Multiple shot magnetic resonance imaging with ghosting stability correction

Patent metadata

Field	Value
Publication number	US-9989606-B2
Application number	US-201314419548-A
Country	US
Kind code	B2
Filing date	Jul 29, 2013
Priority date	Aug 8, 2012
Publication date	Jun 5, 2018
Grant date	Jun 5, 2018

Abstract

An image dataset comprises multiple shots of imaging data acquired using a magnetic resonance imaging (MRI) scanner ( 10 ). The signal power of each shot of the image dataset is normalized ( 24 ) to a reference signal power to generate a power normalized shot representation having total signal power matching the reference signal power. A reconstructed image is generated ( 26 ) from the power normalized shot representations. Odd/even phase correction ( 22 ) may also be performed on the image dataset. The phase correction, normalizing, and generating operations are suitably performed by an electronic data processing device ( 20 ).

First claim

Having described the preferred embodiments, the invention is now claimed to be:

1. An imaging method comprising:
acquiring a dynamic series of nominally identical dynamic image datasets, each image dataset comprising multiple shots of imaging data acquired using a magnetic resonance imaging (MRI) scanner;
normalizing the signal power of each shot of an image dataset of the image datasets to a reference signal power to generate a power-normalized shot representation having total signal power matching the reference signal power; and
generating a reconstructed image from the power-normalized shot representations;
wherein the normalizing and generating are performed by an electronic data processing device.

2. The imaging method of claim 1 , wherein the normalizing comprises:
computing an initial total signal power for each shot of the image dataset;
computing a scaling factor for each shot based on comparison of the initial total signal power computed for the shot and the reference signal power; and
scaling the signal power of each shot of the image dataset using the scaling factor for the shot to generate the power-normalized shot representation.

3. The imaging method of claim 2 , wherein
the reference signal power for each shot of the image dataset is computed as an average of the initial total signal power for the shot and the initial signal power for all corresponding shots of the other dynamic image data sets of the dynamic series.

4. The imaging method of claim 1 , wherein:
the normalizing includes:
zero-padding each shot to form a full dataset for the shot;
reconstructing the full dataset for each shot to generate a shot image for each shot,
computing an initial total signal power for each shot image by summing the squares of the modulus of all pixel values of the shot image,
computing a scaling factor for each shot image based on comparison of the initial total signal power computed for the shot image and a reference signal power;
scaling the pixel intensities of each shot image using the scaling factor for the shot image to generate the power-normalized representations as power-normalized shot images; and

the generating includes combining the power-normalized shot images to generate the reconstructed image.

5. The imaging method of claim 4 , wherein the normalizing further comprises:
computing the reference signal power for each shot image as an average of the initial total signal power for the shot image and the initial signal power for all corresponding shot images of the other image data sets of the dynamic series.

6. The imaging method of claim 1 , further comprising:
performing odd/even phase correction on the image dataset.

7. The imaging method of claim 6 , further comprising generating a corresponding time series of reconstructed images corresponding to the other image data sets, wherein:
the normalizing comprises normalizing corresponding shots of the image datasets that have the same phase encoding to the same reference signal power; and
the odd/even phase correction is performed before the normalizing.

8. The imaging method of claim 7 , wherein the acquiring the dynamic series of nominally identical dynamic image datasets comprises separately acquiring a dynamic series of nominally identical perturbed images and for a dynamic series of nominally identical unperturbed images to generate reconstructed perturbed images and reconstructed unperturbed images, respectively, and the method further comprises:
performing ( 28 ) functional magnetic resonance imaging (fMRI) analysis comparing the reconstructed perturbed images and the reconstructed unperturbed images.

9. The imaging method of claim 1 , wherein the image dataset comprises multiple Echo-Planar Imaging (EPI) shots of imaging data.

10. A non-transitory storage medium storing instructions executable by an electronic data processing device to perform a method operating on an image dataset comprising N shots of imaging data acquired using a magnetic resonance imaging (MRI) scanner where N is an integer greater than one, the method including (i) controlling acquisition of a dynamic series of nominally identical dynamic image datasets, including the image dataset comprising N shots; (ii) determining normalization of the signal power of each shot of the image dataset to a reference signal power to generate power-normalized shot representations of the shots of the image dataset and (iii) generating a reconstructed image from the power-normalized shot representations.

11. The non-transitory storage medium of claim 10 , wherein the normalizing operation (ii) comprises normalizing corresponding shots of all image datasets having the same phase encoding to the same reference signal power.

12. The non-transitory storage medium of claim 11 , wherein the reference signal power for normalizing corresponding shots of the image datasets having the same phase encoding is the average total signal power of the corresponding shots.

13. The non-transitory storage medium of claim 11 , wherein the normalizing operation (ii) is performed in image space operating on shot images wherein the k th shot image is generated by reconstructing the k th shot with zero-padding.

14. The non-transitory storage medium of claim 13 , wherein the generating operation (iii) comprises summing the shot images after performing the normalizing operation (ii).

15. The non-transitory storage medium of claim 10 , wherein the method further includes (iv) performing odd/even phase correction ( 22 ) on the image dataset.

16. The non-transitory storage medium of claim 10 , wherein the image dataset comprises N Echo-Planar Imaging (EPI) shots of imaging data.

17. An apparatus comprising:
an electronic data processing device; operating on a dynamic series of nominally identical image datasets, each image dataset comprising multiple shots of imaging data acquired using a magnetic resonance imaging (MRI) scanner, configured to perform a method including acquiring the image datasets, normalizing the signal power of each shot of the image data sets to a reference signal power and generating a reconstructed image from the power-normalized shots.

18. The apparatus of claim 17 , wherein the method performed by the electronic data processing device further includes performing odd/even phase correction on the image datasets.

19. The apparatus of claim 18 , wherein the odd/even phase correction is performed before normalizing the signal power of each shot.

20. The apparatus of claim 17 , wherein the normalizing includes normalizing corresponding shots of the nominally identical image datasets having the same phase encoding to the same reference signal power.

21. The apparatus of claim 20 , wherein the reference signal power to which corresponding shots of the nominally identical image datasets having the same phase encoding are normalized is the average total signal power of said corresponding shots.

Assignees

• Koninklijke Philips Nv

Inventors

• Foxall David Leslie

Classifications

• G01R33/5659

  caused by a distortion of the RF magnetic field, e.g. spatial inhomogeneities of the RF magnetic field (G01R33/56509, G01R33/56518, G01R33/56536 take precedence) · CPC title

• G01R33/4818

  MR characterised by data acquisition along a specific k-space trajectory or by the temporal order of k-space coverage, e.g. centric or segmented coverage of k-space · CPC title

• G01R33/4806 Primary

  Functional imaging of brain activation · CPC title

• G01R33/56554

  caused by acquiring plural, differently encoded echo signals after one RF excitation, e.g. correction for readout gradients of alternating polarity in EPI · CPC title

• G01R33/561

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