Magnetic resonance elastography

Patent metadata

Field	Value
Publication number	US-9482733-B2
Application number	US-201013513918-A
Country	US
Kind code	B2
Filing date	Dec 20, 2010
Priority date	Dec 21, 2009
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

A magnetic resonance elastography method includes application of mechanical oscillations with an oscillation period (T) to an object to be examined to generate mechanical waves in the object. A motion sensitive magnetic resonance acquisition sequence with repetition time T R issued to acquire magnetic resonance signals from the object. This acquisition sequence including application of one or more phase encoding steps within an individual repetition time. The repetition time times the number of phase encodings within one repetition time is not equal to an integer multiple of the oscillation period. Thus a magnetic resonance image of the wave pattern is reconstructed from the magnetic resonance signals assembled in a sample space spanned by the phase of the mechanical oscillation and the phase encoding.

First claim

The invention claimed is:

1. A magnetic resonance elastography method comprising:
applying mechanical oscillations with an oscillation period (T) to an object to be examined to generate mechanical waves in the object;
applying a motion sensitive magnetic resonance acquisition sequence with repetition time T R to acquire magnetic resonance signals from the object, the acquisition sequence including application of one or more phase encoding steps within an individual repetition time,
wherein the repetition time is independent of the oscillation period, and
wherein a magnetic resonance image of a wave pattern of the generated mechanical waves in the object is reconstructed from the magnetic resonance signals assembled in a sample space spanned by a phase of the mechanical oscillations and a phase encoding.

2. The magnetic resonance elastography method as claimed in claim 1 , wherein:
for each phase encoding, magnetic resonance signals are acquired for at least three different values of the phase of the mechanical oscillation, enabling extraction of a DC component and phase and amplitude of a sine-wave with the oscillation period of the mechanical oscillation at the phase encoding, and
an image of the wave pattern in the object is reconstructed based on at least the DC component, and the phase and amplitude of the mechanical wave.

3. The magnetic resonance elastography method as claimed in claim 1 , further comprising:
interpolating values of the magnetic resonance signals in the sample space spanned by the phase of the mechanical oscillation and the phase encoding to provide interpolated data at additional values of the phase of the mechanical oscillation,
wherein the magnetic resonance image of the wave pattern is reconstructed from the interpolated data, in addition to the assembled magnetic resonance signals.

4. The magnetic resonance elastography method as claimed in claim 1 , wherein the mechanical oscillations are generated in the object at multiple oscillation frequencies simultaneously, wherein the repetition time is independent of the oscillation periods corresponding to the multiple oscillation frequencies.

5. A magnetic resonance examination system, comprising:
an actuator configured to apply mechanical oscillations to an object to be examined for generating mechanical waves in the object;
an RF excitation system and a gradient system configured to apply a motion sensitive magnetic resonance acquisition sequence, the motion sensitive magnetic resonance acquisition sequence including a plurality of phase encoding steps;
an RF receiver system configured to receive magnetic resonance signals generated in the magnetic resonance acquisition sequence;
a reconstructor configured to reconstruct a magnetic resonance image from the received magnetic resonance signals assembled in a sample space spanned by a phase of the mechanical oscillations and a phase encoding; and
a control unit configured to control operations of the RF excitation system, the gradient system, the actuator and the reconstructor, to set a repetition time of the mechanical oscillations, and to set a repetition time of the motion sensitive magnetic resonance acquisition sequence time, the repetition time of the motion sensitive magnetic resonance acquisition sequence time being independent of an oscillation period of the mechanical oscillations,
wherein the reconstructor is further configured to reconstruct the magnetic resonance image of the mechanical waves from the assembled magnetic resonance signals.

6. A computer readable medium containing instructions, executable by a computer processor, for performing magnetic resonance elastography, the computer readable medium comprising:
mechanical oscillation application code for applying mechanical oscillations with an oscillation period (T) to an object to be examined to generate mechanical waves in the object;
magnetic resonance acquisition sequence application code for applying a motion sensitive magnetic resonance acquisition sequence with repetition time T R to acquire magnetic resonance signals from the object, the acquisition sequence including application of one or more phase encoding steps within an individual repetition time,
wherein the repetition time is independent of the oscillation period, and
wherein a magnetic resonance image of a wave pattern of the generated mechanical waves in the object is reconstructed from the magnetic resonance signals assembled in a sample space spanned by a phase of the mechanical oscillation and the phase encoding.

Assignees

• Fuderer Miha
• Koninklijke Philips Nv

Inventors

• Fuderer Miha

Classifications

• G01R33/56358 Primary

  Elastography · CPC title