Magnetic resonance method and system to generate an optimized MR image of an examination subject

Patent metadata

Field	Value
Publication number	US-9229083-B2
Application number	US-201113247428-A
Country	US
Kind code	B2
Filing date	Sep 28, 2011
Priority date	Sep 29, 2010
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

A magnetic resonance method and system for generation of an optimized MR image of an examination subject operate as follows. A pulse sequence including a series of at least two RF pulses is radiated into the examination subject to generate at least one optimized signal, wherein the second and possibly every additional RF pulse is radiated before the effect of the first or a preceding RF pulse on the spin system in the examination subject has decayed. The radiated RF pulses are generated by parallel transmission coils. At least the signal resulting after the last radiated RF pulse of the pulse sequence is acquired. The pulse sequence is repeated with modified spatial coding until signals have been generated and acquired in a desired positional space. The optimized MR image per pulse sequence is calculated from at least one of the acquired signals.

First claim

I claim as my invention:

1. A method for generating an optimized magnetic resonance image of an examination subject, comprising:
placing an examination subject in a magnetic resonance data acquisition unit comprising a plurality of radio frequency (RF) transmission coils;
operating said plurality of RF transmission coils in parallel to radiate at least two RF excitation pulses into the examination subject in the data acquisition unit, that each excite nuclear spins in the subject to cause emission of at least one magnetic resonance signal from the nuclear spins in the subject that have been excited by said at least two RF excitation pulses, with at least a second of said RF excitation pulses being radiated before an effect on said nuclear spins of a preceding RF excitation pulse in said series of at least two RF excitation pulses has subsided, so that said at least one magnetic resonance signal comprises signal contributions from nuclear spins excited by said preceding RF excitation pulse and nuclear spins excited by said at least a second of said RF excitation pulses;
selecting at least said preceding RF excitation pulse and said at least a second of said RF excitation pulses to cause said signal contributions to give said magnetic resonance signal a selected optimization as an optimized magnetic resonance signal;
spatially encoding said at least one optimized signal with a spatial coding;
detecting the at least one optimized and spatially coded magnetic resonance signal with a reception antenna of said data acquisition unit;
repeating radiation of said sequence and modifying said spatial coding with each repetition until all signals have been generated and acquired in a predetermined region of the examination subject; and
in a processor, calculating a magnetic resonance image for each pulse sequence from at least one of the acquired signals, said magnetic resonance image having an image content that is a result of said selected optimization given to said optimized magnetic resonance signal.

2. A method as claimed in claim 1 comprising selecting the radiated RF excitation pulses to give said optimized magnetic resonance image a predetermined image contrast.

3. A method as claimed in claim 1 comprising calculating said optimized magnetic resonance image for each pulse sequence from only said signal acquired after a last radiated RF excitation pulse in said sequence.

4. A method as claimed in claim 1 comprising in each pulse sequence, acquiring at least two signals that occur after each radiated RF excitation pulse and, from said at least two signals arising after each radiated RF excitation pulse, reconstructing individual images and forming said optimized MR image from the reconstructed individual images.

5. A method as claimed in claim 1 comprising obtaining additional information about the examination subject in each pulse sequence from at least one of the acquired signals.

6. A method as claimed in claim 1 comprising acquiring the optimized magnetic resonance signals with parallel reception coils, as said reception antenna, in said data acquisition unit.

7. A magnetic resonance system comprising:
a magnetic resonance data acquisition unit comprising a plurality of radio frequency (RF) transmission coils, and a reception antenna;
a control unit configured to operate said data acquisition unit by providing signals to said plurality of RF transmission coils in parallel to cause said RF transmission coils to radiate at least two RF excitation pulses into an examination subject located in the data acquisition unit, causing that each excite nuclear spins in the subject so as to cause emission of at least one optimized magnetic resonance signal from nuclear spins in the subject that have been excited by said at least two RF excitation pulses, with at least a second of said RF excitation pulses being radiated before an effect on said nuclear spins of a preceding RF excitation pulse in said series of at least two RF excitation pulses has subsided, so that said at least one magnetic resonance signal comprises signal contributions from nuclear spins excited by said preceding RF excitation pulse and nuclear spins excited by said second of said RF excitation pulses;
select at least said preceding RF excitation pulse and said at least a second of said RF excitation pulses to cause said signal contributions to give said magnetic resonance signal a selected optimization as an optimized magnetic resonance signal;
a gradient coil system operated by said control unit to spatially encode said at least one optimized signal with a spatial coding;
said control unit being configured to operate said data acquisition unit to detecting the at least one optimized and spatially coded magnetic resonance signal with a reception antenna of said data acquisition unit;
said control unit being configured to operate said data acquisition unit to repeat radiation of said sequence and modifying said spatial coding with each repetition until all signals have been generated and acquired in a predetermined region of the examination subject; and
a processor configured to calculate an optimized magnetic resonance image for each pulse sequence from at least one of the acquired signals, said magnetic resonance image having an image content that is a result of said selected optimization given to said optimized magnetic resonance signal.

8. A non-transitory, computer-readable storage medium encoded with programming instructions, said storage medium being loaded into a computerized control and evaluation system of a magnetic resonance system having a data acquisition unit having a plurality of radio frequency (RF) transmission coils, said programming instructions causing said computerized control and evaluation system to:
operate said plurality of RF transmission coils in parallel to radiate at least two RF excitation pulses into an examination subject located in the data acquisition unit, to cause emission of at least one optimized magnetic resonance signal from nuclear spins in the subject that have been excited by said at least two RF excitation pulses, with at least a second of said RF excitation pulses being radiated before an effect on said nuclear spins of a preceding RF excitation pulse in said series of at least two RF excitation pulses has subsided, so that said at least one magnetic resonance signal comprises signal contributions from nuclear spins excited by said preceding RF excitation pulse and nuclear spins excited by said second of said RF excitation pulses;
select at least said preceding RF excitation pulse and said at least a second of said RF excitation pulses to cause said signal contributions to give said magnetic resonance signal a selected optimization as an optimized magnetic resonance signal;
spatially encode said at least one optimized signal with a spatial coding;
detect the at least one optimized and spatially coded magnetic resonance signal with a reception antenna of said data acquisition unit;
repeat radiation of said sequence and modifying said spatial coding with each repetition until all signals have been generated and acquired in a predetermined region of the examination subject; and
calculate an optimized magnetic resonance image for each pulse sequence from at least one of the acquired signals, said magnetic resonance image having an image content that is a result of said selected optimization given to said optimized magnetic resonance signal.

Assignees

• Fautz Hans-Peter
• Siemens Ag

Inventors

• Fautz Hans-Peter

Classifications

• G01R33/5659

  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

• A61B5/055

  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging · CPC title

• G01R33/5612 Primary

  Parallel RF transmission, i.e. RF pulse transmission using a plurality of independent transmission channels · CPC title