Magnetic resonance imaging device and magnetic resonance imaging method

Patent metadata

Field	Value
Publication number	US-9713449-B2
Application number	US-201214008868-A
Country	US
Kind code	B2
Filing date	Feb 29, 2012
Priority date	Apr 1, 2011
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

The present invention allows a subject to hold breathing at any position, and it is confirmed whether or not the breath holding is really performed in the middle of imaging to reflect its result to the imaging sequence. An image 411 showing a temporal change of respiratory displacement of the subject is generated from nuclear magnetic resonance signals acquired by executing the navigator sequence 231 repeatedly on the subject. Upon accepting from an operator a confirming operation that the operator viewing the image confirms a state of breath holding, the navigator sequence 231 is switched to the real imaging sequence 211 and the real imaging sequence is executed for a predetermined period of time. Those operations are repeated more than once. It is also possible to determine whether or not the breath holding during the imaging sequence is successfully performed, based on a difference in respiratory displacement between immediately before and immediately after the real imaging sequence.

First claim

What is claimed is:

1. A magnetic resonance imaging device comprising,
a static magnetic field generator which generates a static magnetic field in imaging space where a subject is placed,
a gradient magnetic field generator which applies a gradient magnetic field to the imaging space,
a radio frequency emitter which irradiates the imaging space with an RF magnetic field pulse,
a receiver which receives a nuclear magnetic resonance signal generated from the subject, and
a controller which controls the gradient magnetic field generator, the radio frequency emitter, and the receiver, so as to execute predetermined pulse sequences, wherein the pulse sequences includes a navigator sequence for detecting respiratory displacement of the subject, and a real imaging sequence for taking an image of the subject,
the controller executing one or more programs of instructions to configure the controller to comprise:
a respiratory movement image generator which generates and displays an image showing a temporal change of respiratory displacement based on nuclear magnetic resonance signals acquired by executing the navigator sequence,
a breath-hold confirmation accepting part which accepts a confirming operation from a operator when the operator views the image displayed by the respiratory movement image generator and confirms a state of breath holding,
a real imaging execution part which executes the real imaging sequence at the timing when the breath-hold confirmation accepting part accepts the confirming operation, and
a retake accepting part which obtains and displays a difference in respiratory displacement between, for each real imaging sequence that is repeated more than once, immediately before and after the real imaging sequence, and accepts from the operator an instruction whether or not a retake is performed as to the real imaging sequence for the present time, and upon accepting the instruction for the retake, the retake accepting part sets the imaging position of the real imaging sequence for the present time as the imaging position of the next real imaging sequence.

2. The magnetic resonance imaging device according to claim 1 , wherein,
the controller allows operations by the respiratory movement image generator, the breath-hold confirmation accepting part, and the real imaging execution part, to be repeated more than once in this order, respectively, until all the nuclear magnetic resonance signals necessary for reconstructing an image of a predetermined imaging area are obtained by the real imaging sequence.

3. The magnetic resonance imaging device according to claim 2 , wherein,
the controller obtains a difference in respiratory displacement acquired immediately before each of the real imaging sequences performed repeatedly more than once, and the controller adjusts an imaging position of the second and subsequent real imaging sequences, according to the difference.

4. The magnetic resonance imaging device according to claim 2 , wherein the controller determines whether or not the breath holding is performed successfully during the real imaging sequence for said each real imaging sequence performed repeatedly more than once, and upon determining a failure of the breath holding, the imaging position of the real imaging sequence for the present time is set as the imaging position of the real imaging sequence for the next time.

5. The magnetic resonance imaging device according to claim 4 , wherein when the controller determines that the difference in respiratory displacement between immediately before and immediately after the real imaging sequence is larger than a predetermined threshold, the controller determines the failure of the breath holding during the real imaging sequence.

6. A magnetic resonance imaging method, in a magnetic resonance imaging apparatus including a controller executing one or more programs of instructions to control the magnetic resonance imaging apparatus to perform the magnetic resonance imaging method, comprising a first step and a second step, both steps of which are repeated more than once until obtaining all the nuclear magnetic resonance signals necessary for reconstructing an image of a predetermined imaging area by a real imaging sequence, wherein
the first step generates and displays an image showing a temporal change of respiratory displacement of a subject based on the nuclear magnetic resonance signals acquired by executing a navigator sequence repeatedly on the subject, and
the second step switches from the navigator sequence to the real imaging sequence to perform the real imaging sequence for a predetermined period of time, upon accepting from an operator a confirming operation that the operator views the image and confirms a state of breath holding, and
wherein the magnetic resonance imaging method further comprises:
obtaining and displaying a difference in respiratory displacement between, for each real imaging sequence repeated more than once, immediately before and after the real imaging sequence, and
accepting from the operator an instruction whether or not a retake is performed as to the real imaging sequence for the present time, and upon accepting the instruction for the retake, setting the imaging position of the real imaging sequence for the present time as the imaging position of the next real imaging sequence.

7. The magnetic resonance imaging method according to claim 6 , the second step determines whether or not the breath holding is successfully performed during the real imaging sequence based on a difference in respiratory displacement between immediately before and immediately after the real imaging sequence, and upon determining a failure of the breath holding, second step performs a retake by the next real imaging sequence at the imaging position of the real imaging sequence for the present time.

8. The magnetic resonance imaging device according to claim 3 , wherein the controller determines whether or not the breath holding is performed successfully during the real imaging sequence for said each real imaging sequence performed repeatedly more than once, and upon determining a failure of the breath holding, the imaging position of the real imaging sequence for the present time is set as the imaging position of the real imaging sequence for the next time.

9. The magnetic resonance imaging device according to claim 8 , wherein when the controller determines that the difference in respiratory displacement between immediately before and immediately after the real imaging sequence is larger than a predetermined threshold, the controller determines the failure of the breath holding during the real imaging sequence.

Assignees

• Goto Tomohiro
• Hirai Kosuke
• Hitachi Ltd

Inventors

• Goto Tomohiro
• Hirai Kosuke

Classifications

• A61B5/055

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

• G01R33/56509

  due to motion, displacement or flow, e.g. gradient moment nulling (G01R33/567 takes precedence) · CPC title

• A61B5/0037 Primary

  Performing a preliminary scan, e.g. a prescan for identifying a region of interest · 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

• A61B5/1128

  using image analysis (A61B5/1127 takes precedence) · CPC title