Position marker for use in an MRI apparatus

Patent metadata

Field	Value
Publication number	US-9638769-B2
Application number	US-201214233811-A
Country	US
Kind code	B2
Filing date	Jul 16, 2012
Priority date	Jul 21, 2011
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

A fiducial position marker ( 1 ) for use in a magnetic resonance (MR) imaging apparatus is disclosed for exciting and/or receiving MR signals in/from a local volume which at least substantially surrounds or adjoins the position marker, in order to determine and/or image from these MR signals the position of the position marker in an MR image of an examination object. Such a position marker ( 1 ) is especially used for determining and/or imaging a position of an interventional or non-interventional instrument to which the position marker may be attached, like a catheter, a surgical device, a biopsy needle, a pointer, a stent or another invasive or any non-invasive device in an MR image of an examination object. Further, a position marker system comprising such a position marker ( 1 ) and a circuit arrangement ( 5, 6, 6 a, 8 ) for driving the position marker ( 1 ) for exciting MR signals and/or for processing MR signals received by the position marker is disclosed.

First claim

The invention claimed is:

1. A system for use in a magnetic resonance MR imaging apparatus, the system comprising:
a position marker including at least first and second radio frequency (RF) coils having a direction of main radiation sensitivity oriented at least substantially orthogonal to each other for at least one of providing and receiving signals to and from a local volume in an examination object, the local volume at least partly surrounding or adjoining the position marker; and
a circuit arrangement connected with the position marker and configured to:
drive the at least first and second RF coils to transmit RF signals for exciting MR signals, and
select at least one of the MR signals having a signal strength or a signal to noise ratio exceeding a predetermined threshold value, and having a highest signal strength or a highest signal to noise ratio of the MR signals.

2. The system according to claim 1 ,
comprises a diversity switch connected to a control unit for comparing the signal strengths or the signal to noise ratios of the MR signals with each other or with the predetermined threshold value.

3. The system according to claim 1 ,
further comprising a third RF coil having a direction of main radiation sensitivity, the first, second, and third RF coils are arranged such that their respective directions of main radiation sensitivity are at least substantially orthogonal to each other.

4. The system according to claim 3 , wherein the first, second, and third RF coils are arranged on a common carrier.

5. The system according to claim 3 , further comprising an instrument for including the position marker.

6. The system according to claim 5 , wherein at least two RF coils of the first, second, and third RF coils comprise strip lines or wires applied onto a surface of the instrument or a part of the instrument.

7. The system according to claim 1 , wherein the first RF coil at least substantially encloses the second RF coil.

8. In a magnetic resonance (MR) imaging apparatus, a method for imaging a position of an instrument in an examination object in which a position marker including at least first and second radio frequency (RF) coils having a direction of main radiation sensitivity oriented at least substantially orthogonal to each other for at least one of providing and receiving signals to and from a local volume in the examination object, the local volume at least partly surrounding or adjoining the position marker, the method comprising:
driving the at least first and second RF coils to transmit RF signals for exciting MR signals;
selecting one of the MR signals having at least one of a signal strength and a signal to noise ratio exceeding a predetermined threshold value, and having at least one of the highest signal strength and the highest signal to noise ratio of the MR signals,
determining a position of the position marker based on the selected MR signal and imaging a related position indication in the MR image of the examination object,
comparing the signal strength and/or the signal to noise ratio of the selected MR signal with the related predetermined threshold value and
repeating the acts of selecting and determining if the at least one of the signal strength and the signal to noise ratio of the selected MR signal is below the predetermined threshold value.

9. The method according to claim 8 , further comprising an arranging the position marker at a remote location remote from a first location of a part of the instrument, wherein the remote and first locations have a known spatial relationship to one another, and wherein the determining comprises:
determining the position of the position marker based on the selected MR signal,
determining the position of the part of the instrument based on the determined position of the position marker and the known spatial relationship between the remote location of the position marker and the first location of the part of the instrument, and
imaging a related position indication in the MR image at the determined position of the part.

10. A computer readable storage medium for storing software program code, executable on a programmable microprocessor, for executing the method of claim 8 .

11. The method according to claim 10 , wherein the computer program code is configured to be downloaded to an MR imaging apparatus or one of its components which comprise a programmable microprocessor for conducting a method the MR imaging apparatus being connected to an computer that is external to the MR imaging apparatus.

Assignees

• Wirtz Daniel
• Leussler Christoph
• Krueger Sascha
• Koninklijke Philips Nv

Inventors

• Wirtz Daniel
• Leussler Christoph
• Krueger Sascha

Classifications

• G01R33/58

  Calibration of imaging systems, e.g. using test probes {, Phantoms; Calibration objects or fiducial markers such as active or passive RF coils surrounding an MR active material} · CPC title

• G01R33/28 Primary

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

• G01R33/287 Primary

  involving active visualization of interventional instruments, e.g. using active tracking RF coils or coils for intentionally creating magnetic field inhomogeneities · CPC title