Nuclear magnetic resonance (NMR) fingerprinting tissue classification and image segmentation

Patent metadata

Field	Value
Publication number	US-10527698-B2
Application number	US-201816053873-A
Country	US
Kind code	B2
Filing date	Aug 3, 2018
Priority date	Apr 21, 2014
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

Apparatus, methods, and other embodiments associated with NMR fingerprinting are described. One example NMR apparatus includes an NMR logic that repetitively and variably samples a (k, t, E) space associated with an object to acquire a set of NMR signals that are associated with different points in the (k, t, E) space. Sampling is performed with t and/or E varying in a non-constant way. The NMR apparatus may also include a signal logic that produces an NMR signal evolution from the NMR signals, and a characterization logic that characterizes a resonant species in the object as a result of comparing acquired signals to reference signals. The NMR signal evolution may be assigned to a cluster based on the characterization of the resonant species. Cluster overlay maps may be produced simultaneously based, at least in part, on the clustering. The clusters may be associated with different tissue types.

First claim

What is claimed is:

1. A method, comprising:
accessing a set of known signal evolutions having corresponding magnetic resonance (MR) parameters;
accessing a nuclear magnetic resonance (NMR) signal acquired from a subject, where the acquired NMR signal is acquired from a volume that contains one or more resonant species that simultaneously produced individual NMR signals in response to magnetic resonance fingerprinting (MRF) excitation using a series of variable sequence blocks that include varied imaging parameters;
finding a selected entry in the set of known signal evolutions that matches the acquired NMR signal;
identifying two or more MR parameters for the volume based on the stored MR parameters associated with the selected entry, where the two or more MR parameters include:
a default or natural alignment to which spins align when placed in a main magnetic field (M 0 ) of an MRI system used to acquire the NMR signal; and
at least one of T1 relaxation associated with the resonance species, T2 relaxation associated with the resonant species, off-resonance relaxation associated with the resonant species, and diffusion weighted relaxation associated with the resonant species, T1 being spin-lattice relaxation, T2 being spin-spin relaxation;

analyzing the two or more MR parameters to define a plurality of clusters, each cluster associated with the two or more MR parameters; and
generating an image of the subject, wherein at least a portion of the volume is assigned to a cluster in the plurality of clusters within the image.

2. The method of claim 1 , where assigning the volume to the cluster includes generating a plot using the two or more MR parameters, wherein the cluster is assigned from the plurality of clusters within the plot using k-means clustering.

3. The method of claim 2 , wherein the k-means clustering partitions n observations into k clusters in the plot, wherein each observation belongs to the cluster with the nearest mean.

4. The method of claim 2 , comprising selecting k as a function of the number of expected material components in the volume.

5. The method of claim 1 , where the two MR parameters are T1 and T2.

6. The method of claim 1 , where the three MR parameters are T1, T2, and M0.

7. The method of claim 1 , where the two or more MR parameters include a diffusion coefficient associated with the volume, a spin density associated with the volume, a proton density associated with the volume, a magnetic field to which the volume is exposed, or a gradient field to which the volume was exposed.

8. The method of claim 1 , wherein generating the image includes producing and displaying one or more MR overlay, wherein the one or more MR overlay is produced from data associated with the cluster from the plurality of clusters.

9. The method of claim 8 , wherein generating the image includes producing and displaying one or more overlaid map, wherein the one or more overlaid map is produced by combining pixels associated with the one or more MR overlay and one or more MR map, wherein the one or more MR map is generated from a plurality of acquired NMR signals.

10. The method of claim 9 , wherein the one or more MR map comprises a T1 weighted map, a T2 weighted map, or a M 0 weighted map.

11. The method of claim 1 , where the volume is located in a human tissue.

12. The method of claim 4 , where the plurality of clusters includes a cluster associated with normal tissue and a cluster associated with abnormal tissue.

13. The method of claim 1 , where the volume is located in a human brain.

14. The method of claim 6 , where the plurality of clusters includes a cluster associated with grey matter, a cluster associated with white matter, and a cluster associated with cerebrospinal fluid (CSF).

15. The method of claim 7 , where the plurality of clusters includes a cluster associated with a tumor core, a cluster associated with tumor edema, and a cluster associated with an aggressive tumor growth region.

16. An apparatus, comprising:
a nuclear magnetic resonance (NMR) system that receives a first set of data from a magnetic resonance fingerprinting (MRF) apparatus that repetitively and variably samples a (k, t, E) space associated with an object to acquire a set of NMR signals, where members of the first set of data are associated with different points in the (k, t, E) space, where t is time and E includes a set of at least one of T1, T2, and one other parameter, T1 being spin-lattice relaxation, and T2 being spin-spin relaxation, and where one or more oft and E vary non-linearly, where the (k, t, E) space is produced as a function of applying RF energy to the object according to a magnetic resonance fingerprinting (MRF) approach;
a computer system that:
produces an NMR signal evolution from the first set of data;
selects from a collection of stored signal evolutions a stored signal evolution that most closely matches the NMR signal evolution;
characterizes the object based, at least in part, on two or more magnetic resonance (MR) parameters associated with the selected signal evolution and at least one of the two or more MR parameters including a default or natural alignment to which spins align when placed in a main magnetic field (M 0 ) of an MRI system used to acquire the NMR signal;
analyzes the two or more MR parameters to define a plurality of clusters, each cluster associated with the two or more MR parameters; and
assigns a location in the object that produced the first set of data to a cluster selected from the plurality of clusters, where the plurality of clusters represent Voronoi groups produced by a k-means analysis, and where the plurality of clusters segment an MR parameter data space associated with the object; and
a display to display the cluster.

17. The apparatus of claim 16 , wherein computer system assigns the location in the object to the cluster with an accuracy of at least 99.7%.

18. The apparatus of claim 16 , where the computer system assigns the location to the cluster by generating a plot using the two or more MR parameters and assigns the cluster from the plurality of clusters within the plot using k-means clustering, wherein the k-means clustering includes partitioning n observations into k clusters in which each observation belongs to the cluster with the nearest mean.

19. The apparatus of claim 16 , where the computer system is further configured to produce one or more MR overlay, wherein the one or more MR overlay is produced from data associated with the cluster from the plurality of clusters and wherein the display is configured to display the MR overlay.

20. The apparatus of claim 19 , where the computer system produces an MR image of the object based, at least in part, on the first set of data, and wherein the overlay logic further produces one or more overlaid map, wherein the one or more overlaid map is produced by combining pixels associated with the one or more MR overlay and one or more MR image, wherein the one or more MR image is generated from a plurality of acquired NMR signal and the display is configured to display the MR image and the one or more MR overlay to display the cluster.

Assignees

• Univ Case Western Reserve

Inventors

• Griswold Mark A
• Jiang Yun
• Ma Dan
• Deshmane Anagha
• Badve Chaitra
• Gulani Vikas
• Sunshine Jeffrey L

Classifications

• G01R33/50

  based on the determination of relaxation times {, e.g. T1 measurement by IR sequences; T2 measurement by multiple-echo sequences} · 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

• G01R33/4828

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