Method, computer readable medium and mri apparatus for performing phase-encode ghosting detection and mitigation in mri

Patent metadata

Field	Value
Publication number	US-2016148351-A1
Application number	US-201514948599-A
Country	US
Kind code	A1
Filing date	Nov 23, 2015
Priority date	Nov 21, 2014
Publication date	May 26, 2016
Grant date	—

Abstract

A method detects phase-encoding ghosting in a MR image of an object to be imaged and mitigates the corresponding artifact in the MR image. The method includes acquiring MRI raw data of the object by a MRI apparatus. The MRI apparatus has multiple receiver channels for acquiring the MRI raw data. An artifact map of at least one part of the object to be imaged is calculated from the MRI raw data, the artifact map is configured for highlighting artifact appearing in the MR image. An outlier mask representing detected phase-encoding artifact is created in the artifact map. The phase-encode ghosting in the MR image is mitigated by using the previously obtained artifact map and the outlier mask for obtaining an improved MR image.

First claim

1 . A computer-implemented method for detecting phase-encoding ghosting in a magnetic resonance (MR) image of an object to be imaged and mitigating corresponding artifact in the MR image, the computer-implemented method comprises the steps of:
acquiring magnetic resonance imaging (MRI) raw data of the object by means of a MRI apparatus, the MRI apparatus having multiple receiver channels for acquiring the MRI raw data; calculating an artifact map of at least one part of the object to be imaged from the MRI raw data; creating an outlier mask representing detected phase-encoding artifact in the artifact map; and mitigating phase-encode ghosting in the MR image by using a previously obtained artifact map and the outlier mask for obtaining an improved MR image.

2 . The computer-implemented method according to claim 1 , wherein the step of calculating the artifact map further comprises:
generating a duplicate k-space based on a fully-sampled centric-ordered and non-interleaved k-space (hereafter original k-space) that represents the MRI raw data; and subtracting the duplicate k-space with the original k-space for obtaining the artifact map.

3 . The computer-implemented method according to claim 2 , which further comprises generating the duplicate k-space using a generalized auto-calibrating partially parallel acquisition (GRAPPA) interpolation kernel.

4 . The computer-implemented method according to claim 1 , wherein the step of creating the outlier mask further includes applying a threshold t to separate high intensity ghosting from background noise in the artifact map.

5 . The computer-implemented method according to claim 4 , which further comprises applying a morphological erode operator for improving a detection of artifacts in the MR image.

6 . The computer-implemented method according to claim 1 , wherein the step of mitigating phase-encode ghosting in the MR image further comprises replacing each image voxel of an inverse Fourier transformed original k-space that is indicated as artifactual in the outlier mask by a corresponding image voxel of the duplicate for obtaining the improved MR image.

7 . A computer readable medium, comprising:
a memory storing non-transitory computer executable instructions for detecting phase-encoding ghosting in a magnetic resonance (MR) image of an object to be imaged and mitigating corresponding artifact in the MR image, the computer executable instructions comprises the steps of:
acquiring magnetic resonance imaging (MRI) raw data of the object by means of a MRI apparatus, the MRI apparatus having multiple receiver channels for acquiring the MRI raw data;
calculating an artifact map of at least one part of the object to be imaged from the MRI raw data;
creating an outlier mask representing detected phase-encoding artifact in the artifact map; and
mitigating phase-encode ghosting in the MR image by using a previously obtained artifact map and the outlier mask for obtaining an improved MR image.

8 . A magnetic resonance imaging apparatus for imaging an object, the magnetic resonance imaging apparatus being configured for performing the method steps of claim 1 in order to obtain an improved MR image of the object.

Assignees

• Siemens Ag

Inventors

• Hilbert Tom
• Krueger Gunnar

Classifications

• G06T2207/10088

  Magnetic resonance imaging [MRI] · CPC title

• G06T7/0012

  Biomedical image inspection · CPC title

• G06T5/002 Primary

  Physics · mapped topic

• G06T2207/10004

  Still image; Photographic image · CPC title

• G01R33/5608 Primary

  Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels (image data processing or generation, in general G06T) · CPC title