⁢
u
^
=
[
A
*
⁢
A
+
μ
u
⁢
I
]
-
1
⁡
[
A
*
⁢
g
+
μ
u
⁡
(
v
+
η
u
)
]
where JAL is quadratic with respect to μ, A is the system model, g is the image data, u and v are “dummy” variables that extended cost functions, μu,μv>0, and wherein ηu and ηv are Lagrange multiplier vectors.

### Claim 9 (depends on 2)

The system of claim 2 wherein the medical imaging system is a magnetic resonance imaging (MRI) system and the physics-based model includes a magnetic resonance signal model.

### Claim 10

A method for estimating a physiological parameter from data acquired with a medical imaging system, the steps of the method comprising:
a) acquiring data with the medical imaging system;
b) estimating a physiological parameter from the acquired data by inputting the acquired data to an estimation model comprising a model of the medical imaging system that is decoupled from a physics-based model of the acquired data, generating output as the estimate of the physiological parameter, wherein the physics-based model comprises a nonlinear signal model functional that models the acquired data such that the acquired data have a nonlinear dependence on at least one parameter of the physics-based signal model, and the model of the medical imaging system is actively decoupled from the physics-based model by applying a multi-level splitting routine to the model of the medical imaging system and the physics-based model; and
c) reconstructing a set of medical images from the data, the medical images at least including the physiological parameter.

### Claim 11 (depends on 10)

The method as recited in claim 10 wherein step b) includes iteratively minimizing a cost function that includes the model of the medical imaging system and the physics-based model of the acquired data.

### Claim 12 (depends on 11)

The method as recited in claim 11 wherein step b) includes marginalizing unwanted variables out of the cost functional.

### Claim 13 (depends on 12)

The method as recited in claim 12 wherein step b) in which one level of the multi-level splitting routine includes decoupling the model of the medical imaging system from the physics-based model of the acquired data.

### Claim 14 (depends on 10)

The method as recited in claim 10 wherein step b) includes using an alternating direction method of multipliers routine to decouple the model of the medical imaging system from the physics-based model of the acquired data.

### Claim 15 (depends on 10)

The method as recited in claim 10 wherein the medical imaging system is a magnetic resonance imaging (MRI) system, the model of the medical imaging system includes a Fourier transform, and the physics-based model of the acquired data is a magnetic resonance signal model.

### Claim 16

A magnetic resonance imaging (MRI) system, comprising:
a magnet system configured to generate a polarizing magnetic field about at least a portion of a subject arranged in the MRI system;
a magnetic gradient system including a plurality of magnetic gradient coils configured to apply at least one magnetic gradient field to the polarizing magnetic field;
a radio frequency (RF) system configured to apply an RF field to the subject and to receive magnetic resonance signals from the subject using a coil array;
a computer system processor programmed to:
control the magnetic gradient system and the RF system to acquire image data;
estimate a physiological parameter from the image data by inputting the image data to an estimation model comprising a model of the MRI system that is decoupled from a physics-based model of the image data, generating output as the estimate of the physiological parameter, wherein the physics-based model comprises a nonlinear signal model functional that models the image data such that the image data have a nonlinear dependence on at least one parameter of the physics-based signal model, and the model of the medical imaging system is actively decoupled from the physics-based model by applying a multi-level splitting routine to the model of the medical imaging system and the physics-based model;
and
generate a quantitative image of the subject with the physiological parameter.

### Claim 17 (depends on 16)

The MRI system of claim 16 wherein to estimate the physiological parameter the processor is further caused to apply the multi-level splitting routine in order to prospectively enable the use of a dimensionality reduction strategy to reduce overall complexity of the estimation due to non-uniqueness of data.

### Claim 18 (depends on 16)

The MRI system of claim 16 wherein to estimate the physiological parameter the processor is further caused to form separable nonlinear least squares problems.

### Claim 19 (depends on 16)

The MRI system of claim 16, further comprising iteratively minimizing a cost function, the processor programmed to control an influence of ancillary parameters, f, that are not associated with the physiological parameter.

### Claim 20 (depends on 19)

The MRI system of claim 19 wherein to control an influence of ancillary parameters, f, the processor is further caused to marginalize f out of estimations by constructing a specific alternating direction method of multipliers (“ADMM”) paradigm.