Magnetic resonance imaging apparatus and controlling method thereof

• US 9,696,401 B2
• Filed: 08/11/2010
• Issued: 07/04/2017
• Est. Priority Date: 08/11/2009
• Status: Active Grant

• Current Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Original Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Inventors: Yui, Masao
• Primary Examiner(s): Gort, Elaine
• Assistant Examiner(s): RAJ, RAJIV J
• Application Number:
  US12/854,426
• Publication Number:
  US 20110038520A1
• Time in Patent Office: 2,519 Days
• Field of Search: 382131, 324309
• CPC Class Codes: G01R 33/4835 of multiple slices
• CPC Class Codes: G01R 33/5676 Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction

Abstract

In a magnetic resonance imaging system, MRI data acquisition sequences are repeatedly and alternately executed for (a) a diagnostic image and (b) a navigator image that is an image for motion detection. Each subsequent navigator image is analyzed to detect the position of a mark indicating the position of a slice excited by the prior execution of a diagnostic imaging sequence. The respiratory motion of a portion of the subject is estimated based on the detected position of the mark.

Claims

1. A magnetic resonance imaging (MRI) apparatus, comprising:

a sequence execution control unit configured to repeatedly and alternately execute MRI data acquisition sequences for (a) a diagnostic image and (b) a navigator image from a subject being imaged, the navigator image being an image used for motion detection;

a slice position detecting unit configured to analyze each subsequent navigator image and thereby detect a position of a mark that indicates a position of a slice excited by the prior execution of a diagnostic imaging sequence;

a respiratory motion estimating unit configured to estimate motion of a portion of the subject due to respiration, based on the position of the mark; and

a sequence correcting unit configured to correct a diagnostic imaging sequence to be subsequently executed, based on the estimated respiratory motion.

2. The magnetic resonance imaging apparatus according to claim 1, wherein the slice position detecting unit detects, as the position of the mark, a low-signal region formed on the navigator image by excitation of the slice in the prior diagnostic imaging sequence.

3. The magnetic resonance imaging apparatus according to claim 2, wherein the slice position detecting unit performs model fitting onto a profile of the navigator image in a predetermined direction, and thereby detects the position of the mark.

4. The magnetic resonance imaging apparatus according to claim 2, wherein the slice position detecting unit performs pixel difference processing on pixels aligned in a predetermined direction on the navigator image, and thereby detects the position of the mark.

5. The magnetic resonance imaging apparatus according to claim 1, wherein:

the navigator sequence collects navigator image data from a dummy slice that is set in a different position from that of the slice of the diagnostic image; and

the slice position detecting unit detects, as the position of the mark, a high-signal region formed on the navigator image by excitation of the dummy slice.

6. The magnetic resonance imaging apparatus according to claim 5, wherein the slice position detecting unit performs model fitting onto a profile of the navigator image in a predetermined direction, and thereby detects the position of the mark.

7. The magnetic resonance imaging apparatus according to claim 5, wherein the slice position detecting unit performs pixel difference processing on pixels aligned in a predetermined direction on the navigator image, and thereby detects the position of the mark.

8. The magnetic resonance imaging apparatus according to claim 1, wherein the slice position detecting unit performs model fitting onto a profile of the navigator image in a predetermined direction, and thereby detects the position of the mark.

9. The magnetic resonance imaging apparatus according to claim 1, wherein the slice position detecting unit performs pixel difference processing on pixels aligned in a predetermined direction on the navigator image, and thereby detects the position of the mark.

10. A magnetic resonance imaging (MRI) apparatus, comprising:

a sequence execution control unit configured to repeatedly and alternately execute MRI data acquisition sequences for (a) a diagnostic image and (b) a navigator image from a subject being imaged, the navigator image being an image used for motion detection;

a slice position detecting unit configured to analyze each subsequent navigator image and thereby detect a position of a mark that indicates a position of a slice excited by the prior execution of a diagnostic imaging sequence; and

a respiratory motion estimating unit configured to estimates motion of a portion of the subject due to respiration, based on the position of the mark.

11. A method of controlling a magnetic resonance imaging (MRI) apparatus, said method comprising:

controlling a sequence execution control unit to repeatedly and alternately execute MRI data acquisition sequences for (a) a diagnostic image and (b) a navigator image from a subject being imaged, the navigator image being an image used for motion detection;

controlling a slice position detecting unit to analyze each subsequent navigator image and thereby detect a position of a mark that indicates a position of a slice excited by the prior execution of a diagnostic imaging sequence; and

controlling a respiratory motion estimating unit to estimate motion of a portion of the subject due to respiration based on the position of the mark.