System and method for determining patient parameters using radio frequency phase increments in magnetic resonance imaging

Patent metadata

Field	Value
Publication number	US-10845446-B2
Application number	US-201916393806-A
Country	US
Kind code	B2
Filing date	Apr 24, 2019
Priority date	Apr 24, 2019
Publication date	Nov 24, 2020
Grant date	Nov 24, 2020

Abstract

A system and method are provided for controlling a magnetic resonance imaging system to perform a gradient echo pulse sequence that includes varying a phase of an RF pulse of the gradient echo pulse sequence between repetitions and acquire complex MR data. The method includes processing the complex MR data to determine signal contributions from transverse relaxation (T2) in the subject, generating a quantitative T2 map of the subject using the signal contributions from T2 in the subject, and displaying the quantitative T2 map.

First claim

The invention claimed is:

1. 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 plurality of gradient coils configured to apply magnetic gradients to the polarizing magnetic field;
a radio frequency (RF) system configured to apply an excitation field to the subject and acquire MR image data from the subject;
a computer system programmed to:
control the plurality of gradient coils and the RF system to perform a gradient echo pulse sequence that includes varying a phase of an RF pulse of the gradient echo pulse sequence between repetitions and acquire complex MR data;
process the complex MR data to determine signal contributions from transverse relaxation (T2) in the subject;
generate a quantitative T2 map of the subject using the signal contributions from T2 in the subject;

a display configured to receive the quantitative T2 map from the computer and display the quantitative T2 map.

2. The MRI system of claim 1 , wherein the computer system is configured to vary the phase using at least two phase increments that are equal in magnitude and opposite in sign and wherein the computer system is configured to separate signal contributions from T2 from background phase effects by subtracting MR data acquired with the phase increments that are equal in magnitude and opposite in sign.

3. The MRI system of claim 1 , wherein the computer system is configured to determine signal contributions of T2 and T1 using at least one of a model and lookup table.

4. The MRI system of claim 1 , wherein the computer system is configured to determine signal contributions from T2 using:

θ
⁡

(

Δ
⁢
Φ

,

⁢
α
,

TR
|

T
1

,

T
2

)

=

(

∠S
⁡

(

Δ
⁢
Φ

,
α
,

TR
|

T
1

,

T
2

)

-

∠S
⁢

(

-
Δ

⁢
Φ

,
α
,

TR
|

T
1

,

T
2

)

)

2

;

where θ(ΔΦ, α,TR| T 1 , T 2 ) is signal phase of the complex MR data as a function of the phase increment (ΔΦ), flip angle (α) repetition time of the pulse sequence (TR), latitudinal relaxation time (T1), and longitudinal relaxation time (T2), and S(T1,T2;ΔΦ, α,TR) is a gradient signal acquired using the gradient echo pulse sequence.

5. The MRI system of claim 1 , wherein the computer system is configured to determine signal contributions of T2 and T1 using:

S
1

S
2

=

η
⁡

(

Δ
⁢

Φ
1

,

α
1

,

TR
|

T
1

,

T
2

)

η
⁡

(

Δ
⁢

Φ
2

,

α
2

Assignees

• Wisconsin Alumni Res Found

Inventors

• Reeder Scott B
• Wang Xiaoke

Classifications

• G01R33/50 Primary

  based on the determination of relaxation times {, e.g. T1 measurement by IR sequences; T2 measurement by multiple-echo sequences} · CPC title

• G01R33/56341

  Diffusion imaging · CPC title

• G01R33/543

  Control of the operation of the MR system, e.g. setting of acquisition parameters prior to or during MR data acquisition, dynamic shimming, use of one or more scout images for scan plane prescription (G01R33/546 takes precedence) · CPC title