Magnetic resonance imaging apparatus

Patent metadata

Field	Value
Publication number	US-9804246-B2
Application number	US-201113010007-A
Country	US
Kind code	B2
Filing date	Jan 20, 2011
Priority date	Jan 20, 2010
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

According to one embodiment, an image processing apparatus includes a storage unit configured to store data of a series of slice images associated with a region including a target region of an object, a first rest period specifying unit configured to specify a first rest period based on a change between images of the series of slice images, and a second rest period specifying unit configured to specify a second rest period shorter than the first rest period by tracking the target region on a plurality of slice images corresponding to the specified first rest period or a rest period enlarged from the first rest period.

First claim

What is claimed is:

1. A magnetic resonance (MR) imaging apparatus comprising:
gradient magnetic field generators, at least one radio frequency (RF) coil coupled to an imaging volume, transmitting and receiving units for the at least one RF coil, and a computer system connected to control said gradient magnetic field generators and said RF coil to acquire and process MR signals from patient tissue disposed in said imaging volume, said computer system being configured to
repeat an MR imaging scan on an overall heart of a patient,
detect displacement of a patient diaphragm due to respiratory movement of the patient by executing an MR probe scan immediately before each of the MR imaging scans,
displace an imaging range for each of the MR imaging scans based on the detected displacement of the diaphragm,
before each said MR probe scan, generate a series of slice images by executing a preliminary MR scan which repeatedly images a region including the heart using electrocardiogram (ECG) gating,
specify, for the series of slice images, a first rest period in which a variation in position of a coronary artery falls within a predetermined range in a cardiac cycle, based on a change in the MR image of the overall heart,
specify a second rest period of the coronary artery in the cardiac cycle, after specifying the first rest period, by tracking movement of the coronary artery only within a local range including the coronary artery for a plurality of slice images of the series of slice images, wherein the plurality of slice images corresponds to the first rest period or a rest period enlarged from the first rest period, and the second rest period is included in the first rest period or the rest period enlarged from the first rest period, and
reconstruct an image based on MR data acquired using said MR imaging scan in the second rest period.

2. The apparatus according to claim 1 , wherein the computer system is further configured to remove a still portion from the series of slice images.

3. The apparatus according to claim 2 , wherein the computer system is further configured to Fourier-transform a temporal change in pixel value of each pixel of the series of slice images and remove a pixel exhibiting a frequency not more than a predetermined frequency as the still portion.

4. The apparatus according to claim 2 , wherein the computer system is further configured to determine, based on a spatial change in difference between a maximum pixel value and a minimum pixel value in a predetermined period, whether each pixel of the series of slice images is the still portion.

5. The apparatus according to claim 1 , wherein the computer system is further configured to specify the first rest period based on a difference result between adjacent frames of the series of slice images.

6. The apparatus according to claim 1 , wherein the computer system is further configured to specify the first rest period based on a correlation coefficient between adjacent frames of the series of slice images.

7. The apparatus according to claim 5 , wherein the computer system is further configured to calculate the difference result only within a local region including the overall heart.

8. The apparatus according to claim 6 , wherein the computer system is further configured to calculate the correlation coefficient only within a local region including the overall heart.

9. The apparatus according to claim 1 , wherein the computer system is further configured to enlarge the specified first rest period forward and backward by a predetermined time width.

10. The apparatus according to claim 1 , wherein the computer system is further configured to set the local range on each of a left coronary artery and a right coronary artery.

11. The apparatus according to claim 10 , wherein the computer system is further configured to set a local range for the left coronary artery and a local range for the right coronary artery by using templates in which a local range for the left coronary artery and a local range for the right coronary artery on slices traversing the heart are respectively set at initial positions.

12. The apparatus according to claim 10 , wherein the computer system is further configured to specify the second rest period based on a time curve associated with an index indicating a variation in position of the left coronary artery and a time curve associated with an index indicating a variation in position of the right coronary artery.

13. The apparatus according to claim 10 , wherein the computer system is further configured to specify, as the second rest period, a period in which a second rest period candidate obtained from a time curve associated with an index indicating a variation in position of the left coronary artery overlaps a second rest period candidate obtained from a time curve associated with an index indicating a variation in position of the right coronary artery.

14. The apparatus according to claim 10 , wherein the computer system is further configured to specify, as the second rest period, one of a second rest period candidate obtained from a time curve associated with an index indicating a variation in position of the left coronary artery and a second rest period candidate obtained from a time curve associated with an index indicating a variation in position of the right coronary artery.

15. The apparatus according to claim 10 , wherein the computer system is further configured to determine the second rest period corresponding to each of a systolic phase and diastolic phase of the heart.

16. The apparatus according to claim 1 , wherein the computer system is further configured to identify a moving position of the coronary artery from a correlation coefficient of a pixel distribution in the local range between adjacent frames of the slice images.

17. A magnetic resonance (MR) imaging apparatus comprising:
gradient magnetic field generators, at least one radio frequency (RF) coil coupled to an imaging volume, transmitting and receiving units for the at least one RF coil, and a computer system connected to control said gradient magnetic field generators and said RF coil to acquire and process MR signals from patient tissue disposed in said imaging volume, said computer system being configured to
repeat an MR imaging scan on a first organ of a patient,
detect displacement of a second organ of the patient by executing a MR probe scan immediately before each of the MR imaging scans,
displace an imaging range for each of the MR imaging scans based on the detected displacement of the second organ,
before each said MR probe scan, generate a series of slice images by executing a preliminary MR scan which repeatedly images a region including the first organ using electrocardiogram (ECG) gating,
specify a first rest period in which a variation in position of the second organ falls within a predetermined range in a cardiac cycle, by using the series of slice images,
specify, after specifying the first rest period, a second rest period of the second organ by tracking movement of the second organ only within a local range including the second organ for a plurality of slice images of the series of slice images, wherein the plurality of slice images corresponds to the first rest period or a rest period enlarged from the first rest period, and the second rest period is included in the first rest period or the rest period enlarged from the first rest period, and
reconstruct an image based on MR data acquired using said MR imaging scan in the second rest period.

18. An image processing apparatus c

Assignees

• Kuhara Shigehide
• Ninomiya Ayako
• Toshiba Medical Sys Corp

Inventors

• Kuhara Shigehide
• Ninomiya Ayako

Classifications

• G06T2207/30048

  Heart; Cardiac · CPC title

• G06T2207/20016

  Hierarchical, coarse-to-fine, multiscale or multiresolution image processing; Pyramid transform · CPC title

• G06T2207/10088

  Magnetic resonance imaging [MRI] · CPC title

• G06T7/20

  Analysis of motion (motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51) · CPC title

• G01R33/5676

  Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction · CPC title