Method and magnetic resonance system for fat saturation

Patent metadata

Field	Value
Publication number	US-10317488-B2
Application number	US-201514661238-A
Country	US
Kind code	B2
Filing date	Mar 18, 2015
Priority date	Mar 18, 2014
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

In a method and a magnetic resonance system for fat saturation when acquiring magnetic resonance data in a predetermined volume segment of an examination object, a SPAIR pulse is emitted and an RF excitation pulse is emitted following a predetermined time period after the SPAIR pulse, and magnetic resonance data are thereafter acquired. The time period of at least one slice is set so as to be different from the time period for the remaining slices.

First claim

We claim as our invention:

1. A method for generating a magnetic resonance (MR) image, comprising:
in a computer, designing an MR data acquisition pulse sequence comprising a Spectrally Adiabatic Inversion Recovery (SPAIR) pulse followed, after a predetermined time period, by a radio-frequency (RF) excitation pulse;
in said computer, generating control signals corresponding to said MR data acquisition sequence and providing said control signals to an MR scanner, comprising an RF radiator and a gradient coil system, in order to operate the MR scanner so as to execute the MR data acquisition sequence;
in said MR scanner, executing said MR data acquisition sequence according to said control signals so as to radiate said SPAIR pulse from said RF radiator for each slice among a plurality of slices in a predetermined volume of an examination subject situated in the MR scanner, and to radiate, for each of said slices, said RF pulse at said predetermined time period following said SPAIR pulse for that respective slice;
in said computer, generating said control signals so as to operate said MR scanner so as to execute said MR data acquisition sequence according to said control signals so as to operate said gradient coil system to acquire MR data, comprising a fat signal, from each of said plurality of slices, with said time period for at least one of said slices being different from said time period for others of said slices, by setting said time period in said computer for said at least one of said slices using a function of a time duration TR-SPAIR that exists between two of said SPAIR pulses that occur successively in time, in which function TR-SPAIR is assumed to be infinitely long, and acquiring said MR data respectively from said plurality of slices with a level of fat saturation, represented by said fat signal thereby being homogenized over said slices in said plurality of slices; and
providing said MR data to an image reconstruction computer and, in said image reconstruction computer, reconstructing respective images of said slices with said homogenized levels of fat saturation.

2. A method as claimed in claim 1 comprising acquiring said MR data from said at least one slice first, before acquiring said MR data from said others of said slices.

3. A method as claimed in claim 1 comprising, in said computer, setting said time period for said at least one slice as a function of a predetermined requirement for said fat signal.

4. A method as claimed in claim 3 comprising, in said computer, using, as said predetermined requirement, a requirement that the fat signal represent as uniform a fat saturation as possible across all of said plurality of slices, or a requirement that the fat signal represents a maximum fat saturation for each slice in said plurality of slices.

5. A method as claimed in claim 1 comprising, in said control computer, setting said time period for said at least one slice to be longer than the time period for any of said others of said slices.

6. A method as claimed in claim 1 comprising, in said control computer, setting said predetermined time period to be TI for said others of said slices according to:

TI
=

a
×
T
⁢

⁢
1
×

(

b
-

1
⁢

⁢

g
⁡

(

1
+

e

-

(

TR
-
SPAIR
-
c

T
⁢

⁢
1

)

)

)

+
TIadd

wherein TR-SPAIR is said time duration, T 1 is the longitudinal relaxation time of nuclear spins from which said MR data originate, and wherein a, b and c are empirically determined constants, and wherein Tladd is an additional time relevant to said requirement for fat saturation.

7. A method as claimed in claim 1 comprising, in said control computer, determining said predetermined time period to be TI for said at least one slice according to:

TI
i

=

1
i

×

f
⁡

(

TR
-
SPAIR

=
∞

)

+

(

i
-
1

)

×

f
⁡

(

TR
-
SPAIR

)

wherein f(TR-SPAIR) is said function of said time duration TR-SPAIR, and wherein i is an index, and wherein TIi is the time period of an i-th slice, which is the i-th slice in time from which said MR data are acquired.

8. A method as claimed in claim 1 comprising, in said control computer, setting said time period for said at least one slice of a function of a predetermined requirement for said fat signal, and determining said time pe

Assignees

• Siemens Ag

Inventors

• Blumhagen Jan Ole
• Paul Dominik
• Splitthoff Daniel Nico

Classifications

• G01R33/4828 Primary

  Resolving the MR signals of different chemical species, e.g. water-fat imaging · CPC title

• G01R33/4835

  of multiple slices · CPC title

• G01R33/5607 Primary

  by reducing the NMR signal of a particular spin species, e.g. of a chemical species for fat suppression, or of a moving spin species for black-blood imaging · CPC title

• G01R33/34

  Constructional details, e.g. resonators {, specially adapted to MR} · CPC title