Magnetic resonance tomography (MRT) imaging, employing RF receive coils with temporal sensitivity profile modulation

Patent metadata

Field	Value
Publication number	US-11378634-B2
Application number	US-202016984853-A
Country	US
Kind code	B2
Filing date	Aug 4, 2020
Priority date	Aug 14, 2019
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

A method of magnetic resonance tomography includes arranging an object in a static magnetic field, subjecting it to radiofrequency (RF) pulses and magnetic field gradients for creating spatial encoding of magnetic resonance signals, acquiring the signals with at least two RF receive coils, each with a self-resonance frequency and a spatially restricted sensitivity profile, and reconstructing an object image. Spatial encoding of the signals by the gradients and the profiles is utilized, wherein the profile of at least one of the coils is subjected to a temporal sensitivity profile modulation while acquiring the signal. The self-resonance frequency of the at least one coil is set within a predetermined receive bandwidth of a constant resonance frequency value during the modulation. The reconstructing further utilizes the modulation for obtaining additional spatial information to the spatial encoding of the signals by the gradients. Furthermore, an MRI device is described.

First claim

What is claimed is:

1. A method of magnetic resonance tomography (MRT) imaging an object, comprising the steps of:
arranging the object in a static magnetic field;
subjecting the object to radiofrequency (RF) pulses and magnetic field gradients for creating spatial encoding of magnetic resonance signals;
acquiring the magnetic resonance signals with at least two RF receive coils, each with a self-resonance frequency and a spatially restricted sensitivity profile; and
reconstructing an object image, wherein the spatial encoding of the magnetic resonance signals by the magnetic field gradients and by spatially restricted sensitivity profiles of the RF receive coils is utilized, wherein:
the spatially restricted sensitivity profile of at least one of the RF receive coils is subjected to a temporal sensitivity profile modulation during the step of acquiring the magnetic resonance signals, wherein the spatially restricted sensitivity profile of the at least one of the RF receive coils is temporally changed relative to the at least one of the RF receive coils as a function of time and the self-resonance frequency of the at least one modulated RF receive coil is set within a predetermined receive bandwidth of a constant resonance frequency value during the temporal sensitivity profile modulation, and
the step of reconstructing the object image further utilizes the temporal sensitivity profile modulation for obtaining additional spatial information to the spatial encoding of the magnetic resonance signals by the magnetic field gradients.

2. The MRT imaging method according to claim 1 , wherein the temporal sensitivity profile modulation is created by at least one electronically driven modulation component coupled with the at least one modulated RF receive coil.

3. The MRT imaging method according to claim 2 , wherein the at least one modulation component comprises at least one tunable capacitor component of the at least one modulated RF receive coil.

4. The MRT imaging method according to claim 3 , wherein the at least one modulation component comprises at least one tunable capacitor component of the at least one modulated RF receive coil with at least one of at least one varactor diode and at least one digitally programmable capacitor.

5. The MRT imaging method according to claim 3 , wherein the at least one modulation component is controlled via wire connectors including blocking inductors or via opto-coupling.

6. The MRT imaging method according to claim 2 , wherein the at least one modulation component comprises at least one tunable metamaterial placed between the at least one modulated RF receive coil and at least one of the object and at least one auxiliary modulation coil.

7. The MRT imaging method according to claim 6 , wherein the at least one modulation component is controlled via wire connectors including blocking inductors or via opto-coupling.

8. The MRT imaging method according to claim 1 , wherein:
the sensitivity profile of multiple RF receive coils is subjected to the temporal sensitivity profile modulation, and
the temporal profile modulation of the sensitivity profiles of different RF receive coils have different spatiotemporal sensitivity patterns.

9. The MRT imaging method according to claim 8 , wherein the temporal profile modulation of the sensitivity profiles of different RF receive coils have at least one of different magnitudes, frequencies, phases and modulation shapes.

10. The MRT imaging method according to claim 1 , wherein the temporal profile modulation has a periodic modulation shape.

11. The MRT imaging method according to claim 1 , wherein the temporal profile modulation has a non-periodic modulation shape.

12. The MRT imaging method according to claim 1 , wherein the RF receive coils have at least one of the features:
the RF receive coils are mechanically static coils;
the RF receive coils, to which the temporal sensitivity profile modulation is applied, are provided in a quantity from 2 to 100; and
the temporal profile modulation has a modulation frequency in a range from 100 Hz to 1 MHz.

13. The MRT imaging method according to claim 1 , wherein at least one of the RF receive coils is used as the at least one RF transmit coil.

14. The MRT imaging method according to claim 1 , wherein the step of reconstructing the object image m includes solving a linear equation system s=E m by a regularized optimization, wherein s includes the magnetic resonance signals and E is an encoding matrix being determined by the spatial encoding of the magnetic resonance signals and depending on time-varying modulation components.

15. A magnetic resonance imaging (MRI) device, comprising:
a magnetic resonance scanner being configured for accommodating an object to be imaged, including a static magnetic field device being configured for creating a static magnetic field, at least one RF transmit coil being configured for creating RF pulses, at least two RF receive coils, each having a self-resonance frequency and a spatially restricted sensitivity profile and being configured for acquiring magnetic resonance signals, and a gradient device being configured for creating magnetic field gradients;
a control device being configured for controlling the magnetic resonance scanner; and
a reconstruction device being configured for reconstructing an object image based on the acquired magnetic resonance signals, wherein:
the magnetic resonance scanner includes at least one modulation device, which is further adapted for subjecting the sensitivity profile of at least one of the RF receive coils to a temporal profile modulation during the step of acquiring the magnetic resonance signals, wherein the sensitivity profile of the at least one of the RF receive coils is temporally changed relative to the at least one of the RF receive coils as a function of time and the self-resonance frequency is set within a predetermined receive bandwidth of a constant resonance frequency value; and
the reconstruction device is configured for reconstructing the object image by utilizing the temporal profile modulation for obtaining spatial image information from the spatially encoded magnetic resonance signals.

16. The MRI device according to claim 15 , wherein the at least one modulation device comprises an electronically driven modulation component coupled with the at least one modulated RF receive coil.

17. The MRI device according to claim 16 , wherein the modulation component includes at least one of:
at least one tunable capacitor component of the at least one modulated RF receive coil;
at least one tunable metamaterial being placed between the at least one modulated RF receive coil and the object; and
at least one auxiliary modulation coil.

18. The MRI device according to claim 16 , further comprising wire connectors including blocking inductors or opto-couplers being arranged for controlling the at least one modulation device.

19. A magnetic resonance imaging (MRI) device, comprising:
a magnetic resonance scanner being configured for accommodating an object to be imaged, including a static magnetic field device being configured for creating a static magnetic field, at least one RF transmit coil being configured for creating RF pulses, at least two RF receive coils, each having a self-resonance frequency and a spatially restricted sensitivity profile and being configured for acquiring magnetic resonance signals, and a gradient device being configured for creating magnetic field gradients;
a control device being configured for controlling the

Assignees

• Max Planck Gesellschaft

Inventors

• Scheffler Klaus
• Bause Jonas
• Loktyushin Alexander
• Buckenmaier Kai

Classifications

• A61B5/055

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

• G01R33/5608

  Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels (image data processing or generation, in general G06T) · CPC title

• G01R33/3664

  Switching for purposes other than coil coupling or decoupling, e.g. switching between a phased array mode and a quadrature mode, switching between surface coil modes of different geometrical shapes, switching from a whole body reception coil to a local reception coil or switching for automatic coil selection in moving table MR or for changing the field-of-view (G01R33/3671 takes precedence) · CPC title

• G01R33/3642

  Mutual coupling or decoupling of multiple coils, e.g. decoupling of a receive coil from a transmission coil, or intentional coupling of RF coils, e.g. for RF magnetic field amplification · CPC title

• G01R33/3671 Primary

  involving modulation of the quality factor of the RF coil (G01R33/3642 takes precedence) · CPC title