Method and control device to control a magnetic resonance system

Patent metadata

Field	Value
Publication number	US-9739859-B2
Application number	US-201314026291-A
Country	US
Kind code	B2
Filing date	Sep 13, 2013
Priority date	Sep 14, 2012
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

A method and control device operate a magnetic resonance system in order to execute a first pulse sequence that includes an excitation phase and an acquisition phase. In the excitation phase, a first gradient is applied in a gradient direction to generate a spatially dependent basic magnetic field. A selective radio-frequency excitation pulse is executed, wherein the selective radio-frequency excitation pulse excites a first material and does not excite a second material in a first partial region of an examination volume, and wherein the selective radio-frequency excitation pulse does not excite the first material and excites the second material in a second partial region of the examination volume. In the acquisition phase, non-selective refocusing pulses are executed in order to acquire raw data of the first and second partial region of the examination volume, which acquisition is spatially coded along the gradient direction.

First claim

We claim as our invention:

1. A method for operating a magnetic resonance system comprising a data acquisition scanner comprising a radio-frequency (RF) radiator and a gradient system, said method comprising:
from a control computer, operating said data acquisition scanner according to a pulse sequence;
in said pulse sequence, generating a gradient, with said gradient system, in a gradient direction, as a spatially dependent magnetic field;
while said gradient is generated, radiating a selective RF excitation pulse with said RF transmission system, said selective RF excitation pulse being configured to excite nuclear spins of a first material in a first partial region of an examination subject and not to excite nuclear spins of a second material in said first partial region, and to not excite nuclear spins of said first material in a second partial region of the examination subject and to excite nuclear spins of said second material in said second partial region;
in said pulse sequence, radiating a number of refocusing pulses and acquiring raw magnetic resonance data from said first and second partial regions resulting from excitation of said nuclear spins of said first material and excitation of said nuclear spins of said second material, and spatially coding said raw magnetic resonance data along said gradient direction; and
storing said raw magnetic resonance data in electronic form in a memory and making said raw magnetic resonance data stored in said memory available in said electronic form for further processing.

2. A method as claimed in claim 1 comprising radiating at least one of said refocusing pulses as a non-selective refocusing pulse.

3. A method as claimed in claim 1 comprising acquiring said raw magnetic resonance data with three-dimensional spatial coding.

4. A method as claimed in claim 3 comprising executing said three-dimensional spatial coding as phase coding in a first direction of a Cartesian coordinate system, and in a second direction of said Cartesian coordinate system, and as frequency coding in a third direction of said Cartesian coordinate system.

5. A method as claimed in claim 4 comprising executing said phase coding along said gradient direction.

6. A method as claimed in claim 1 comprising adjusting said spatially dependent magnetic field with said gradient to cause a resonance frequency of the nuclear spins of the first material in the first partial region to be between a first frequency and a second frequency and to cause a resonant frequency of the nuclear spins of the second material in the second partial region to be between said first frequency and said second frequency.

7. A method as claimed in claim 6 comprising radiating said selective RF excitation pulse with a frequency spectrum between said first frequency and said second frequency.

8. A method as claimed in claim 1 wherein said pulse sequence is a first pulse sequence and wherein said gradient is a first gradient, and comprising operating said data acquisition scanner from said control computer with a second pulse sequence in which a second gradient is generated to generate a spatially dependent magnetic field that differs from the spatially dependent magnetic field generated by said first gradient in terms of algebraic sign, and also radiating a selective RF excitation pulse in said second pulse sequence during said second gradient.

9. A method as claimed in claim 8 comprising radiating said selective RF excitation pulse in said second pulse sequence with a frequency offset with respect to the selective RF excitation pulse in said first pulse sequence.

10. A control device computer for operating a magnetic resonance system comprising a data acquisition scanner comprising a radio-frequency (RF) radiator and a gradient system, said control computer comprising:
a processor configured to operate said data acquisition scanner according to a pulse sequence;
said processor being configured, in said pulse sequence, to cause a gradient to be generated with said gradient system, in a gradient direction, as a spatially dependent magnetic field;
said processor being configured to cause, while said gradient is generated, a selective RF excitation pulse to be radiated with said RF transmission system, said selective RF excitation pulse being configured to excite nuclear spins of a first material in a first partial region of an examination subject and not to excite nuclear spins of a second material in said first partial region, and to not excite nuclear spins of said first material in a second partial region of the examination subject and to excite nuclear spins of said second material in said second partial region;
said processor being configured to operate said data acquisition scanner in said pulse sequence to radiate a number of refocusing pulses and acquire raw magnetic resonance data from said first and second partial regions resulting from excitation of said nuclear spins of said first material and excitation of said nuclear spins of said second material, and spatially coding said raw magnetic resonance data along said gradient direction; and
said processor being configured to store said raw magnetic resonance data in electronic form in a memory and make said raw magnetic resonance data stored in said memory available in said electronic form for further processing.

11. A magnetic resonance system comprising:
a data acquisition scanner comprising a radio-frequency (RF) transmission system, and a gradient system;
a control computer configured to operate said data acquisition unit according to a pulse sequence;
said control computer being configured to cause, in said pulse sequence, a gradient to be generated with said gradient system, in a gradient direction, as a spatially dependent magnetic field;
said control computer being configured to cause, while said gradient is generated, a selective RF excitation pulse to be radiated with said RF transmission system, said selective RF excitation pulse being configured to excite nuclear spins of a first material in a first partial region of an examination subject and not to excite nuclear spins of a second material in said first partial region, and to not excite nuclear spins of said first material in a second partial region of the examination subject and to excite nuclear spins of said second material in said second partial region;
said control computer being configured to operate said data acquisition scanner in said pulse sequence to radiate a number of refocusing pulses and acquire raw magnetic resonance data from said first and second partial regions resulting from excitation of said nuclear spins of said first material and excitation of said nuclear spins of said second material, and spatially coding said raw magnetic resonance data along said gradient direction; and
said control computer being configured to store said raw magnetic resonance data in electronic form in a memory and make said raw magnetic resonance data stored in said memory available in said electronic form for further processing.

12. A non-transitory, computer-readable data storage medium encoded with programming instructions, said storage medium being loaded into a control computer of a magnetic resonance system that also comprises a data acquisition scanner comprising a radio-frequency (RF) transmission system and a gradient system, said programming instructions causing said control computer to operate said data acquisition scanner to:
execute a magnetic resonance data acquisition pulse sequence;
in said pulse sequence, generate a gradient, with said gradient system, in a gradient direction, as a spatially dependent magnetic field;
while said gradient is gener

Assignees

• Bachschmidt Theresa
• Fautz Hans-Peter
• Gumbrecht Rene
• Paul Dominik
• Siemens Ag

Inventors

• Bachschmidt Theresa
• Fautz Hans-Peter
• Gumbrecht Rene
• Paul Dominik

Classifications

• G01R33/4833

  using spatially selective excitation of the volume of interest, e.g. selecting non-orthogonal or inclined slices · CPC title

• G01R33/4828 Primary

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