Method for operating a magnetic resonance imaging apparatus ensuring coincidence of images obtained in different examinations with respectively different positions of a subject

• US 6,556,008 B2
• Filed: 06/14/2001
• Issued: 04/29/2003
• Est. Priority Date: 06/15/2000
• Status: Active Grant

• Current Assignee: Siemens Healthcare GMBH (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Thesen, Stefan
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): Vargas, Dixomara
• Application Number:
  US09/881,589
• Publication Number:
  US 20020005718A1
• Time in Patent Office: 684 Days
• Field of Search: 324/307, 324/309
• US Class Current: 324/307
• CPC Class Codes: A61B 5/0037 Performing a preliminary scan, e.g. a prescan for identifying a region of interest
• 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 33/5676 Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction

Abstract

In a method for the operation of a magnetic resonance apparatus, in a first examination of an examination subject, a first scout dataset of the examination subject is produced and with reference to which at least one first slice of an examination subject to be imaged is determined. A further scout dataset of the examination subject is produced in at least one further examination of the examination subject temporally following the first examination. A change in position between the first and the further scout dataset is identified, and at least one further slice of the examination subject to be imaged is defined according to the identified positional change, this at least one further slice exhibiting an identical positioning within the examination subject with respect to the first slice.

Claims

1. A method for operating a magnetic resonance apparatus, comprising the steps of:

in a first examination of a subject in a first position in a magnetic resonance apparatus, obtaining a first scout dataset, representing magnetic resonance signals from said subject, and subsequently defining a first slice of said subject based on said first scout dataset;

repositioning said subject to a second position, different from said first position, in said magnetic resonance apparatus and, in a further, subsequent examination of said subject in said magnetic resonance apparatus, obtaining a further scout dataset, representing magnetic resonance signals from said subject;

identifying a change in said position of said subject between said first scout dataset and said further scout dataset; and

defining a further slice of said examination subject dependent on said change in position, said further slice having an identical positioning within said subject as said first slice.

2. A method as claimed in claim 1 wherein the step of identifying said change in position comprises the steps of:

representing at least selected values of said first scout dataset in a first vector;

identifying values of said second scout dataset, respectively corresponding to said selected values of said first scout dataset, and representing said values of said second dataset in a second vector;

representing six parameters in a third vector, which allowed description of an arbitrary change in position in three-dimensional space;

forming a Jacobi functional matrix having a plurality of rows wherein each of said rows is comprised of partial derivatives of respective values of said first vector with respect to said six parameters, and forming a first order tailor expansion equation wherein a difference between said second vector and said first vector is set equal to a product of said Jacobi functional matrix and said third vector; and

solving said equation by an iterative technique to determine said six parameters.

3. A method as claimed in claim 1 comprising generating said first scout dataset as a three-dimensional image dataset and generating said further scout dataset as a three-dimensional image dataset.

4. A method as claimed in claim 1 comprising generating said first scout dataset with a fast magnetic resonance imaging technique and generating said further scout dataset with a fast magnetic resonance imaging technique.

5. A method as claimed in claim 4 comprising generating said first scout dataset with an echo planar technique and generating said further scout dataset with an echo planar technique.

6. A method as claimed in claim 1 comprising automatically positioning said subject in a magnetic resonance apparatus in said further examination using data stored from said first examination.