Sub voxel resolution magnetic resonance fingerprinting imaging

Patent metadata

Field	Value
Publication number	US-11092659-B2
Application number	US-201816498555-A
Country	US
Kind code	B2
Filing date	Mar 30, 2018
Priority date	Mar 30, 2017
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

A magnetic resonance imaging (MRI) system (100) includes a memory (134) for storing machine executable instructions (140) and magnetic resonance fingerprinting (MRF) pulse sequence commands (142) which cause the MRI system to acquire MRF magnetic resonance data (144) according to an MRF protocol. The pulse sequence commands are configured for acquiring the MRF magnetic resonance data in two-dimensional slices (410, 412, 414, 416, 418, 420), having a slice selection direction. A train of pulse sequence repetitions includes a sampling event where the MRF data is repeatedly sampled. Execution of the machine executable instructions causes a processor to control the MRI system to: acquire (200) the MRF magnetic resonance data; construct (202) a series (148) of at least one magnetic resonance parameter value for each voxel of the two dimensional slices; and calculate (204) a composition (502, 504, 506, 508) of each of a set of predetermined substances within two or more sub-voxels (306, 308) for each voxel of the two dimensional slices using a sub-voxel magnetic resonance fingerprinting dictionary (150) for each of the two or more sub-voxels and the series of the at least one magnetic resonance parameter value. Each voxel in the slice selection direction is divided into two or more sub-voxels.

First claim

The invention claimed is:

1. A magnetic resonance imaging system comprising:
a memory for storing machine executable instructions and magnetic resonance fingerprinting (MRF) pulse sequence commands, wherein the MRF pulse sequence commands cause the magnetic resonance imaging system to acquire MRF magnetic resonance data according to an MRF protocol, wherein the pulse sequence commands are configured for acquiring the MRF magnetic resonance data in two dimensional slices, wherein the two dimensional slices have a slice selection direction, wherein the pulse sequence commands comprises a train of pulse sequence repetitions, wherein the train of pulse sequence repetitions comprises a sampling event where the MRF magnetic resonance data is repeatedly sampled;
a processor for controlling the magnetic resonance imaging system, wherein execution of the machine executable instructions causes the processor to:
acquire the MRF magnetic resonance data by controlling the magnetic resonance imaging system with the MRF pulse sequence commands; and
construct a series of at least one magnetic resonance parameter value for each voxel of the two-dimensional slices using the MRF magnetic resonance data, wherein each of the series corresponds to the sampling event of each pulse sequence repetition; and
calculate a composition of each of a set of predetermined substances within two or more sub-voxels of each voxel of the two dimensional slices using a sub-voxel magnetic resonance fingerprinting dictionary for each of the two or more sub-voxels and the series of the at least one magnetic resonance parameter value, wherein sub-voxels divide each voxel in the slice selection direction, wherein each sub-voxel magnetic resonance fingerprinting dictionary comprises separate fingerprints calculated by integrating over distinct parts of an excitation pulse profile for each of the two or more sub-voxels, wherein the excitation pulse profile is a flip angle distribution and a phase angle distribution, wherein the composition within the two or more sub-voxels is calculated by determining the contribution from each of the two or more sub-voxels using linear optimization wherein any one of the following:
the excitation pulse profile has a symmetric flip angle distribution and has an anti-symmetric phase distribution;
the pulse sequence commands specify a radiofrequency pulse, wherein the radio-frequency pulse is asymmetric; and
combinations thereof.

2. A non-transitory computer-readable program product comprising machine executable instructions for execution by a processor controlling a magnetic resonance imaging system, wherein execution of the machine executable instructions causes the processor to:
acquire magnetic resonance fingerprinting (MRF) data by controlling the magnetic resonance imaging system with MRF pulse sequence commands, wherein the MRF pulse sequence commands cause the magnetic resonance imaging system to acquire the MRF data according to a magnetic resonance fingerprinting protocol, wherein the pulse sequence commands are configured for acquiring the MRF data in two dimensional slices, wherein the two dimensional slices have a slice selection direction, wherein the pulse sequence commands comprises a train of pulse sequence repetitions, wherein the train of pulse sequence repetitions comprises a sampling event where the MRF data is repeatedly sampled; and
construct a series at least one magnetic resonance parameter value for each voxel of the two-dimensional slices using the MRF data, wherein each of the series corresponds to the sampling event of each pulse sequence repetition; and
calculate a composition of each of a set of predetermined substances within two or more sub-voxels for each voxel of the two-dimensional slices using a sub-voxel MRF dictionary for each of the two or more sub-voxels and the series of the at least one magnetic resonance parameter value, wherein the sub-voxels divide each voxel in the slice selection direction, wherein the sub-voxel MRF dictionary comprises separate fingerprints calculated by integrating over distinct parts of an excitation pulse profile for each of the two or more sub-voxels, wherein the composition within the two or more sub-voxels is calculated by determining the contribution from each of the two or more sub-voxels using linear optimization; and
wherein any one of the following:
the excitation pulse profile has a symmetric flip angle distribution and has an anti-symmetric phase distribution,
the pulse sequence commands specify a radio-frequency pulse, wherein the radio-frequency pulse is asymmetric, and
combinations thereof.

3. A method of operating a magnetic resonance imaging system, wherein the method comprises:
acquiring magnetic resonance fingerprinting (MRF) magnetic resonance data by controlling the magnetic resonance imaging system with MRF pulse sequence commands, wherein the MRF pulse sequence commands cause the magnetic resonance imaging system to acquire the MRF magnetic resonance data according to a magnetic resonance fingerprinting protocol, wherein the pulse sequence commands are configured for acquiring the MRF magnetic resonance data in two dimensional slices, wherein the two dimensional slices have a slice selection direction, wherein the pulse sequence commands comprises a train of pulse sequence repetitions, wherein the train of pulse sequence repetitions comprises a sampling event where the MRF magnetic resonance data is repeatedly sampled; and
constructing a series of at least one magnetic resonance parameter value for each voxel of the two-dimensional slices using the MRF magnetic resonance data, wherein each of the series corresponds to the sampling event of each pulse sequence repetition; and
calculating a composition of each of a set of predetermined substances within two or more sub-voxels for each voxel of the two dimensional slices using a sub-voxel magnetic resonance fingerprinting dictionary for each of the two or more sub-voxels and the series of the at least one magnetic resonance parameter value, wherein sub-voxels divide each voxel in the slice selection direction, wherein the sub-voxel magnetic resonance fingerprinting dictionary comprises separate fingerprints calculated by integrating over distinct parts of an excitation pulse profile for each of the two or more sub-voxels, wherein the composition within the two or more sub-voxels is calculated by determining the contribution from each of the two or more sub-voxels using linear optimization wherein any one of the following:
the excitation pulse profile has a symmetric flip angle distribution and has an anti-symmetric phase distribution;
the pulse sequence commands specify a radio-frequency pulse, wherein the radio-frequency pulse is asymmetric; and
combinations thereof.

4. The magnetic resonance imaging system of claim 1 , wherein each of the train of pulse sequence repetitions comprises a radio frequency pulse chosen from a predetermined distribution of radio frequency pulses, wherein the predetermined distribution of radio frequency pulses are configured to cause magnetic spins to rotate to a distribution of flip angles, wherein the sub-voxel magnetic resonance fingerprinting dictionary for each of the two or more sub-voxels is dependent upon the predetermined distribution of flip angles.

5. The magnetic resonance imaging system of claim 4 , wherein the distribution of flip angles varies by any one of the following: within a range of 30 degrees, within a range of 70 degrees, within a range of 110 degrees, within a range of 150 degrees, and within a range of 180 degrees.

6. The magnetic resonance imaging system of claim 1 , wherein execution of the machine executable instructions causes the processor to calculate a composition image descriptive of a composition of

Assignees

• Koninklijke Philips Nv

Inventors

• Amthor Thomas Erik
• Doneva Mariya Ivanova
• Sommer Karsten
• Koken Peter

Classifications

• A61B5/055

  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging · CPC title

• 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

• G01R33/4828

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

• G01R33/4835 Primary

  of multiple slices · CPC title

• G01R33/246

  Spatial mapping of the RF magnetic field B1 · CPC title