JP2013005985A - Magnetic resonance imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic resonance imaging apparatus capable of ending image reconstruction within the time desired by an operator and immediately displaying the prepared image.SOLUTION: The magnetic resonance imaging apparatus (10) displays a first tomographic image of a subject at a display part (180) using magnetic resonance signals generated from the subject (SB). Then, the apparatus includes: a condition input part (190) for inputting an imaging condition for obtaining the first tomographic image; and a calculation part (175) for calculating a second image reconstruction condition for reconstructing an image in a shorter period of time than the time required for image reconstruction under a first image reconstruction condition for image-reconstructing the first tomographic image on the basis of the imaging condition, and a second tomographic image image-reconstructed under the second image reconstruction condition is displayed at the display part.

Description

  The present invention relates to a magnetic resonance imaging apparatus for imaging a magnetic resonance signal generated from a subject. In particular, the present invention relates to a technique for quickly displaying MR images to an operator.

  In a conventional magnetic resonance imaging apparatus, an image reconstructed for each pulse sequence is sequentially displayed on an image display apparatus by an auto viewer function installed in the magnetic resonance imaging apparatus. The auto viewer function is a function that automatically displays the reconstructed images sequentially. With recent advances in magnetic resonance imaging apparatus, the number of images or image reconstruction time tends to increase. On the other hand, the imaging time tends to be shortened with the progress of the pulse sequence.

  As shown in Patent Document 1, images reconstructed for each pulse sequence or for each part were sequentially displayed. For this reason, the operator operating the magnetic resonance imaging apparatus waits until the desired image is displayed even after the photographing is completed in order to confirm whether the desired image is captured, and confirms the desired image. Since then, the subject has been removed from the magnetic resonance imaging apparatus.

JP 2010-110510 A

  Since the magnetic resonance imaging apparatus is photographed by bringing the subject into a narrow bore (internal space), there is a situation where the operator wants to remove the subject from the bore as soon as possible for the subject. . Further, in a medical field engaged in emergency medical care such as a hospital, there are situations where an operator wants to increase the per-capacity throughput of imaging by a magnetic resonance imaging apparatus or has to quickly complete imaging and move to treatment.

  There is a current situation where doctors and the like who observe the imaging result desire a large number of images and images by a large number of pulse sequences. The operator is required to take as many images and images with as many pulse sequences as possible in a limited time frame and to take as many subjects as possible. For this reason, the magnetic resonance imaging apparatus is required to reduce the imaging time per subject and improve the throughput. Furthermore, the magnetic resonance imaging apparatus has good image quality of images to be taken, and many pulse sequences and image reconstruction of many images such as a plurality of cross sections are required at the same time.

  Therefore, the present invention provides a magnetic resonance imaging apparatus capable of displaying a created image within a time desired by an operator.

A magnetic resonance imaging apparatus according to a first aspect is a magnetic resonance imaging apparatus that displays a first tomographic image of a subject on a display unit using a magnetic resonance signal generated from the subject. The apparatus includes a condition input unit for inputting imaging conditions for obtaining a first tomographic image,
A calculation unit for calculating a second image reconstruction condition for reconstructing an image in a time shorter than a time required for the image reconstruction in the first image reconstruction condition for reconstructing the first tomographic image based on the imaging condition; Prepared,
A magnetic resonance imaging apparatus for displaying on a display unit a second tomographic image reconstructed under a second image reconstruction condition.

  In the magnetic resonance imaging apparatus according to the second aspect, the calculation unit calculates a time until the first tomographic image is displayed on the display unit under the first image reconstruction condition.

A magnetic resonance imaging apparatus according to a third aspect includes a storage unit that stores an image reconstruction time required for image reconstruction for each of a plurality of parameters constituting an image reconstruction condition that can be set by a condition input unit,
The calculation unit calculates a second image reconstruction condition by combining parameters, and calculates a time until the second tomographic image is displayed on the display unit under the second image reconstruction condition.

  In the magnetic resonance imaging apparatus according to the fourth aspect, the time until the second tomographic image is displayed on the display unit, or the ratio of the time until the second tomographic image is displayed with respect to the time when the first tomographic image is displayed. Is provided with a display time input unit.

In the magnetic resonance imaging apparatus of the fifth aspect, the first image reconstruction condition includes a type of pulse sequence for obtaining a magnetic resonance signal and a resolution of a tomographic image,
The calculation unit calculates a second image reconstruction condition with a reduced resolution based on the time or ratio input by the display time input unit.

In the magnetic resonance imaging apparatus of the sixth aspect, the first image reconstruction condition includes the number of additions of tomographic images in order to reduce noise in the tomographic images,
The calculation unit calculates a second image reconstruction condition in which the number of additions is reduced based on the time or ratio input by the display time input unit.

In the magnetic resonance imaging apparatus of the seventh aspect, the first image reconstruction condition includes an image selection condition that enhances a part or all of the tomographic image,
The calculation unit calculates a second image reconstruction condition without the image selection condition based on the time or the ratio input by the display time input unit.

In the magnetic resonance imaging apparatus according to the eighth aspect, the time or the ratio is set in advance via the display time input unit for each subject or for each operator who operates the magnetic resonance imaging apparatus.
In the magnetic resonance imaging apparatus of the ninth aspect, after the completion of the image reconstruction of the first tomographic image, the display unit displays the first tomographic image instead of the second tomographic image.

  According to the present invention, it is possible to realize an improvement in inspection throughput by terminating image reconstruction at a time desired by an operator.

It is a schematic block diagram of a magnetic resonance imaging apparatus. It is a flowchart which concerns on the test | inspection by a magnetic resonance imaging apparatus. It is the figure which showed the time table of imaging | photography and image reconstruction. (A) is a figure at the time of displaying the 1st image G1 and the 2nd image G2 side by side. (B) is a figure at the time of carrying out the tab display of the 1st image G1 and the 2nd image G2. It is a flowchart which shows the outline | summary of operation | movement of the calculation part 175 concerning the imaging | photography of a magnetic resonance imaging apparatus. (A) is the table | surface which showed an example of imaging | photography protocol HEAD1. (B) is a table showing an example of the imaging protocol HEAD2. It is the figure which showed an example of the input screen of the display time input part 195 which inputs 2nd image reconstruction time Ta2. 10 is a flowchart by a display time input unit 195. (A) is the figure which showed the input screen of 2nd image pixel number Ax and 2nd image pixel number Ay. (B) is a diagram showing an input screen for the image addition count NEX. (C) is a diagram showing an input screen for an option OP.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The scope of the present invention is not limited to these forms.

<Configuration of magnetic resonance imaging apparatus>
FIG. 1 is a schematic configuration diagram of a magnetic resonance imaging apparatus 10 according to the first embodiment. With reference to FIG. 1, the configuration and basic operation of the magnetic resonance imaging apparatus 10 of the present embodiment will be described.

  The magnetic resonance imaging apparatus 10 of the present embodiment includes a magnet system 100, a storage unit 110, a gradient coil drive unit 130, an RF coil drive unit 140, a data collection unit 150, a sequence control unit 160, a data processing unit 170, a display unit 180, and A condition input unit 190 is included.

  The magnet system 100 includes a main magnetic field coil unit 102, a gradient coil unit 106, and an RF coil unit 108. Each of these coil portions has a substantially cylindrical shape, and is arranged coaxially with each other in a substantially columnar bore. The subject SB is placed on the bed 200 in the bore, and the bed 200 can move in the bore in the magnet system 100 according to the imaging region.

  The main magnetic field coil unit 102 forms a static magnetic field in the internal space of the magnet system 100. The direction of the static magnetic field is generally parallel to the direction of the body axis of the subject SB and forms a horizontal magnetic field. The main magnetic field coil unit 102 is normally configured using a superconducting coil, but may be configured using a permanent magnet or the like without being limited to the superconducting coil.

  The gradient coil unit 106 has three types of gradients for imparting gradients to the static magnetic field strength formed by the main magnetic field coil unit 102 in three axes orthogonal to each other, that is, in the direction of the slice axis, the phase axis, and the frequency axis. Generate a magnetic field. In order to make it possible to generate such a gradient magnetic field, the gradient coil unit 106 has three gradient coils (not shown). A gradient coil drive unit 130 is connected to the gradient coil unit 106, and the gradient coil drive unit 130 gives a drive signal to the gradient coil unit 106 to generate a gradient magnetic field. The gradient coil drive unit 130 has three drive circuits (not shown) corresponding to the three gradient coils in the gradient coil unit 106.

  The gradient magnetic field in the slice axis direction is called a slice gradient magnetic field, the gradient magnetic field in the phase axis direction is called a phase encode gradient magnetic field (or phase encode gradient magnetic field), and the gradient magnetic field in the frequency axis direction is read out gradient magnetic field (or frequency encode) Gradient magnetic field).

  In the three-dimensional orthogonal coordinate system, when coordinate axes orthogonal to each other in the static magnetic field space are an X axis, a Y axis, and a Z axis, any of the axes can be a slice axis. In the present embodiment, the slice axis is the body axis direction of the subject SB is the Z-axis direction, one of the remaining two axes is the phase axis, and the other is the frequency axis. Note that the slice axis, the phase axis, and the frequency axis can have an arbitrary inclination with respect to the X, Y, and Z axes while maintaining the orthogonality therebetween.

  The RF coil unit 108 forms a high-frequency magnetic field for exciting spins in the body of the subject SB in the static magnetic field space. Formation of a high-frequency magnetic field is called transmission of an RF excitation signal, and the RF excitation signal is called an RF pulse. An RF coil drive unit 140 is connected to the RF coil unit 108, and the RF coil drive unit 140 provides a drive signal to the RF coil unit 108 to transmit an RF pulse. An electromagnetic wave generated by the excited spin, that is, a magnetic resonance (MR) signal is received by the RF coil unit 108. A data collection unit 150 is connected to the RF coil unit 108. The data collection unit 150 collects echo signals (or MR reception signals) received by the RF coil unit 108 as digital data.

  The MR signal detected by the RF coil unit 108 and collected by the data collecting unit 150 becomes a signal in the frequency domain (frequency domain), for example, Fourier space. Since the MR signal is encoded in two axes by the gradient in the phase axis direction and the frequency axis direction, the MR signal is obtained as a signal in a two-dimensional Fourier space, for example, when the frequency space is illustrated in Fourier space. The two-dimensional Fourier space is also called k-space. The phase encoding and magnetic field encoding (readout) gradient fields determine the sampling position of the signal in two-dimensional Fourier space.

  The storage unit 110 stores a pulse sequence database (hereinafter referred to as PSD), various programs, and various data, and is appropriately read and written. The storage unit 110 stores imaging conditions for imaging the PSD and the subject SB as an imaging protocol. This photographing protocol is stored as various image reconstruction setting conditions (hereinafter referred to as parameters) from the photographed data. The imaging protocol can be stored for each imaging region and imaging method, and can also be stored for each subject SB. Furthermore, a photographing protocol can be created for each operator, and parameters desired by the operator can be easily read out.

A sequence control unit 160 is connected to the gradient coil drive unit 130, the RF coil drive unit 140, and the data collection unit 150.
The sequence control unit 160 drives the gradient coil driving unit 130 and the RF coil driving unit 140 in accordance with the imaging conditions input by the operator, that is, the imaging protocol.

  The display unit 180 is configured by a graphic display or the like. The display unit 180 is connected to the data processing unit 170. The display unit 180 can display a plurality of windows, and can display a captured image display window, various operation windows, and the like, for example. The display unit 180 can display the first image G1 and the second image G2 (see FIG. 4) and various types of information output from the data processing unit 170.

  The condition input unit 190 includes a keyboard or the like equipped with a pointing device. The condition input unit 190 is connected to the data processing unit 170. The condition input unit 190 is operated by the operator via the display unit 180 to read out the shooting protocol from the storage unit 110 or change the parameters of the shooting protocol and input them to the data processing unit 170. Used. The condition input unit 190 may arrange a touch panel on the display unit 180 instead of a keyboard or the like.

  In addition, the condition input unit 190 includes a display time input unit 195 for a graphic user interface. Via the display time input unit 195, it is possible for the operator to set the time required to display the second image G2 (see FIG. 4) on the display unit 180 with an emphasis on speed in order to confirm the imaging region and the like. is there.

  A number of MR signals (hereinafter referred to as imaging data) collected by the data collection unit 150 are input to the data processing unit 170. The data processing unit 170 stores the shooting data collected by the data collection unit 150 in the storage unit 110. A data space corresponding to the k space described above is formed in the storage unit 110. The data processing unit 170 reconstructs an image of captured image data by performing inverse frequency transform, for example, two-dimensional inverse Fourier transform, on k-space data. The data processing unit 170 reconstructs the first image G1 and the second image G2 (see FIG. 4). Normally, the first image G1 using the image-oriented parameter for one slice section and the second image G2 using the speed-oriented parameter are reconstructed. The first image G1 can create not only one tomographic image for one slice cross section but also a plurality of tomographic images using various parameters such as image addition, edge enhancement, fat enhancement, and water enhancement. Note that edge enhancement, fat enhancement, water enhancement, and the like are image reconstruction techniques that enhance part or all of an image.

  Further, the data processing unit 170 has a calculation unit 175. The calculation unit 175 calculates the image reconstruction time required for image reconstruction based on the imaging protocol input by the operator. An image reconstruction time of an imaging protocol (hereinafter referred to as a basic imaging protocol PC) that is the basis of calculation is stored in the storage unit 110. The basic photographing protocol PC is composed of a PSD and a plurality of parameters. In addition, the storage unit 110 stores image reconstruction time required for image reconstruction based on various parameters such as image quality, image addition, edge enhancement, fat enhancement, and water enhancement.

  For example, the storage unit 110 stores an image reconstruction time based on PSD without adding a parameter of the basic imaging protocol PC as Ta seconds, and stores an image reconstruction time based on the added parameter as Tb seconds. Further, the storage unit 110 stores, for each PSD different from the PSD of the basic imaging protocol PC, differential times Dta1, Dta2,..., Dtan from the PSD image reconstruction time Ta of the basic imaging protocol PC. Further, for each parameter to be added, difference times Dtb1, Dtb2,..., Dtbn from the image reconstruction time Tb of the parameters of the basic photographing protocol PC are stored.

  The calculation unit 175 calculates a first image reconstruction time Ta1 required to display the first image G1 based on a shooting protocol (hereinafter referred to as a set shooting protocol PC1) in which shooting conditions are set by the operator. . The calculation unit 175 reads the difference time between the PSD of the basic shooting protocol PC and the PSD of the setting shooting protocol PC1 from the storage unit 110. For example, the calculation unit 175 reads the difference time Dta3. Further, the calculation unit 175 reads the difference time between the various parameters of the basic photographing protocol PC and the various parameters of the set photographing protocol PC1 from the storage unit 110. For example, the calculation unit 175 has two different parameters, reads the difference time Dtb2 + Dtb5, and calculates the total time. Thereby, the calculation unit 175 calculates the first image reconstruction time Ta1 (= Ta + Tb + Dta3 + Dtb2 + Dtb5) required to display the first image G1 based on the set photographing protocol PC1. The basic photographing protocol PC may store one type or a plurality of types. For example, a plurality of types of basic photographing protocols PC may be prepared for each photographing method such as two-dimensional photographing, three-dimensional photographing, and angio photographing.

  Further, the calculation unit 175 calculates the first image reconstruction time Ta1 of the first image G1 based on the difference time between the basic photographing protocol PC and the set photographing protocol PC1, but the image reconstruction time for each PSD and each parameter. A list of the first image reconstruction times Ta1 calculated by combining the image reconstruction times required for the image is stored in advance as data, and the first image reconstruction time Ta1 having the same PSD and parameters as the set photographing protocol PC1 is read out. The method may be used.

  Further, the calculation unit 175 displays the second image G2 on the display unit 180 within the input time if any parameter is changed from the set photographing protocol PC1 based on the time input by the display time input unit 195. Calculate what you can do. For example, the calculation unit 175 calculates from the setting imaging protocol PC1 that the second image G2 can be displayed in time if the time required for image reconstruction for fat emphasis is eliminated. Then, the data processing unit 170 reconstructs the second image G2 (see FIG. 4) without the fat emphasis parameter.

  As described above, the magnetic resonance imaging apparatus 10 according to the present embodiment can improve the throughput by reconstructing the second image G2 that emphasizes the speed corresponding to the time desired by the operator.

<Inspection flowchart>
FIG. 2 is a flowchart relating to the examination by the magnetic resonance imaging apparatus 10 of the present embodiment. The magnetic resonance imaging apparatus 10 is logged in with an operator ID and password when the power is turned on.

  In step S01, the operator enters the subject SB into the imaging room of the magnetic resonance imaging apparatus 10. The operator enters the subject room with attention to bringing in the body metal and the body metal in order to enter the subject SB in the imaging room in a high magnetic field.

  In step S02, the operator places the subject SB on the bed 200. The operator lays the subject SB on the bed 200 of the magnetic resonance imaging apparatus 10 and prepares for imaging such as installing a receiving coil at a desired imaging site if necessary.

  In step S03, the operator conveys the subject SB into the bore of the magnetic resonance imaging apparatus. The operator operates the carry-in switch of the bed 200 to place the subject SB at a predetermined position in the bore.

  In step S04, the operator leaves the shooting room and performs shooting. The operator operates the condition input unit 190 to read out a desired shooting protocol, and further changes shooting protocol parameters as necessary. In addition, the operator sets a time for displaying the second image G <b> 2 emphasizing speed via the display time input unit 195. Then, the RF coil drive unit 140 gives a drive signal to the RF coil unit 108 and transmits an RF pulse to perform a series of imaging.

  As for the PSD of the photographing protocol to be read, a plurality of images are photographed for one PSD. Actually, it is possible to set a plurality of PSDs as an imaging protocol and to simultaneously read out a plurality of imaging protocols, and tens to hundreds of images can be taken for one subject SB. Done.

  In step S05, the operator confirms a plurality of second images G2 reconstructed by the data processing unit 170 with an emphasis on speed. Image reconstruction creates a plurality of second images G2 for one PSD. FIG. 3 is a diagram showing a time table for photographing, image reconstruction, and image display. As shown in the drawing, when the first shooting by PSD is finished, the first second image G2 is reconstructed after the shooting is finished, and when the second shooting by the next PSD is finished, the second shot after the shooting is finished. The second image G2 is reconstructed. The data processing unit 170 preferentially reconstructs the second image G2. The second image G2 is automatically displayed on the display unit 180 in the order of image reconstruction. Note that the shooting time MRt of one PSD differs from PSD to PSD, and the second reconstruction time Ta2 of the second image G2 also changes depending on the PSD and parameters.

  The operator looks at the second image G2 that is automatically displayed in sequence for each shooting, and checks whether the target range is shot, whether there is any movement due to the body movement of the subject SB, and the like. If the operator confirms the second image G2, the process proceeds to step S07. If the image is out of the target range or the subject SB moves, the operator returns to step S04, and again the subject Shoot SB.

  In step S06, the data processing unit 170 reconstructs a plurality of first images G1 according to the shooting conditions in the idle time. Image reconstruction creates a plurality of first images G1 for one PSD. As shown in FIG. 3, when the first shooting with one PSD is completed, the first first image G1 is reconstructed after the completion of the image reconstruction of the second image G2, and the second shooting is completed. Then, after the first image reconstruction of the first image G1, the second first image G1 is reconstructed. In addition, since the image reconstruction of the second image G2 has priority over the image reconstruction of the first image G1, the second second image G2 image even during the first image reconstruction of the first image G1. The reconstruction is started, and the first image reconstruction of the first image G1 is temporarily stopped. When the second image reconstruction of the second image G2 is completed, the first image reconstruction of the first image G1 is resumed. The data processing unit 170 preferentially reconstructs the second image G2, and reconstructs the first image G1 at a free time. Note that the first reconstruction time Ta1 of the first image G1 varies depending on the PSD and the parameters.

  In general, the first image G1 has higher image quality than the second image G2. The data processing unit 170 creates the first image G1 that emphasizes image quality after the image reconstruction of the second image G2 is completed, and stores the first image G1 in the storage unit 110. When the first image G1 that emphasizes image quality for each slice is reconstructed, the data processing unit 170 may overwrite the corresponding second image G2 that emphasizes the speed of the slice and display the image on the display unit 180. . By overwriting the second image G2 to the first image G1, it is possible to view a part or all of the first image G1 with an emphasis on image quality depending on the timing at which the operator performs the image checking operation.

  In step S07, the operator carries the subject SB out of the bore from the bore. The operator operates the carry-out switch of the bed 200 to place the subject SB at a predetermined position outside the bore.

  In step S08, the operator removes the receiving coil or the like attached to the subject SB, and causes the subject SB to leave the imaging room.

  As shown in the examination flowchart, the examination time of the magnetic resonance imaging apparatus 10 devote a lot of time to the procedure before imaging in steps S01 to S03 and the procedure after imaging in steps S07 and S08. The operator can move to the unloading operation of the subject SB in step S07 by confirming whether the target range is photographed by the second image G2 with an emphasis on speed or whether there is any movement due to body movement. Therefore, the inspection throughput is improved. The examination by the magnetic resonance imaging apparatus 10 often reads out a plurality of imaging protocols and generates a lot of images using a plurality of PSDs. Therefore, even in the second image G2 in which speed is important, image reconstruction takes a long time. Such an imaging protocol can be first selected, and the operator can variably select the imaging protocol in which the image reconstruction is completed in a short time in the second image G2, for example.

  FIG. 4 is an example in which a first image G1 and a second image G2 of a plurality of images are displayed. FIG. 4A is a diagram when the first image G1 and the second image G2 are displayed side by side. As shown in the drawing, the image quality of the first image G1 reconstructed by the imaging protocol input by the operator via the condition input unit 190 is emphasized. Further, since the second image G2 emphasizes display speed, the resolving power is lower than the imaging protocol input by the operator or there are no optional parameters. However, the operator can determine whether or not the shooting range is correct even for the second image G2.

  FIG. 4B is a diagram when the first image G1 and the second image G2 are displayed as tabs. The display time input unit 195 may alternately display the first image G1 and the second image G2 by switching tabs at the top of the screen.

<Operation of calculation unit during shooting>
FIG. 5 is a flowchart showing an outline of the operation of the calculation unit 175 during photographing according to the present embodiment. The following is the operation of the calculation unit 175 at the time of photographing in step S04 of the inspection flowchart shown in FIG.

  In step S41, the operator reads out the imaging protocol stored in advance in the storage unit 110 of the magnetic resonance imaging apparatus 10, further changes the parameters of the imaging protocol as necessary, and prepares desired imaging conditions. FIG. 6 is a table showing an example of the imaging protocol. The shooting protocol includes a shooting protocol name and PSD as a shooting method. In addition, the imaging protocol includes the X-axis first image pixel number Ix, the Y-axis first image pixel number Iy, the X-axis second image pixel number Ax, and the Y-axis second image pixel number, which are parameters for image reconstruction. Items Ay, the image addition count NEX, and options OP1 to OPn are included. FIG. 6A is a table showing an example of the imaging protocol HEAD1, and FIG. 6B is a table showing an example of the imaging protocol HEAD2.

  As shown in FIG. 6A, the shooting protocol HEAD1 includes three PSDs, T1 weighted T1w, T2 weighted T2w, and other PSDs, and the first image pixel number Ix for each PSD. The first image pixel number Iy, the second image pixel number Ax, the second image pixel number Ay, the image addition number NEX, and ON / OFF of the options OP1 to OPn are set. In general, T1 weighted T1w and T2 weighted T2w read from PSD collect two-dimensional photographing data, and based on parameters, dozens of two-dimensional second images G2 and first images from the two-dimensional photographing data. G1 is reconstructed. Note that the slice interval in the Z-axis direction is set by PSD.

  As shown in FIG. 6B, in the shooting protocol HEAD2, 3D shooting 3D1 is selected from one PSD, and for this PSD, the first image pixel number Ix, the first image pixel number Iy, The two-image pixel number Ax, the second image pixel number Ay, the number of image additions NEX, and ON / OFF of the options OP1 to OPn are set. In general, the 3D image 3D1 read out from the PSD collects 3D image data that is 3D, and based on the parameters, several tens to several hundreds of 2D second images G2 are obtained from the 3D image data. And the first image G1 is reconstructed. Note that the interval of image reconstruction in the Z-axis direction is set by PSD.

  As shown in FIG. 6, a plurality of PSDs or one PSD can be set for one shooting protocol as shooting conditions, and the first image which is a parameter for image reconstruction for each PSD. The number of pixels Ix, the number of first image pixels Iy, the number of second image pixels Ax, the number of second image pixels Ay, the number of image additions NEX, and ON / OFF of options OP1 to OPn can be set. Further, the second image pixel number Ax and the second image pixel number Ay are not set in advance or set by the operator, but according to the time input by the calculation unit 175 by the display time input unit 195. It may be set automatically.

  The magnetic resonance imaging apparatus 10 can simultaneously read out a plurality of imaging protocols of the imaging protocol HEAD1 and the imaging protocol HEAD2, and the operator can add and delete imaging protocols as necessary. The operator can also add and delete PSDs. For example, the operator can capture a PSD desired by the operator by reading a plurality of preset imaging protocols and deleting the PSDs that are not duplicated or unnecessary. In addition, an imaging protocol suitable for the operator who logged in to the magnetic resonance imaging apparatus 10 can be read by creating an imaging protocol for each operator and storing it in the storage unit 110. Further, if the subject to be photographed knows the disease name or the like in the brain, the photographing protocol suitable for the subject SB can be read out.

  For the sake of simplicity, the following describes a case where one PSD is read out for one imaging protocol HEAD2 shown in FIG. 6B.

  In the shooting protocol HEAD2, one 3D shooting 3D1 is selected from PSDs as a 3D shooting method.

  The first image pixel number Ix on the X axis and the first image pixel number Iy on the Y axis are pixel values of the first image G1 in which image quality is emphasized. For example, the pixel value of the first image G1 is set so that the first image pixel number Ix is 256 pixels and the first image pixel number Iy is 256 pixels. The first image pixel number Ix on the X axis and the first image pixel number Iy on the Y axis are also the phase encode number and frequency encode number at the time of shooting. There are a method of setting the phase encoding direction in the X-axis direction and setting the frequency encoding direction in the Y-axis direction, and a method of setting the frequency encoding direction in the X-axis direction and setting the phase encoding direction in the Y-axis direction.

  The second image pixel number Ax on the X axis and the second image pixel number Ay on the Y axis are pixel values of the second image G2 in which speed is important. For example, the pixel value of the second image G2 is set such that the second image pixel number Ax is 64 pixels and the second image pixel number Ay is 64 pixels. Further, the ratio may be changed between the X-axis direction and the Y-axis direction such that the second image pixel number Ax is 64 pixels and the second image pixel number Ay is 128 pixels. Furthermore, the calculation unit 75 may automatically set the time according to the time input by the display time input unit 195.

  The image addition number NEX represents the number of times PSD is repeated and is an integer multiple of 1, 2, or 3 or more. The number of image additions NEX in the present embodiment is a setting value of the number of PSDs used for image reconstruction. If PSD is executed three times at the time of shooting, one to three image addition times can be selected. . Note that the number of times of image addition NEX at the time of shooting is set to PSD. The first image G1 is reconstructed with the image addition count NEX executed at the time of shooting.

  A plurality of options OP can be set, and options OP1 to OPn can be set. For example, the option OP can set image edge enhancement, fat enhancement, water enhancement, and the like, and sets selection or non-selection from a plurality of options OP. Edge enhancement, fat enhancement, water enhancement, and the like are image reconstruction techniques that enhance part or all of an image.

  Furthermore, the operator can specify the second reconstruction time Ta2 required to display the second image G2 with importance on speed via the display time input unit 195 as a numerical value. Specifically, the second image reconstruction time Ta2 until the second image G2 is displayed is input as 10 seconds. Further, the second image G2 is displayed in a time of 50% or 25% of the first image reconstruction time Ta1 until the first image G1 is displayed based on the imaging protocol set by the operator. It is also possible to display the second image G2 in terms of time or to input at a rate of time.

Returning to the flowchart of FIG. 5, in step S42, the calculation unit 175 calculates the basic image reconstruction time Ta. The basic image reconstruction time Ta is a time required for image reconstruction by the basic photographing protocol PC used by the calculation unit 175 for calculation. The basic image reconstruction time Ta is the PSD, the first image pixel number Ix on the X axis of the first image G1, the first image pixel number Iy on the Y axis of the first image, and the second X axis on the second image G2. It has parameters of an image pixel number Ax, a second image pixel number Ay on the Y axis of the second image G2, an image addition count NEX, and options OP1 to OPn. The basic image reconstruction time Ta in the basic photographing protocol PC can be expressed by Equation 1 shown below. Note that f is a function, and a predetermined function is assigned. Note that the basic image reconstruction time Ta of the basic imaging protocol PC is acquired as an experimental value in advance and stored in the storage unit 110.
Ta = f (PSD, Ix, Iy, Ax, Ay, NEX, OP)

  In step S43, the calculation unit 175 calculates a time until an image is displayed, that is, a first image reconstruction time Ta1 based on the set shooting protocol PC1 in which the operator sets shooting conditions. The calculation unit 175 may calculate the first image reconstruction time Ta1 based on the difference between the set photographing protocol PC1 and the basic photographing protocol PC, or may add and calculate the necessary image reconstruction time for each parameter. . Note that the parameters of the second image pixel number Ax and the second image pixel number Ay are not used for calculating the first image reconstruction time Ta1.

  In step S <b> 44, the calculation unit 175 calculates shooting protocol parameters so that the second image G <b> 2 can be reconstructed within the reconstruction time input by the display time input unit 195. For example, it is assumed that the calculation unit 175 has the parameter image addition count NEX of 3 and the fat emphasis option OP has been selected to display the first image G1. Even in such a case, the image addition count NEX is set to 1 to display the second image G2 within the reconstruction time input by the display time input unit 195, and the fat emphasis option OP is eliminated. As described above, the calculation unit 175 calculates a parameter indicating which parameter is changed so that the second image G2 can be reconstructed within the reconstruction time input by the display time input unit 195.

  Even if the image addition count NEX is set to 1 and the fat emphasis option OP is omitted, the second image G2 may not be displayed within the second image reconstruction time Ta2 input by the display time input unit 195. Therefore, the calculation unit 175 coarsens the resolution and shortens the image reconstruction time. That is, the parameters of the second image pixel number Ax and the second image pixel number Ay are changed to 1/2 or 1/4 of the first image pixel number Ix and the first image pixel number Iy of the setting photographing protocol PC1.

  In step S45, the calculation unit 175 displays the first image reconstruction time Ta1 until the image is displayed based on the set photographing protocol PC1 set by the operator on the display unit 180. In addition, the imaging protocol parameter for displaying the second image G2 within the second image reconstruction time Ta2 calculated by the calculation unit 175 is displayed on the display unit 180.

  In step S46, after confirming the displayed first image reconstruction time Ta1 or the parameters of the imaging protocol, the operator starts imaging. After the end of shooting, the operator returns to step S05 in FIG. 2 and confirms the second image G2 focusing on speed.

  In step S41, the setting photographing protocol PC1 preferably stores in advance the parameters (second image pixel number Ax, second image pixel number Ay, image addition number NEX, and option OP) in the storage unit 110 for each operator. Moreover, it is preferable to memorize | store the display time which displays the 2nd image G2 on the display part 180 for every operator. Since the operator's favorite parameters are read, the operator does not need to change the set value of the second image reconstruction time Ta2 every time the photographing protocol is read. In addition, the setting imaging protocol PC1 is stored not only for each operator but also for each subject SB or imaging region in advance as an imaging protocol in the storage unit 110, thereby shortening the examination time.

  FIG. 7 is an example of the display time input unit 195 of the graphic user interface displayed on the display unit 180. The operator can finely set the second image reconstruction time Ta2 until the second image G2 is displayed on the display unit 180 using the display time input unit 195.

  In the first example shown in FIG. 7A, the display time input unit 195 displays a numerical display (for example, 60 sec) of the first image reconstruction time Ta1 calculated by the calculation unit 175. The second image reconstruction time Ta2 is scaled and displayed as a percentage. In the scale display, the first image reconstruction time Ta1 is displayed in full scale (100%), and the second image reconstruction time Ta2 is displayed as a percentage as the scale tool ST at a ratio to the first image reconstruction time Ta1. In the display time input unit 195, the operator can change the second image reconstruction time Ta2 by moving the scale tool ST left and right in the direction indicated by the arrow AR1. The calculating unit 175 calculates parameters for image reconstruction within the second image reconstruction time Ta2. Then, these parameters are displayed on the display unit 180.

  In the second example shown in FIG. 7B, a numerical display of the first image reconstruction time Ta1 calculated by the calculation unit 175 is displayed. In the second example, the operator can input an arbitrary reconstruction time desired by the display time input unit 195 as a numerical value. A specific numerical value can be input in the frame of the second image reconstruction time Ta2 shown in the figure. In addition, the display time input unit 195 prepares a check box CB, and an option OP item that the operator wants to emphasize when displaying the second image G2 can be selected by selecting an option OP using the check box CB. . On the premise of the second image reconstruction time Ta2 input by the operator and the designated option OP, the calculation unit 175 displays parameters that can be terminated within the second image reconstruction time Ta2, and allows the operator to confirm. Can do.

  Also in the third example shown in FIG. 7C, the numerical display of the first image reconstruction time Ta1 calculated by the calculation unit 175 is displayed. Further, the display time input unit 195 prepares a pull-down menu PD, and the operator can select an item he / she wants to focus on by confirming the second image G2 by selecting the pull-down menu PD. For example, a desired number of pixels can be specified in the pull-down menu PD1, and an image addition count NEX can be specified in the pull-down menu PD2. Then, the calculation unit 175 calculates the second image reconstruction time Ta2 using the parameters specified in the pull-down menus PD1 and PD2. For example, if the first image G1 is reconstructed with 256 × 256 pixels and the second image G2 is designated with 128 × 128 pixels, the amount of data used in the image reconstruction of the second image G2 becomes ¼. The second image reconstruction time Ta2 is shortened. The calculation result of the second image reconstruction time Ta2 is displayed as a numerical value in FIG. 7C, and the operator is made to recognize the second image reconstruction time Ta2.

  Although the first to third examples are shown in FIG. 7, it goes without saying that the method of setting the second image reconstruction time Ta2 is not limited to these. For example, the first example to the third example may be combined. In the first to third examples, the first image reconstruction time Ta1 is displayed. However, the first image reconstruction time Ta1 may not be displayed for an experienced operator.

<Modification>
The input screen by the display time input unit 195 described above can change all the parameters on one screen for the master of the magnetic resonance imaging apparatus 10, and can set the second image G2 desired by the operator. The magnetic resonance imaging apparatus 10 is highly advanced with new PSDs and updated parameters. For this reason, it is difficult for an unskilled person and a temporary operator of the magnetic resonance imaging apparatus 10 to imagine changes due to PSD and parameters. This modification will explain a display time input unit 195 that is friendly to unskilled users.

  As described above, the setting shooting protocol PC1 is the shooting method PSD, the first image pixel number Ix, the first image pixel number Iy, the second image pixel number Ax, the second image pixel number Ay, the image addition number NEX, and The parameter configuration includes option OP1 to option OPn. It is difficult for an unskilled person of the magnetic resonance imaging apparatus 10 to imagine an image reconstructed with these parameters. For example, the operator can use several tens to several hundreds of normal PSD images, a difference in image quality due to the difference between the first image pixel number and the second image pixel number, a difference in image quality due to a difference in the number of image additions NEX, and various options. It is difficult to imagine an image created by OP.

  The display time input unit 195 can assist the operator in inputting parameters by specifically displaying the difference in image quality depending on the parameters on the display unit.

  FIG. 8 is a flowchart by the display time input unit 195. The flowchart of FIG. 8 shows a method of inputting parameter values in an interactive format suitable for unskilled users of the magnetic resonance imaging apparatus 10. The flowchart of FIG. 8 replaces steps S41 to S45 shown in FIG.

  In step S51, the display time input unit 195 displays a normal example image of the first image G1 in the set photographing protocol PC1. The display time input unit 195 displays a normal example image of the first image G1 in the corresponding PSD representative portion stored in the storage unit 110 in advance.

In step S52, the display time input unit 195 inputs the values of the second image pixel number Ax and the second image pixel number Ay. The display time input unit 195 allows the operator to input values of the second image pixel number Ax and the second image pixel number Ay by a pull-down menu and manual input. FIG. 9A is a diagram showing an input screen for the second image pixel number Ax and the second image pixel number Ay. In FIG. 9, the image display method uses the tab display shown in FIG.
As shown in FIG. 9A, the change in image quality due to the input value can be displayed as an image by switching tabs on the right side of the input screen of the second image pixel number Ax and the second image pixel number Ay. is there. One normal example of the representative part displayed in step S51 is displayed on the first image G1, and the result of processing the normal example by the image reconstruction unit is displayed on the second image G2, or the storage unit 110 is stored in advance. Display what has been saved in.

  As shown in FIG. 9A, in the upper part of the normal example displayed by the display time input unit 195, the display of the value of the first image reconstruction time Ta1 of the setting photographing protocol PC1 and the second according to the change of the parameters are displayed. The ratio and value of the image reconstruction time Ta2 are displayed. Also in the following FIGS. 9B and 9C, the value of the first image reconstruction time Ta1 and the ratio and value of the reconstruction time Ta2 are displayed.

  Returning to FIG. 8, in step S <b> 53, the display time input unit 195 determines whether the image addition count NEX is 2 or more. If the image addition count NEX is 1, the process proceeds to step S54. If the image addition count NEX is 2 or more, the process proceeds to step S53.

  In step S54, the display time input unit 195 inputs the image addition count NEX. The display time input unit 195 allows the operator to input a value of the image addition count NEX of 2 or more by pull-down menu and manual input. In this case, the number of image additions NEX that can be input is an integer, and the number of image additions NEX used for image reconstruction is input from among the numbers added by PSD. FIG. 9B is a diagram showing an input screen for the image addition count NEX. As shown in FIG. 9B, the change in the image quality of the input value can be displayed as the second image G2 on the right side of the input screen for the image addition count NEX. The second image G2 may display the result of processing the first image G1 at the representative part displayed in step S51 by the image reconstruction unit or may be stored in the storage unit 110 in advance.

  Returning to FIG. 8, in step S55, the display time input unit 195 inputs ON / OFF of the option OP. The display time input unit 195 allows the operator to input optional on / off using a check box or the like. FIG. 9C is a diagram showing an input screen for an option OP. As shown in FIG. 9C, a second image G2 that changes depending on whether the check box is on or off is displayed on the right side of the option OP input screen. The second image G2 may display the result of processing the first image G1 at the representative part displayed in step S51 by the image reconstruction unit or may be stored in the storage unit 110 in advance.

  Returning to FIG. 8, in step S56, the display time input unit 195 determines whether or not the input has been completed for all options. The display time input unit 195 ends when the input from the option OP1 to the option OPn is completed, and when it is not input, returns to step S55 and restarts the input.

  In this modification, all parameters are input. However, the input may be performed only when the value of the setting photographing protocol PC1 is changed. Further, the display screens shown in FIGS. 9A to 9C can be arranged and displayed on one screen, and the operator can input only items to be changed.

  According to the modification shown above, the magnetic resonance imaging apparatus 10 can reconstruct a desired second image G2 even by an untrained person.

  As described above, the optimal embodiment of the present invention has been described in detail. However, as will be apparent to those skilled in the art, the present invention can be implemented with various modifications and variations within the technical scope thereof. For example, although the display time input unit 195 is provided in the present embodiment, the display time input unit 195 is not necessarily provided when the display is performed in a fixed short time. For example, you may make it display the 2nd image which reconfigure | reconstructs an image uniformly in 1/4 time of the imaging | photography protocol which the conditions set by the operator.

DESCRIPTION OF SYMBOLS 10 ... Magnetic resonance imaging apparatus 100 ... Magnet system 102 ... Main magnetic field coil part 106 ... Gradient coil part 108 ... Coil part 110 ... Storage part 130 ... Gradient coil drive part 140 ... Coil drive part 150 ... Data collection part 160 ... Sequence control part 170 ... Data processing unit 175 ... Calculation unit 180 ... Display unit 190 ... Input unit 195 ... Display time input unit 200 ... Bed Ax ... Second image pixel number Ay in the x-axis direction ... Second image pixel number CB in the y-axis direction ... Check box Ix ... Number of first image pixels in the x-axis direction Iy ... Number of first image pixels in the y-axis direction NEX ... Number of image additions OP ... Option PC ... Basic imaging protocol PC1 ... Imaging protocol PD ... Pull-down menu SB ... Subject ST ... Scale tool T1w ... T1 emphasis, T2w ... T2 emphasis T ... basic image reconstruction time Ta1 ... first image reconstruction time, Ta2 ... second image reconstruction time Ta3 ... desired image reconstruction time G1 ... first image G2 ... second image

Claims (9)

In a magnetic resonance imaging apparatus for displaying a first tomographic image of the subject on a display unit using a magnetic resonance signal generated from the subject,
A condition input unit for inputting imaging conditions for obtaining the first tomographic image;
A calculating unit that calculates a second image reconstruction condition for reconstructing an image in a time shorter than a time required for image reconstruction in the first image reconstruction condition for reconstructing the first tomographic image based on the imaging condition; With
A magnetic resonance imaging apparatus that displays a second tomographic image reconstructed under the second image reconstruction condition on the display unit.   The magnetic resonance imaging apparatus according to claim 1, wherein the calculation unit calculates a time until the first tomographic image is displayed on the display unit under the first image reconstruction condition. A storage unit for storing an image reconstruction time required for image reconstruction for each of a plurality of parameters constituting an image reconstruction condition that can be set by the condition input unit;
The calculation unit calculates the second image reconstruction condition by combining the parameters, and calculates a time until the second tomographic image is displayed on the display unit under the second image reconstruction condition. Item 3. A magnetic resonance imaging apparatus according to item 1 or 2.   A display time input unit for inputting a time until the second tomographic image is displayed on the display unit or a ratio of a time until the second tomographic image is displayed with respect to a time when the first tomographic image is displayed. A magnetic resonance imaging apparatus according to any one of claims 1 to 3, further comprising: The first image reconstruction condition includes the type of pulse sequence for obtaining the magnetic resonance signal and the resolution of the tomographic image,
The magnetic resonance imaging apparatus according to claim 4, wherein the calculation unit calculates the second image reconstruction condition with the resolution reduced based on the time or the ratio input by the display time input unit. The first image reconstruction condition includes the number of additions of the tomographic image to reduce noise of the tomographic image,
The magnetic resonance imaging apparatus according to claim 4, wherein the calculation unit calculates the second image reconstruction condition in which the number of additions is reduced, based on the time or the ratio input by the display time input unit. The first image reconstruction condition includes an image selection condition that emphasizes part or all of the tomographic image,
The magnetic resonance imaging apparatus according to claim 4, wherein the calculation unit calculates the second image reconstruction condition without the image selection condition based on the time or the ratio input by the display time input unit. .   8. The magnetic resonance according to claim 4, wherein the time or the ratio is set in advance via the display time input unit for each subject or for each operator who operates the magnetic resonance imaging apparatus. Imaging device.   9. The magnetic resonance according to claim 1, wherein after the image reconstruction of the first tomographic image is completed, the display unit displays the first tomographic image instead of the second tomographic image. 10. Imaging device.