Method and apparatus for acquiring B1 magnetic field information

Patent metadata

Field	Value
Publication number	US-9594145-B2
Application number	US-201314096372-A
Country	US
Kind code	B2
Filing date	Dec 4, 2013
Priority date	Dec 4, 2012
Publication date	Mar 14, 2017
Grant date	Mar 14, 2017

Abstract

A method acquires RF magnetic field information (B1 magnetic field information) in response to generated radio frequency (RF) pulses in a magnetic resonance imaging (MRI) system. An RF excitation pulse sequence is generated, and the generated RF excitation pulse sequence includes a plurality of RF excitation pulses individually having different flip angles. The generated RF excitation pulse sequence is transmitted to a target object. RF echo response signals are received from the target object corresponding to the plurality of RF excitation pulses and B1 information is acquired by processing the received RF echo response signals.

First claim

What is claimed is:

1. A method of acquiring B1 magnetic field information in response to generated radio frequency (RF) pulses in a magnetic resonance imaging (MRI) system, the method comprising:
generating an RF excitation pulse sequence including interleaved first, second and third RF excitation pulses which are individually associated with different flip angles;
transmitting the generated RF excitation pulse sequence to a target object;
receiving RF echo response signals from the target object corresponding to the first, second and third RF excitation pulses; and
acquiring B1 information by processing the received RF echo response signals,
wherein, the first RF excitation pulse is associated with a first flip angle α, the second RF excitation pulse is associated with a second flip angle β, and the third RF excitation pulse is associated with a third flip angle γ, and the second flip angle β and the third flip angle γ are different integer multiples of the first flip angle α, and
where the acquiring of the B1 information comprises;
acquiring first ratio information determined using a magnitude of an echo response signal associated with the first RF excitation pulse and a magnitude of an echo response signal associated with the second RF excitation pulse;
acquiring second ratio information determined using a magnitude of an echo response signal associated with the second RF excitation pulse and a magnitude of an echo response signal associated with the third RF excitation pulse, and
acquiring a first flip angle α value of the first RF excitation pulse by using the first ratio information and the second ratio information.

2. The method of claim 1 , wherein the first, second and third RF excitation pulses are interleaved at a predetermined time interval.

3. The method of claim 1 , wherein the first, second and third RF excitation pulses are pulses of different respective magnitudes.

4. The method of claim 1 , wherein the first ratio information is acquired according to Equations (1) and (3) below,
the second ratio information is acquired according to Equations (2) and (3) below,

R
1

=

S
1

S
2

=

sin
⁢

⁢

β
⁡

(

1
+

cos
⁢

⁢

α
·

E
1

+

cos
⁢

⁢

γ
·
cos

⁢

⁢

α
·

E
1
2

)

sin
⁢

⁢

α
⁡

(

1
+

cos
⁢

⁢

γ
·

E
1

+

cos
⁢

⁢

β
·
cos

⁢

⁢

γ
·

E
1
2

)

,

(
1
)

Assignees

• Samsung Electronics Co Ltd
• Ind Acad Coop Found Kyunghee Univ

Inventors

• Lee Ju-Hyung
• Lee Soo-Yeol

Classifications

• G01R33/5659 Primary

  caused by a distortion of the RF magnetic field, e.g. spatial inhomogeneities of the RF magnetic field (G01R33/56509, G01R33/56518, G01R33/56536 take precedence) · CPC title

• G01R33/246 Primary

  Spatial mapping of the RF magnetic field B1 · CPC title

• G01R33/586

  for optimal flip angle of RF pulses · CPC title

• G01R33/34092

  RF coils specially adapted for NMR spectrometers · CPC title