Method and local coil system for producing a magnetic resonance radio frequency field

Patent metadata

Field	Value
Publication number	US-10345399-B2
Application number	US-201414245181-A
Country	US
Kind code	B2
Filing date	Apr 4, 2014
Priority date	Apr 5, 2013
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A magnetic resonance RF field is produced in a magnetic resonance imaging system that includes a main magnetic field apparatus and an object-bearing table movable relative to the main magnetic field apparatus and on which a local coil system is arranged. The local coil system includes a plurality of transmission elements. A current location of the object-bearing table relative to the main magnetic field apparatus is established. The transmission elements are automatically connected based on the current location of the object-bearing table.

First claim

The invention claimed is:

1. A method for producing a magnetic resonance RF field in a magnetic resonance imaging system, the magnetic resonance imaging system comprising a main magnetic field apparatus and an object-bearing table, wherein the object-bearing table is movable relative to the main magnetic field apparatus and wherein a local coil system is arranged on, in, or on and in the object-bearing table, the local coil system comprising a plurality of local coils and a plurality of transmission elements, each local coil of the plurality of local coils including a portion of transmission elements of the plurality of transmission elements, wherein the transmission elements are configured to transmit the magnetic resonance RF field, the method comprising:
establishing a current location of the object-bearing table relative to the main magnetic field apparatus; and
automatically activating a set of transmission elements of the plurality of transmission elements based on the current location of the object-bearing table and a size of a patient target volume segment of a patient target volume in a measurement region at the current location of the object-bearing table, the patient target volume segment being an intersection between the patient target volume and the measurement region, the size of the patient target volume segment comprising a height extent and a transverse extent, wherein the height extent is a distance in a vertical direction relative to the object-bearing table and the transverse extent is a distance in a horizontal direction perpendicular to the height extent in a plane parallel to the object-bearing table.

2. The method of claim 1 , wherein each activated transmission element of the set of transmission elements is a component of a different local coil of the plurality of local coils.

3. The method of claim 1 , wherein automatically activating a set of transmission elements comprises activating individual transmission elements of the respective portion of transmission elements based on a position of a defined region of the object-bearing table relative to the measurement region, and
wherein a position of the measurement region is constant relative to the main magnetic field apparatus.

4. The method of claim 3 , wherein automatically activating a set of transmission elements comprises activating at least one transmission element of the plurality of transmission elements depending on a position relative to the target volume segment of the patient target volume of a patient in the measurement region.

5. The method of claim 4 , wherein automatically activating a set of transmission elements comprises connecting the at least one transmission element depending on the height extent or the transverse extent of the patient target volume in the measurement region.

6. The method of claim 4 , wherein automatically activating a set of transmission elements comprises connecting the at least one transmission element depending on a pre-measurement of the patient.

7. The method of claim 4 , wherein automatically activating a set of transmission elements comprises connecting the at least one transmission element depending on previously defined RF exposure values.

8. The method of claim 4 , further comprising:
determining the patient target volume of the patient;
establishing a position of the patient target volume relative to a position of the object-bearing table in a pre-measurement of the patient;
establishing a field distribution of a magnetic resonance RF field produced at least in the patient target volume in the pre-measurement by a number of transmission elements of the local coil system;
positioning the target volume segment of the patient target volume in the measurement region based on the pre-measurement;
selecting at least one transmission element of the plurality of transmission elements disposed with respect to the target volume segment in accordance with a predetermined criterion; and
actuating the at least one transmission element to emit the magnetic resonance RF field in the direction of the target volume segment disposed in the measurement region,
wherein the at least one transmission element is actuated based on the field distribution established during the pre-measurement such that a current field distribution of the magnetic resonance RF field produced by the at least one transmission element corresponds with a predetermined target distribution in the target volume segment.

9. A magnetic resonance imaging system comprising a main magnetic field apparatus;
an object-bearing table movable relative to the main magnetic field apparatus;
a local coil system arranged on, in, or on and in the object-bearing table, the local coil system comprising a plurality of local coils, each local coil of the plurality of local coils including transmission elements to produce a magnetic resonance RF field;
a location establishment unit to establish a current location of the object-bearing table relative to the main magnetic field apparatus; and
a switching apparatus connected to the location establishment unit and configured to connect a set of the transmission elements based on the current location of the object-bearing table and a size of a patient target volume segment of a patient target volume in a measurement region at the current location of the object-bearing table, the patient target volume segment being an intersection between the patient target volume and the measurement region, the size of the patient target volume segment comprising a height extent and a transverse extent, wherein the height extent is a distance in a vertical direction relative to the object-bearing table and the transverse extent is a distance in a horizontal direction perpendicular to the height extent in a plane parallel to the object-bearing table.

10. The magnetic resonance imaging system of claim 9 , further comprising:
a position detection unit to detect a position of the patient target volume relative to a location of the object-bearing table;
a field distribution establishment unit to establish a field distribution of a magnetic resonance RF field produced by a number of transmission elements of the local coil system in the patient;
a positioning unit to position the target volume segment of the patient target volume in the measurement region;
a selection unit to select at least one transmission element of the transmission elements; and
a control system to actuate the at least one transmission element to emit a magnetic resonance RF field in the direction of the target volume segment disposed in the measurement region.

11. A computer program product to implement a method of producing a magnetic resonance RF field in a magnetic resonance imaging system, the magnetic resonance imaging system comprising a main magnetic field apparatus and an object-bearing table, wherein the object-bearing table is movable relative to the main magnetic field apparatus and wherein a local coil system is arranged on, in, or on and in the object-bearing table, the local coil system comprising a plurality of local coils and a plurality of transmission elements, each local coil of the plurality of local coils including a portion of transmission elements of the plurality of transmission elements, wherein the transmission elements are configured to transmit the magnetic resonance RF field, the computer program product comprising one or more non-transitory computer-readable storage media having stored thereon instructions executable by one or more processors of a computing system configured as a programmable control apparatus, an image production unit, or both, to cause the computing system to perform operations comprising:

Assignees

• Fautz Hans Peter
• Renz Wolfgang
• Schmitt Franz
• Siemens Ag

Inventors

• Fautz Hans-Peter
• Renz Wolfgang
• Schmitt Franz

Classifications

• 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

• G01R33/28 Primary

  Details of apparatus provided for in groups G01R33/44 - G01R33/64 · CPC title

• G01R33/3415

  comprising arrays of sub-coils {, i.e. phased-array coils with flexible receiver channels} · CPC title

• G01R33/34046 Primary

  Volume type coils, e.g. bird-cage coils; Quadrature bird-cage coils; Circularly polarised coils · CPC title