Method for determining the position of a local antenna in an examination chamber of a magnetic resonance apparatus

• US 5,936,406 A
• Filed: 12/22/1997
• Issued: 08/10/1999
• Est. Priority Date: 12/20/1996
• Status: Expired due to Term

• Current Assignee: Siemens Healthcare GMBH (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Potthast, Andreas
• Primary Examiner(s): ARANA, LOUIS M
• Application Number:
  US08/995,317
• Time in Patent Office: 596 Days
• Field of Search: 324/318, 324/322, 324/300, 324/306, 324/307, 324/309, 324/314, 600/424, 600/423, 600/422, 600/421
• US Class Current: 324/318
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01B 7/004 for measuring coordinates of points
• CPC Class Codes: G01R 33/28 Details of apparatus provided for in groups G01R33/44 - G01R33/64

Abstract

In a method for determining the position of at least one local antenna in an examination chamber of a magnetic resonance apparatus, magnetic resonance signals emitted by a body arranged in the examination chamber are received, locus-encoded in at least one coordinate direction, by an antenna that has a homogeneous sensitivity distribution. From the received magnetic resonance signals, image data that are locus-resolved in the at least one coordinate direction are produced in the form of first intensity values. Magnetic resonance signals emitted by the body are received, locus-encoded in the coordinate direction, by the at least one local antenna. From the received magnetic resonance signals, image data that are locus-resolved in the at least one coordinate direction are produced in the form of second intensity values. From the second intensity values, normalized intensity values are formed by relating the second intensity values respectively to the first intensity values belonging to the same coordinate values. The normalized intensity values are searched for their largest value. A coordinate value that belongs to the largest normalized intensity value indicates the position of the at least one local antenna in the coordinate direction.

Claims

1. A method for determining a position of at least one local antenna in an examination chamber of a magnetic resonance apparatus, comprising the steps of:

receiving magnetic resonance signals, emitted by a subject disposed in an examination chamber using an antenna disposed in said examination chamber having a homogenous sensitivity distribution, and locus-encoding said magnetic resonance signals in at least one coordinate direction to obtain locus-encoded signals;

from said locus-encoded signals, obtaining image data, in a form of first intensity values, locus-resolved in said at least one coordinate direction;

receiving magnetic resonance signals emitted by said subject using at least one local antenna disposed in said examination chamber, and locus-encoding said magnetic resonance signals received by said at least one local antenna to obtain local antenna locus-encoded signals;

from said local antenna locus-encoded signals, obtaining image data, in a form of second intensity values, locus-resolved in said at least one coordinate direction, said second intensity values respectively having coordinate values associated therewith;

from said second intensity values, forming normalized intensity values by relating said second intensity values respectively to said first intensity values having the same respective coordinate values;

searching said normalized intensity values for a largest normalized intensity value, said first intensity values respectively having coordinate values associated therewith; and

selecting a coordinate value associated with said largest normalized intensity value as an identification of the position of said at least one local antenna in said at least one coordinate direction.

2. A method as claimed in claim 1 wherein said image data from which said first and second intensity values are formed comprise spatial projections of said subject.

3. A method as claimed in claim 1 wherein said image data from which said first and second intensity values are formed comprise tomography information.

4. A method as claimed in claim 1 for use with a plurality of local antennas in said examination chamber which simultaneously receive said magnetic resonance signals from said subject, and wherein a set of second intensity values is produced for each local antenna in said plurality of local antennas, with each set of second intensity values being allocated to the local antenna which produced the set of second intensity values.

5. A method as claimed in claim 1 comprising the additional step of spatially smoothing said first and second intensity values.

6. A method as claimed in claim 1 comprising the additional step of filtering said first and second intensity values.

7. A method as claimed in claim 1 comprising the additional steps of:

forming first raw intensity values from said locus-encoded signals obtained from said antenna having a homogenous sensitivity distribution, and normalizing said first raw intensity values to a noise power to produce said first intensity values; and

producing second raw intensity values from said local antenna locus-encoded signal, and normalizing said second raw intensity values to said noise power to produce said second intensity values.