JP2013094335A - Magnetic resonance apparatus and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately reproduce past slice positions because a slice position in executing first main scan is set based on the past slice positions set when past image data are acquired.SOLUTION: Slice positions SL-SLare set based on localizer image data acquired at the first photography, and the main scan is executed. After execution of the main scan, the slice positions SL-SLare registered in association with T1 emphasized image data D. At the second photography and thereafter, localizer image data Dare acquired, and the T1 emphasized image data Dregistered at the first photography are positioned with the localizer image data Dvol, and slice positions SL-SLat the second photography and thereafter are set.

Description

  The present invention relates to a magnetic resonance apparatus and a program for imaging a subject.

  When a lesioned part is found in the subject, the subject may be photographed regularly (for example, every month) in order to observe the lesioned part over time. When imaging a subject, an operator generally needs to set a scan position. However, in recent years, a method for automatically setting a scan position has been disclosed from the viewpoint of reducing the operator's workload. (See Patent Document 1).

JP 2007-326078

  When observing a diseased part over time, it is important to perform the second and subsequent imaging at the same slice position set at the first imaging. Therefore, it is desirable that the slice position set at the first photographing can be automatically reproduced when the second and subsequent photographing is performed. However, in the general automatic slice position setting method, there is a problem that it is difficult to accurately reproduce the slice position set at the first imaging at the second and subsequent imaging. Therefore, it is desired to improve the reproducibility of the slice position.

A first aspect of the present invention is a magnetic resonance apparatus for acquiring image data of an imaging region of a subject,
First localizer scan for obtaining first localizer image data used when setting the first slice position of the imaging region, and image data of the imaging region based on the first slice position Scanning means for executing a series of scans including a first main scan for acquiring
Past image data of the imaging region acquired before executing the series of scans, past slice positions set in the imaging region when the past image data was acquired, and the first localizer Slice position setting means for setting the first slice position based on image data;
Is a magnetic resonance apparatus.

According to a second aspect of the present invention, there is provided a first localizer scan for obtaining first localizer image data used when setting a first slice position of an imaging region of a subject; A program for a magnetic resonance apparatus that executes a series of scans including a first main scan for acquiring image data of the imaging region based on a slice position,
Past image data of the imaging region acquired before executing the series of scans, past slice positions set in the imaging region when the past image data was acquired, and the first localizer A slice position setting process for setting the first slice position based on image data;
Is a program for causing a computer to execute.

  Since the slice position for executing the first main scan is set based on the past slice position set when the past image data is acquired, the past slice position can be accurately reproduced.

It is the schematic of the magnetic resonance apparatus of one form of this invention. It is a figure which shows an example of the scan performed with this form. It is a figure which shows an imaging | photography site | part schematically. It is a figure which shows the operation | movement flow of MR apparatus 100 at the time of first imaging | photography. It is explanatory drawing of the localizer image data acquired by the localizer scan A at the time of first imaging | photography. The slice position _SL 1 to SL _n set for the subject 12 head is a view schematically showing. The slice position _SL 1 to SL _n, which is registered in association with T1 weighted image data _{D T1} is a diagram schematically showing. It is a figure which shows the operation | movement flow of MR apparatus 100 at the time of the imaging | photography after the 2nd time. It is explanatory drawing of the localizer image data acquired by the localizer scan at the time of the imaging | photography after the 2nd time. Localizer is a diagram showing another example of the image data D _vol. It is explanatory drawing of alignment.

    Hereinafter, although the form for inventing is demonstrated, this invention is not limited to the following forms.

FIG. 1 is a schematic view of a magnetic resonance apparatus according to one embodiment of the present invention.
A magnetic resonance apparatus (hereinafter referred to as “MR apparatus”, MR: Magnetic Resonance) 100 includes a magnet 2, a table 3, a receiving coil 4, and the like.

  The magnet 2 has a bore 21 in which the subject 12 is accommodated. The magnet 2 includes a superconducting coil 22, a gradient coil 23, a transmission coil 24, and the like. The superconducting coil 22 applies a static magnetic field, the gradient coil 23 applies a gradient pulse, and the transmission coil 24 transmits an RF pulse. In place of the superconducting coil 22, a permanent magnet may be used.

  The table 3 has a cradle 3a. The cradle 3a is configured to be able to move into the bore 21. The subject 12 is transported to the bore 21 by the cradle 3a.

  The reception coil 4 is attached to the head of the subject 12. The receiving coil 4 receives a magnetic resonance signal from the subject 12.

  The MR apparatus 100 further includes a sequencer 5, a transmitter 6, a gradient magnetic field power supply 7, a receiver 8, a central processing unit 9, an operation unit 10, and a display unit 11.

  Under the control of the central processing unit 9, the sequencer 5 sends pulse sequence information to the transmitter 6 and the gradient magnetic field power supply 7.

  The transmitter 6 outputs a signal for driving the RF coil 24 based on the information sent from the sequencer 5.

  The gradient magnetic field power supply 7 outputs a signal for driving the gradient coil 23 based on the information sent from the sequencer 5.

  The receiver 8 processes the magnetic resonance signal received by the receiving coil 4 and outputs it to the central processing unit 9. A combination of the magnet 2, the transmitter 6, the gradient magnetic field power source 7, and the receiver 8 corresponds to the scanning means.

  The central processing unit 9 implements various operations of the MR apparatus 100 such as transmitting necessary information to the sequencer 5 and the display unit 11 and reconstructing an image based on data received from the receiver 8. The operation of each part of the MR apparatus 100 is controlled. The central processing unit 9 is constituted by a computer, for example. The central processing unit 9 includes a slice position setting unit 91 that sets a slice position, a registration unit 92 that registers a slice position, and the like.

  The central processing unit 9 is an example constituting the slice position setting unit 91 and the registration unit 92, and functions as these units by executing a predetermined program.

The operation unit 10 is operated by an operator and inputs various information to the central processing unit 9. The display unit 11 displays various information.
The MR apparatus 100 is configured as described above.

  FIG. 2 is a diagram showing an example of a scan executed in this embodiment, and FIG. 3 is a diagram schematically showing an imaging region.

  In this embodiment, a series of scans C including the localizer scan A and the main scans B1 to B3 are executed, and the head is imaged.

  The localizer scan A is a scan for acquiring localizer image data used when setting the slice position of the head.

  The main scans B1 to B3 are scans for photographing the head based on the slice position set using the localizer image data. In this embodiment, three main scans B1 to B3 are executed, but one or two main scans may be executed, or four or more main scans may be executed. In this embodiment, the main scan B1 is a scan for acquiring T1-weighted image data, the main scan B2 is a scan for acquiring T2-weighted image data, and the main scan B3 is acquired FLAIR (Fluid attenuated IR) image data. It is a scan to do. However, the main scan may be a scan for acquiring image data other than these.

  Next, a flow when the subject is imaged by the MR apparatus 100 will be described. In the following, there will be described a case where a lesion is present on the head of the subject 12 and the head of the subject 12 is photographed regularly (for example, every three months) in order to observe the size of the lesion. To do. In this embodiment, the operation flow of the MR apparatus at the first imaging when the head of the subject 12 is imaged for the first time is different from the operation flow of the MR apparatus at the second and subsequent imaging performed for follow-up observation. Yes. Hereinafter, an operation flow of the MR apparatus at the time of the first imaging and an operation flow of the MR apparatus at the second and subsequent imaging will be described in order.

(1) Operation Flow of MR Device 100 at First Shooting FIG. 4 is a diagram showing an operation flow of the MR device 100 at the first shooting.

  In step ST1, a localizer scan A is executed to acquire localizer image data used when setting the slice position of the head (see FIG. 5).

  FIG. 5 is an explanatory diagram of localizer image data acquired by the localizer scan A at the time of the first shooting.

  In this embodiment, localizer image data DA, DC, and DS for three surfaces are acquired in the localizer scan at the time of the first imaging. Specifically, the localizer image data DA, DC, and DS for the axial plane, the coronal plane, and the sagittal plane are acquired. After obtaining the localizer image data DA, DC, and DS, the process proceeds to step ST2.

In step ST2, a slice position is set on the head of the subject based on the three-surface localizer image data DA, DC, and DS. For example, the operator can manually input the slice position information by operating the operation unit 10. Specifically, the localizer image data DA, DC, and DS of the three surfaces are displayed on the display unit 11, and the operator refers to the localizer image data DA, DC, and DS, and displays the position information of the slice position. Can be entered. The slice position setting unit 91 (see FIG. 1) sets the slice position input by the operator as the slice position when imaging the head of the subject. FIG. 6 schematically shows slice positions SL _{1 to} SL _n set for the head of the subject 12. In recent years, since a technique for automatically setting the slice position is also widespread, the slice position setting unit 91 may automatically set the slice position. After setting the slice position, the process proceeds to step ST3.

At step ST3, the following set slice position _SL 1 to SL _n in step ST2, the main scan B1~B3 is performed. In this embodiment, the T1-weighted image data, the T2-weighted image data, and the FLAIR image data are acquired by executing the main scans B1 to B3. After obtaining these image data, the process proceeds to step ST4.

In step ST4, the T1 weighted image data acquired by the main scan B1 and the slice positions SL _{1 to} SL _n are registered. The operator operates the operation unit 10 to input a command for performing this registration. When this command is input, the registration unit 92 (see FIG. 1) registers the slice positions SL _{1 to} SL _n in association with the T1 weighted image data acquired by the main scan B1 in the database. FIG. 7 schematically shows T1-weighted image data D _T1 associated with slice positions SL _{1 to} SL _n . In this way, the flow shown in FIG. 4 ends.

(2) Operation Flow of MR Device 100 at Second Shooting FIG. 8 is a diagram showing an operation flow of the MR device 100 at the second shooting.

  In step ST1, a localizer scan A (see FIG. 2) for acquiring localizer image data is executed as in the first imaging. However, in the second time, the localizer image data of the entire head is acquired instead of the three-surface localizer image data DA, DC, and DS (see FIG. 9).

  FIG. 9 is an explanatory diagram of localizer image data acquired by the localizer scan at the time of the second shooting.

In the second shooting, the localizer image data D _vol of the head is acquired. The localizer image data D _vol is not the image data of three surfaces (axial surface, coronal surface, sagittal surface) crossing the head, but volume image data of the head. The localizer image data D _vol may be acquired by 2D scanning or may be acquired by 3D scanning. Note that the localizer image data D _vol may include an area where data is not collected as shown in FIG. 10 as long as the rough shape of the entire head can be represented. In this embodiment, it is assumed that the localizer image data D _vol is collected from the entire head as shown in FIG. After acquiring localizer image data _{D vol,} the process proceeds to step ST2.

In step ST2, the T1 weighted image data D _T1 (see FIG. 7) registered after the first photographing is read. Since the T1 weighted image data _{D T1} are associated with each slice position _SL 1 to SL _n, T1 weighted image by reading the data _{D T1,} past the slice position _SL 1 to SL which is set at the time of the first shooting _n can be known. After reading the T1-weighted image data D _T1 associated with the slice positions SL _{1 to} SL _n , the process proceeds to step ST3.

In step ST3, the slice position setting unit 91 performs alignment between the localizer image data _Dvol and the read T1 weighted image data _DT1 (see FIG. 11).

FIG. 11 is an explanatory diagram of alignment.
The slice position setting unit 91 aligns the localizer image data D _vol and the T1 weighted image data D _{T1 so} that the positional deviation between the localizer image data D _vol and the T1 weighted image data D _T1 is _minimized. . As an alignment method, for example, affine transformation can be used. T1 weighted The image data _{D T1,} since past the slice position _SL 1 to SL _n, which is set at the time of the first shooting is associated, and localizer image data _{D vol,} alignment of the T1 weighted image data _{D T1} By performing the above, it is possible to position the past slice positions SL _{1 to} SL _n set at the time of the first imaging with respect to the localizer image data D _vol . The slice positions SL _{1 to} SL _n thus positioned are set as slice positions at the time of the second imaging. After setting the slice position at the time of the second imaging, the process proceeds to step ST4.

In step ST4, in accordance with the set slice position _SL 1 to SL _n in step ST3, the main scan is performed. In the main scan, T1-weighted image data, T2-weighted image data, FLAIR image data, and the like are acquired as in the first shooting. In this way, the second shooting is completed.

Even when the third shooting is performed, the shooting is executed according to the flow shown in FIG. Specifically, running localizer scan (step ST1), reads the T1 weighted image data _{D T1} registered at the time of photographing the first time (step ST2), and the read T1 weighted image data _{D T1,} the third-shooting Alignment with the localizer image data acquired at times is performed, and slice positions SL _{1 to} SL _n are set (step ST 3). Then, based on the set slice position _SL 1 to SL _n, the main scan is executed (step ST4). Even when shooting for the fourth and subsequent times, shooting is executed according to the flow shown in FIG.

In this embodiment, when the head of the subject 12 is observed, the slice position when performing the second and subsequent imaging is set based on the past slice positions SL _{1 to} SL _n obtained at the first imaging. . Therefore, the past slice position set at the first photographing can be accurately reproduced at the second and subsequent photographing, and the follow-up observation can be performed at the same slice position.

In this embodiment, the localizer image data D _vol is volume image data in a localizer scan of a series of scans executed during the second and subsequent imaging. By using the volume image data as localizer image data _{D vol,} it can be aligned with the localizer image data _{D vol} and T1 weighted image data _{D T1} in step ST3 (see FIG. 8) with high accuracy. Therefore, the past slice position set at the time of the first photographing can be accurately reproduced at the second and subsequent photographing. If the alignment can be performed with sufficient accuracy, the image data of the tomographic plane such as the axial plane, the sagittal plane, and the coronal plane can be used instead of the volume image data even in the second and subsequent shootings. You may acquire as localizer image data.

In this embodiment, the slice positions SL _{1 to} SL _n set at the time of the first photographing are registered in association with the T1 weighted image data D _T1 . However, in step ST3 the time of the first shot (see FIG. 4), in addition to the T1 weighted image data _{D T1,} and T2-weighted image data, FLAIR image data is also acquired. Thus, instead of T1 weighted image data _{D T1,} it may be registered in association with the slice position _SL 1 to SL _n in T2 weighted image data or the FLAIR image data.

In this embodiment, the slice position for the second and subsequent shooting is set based on the slice positions SL _{1 to} SL _n set at the first shooting. However, the slice positions SL _{1 to} SL _n may be re-registered during the second and subsequent imaging, and the slice positions may be set based on the re-registered slice positions SL _{1 to} SL _n in subsequent imaging.

  In the present embodiment, localizer image data of three surfaces of an axial surface, a sagittal surface, and a coronal surface is acquired in a localizer scan of a series of scans executed at the time of the first photographing. However, if it is possible to determine the slice position at the time of the first photographing, only the localizer image data of any one of the axial plane, sagittal plane, coronal plane, or any two planes is acquired. Also good. In addition to the axial surface, sagittal surface, and coronal surface, local image data of the oblique surface may be acquired. Furthermore, the volume image data of the imaging region may be used as the localizer image data instead of the three localizer image data of the axial surface, the sagittal surface, and the coronal surface.

In addition, the slice positions SL _{1 to} SL _n set when performing the second and subsequent imaging may be displayed on the display unit so that the operator can check. Furthermore, if necessary, the operator adjusts the slice positions SL _{1 to} SL _n displayed on the display unit, and sets the adjusted slice positions as slice positions when performing the second and subsequent imaging. Good.

  In this embodiment, the first imaging and the second and subsequent imaging are performed using the same MR apparatus. However, the second and subsequent imaging may be executed using an MR apparatus different from the MR apparatus that executed the first imaging. In this case, by associating past image data obtained by the MR apparatus that has performed the first imaging with a past slice position, even when the second or subsequent imaging is performed with another MR apparatus, The past slice position can be accurately reproduced by aligning the past image data and the localizer image data.

  Alternatively, the first imaging may be performed with the CT apparatus, and the second and subsequent imaging may be performed with the MR apparatus. In this case, if the past image data obtained by the CT apparatus and the past slice position are associated with each other, the past image data and the localizer image data can be obtained even when the MR apparatus performs the second and subsequent imaging. , The past slice position can be accurately reproduced.

2 Magnet 3 Table 3a Cradle 4 Receiving coil 5 Sequencer 6 Transmitter 7 Gradient magnetic field power supply 8 Receiver 9 Central processing unit 10 Operation unit 11 Display unit 12 Subject 21 Bore 22 Superconducting coil 23 Gradient coil 24 Transmitting coil 91 Slice position setting Means 92 Registration means

Claims (12)

A magnetic resonance apparatus for acquiring image data of an imaging region of a subject,
First localizer scan for obtaining first localizer image data used when setting the first slice position of the imaging region, and image data of the imaging region based on the first slice position Scanning means for executing a series of scans including a first main scan for acquiring
Past image data of the imaging region acquired before executing the series of scans, past slice positions set in the imaging region when the past image data was acquired, and the first localizer Slice position setting means for setting the first slice position based on image data;
A magnetic resonance apparatus. The past image data is associated with the past slice position,
The slice position setting means includes
The past image data associated with the past slice position is aligned with the first localizer image data, and the first slice position is set based on a result of the alignment. Item 2. The magnetic resonance apparatus according to Item 1. The slice position setting means includes
The past image data associated with the past slice position is aligned with the first localizer image data, and the past slice position with respect to the first localizer image data after the alignment is obtained. The magnetic resonance apparatus according to claim 2. The slice position setting means includes
The magnetic resonance apparatus according to claim 3, wherein the past slice position with respect to the first localizer image data after alignment is set as the first slice position. A display unit for displaying the past slice position with respect to the first localizer image data after alignment;
The slice position setting means includes
4. The magnetic resonance according to claim 3, wherein the past slice position displayed on the display unit is adjusted according to an operation of an operator, and the adjusted past slice position is set as the first slice position. 5. apparatus. The scanning means includes
Before executing the series of scans, a second localizer scan for acquiring second localizer image data used when setting the past slice position, and acquiring the past image data The magnetic resonance apparatus according to claim 1, wherein another series of scans including the second main scan is executed.   The magnetic resonance apparatus according to claim 6, wherein the first localizer image data is volume image data of the imaging region, and the second localizer image data is image data of a cross section of the imaging region. The another series of scans is a scan executed at the time of the first imaging of the imaging region,
The magnetic resonance apparatus according to claim 6, wherein the series of scans are scans executed at the time of the second and subsequent imaging of the imaging region.   The magnetic resonance apparatus according to claim 2, further comprising a registration unit that registers the past slice position in association with the past image data.   The magnetic resonance apparatus according to claim 1, wherein the past image data is acquired using a magnetic resonance apparatus different from the magnetic resonance apparatus.   The magnetic resonance apparatus according to claim 1, wherein the past image data is acquired using a CT apparatus. A first localizer scan for obtaining first localizer image data used when setting the first slice position of the imaging region of the subject, and the imaging region based on the first slice position. A program of a magnetic resonance apparatus that executes a series of scans including a first main scan for acquiring image data,
Past image data of the imaging region acquired before executing the series of scans, past slice positions set in the imaging region when the past image data was acquired, and the first localizer A slice position setting process for setting the first slice position based on image data;
A program to make a computer execute.