METHOD FOR DETERMINING MOTION PARAMETERS OF AN OBJECT IN A MAGNETIC FIELD

• US 20110080167A1
• Filed: 09/16/2010
• Published: 04/07/2011
• Est. Priority Date: 10/02/2009
• Status: Active Grant

• Current Assignee: Siemens Healthineers AG (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: KOBER, TOBIAS, KANNENGISSER, STEPHAN, KRUEGER, GUNNAR
• Granted Patent: US 8,624,596 B2
• Time in Patent Office: Days
• US Class Current: 324/309
• CPC Class Codes: G01R 33/36 Electrical details, e.g. matching or coupling of the coil to the receiver
• CPC Class Codes: G01R 33/56509 due to motion, displacement or flow, e.g. gradient moment nulling G01R33/567 takes precedence
• CPC Class Codes: G01R 33/5673 Gating or triggering based on a physiological signal other than an MR signal, e.g. ECG gating or motion monitoring using optical systems for monitoring the motion of a fiducial marker

Abstract

A method for determining motion parameters of an object by way of at least one coil within a magnetic field adapted for a magnetic resonance based imaging device. Induced pulses are emitted on the coil in order to provide navigator signals that are finally measured in order to provide a spatial position of the object relative to the coil. At least one reference displacement of the object relative to the coil that is spatially and metrically predefined between two positions of the object is generated so that intensity changes of navigator signals at the coil are measured and recorded in a calibration map. Then, for determining each one of a sequence of further positions of an object in motion relatively to the coil, a navigator signal of the coil is measured and is compared to values of intensity changes from the calibration map in order to provide a corrected value of displacement of the object that is recovered from the calibration map and processed so that absolute values of motion parameters of the object are determined.

Claims

1. A method for determining motion parameters of an object by way of at least one coil within a magnetic field adapted for a magnetic resonance based imaging device, the method which comprises:

emitting induced pulses on the coil in order to provide navigator signals that are finally measured in order to provide a spatial position of the object relative to the coil;

generating at least one reference displacement of the object relative to the coil that is spatially and metrically predefined between two positions of the object, so that intensity changes of navigator signals at the coil are measured and recorded in a calibration map;

for determining each one of a sequence of further positions of an object in motion relative to the coil, measuring a navigator signal of the coil and comparing to values of intensity changes from the calibration map in order to provide a corrected value of displacement of the object that is recovered from the calibration map and processed, to thereby determine absolute values of motion parameters of the object.

2. The method according to claim 1, which comprises providing one part of the reference displacement over a translation of the object relative to the coil.

3. The method according to claim 2, which comprises translating the object relative to the coil along a straight motion step of substantially 2 mm.

4. The method according to claim 1, which comprises providing one part of the reference displacement over a rotation of the object relative to the coil.

5. The method according to claim 4, which comprises rotating the object relative to the coil about an angular motion step of substantially 2°

.

6. The method according to claim 1, which comprises recording a sensitivity profile of navigator signals of each coil by way of 2D-tables or 3D-tables in the calibration map according to measured intensity changes of the navigator signals and displacement values.