Method and apparatus for determining dephasing factors in magnetic resonance imaging and spectroscopy

Patent metadata

Field	Value
Publication number	US-2016334482-A1
Application number	US-201615154015-A
Country	US
Kind code	A1
Filing date	May 13, 2016
Priority date	May 13, 2015
Publication date	Nov 17, 2016
Grant date	—

Abstract

In a method and apparatus for determining time-dependent dephasing factors of at least one spectral component of at least two spectral components in a region of interest in an object under examination, measured data of the region of interest and acquired over time by a test measurement in a magnetic resonance scanner. The contribution of at least one of the at least two spectral components in the recorded measured data is determined. Dephasing factors of the at least one spectral component are determined on the basis of the contribution determined therefor in the recorded measured data over time. Dephasing factors determined in this way can be determined individually with relatively little effort and used in Dixon techniques.

First claim

We claim as our invention:

1 . A method for determining time-dependent dephasing factors of at least one spectral component among at least two spectral components acquired in a magnetic resonance (MR) examination of a region of interest in an examination subject, said method comprising:
operating an MR data acquisition scanner to execute a test measurement to acquire test measurement MR data over time of a region of interest of an examination subject situated in the MR data acquisition scanner, said test measurement MR data representing at least two spectral components; providing the test measurement MR data to a computer and, in said computer, automatically determining a contribution over time of at least one spectral component among said at least two spectral components represented in the test measurement MR data; in said computer, automatically determining dephasing factors of said at least one spectral component dependent on the contribution over time thereof in the test measurement MR data; and making an electronic signal available from said computer that represents the determined dephasing factors.

2 . A method as claimed in claim 1 comprising operating said MR data acquisition scanner to execute a STEAM (Stimulated Echo Acquisition Mode) spectroscopy sequence as said test measurement.

3 . A method as claimed in claim 1 wherein said region of interest comprises a volume, and comprising operating said MR data acquisition scanner to acquire said test measurement MR data in said test measurement voxel-by-voxel from said volume.

4 . A method as claimed in claim 1 comprising automatically determining said dephasing factors by determining the free induction decay (FID) in the test measurement MR data.

5 . A method as claimed in claim 1 comprising automatically determining said dephasing factors by determining respective contributions of said at least two spectral components in said test measurement MR data, and determining a contribution of another spectral component, among said at least two spectral components, represented in said test measurement MR data.

6 . A method as claimed in claim 1 comprising automatically determining said dephasing factors by executing at least one algorithm applied to the test measurement MR data, said at least one algorithm being selected from the group consisting of a fit algorithm, a mask operation algorithm, and extrapolation algorithm using a decay model, and an empirical correction algorithm.

7 . A method as claimed in claim 1 comprising automatically determining said dephasing factors by giving dephasing factors determined for a time t=0 a value of one, and scaling respective dephasing factors, with respect to said value of one, that occur following said time t=0.

8 . A method as claimed in claim 7 comprising scaling said respective dephasing factors with an intermediate scaling that gives dephasing factors determined at the time t=0 a value of one minus a percentage of signal contributions of the spectral component for which the dephasing factors are being determined, which is overlap by signal contributions of at least one other spectral component among said at least two spectral components.

9 . A method as claimed in claim 1 comprising automatically determining said dephasing factors as a correction with respect to an exponential decay of the spectral component for which the dephasing factors are being determined.

10 . A method as claimed in claim 1 comprising acquiring said test measurement MR data in said test measurement at respective measuring points separated by a time interval of 1 millisecond or less.

11 . A method for determining time-dependent dephasing factors of at least one spectral component among at least two spectral components acquired in a magnetic resonance (MR) examination of a region of interest in an examination subject, said method comprising:
operating an MR data acquisition scanner to execute a Dixon technique to acquire MR data over time of a region of interest of an examination subject situated in the MR data acquisition scanner, said MR data representing at least two spectral components; providing the MR data to a computer and, in said computer, automatically determining a contribution over time of at least one spectral component among said at least two spectral components represented in the MR data; in said computer, automatically determining dephasing factors of said at least one spectral component dependent on the contribution over time thereof in the MR data; and making an electronic signal available from said computer that represents the determined dephasing factors.

12 . A magnetic resonance (MR) apparatus comprising:
an MR data acquisition scanner; a computer configured to operate said MR data acquisition scanner to execute an MR measurement to acquire measurement MR data over time of a region of interest of an examination subject situated in the MR data acquisition scanner, said measurement MR data representing at least two spectral components; said computer being configured to automatically determine a contribution over time of at least one spectral component among said at least two spectral components represented in the measurement MR data; said computer being configured to automatically determine dephasing factors of said at least one spectral component dependent on the contribution over time thereof in the measurement MR data; and said computer being configured to make an electronic signal available from said computer that represents the determined dephasing factors.

13 . A non-transitory, computer-readable data storage medium encoded with programming instructions, said storage medium being loaded into a control and evaluation computer of a magnetic resonance (MR) apparatus that comprises an MR data acquisition scanner, said programming instructions causing said control and evaluation computer to:
operate the MR data acquisition scanner to execute an MR measurement to acquire measurement MR data over time of a region of interest of an examination subject situated in the MR data acquisition scanner, said measurement MR data representing at least two spectral components; automatically determine a contribution over time of at least one spectral component among said at least two spectral components represented in the test measurement MR data; automatically determine dephasing factors of said at least one spectral component dependent on the contribution over time thereof in the measurement MR data; and make an electronic signal available from said control and evaluation computer that represents the determined dephasing factors.

Assignees

• Siemens Healthcare Gmbh

Inventors

• Kannengiesser Stephan
• Nickel Marcel Dominik

Classifications

• G01R33/46 Primary

  NMR spectroscopy · CPC title

• G01R33/4625

  Processing of acquired signals, e.g. elimination of phase errors, baseline fitting, chemometric analysis · CPC title

• G01R33/4828

  Resolving the MR signals of different chemical species, e.g. water-fat imaging · CPC title

• G01R33/561

  by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences · CPC title