JP2012147920A - Magnetic resonance imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique making imaging effective and highly qualitative regardless of kinds and number of precedent pulses used in imaging using a plurality of precedent pulses.SOLUTION: A user interface can set parameters specifying synthesized precedent pulses in a visually perceiving condition. A means synthesizes the set precedent pulses and applies the same in the case of using the plurality of precedent pulses. The user interface has a text input area and an image input area and reflects the inputs each other.

Description

  The present invention relates to a magnetic resonance imaging technique. In particular, the present invention relates to a preceding pulse setting support technique for performing image contrast decoration, unnecessary signal removal, and the like prior to actual imaging.

  Magnetic resonance imaging is a uniaxial slice selection that identifies the imaging region by applying a high-frequency excitation pulse (excitation RF pulse) with a specific fundamental frequency while a uniform static magnetic field is applied to the subject. After the application of the gradient magnetic field, two-dimensional position is applied to the magnetic resonance signal (echo signal) generated by excitation by applying a gradient magnetic field in two axial directions (phase direction and frequency direction) orthogonal to the slice direction. Image data of a desired tomogram is obtained by reconstructing the obtained echo signal by giving information and measuring. Usually, the gradient magnetic fields that give two-dimensional position information are referred to as a phase encode gradient magnetic field and a frequency encode gradient magnetic field, respectively.

  In such magnetic resonance imaging, an RF pulse may be applied for the purpose of decoration of image contrast, unnecessary signal removal, etc. prior to application of an excitation RF pulse for collecting echo signals. Such an RF pulse is called a preceding pulse, and a plurality of different preceding pulses may be applied depending on the purpose.

  For example, if there is blood flow in the imaging region or there is a part that moves at a specific period, an artifact may occur in the obtained tomographic image. This is because the state of the imaging region changes after the slice selective gradient magnetic field is applied and excited and before the phase encode gradient magnetic field or the frequency encode gradient magnetic field is applied. In order to avoid such an artifact, there is a technique called pre-saturation that suppresses a signal of a part that generates an artifact before the main imaging. This is a technique for suppressing artifacts by sufficiently reducing the signal obtained from this part at the time of main imaging by making the phase of the nuclear spin of the part that generates artifacts random and randomizing it before the main imaging. .

  For example, when imaging a site where two blood vessels flowing in opposite directions exist, it is necessary to presaturate the two sites, and it is necessary to apply two preceding pulses with different suppression target regions. Therefore, it is necessary to execute the pre-saturation sequence twice before the actual imaging sequence. At this time, if the imaging repetition time TR is constant, the number of slices that can be imaged decreases. On the other hand, if the number of slices is made constant, TR is extended, image contrast is changed, and imaging time is prolonged. In order to avoid this, there is a technique of obtaining two presaturation effects in one presaturation sequence by synthesizing and applying two preceding pulses (see, for example, Patent Document 1).

JP 2002-360539 A

  As described above, the preceding pulse changes the contrast of the acquired image, removes a signal unnecessary for diagnosis, or has a large influence on the image, and its parameter setting is complicated, and It requires high accuracy and is difficult. Therefore, as described above, even if the preceding pulse is synthesized and the deterioration of image quality due to the extension of the imaging time or the decrease in the number of imaging slices is suppressed, it takes time to set the parameters of the preceding pulse, or an appropriate setting cannot be made. The effect of synthesis is reduced.

  Depending on the pulse type, application of each RF pulse may cause a time difference between the pulses, which may affect the image quality and image quality, such as signal intensity differences.

  The present invention has been made in view of the above circumstances, and provides a technique for improving the efficiency and quality of imaging regardless of the type and number of preceding pulses used in imaging using a plurality of preceding pulses. With the goal.

  The present invention provides a user interface capable of setting parameters specifying a preceding pulse to be synthesized in a state where it can be easily grasped visually, and also provides means for synthesizing and simultaneously applying the set preceding pulses. The user interface includes a text input area and an on-image input area, and reflects the input to each other.

  Specifically, a magnetic resonance imaging apparatus including an imaging unit that reconstructs an image from echo signals acquired by operating each unit according to an imaging condition set via the imaging condition setting unit and a preset pulse sequence. The imaging condition setting unit generates a combined preceding pulse by combining a preceding pulse setting unit that receives an input of a parameter specifying each of a plurality of preceding pulses and a plurality of preceding pulses received by the preceding pulse setting unit. Preceding pulse synthesizing means, wherein the imaging means controls to apply the synthesized preceding pulse before execution of the main imaging, and the preceding pulse setting means independently sets the excitation region of each preceding pulse. A magnetic resonance imaging apparatus characterized by receiving input of the parameter on a preceding pulse setting screen that can be grasped Subjected to.

  According to the present invention, in imaging using a plurality of preceding pulses, imaging efficiency and quality can be improved regardless of the type and number of preceding pulses used.

It is a block diagram which shows schematic structure of the MRI apparatus of embodiment of this invention. It is a functional block diagram of the control processing system of the embodiment of the present invention. It is explanatory drawing for demonstrating the imaging condition setting initial screen of embodiment of this invention. It is explanatory drawing for demonstrating the preceding pulse setting screen of embodiment of this invention. It is explanatory drawing for demonstrating the synthetic | combination method of a preceding pulse. It is a sequence diagram of the pulse sequence of the embodiment of the present invention. It is a flowchart of the imaging process of embodiment of this invention. It is a flowchart of the preceding pulse setting process of embodiment of this invention. It is explanatory drawing for demonstrating the 1st preceding pulse setting screen of embodiment of this invention. It is explanatory drawing for demonstrating the 2nd preceding pulse setting screen of embodiment of this invention. It is explanatory drawing for demonstrating the 3rd preceding pulse setting screen of embodiment of this invention. It is explanatory drawing for demonstrating the ROI indicator displayed on the 2nd input area of Example 1. FIG. It is explanatory drawing for demonstrating the ROI indicator displayed on the 2nd input area of Example 2. FIG. It is explanatory drawing for demonstrating the ROI indicator displayed on the 2nd input area of Example 3. FIG. It is explanatory drawing for demonstrating the ROI indicator displayed on the 2nd input area of Example 4. FIG.

  Hereinafter, embodiments to which the present invention is applied will be described. Hereinafter, in all the drawings for explaining the embodiments of the present invention, those having the same function are denoted by the same reference numerals, and repeated explanation thereof is omitted.

  First, the MRI apparatus of this embodiment will be described. FIG. 1 is a block diagram showing the overall configuration of the MRI apparatus 10 of the present embodiment. The MRI apparatus 10 according to the present embodiment obtains a tomographic image of the subject 11 using a magnetic resonance phenomenon. As shown in FIG. 1, a static magnetic field generation system 20, a gradient magnetic field generation system 30, and a transmission system. 50, a receiving system 60, a control processing system 70, and a sequencer 40.

  The static magnetic field generation system 20 generates a uniform static magnetic field in the direction perpendicular to the body axis in the space around the subject 11 if the vertical magnetic field method is used, and in the body axis direction if the horizontal magnetic field method is used. The apparatus includes a permanent magnet type, normal conduction type, or superconducting type static magnetic field generation source disposed around the subject 11.

  The gradient magnetic field generation system 30 is a gradient magnetic field coil 31 wound in the three-axis directions of X, Y, and Z, which is a coordinate system (stationary coordinate system) of the MRI apparatus 10, and a gradient magnetic field power source that drives each gradient magnetic field coil. 32, and the gradient magnetic field power supply 32 of each gradient magnetic field coil 31 is driven in accordance with a command from the sequencer 40 to be described later, thereby applying gradient magnetic fields Gx, Gy, Gz in the three axial directions of X, Y, and Z. .

  The transmission system 50 irradiates the subject 11 with a high-frequency magnetic field pulse (hereinafter referred to as “RF pulse”) in order to cause nuclear magnetic resonance to occur in the nuclear spins of the atoms constituting the living tissue of the subject 11. A high-frequency oscillator (synthesizer) 52, a modulator 53, a high-frequency amplifier 54, and a high-frequency coil (transmission coil) 51 on the transmission side are provided. The high frequency oscillator 52 generates an RF pulse and outputs it at a timing according to a command from the sequencer 40. The modulator 53 amplitude-modulates the output RF pulse, and the high-frequency amplifier 54 amplifies the amplitude-modulated RF pulse and supplies the amplified RF pulse to the transmission coil 51 disposed in the vicinity of the subject 11. The transmission coil 51 irradiates the subject 11 with the supplied RF pulse.

  The receiving system 60 detects a nuclear magnetic resonance signal (echo signal, NMR signal) emitted by nuclear magnetic resonance of nuclear spins constituting the biological tissue of the subject 11, and receives a high-frequency coil (receiving coil) on the receiving side. 61, a signal amplifier 62, a quadrature detector 63, and an A / D converter 64. The reception coil 61 is disposed in the vicinity of the subject 11 and detects an NMR signal in response to the subject 11 induced by the electromagnetic wave irradiated from the transmission coil 51. The detected NMR signal is amplified by the signal amplifier 62 and then divided into two orthogonal signals by the quadrature phase detector 63 at a timing according to a command from the sequencer 40, and each is digitally converted by the A / D converter 64. It is converted into a quantity and sent to the control processing system 70.

  The sequencer 40 repeatedly applies RF pulses and gradient magnetic field pulses in accordance with a predetermined pulse sequence. The pulse sequence describes a high-frequency magnetic field, a gradient magnetic field, signal reception timing and intensity, and is stored in the control processing system 70 in advance. The sequencer 40 operates in accordance with instructions from the control processing system 70 and transmits various commands necessary for collecting tomographic image data of the subject 11 to the transmission system 50, the gradient magnetic field generation system 30, and the reception system 60.

  The control processing system 70 performs control of the entire MRI apparatus 10, various data processing, display and storage of processing results, and includes a CPU 71, a storage device 72, a display device 73, and an input device 74. The storage device 72 includes a hard disk and an external storage device such as an optical disk or a magnetic disk. The display device 73 is a display device such as a CRT or a liquid crystal. The input device 74 is an interface for inputting various control information of the MRI apparatus 10 and control information of processing performed by the control processing system 70, and includes, for example, a trackball or a mouse and a keyboard. The input device 74 is disposed in the vicinity of the display device 73. The operator interactively inputs instructions and data necessary for various processes of the MRI apparatus 10 through the input device 74 while looking at the display device 73.

  The CPU 71 implements each process of the control processing system 70 such as control of operations of the MRI apparatus 10 and various data processing by executing a program stored in advance in the storage device 72 in accordance with an instruction input by the operator. . FIG. 2 is a functional block diagram for explaining each function realized by the CPU 71 executing a program in the control processing system 70 of the present embodiment.

  The control processing system 70 according to the present embodiment supports setting of imaging conditions by a program and controls each unit according to the set imaging conditions to realize imaging. In order to realize these, the control processing system 70 of the present embodiment includes an imaging unit 410 that controls each part of the MRI apparatus 10 and performs imaging, and an imaging condition setting unit 420 that supports setting of imaging conditions. The imaging condition setting unit 420 also includes a basic condition setting unit 421 that sets imaging conditions (hereinafter referred to as basic conditions) other than parameters that specify the preceding pulse, and parameters that specify the preceding pulse (preceding pulse parameter and A preceding pulse setting unit 422 for setting the parameters, and a preceding pulse setting unit 422 for synthesizing the preceding pulse for which a parameter is set to be one preceding pulse and calculating the parameter.

  The imaging condition setting unit 420 accepts imaging conditions using a predetermined positioning image. FIG. 3 is an example of the imaging condition setting initial screen 500 that the imaging condition setting unit 420 of the present embodiment generates and displays on the display device 73 to accept the imaging condition setting. As shown in this figure, the imaging condition setting initial screen 500 of this embodiment includes a positioning image display area 510 for displaying a positioning image, a basic condition setting button 520 for accepting an intention to set a basic condition, and a preceding pulse parameter. A preceding pulse condition setting button 530 that accepts an intention to set the image capturing, and an imaging button 540 that accepts an instruction to start imaging.

  In the positioning image display area 510, a positioning image acquired in advance is displayed. When the pressing of the basic condition setting button 520 is accepted, the imaging condition setting unit 420 causes the basic condition setting unit 421 to perform a basic condition setting process described later. In addition, when the pressing of the preceding pulse condition setting button 530 is accepted, the imaging condition setting unit 420 causes the preceding pulse condition setting unit to perform a preceding pulse setting process described later. When the pressing of the imaging button 540 is accepted, the imaging condition setting unit 420 starts imaging with the imaging conditions set in the imaging unit 410.

  The basic condition setting unit 421 receives a basic condition input in accordance with an instruction from the imaging condition setting unit 420 and performs basic condition setting processing for setting as an imaging parameter. This process is the same as the conventional imaging condition setting other than the preceding pulse.

  The preceding pulse setting unit 422 receives the input of the preceding pulse parameter in accordance with an instruction from the imaging condition setting unit 420 and performs a preceding pulse setting process for setting as a preceding pulse parameter. The preceding pulse setting unit 422 generates a preceding pulse setting screen and displays it on the display device 73.

  FIG. 4 shows an example of the preceding pulse setting screen 600 of this embodiment. As shown in the figure, the preceding pulse setting screen 600 of the present embodiment includes a first input area 610 that accepts an input of a preceding pulse parameter by text and the like, and a second input area 620 that accepts an input on a positioning image. A decision button 630 for receiving an instruction to set the input value as the preceding pulse parameter. The preceding pulse setting unit 422 updates the display of the preceding pulse setting screen 600 by reflecting the parameters input by the operator via both input areas.

  The preceding pulse synthesizing unit 423 synthesizes the preceding pulse for which the parameter has been received by the preceding pulse setting unit 422 and sets it as one preceding pulse.

  The synthesis is performed by the method disclosed in Patent Document 1. The outline of the method is as follows. Usually, for the preceding pulse (RF pulse) and the excitation RF pulse for main imaging, a harmonic pulse having a waveform obtained by amplitude-modulating a high frequency having fundamental frequencies f0, f1, and f2 corresponding to the slice position by a sinc function or the like is used. In general, control is performed so that the phase of the waveform of the fundamental frequency is constant for each irradiation at the maximum amplitude position of the sinc function. Here, the maximum amplitude position of the sinc function is when t = 0, where the sinc function is a function of time t.

  As shown in FIG. 5, the plurality of fundamental wave components of the preceding pulse (RF pulse) are synthesized by shifting the phase so that the sum of the amplitudes does not exceed the capacity limit of the transmission system 50. As shown in FIG. 5, the RF pulse 201 whose fundamental frequency is a low frequency does not shift the phase as it is, and the RF pulse 202 whose fundamental frequency is a high frequency shifts the phase of the fundamental wave component by 90 °. As a result, the RF pulse 203, which is the sum of the two, has a smaller amplitude than when both are synthesized as they are. In addition, the phase of the sinc function which is an amplitude modulation function of the RF pulses 201 and 202 is the same. The phase to be shifted is not necessarily optimal at 90 °, but an optimal phase difference is given according to the fundamental frequency.

  The imaging unit 410 controls each unit according to the imaging conditions set by the imaging condition setting unit 420 and the pulse sequence stored in the storage device 72 in advance, and reconstructs an image from the acquired echo signals.

  An example of the pulse sequence 300 executed here is shown in FIG. In this figure, RF, Gs, Gp, and Gf signals represent axes of an RF pulse, a slice gradient magnetic field, a first readout gradient magnetic field, a second readout gradient magnetic field, and an echo signal, respectively.

  In the present embodiment, prior to the main imaging sequence 310, a preceding pulse sequence 320 for applying a preceding pulse is executed. In the preceding pulse sequence, a plurality of preceding pulses to be applied are combined and applied as one preceding pulse 321. In the imaging sequence 310, an excitation RF pulse 311 is applied together with an imaging slice selection gradient magnetic field 312 for selecting an imaging slice, encoding gradient magnetic fields 313 and 314 that give position information to the echo signal are applied in two directions, and an echo signal 315 is applied. Are collected.

  Here, the flow of the imaging process of the present embodiment by the above-described units will be described. It is assumed that the positioning image has been acquired first. Here, a case will be described as an example where the basic conditions are set and then the preceding pulse parameters are set. FIG. 7 is a processing flow of the imaging process of the present embodiment.

  When receiving an instruction from the operator, the imaging condition setting unit 420 displays the imaging condition setting initial screen 500. When the operator presses the basic condition setting button 520, the imaging condition setting unit 420 displays the basic condition setting. The basic condition setting process is performed by the unit 421, and the setting of the basic condition is accepted (step S1101). Then, the imaging condition setting initial screen 500 is displayed again.

  Next, when the operator presses down the preceding pulse condition setting button 530, the imaging condition setting unit 420 causes the preceding pulse setting unit 422 to perform a preceding pulse setting process and accepts a preceding pulse parameter (step S1102). Then, the preceding pulse synthesizing unit 423 is caused to perform the preceding pulse synthesizing process (step S1103). Then, the imaging condition setting initial screen 500 is displayed again.

  When accepting pressing of the imaging button 540 by the operator, the imaging unit 410 performs imaging (step S1104).

  Next, details of the preceding pulse setting process by the preceding pulse setting unit 422 in step S1102 will be described. Here, parameters of a plurality of different types of preceding pulses are set. The preceding pulse to be set is applied as a set of two pulses having different excitation regions. The parameters to be set are, for example, the type (pulse type), shape, size, FA (flip angle), number of applications, and application position of the preceding pulse. The pulse type and shape are set for each pulse type, and the size, FA, number of applications, and application position are set for each pulse. FIG. 8 is a process flow of the preceding pulse setting process of the present embodiment.

  When receiving the instruction to start the preceding pulse setting process, the preceding pulse setting unit 422 generates an initial screen (first preceding pulse setting screen 601) of the preceding pulse setting screen 600 and displays it on the display device 73 (step S1201). . FIG. 9 shows a screen example of the first preceding pulse setting screen 601 displayed on the display device 73 at this time. As shown in the figure, in the first preceding pulse setting screen 601, a first pulse type input area 611 for inputting the number of types of preceding pulses used in imaging is displayed in the first input area 610. Positioning images are displayed in the second input area 620, respectively.

  Various data necessary for generating the first preceding pulse setting screen 601 data is stored in the storage device 72 in advance.

  When the operator inputs the number of preceding pulse types (preceding pulse type) via the preceding pulse type input area 611, the preceding pulse setting unit 422 receives the input preceding pulse type number. (Step S1202) Then, a second preceding pulse setting screen 602 corresponding to the accepted number of preceding pulses is generated and displayed on the display device 73 (Step S1203). The generated second preceding pulse setting screen 602 includes seed-specific parameter input areas 615 corresponding to the number of preceding pulse types in the first input area 610. Each parameter input area 615 includes a pulse type input area 612 for inputting the number of preceding pulse types, and a shape input area 613 for inputting the shape of the preceding pulse.

  FIG. 10 shows a screen example of the second preceding pulse setting screen 602 displayed on the display device 73 when 2 is input as the number of preceding pulse types. As shown in the figure, in the second preceding pulse setting screen 602, a parameter input area 615 for each type including a pulse type input area 612 for the number of preceding pulse types and a shape input area 613 in the first input area 610. Is displayed for each preceding pulse type, and a positioning image is displayed in the second input area 620.

  Various data necessary for generating the second preceding pulse setting screen 602 is stored in the storage device 72 in advance. The pulse type and shape may be configured such that a settable pulse type is presented to the operator and the operator can select it. The pulse types that can be set are, for example, the preceding pulses (for example, MRS, Black Blood, Presachi, labeling) and others described in the embodiments described later, and the shapes are ellipses, circles, belts, and the like. These data are stored in the storage device 72 in advance. The presentation is performed using, for example, a pull-down menu.

  Further, a standard shape for each pulse type is held in the storage device 72, and when a pulse type other than the other is selected, a standard shape is presented according to the selection of the pulse type. Also good. The standard shape is, for example, a shape given in each example described later. In addition, the operator can change the shape after the presentation.

  When the operator inputs the number of pulse types and the shape of the preceding pulse for the number of preceding pulse types via the pulse type input area 612 and the shape input area 613, the preceding pulse setting unit 422 receives it (step S1204). Then, the preceding pulse setting unit 422 generates a third preceding pulse setting screen 603 and displays it on the display device 73 (step S1205). The generated third preceding pulse setting screen 603 further includes two individual parameter input areas 614 for setting parameters for each preceding pulse in the various parameter input areas 615. This is because the preceding pulses set in the present embodiment are a set of two preceding pulses having different excitation regions. At this time, a region (ROI) excited by a preceding pulse corresponding to the pulse type and shape input in the pulse type input region 612 and the shape input region 613 is positioned on the positioning image of the second input region 620. Display at the initial position.

  FIG. 11 shows a screen example of the third preceding pulse setting screen 603 when the preceding pulse type is input as MRS and the shape is input as an ellipse. Here, the case where the parameters set as the preceding pulse parameters in the individual parameter input area 614 are the size, FA (flip angle), and the number of times is exemplified. As shown in the figure, on the third preceding pulse setting screen 603, a parameter input area 615 for each type is displayed in the first input area 610 for each preceding pulse type. In the type-specific parameter input area 615, a pulse type input area 612, a shape input area 613, and an individual parameter input area 614 are displayed. In the second input area 620, an indicator for identifying an area (ROI) excited by a preceding pulse corresponding to the pulse type and shape input in the pulse type input area 612 and the shape input area 613 on the positioning image. (ROI indicator) 621 is displayed at the initial position.

  Of the parameters input to the first input area 610, the size varies depending on the shape. In other words, the diameter of the circle is accepted, the length of the minor axis and the major axis is accepted if it is an ellipse, and the width is entered if it is a band.

  In addition, the ROI indicator 621 displayed in the second input area 620 has a display mode that can be specified for each pulse type, such as changing the display color. In addition, among parameters set via the first input area 610, the display mode of the ROI indicator 621 is similarly changed for parameters such as FA that cannot display their characteristics on the positioning image so that they can be specified. Good. For example, a predetermined pattern is arranged and displayed on the ROI indicator 621 according to FA. In addition, a numerical value input to the first input area 610 may be displayed in the vicinity of the corresponding ROI indicator 621.

  Various data necessary for generating the third preceding pulse setting screen 603 including the initial position of the ROI is stored in the storage device 72 in advance.

  In step S1204, when the operator inputs a pulse type, not only the shape but also each individual parameter may be automatically presented. Similar to the shape, the individual parameters used in each embodiment described later are stored in the storage device 72 in advance, and the operator selects the pulse type and displays it. Also in this case, the operator can change the shape after presentation. When other pulse types are selected, the operator inputs all the shapes and individual parameters, and the preceding pulse is applied based on the input shapes and parameters.

  The operator inputs parameters independently for each preceding pulse to be applied via the third preceding pulse setting screen 603. That is, a numerical value or the like is directly input to the first input area 610. In addition, the size and position of the ROI are set by giving a change instruction to the ROI indicator 621 displayed in the second input area 620 using the input device 74. The preceding pulse setting unit 422 performs control so that the data input to the first input area 610 matches the data specified via the second input area 620.

  For example, when the size is input to the first input area 610, the preceding pulse setting unit 422 calculates the ROI displayed in the second input area 620 accordingly, and displays the size according to the input size. Update. Conversely, when the size is changed in the second input area 620, the preceding pulse setting unit 422 calculates the changed size and displays it in the first input area 610. When FA is input in the first input area 610, a numerical value is displayed in the vicinity of the corresponding ROI in the second input area 620.

  As an example, this flow will be described using an example in which the position and size are set on the positioning image of the second input area 620, and then the size, FA, and number of times are set in the first input area 610. To do. In this flow, N (an integer of 1 or more) is the number of preceding pulses, and n (an integer satisfying 1 ≦ n ≦ N) is a counter.

  For each preceding pulse (step S1206), first, the operator operates the ROI indicator 621 on the positioning image in the second input area 620 to input the position and size of the ROI. The preceding pulse setting unit 422 receives the input, calculates and holds the parameter value, and reflects the parameters that can be input in the first input area 610 in the first input area 610 (step S1207). Then, the operator inputs parameters (here, size, FA, number of times) in the first input area 610. The preceding pulse setting unit 422 receives the input and reflects it in the second input area 620 (step S1208).

  The processes in steps S1206 and S1207 are repeated for all the preceding pulses (steps S1209 and 1210), and when the input of desired values is completed, the operator presses the enter button 630 to instruct the end of setting. When the pressing of the determination button 630 is accepted, the preceding pulse setting unit 422 sets the parameter input at that time as the preceding pulse parameter (step S1211), and ends the process.

  In the above embodiment, the case where the pulse type, shape, position, size, FA, and number of times are set as the parameters of the preceding pulse has been described as an example. However, the parameters to be set are not limited to this. For example, the TI may be set.

  As described above, according to the present embodiment, the parameters can be easily set when a plurality of preceding pulses are applied. Therefore, the parameters of a plurality of preceding pulses can be set efficiently and accurately. For this reason, the preceding pulse is applied with high accuracy, and the quality of the obtained image is improved.

  In addition, according to the present embodiment, since the plurality of preceding pulses set by the operator are combined and applied, it is possible to further improve the efficiency of imaging. In particular, in imaging, when a plurality of the same preceding pulses are applied at the same Null time, such as a Null point, where the application timing between the excitation RF pulse of the main imaging is important and the same Null time is applied, they are combined to form one preceding pulse. Therefore, all can be applied at the best application timing, and the image quality can be improved.

  In addition, depending on the pulse type, application of each RF pulse causes a time difference between the pulses, which may affect the image quality and image quality, such as a difference in signal intensity. However, according to the present embodiment, since a plurality of RF pulses are simultaneously applied, such an influence can be improved.

  An example using the above embodiment will be described below.

<Example 1>
In the brain imaging by MRS (Magnetic Resonance Spectroscopy), an example will be described in which the parameters of the preceding pulse (MRS preceding pulse) applied to suppress the cranial subcutaneous fat of the brain are set.

  In this case, the operator inputs 1 as the type number of the preceding pulse and MRS as the pulse type. Also, an ellipse is selected as the shape.

  An example of the ROI indicator 621 displayed in the second input area 620 at this time is shown in FIG. As shown in the figure, two ROI indicators 621 (ROI1, ROI2) are displayed at predetermined positions on the positioning image. An operator sets each position so that each ROI1 and ROI2 may overlap in a concentric shape with different sizes. Here, the inner ROI indicator is ROI1, and the outer ROI indicator is ROI2. At that time, as shown in FIG. 12, the scalp fat part is outside the ROI1 ellipse and inside the ROI2 ellipse, and the part inside the brain is inside the ROI1 and ROI2 ellipses. The size and position of the ellipses of both ROI1 and ROI2 are set using an input device such as a mouse.

  The preceding pulse setting unit 422 reads the size from each ROI 1 and ROI 2 set by the operator on the positioning image, and displays them as numerical values in the individual parameter input area 614.

  The operator sets the FA and the number of times in the individual parameter input area 614. Here, FA is 90 degrees for ROI1, -90 degrees for ROI2, and the number of times is one. At this time, the size may be finely adjusted.

  The preceding pulse setting unit 422 displays the set FA in the second input area 620.

  When MRS is input as a pulse type, initial values of parameters such as the corresponding shape, size, FA, and number of times are displayed in the type-specific parameter input area 615 from the database stored in the storage device 72 in association with the MRS. Then, the initial excitation area corresponding thereto may be displayed in the second input area 620.

  With the above procedure, the setting of two types of preceding pulses that are different in excitation area is completed. The preceding pulse synthesizing unit 423 synthesizes the set preceding pulse and reflects it in the pulse sequence. The imaging unit 410 performs imaging according to a pulse sequence.

  When the parameters of the preceding pulse are set as described above, the fat signal in the region inside both ROI1 and ROI2 is acquired by the main imaging, and the fat signal in the region outside ROI1 and inside ROI2 is suppressed. Therefore, it is possible to suppress the cranial fat of the brain to be circular. Further, at this time, since the RF pulse obtained by synthesizing two RF pulses is irradiated as the preceding pulse, the time taken for the preceding pulse is about half that of the conventional one, and the imaging time is shortened.

<Example 2>
An example of setting parameters of a preceding pulse (Black Blood preceding pulse) for image formation by dropping a blood signal flowing into the imaging section in Black Blood imaging will be described.

  Here, the operator inputs 1 as the number of preceding pulse types and Black Blood as the pulse type. In addition, a band is input as the shape.

  An example of the ROI indicator 621 displayed in the second input area 620 at this time is shown in FIG. Here, as shown in the figure, two ROIs (ROI1, ROI2) are displayed at predetermined positions on the positioning image. The operator sets the positions of the two ROIs 1 and ROI 2 having different widths so that the centers in the body axis directions overlap each other. At that time, as shown in FIG. 13, the width in the body axis direction is set to the maximum width ROI1 can set on the positioning image. In addition, ROI2 is the minimum width including the imaging slice.

  The preceding pulse setting unit 422 reads the width from each ROI 1 and ROI 2 set by the operator on the positioning image, and displays the width in the individual parameter input area 614 as a numerical value.

  The operator sets the FA and the number of times in the individual parameter input area 614. Here, ROI1 is 180 degrees, ROI2 is -180 degrees, and the number of times is one. At this time, the size may be finely adjusted.

  The preceding pulse setting unit 422 displays the set FA in the second input area 620.

  When Black Blood is input as the pulse type, the initial values of the parameters such as the corresponding shape, size, FA, and number of times are stored in the type-specific parameter input area 615 from the database stored in the storage device 72 in association with the pulse type. The initial excitation area corresponding to the display area may be displayed in the second input area 620.

  With the above procedure, the setting of two types of preceding pulses that are different in excitation area is completed. The preceding pulse synthesizing unit 423 synthesizes the set preceding pulse and reflects it in the pulse sequence. At this time, the TI is set so that the time from the preceding pulse to the excitation RF pulse for main imaging becomes a null point of the magnetization of the blood flow reversed by the preceding pulse.

  When the parameters of the preceding pulse are set as described above, in imaging of the slice where ROI1 and ROI2 overlap, the blood flow flowing in from both sides of the slice portion is imaged in a state where the signal value is 0, and the blood becomes black An image to be displayed is obtained. Further, at this time, since the two RF pulses are synthesized and irradiated, the time taken for the preceding pulse is about half that of the conventional one, and the imaging time is shortened.

<Example 3>
An example in which parameters of a preceding pulse (presatiated preceding pulse) for suppressing artifacts due to arteriovenous flow from above and below in abdominal imaging will be described.

  Here, the operator inputs 1 as the number of preceding pulse types and presati as the pulse type. In addition, the shape is set to a band shape.

  An example of the ROI indicator 621 displayed in the second input area 620 at this time is shown in FIG. Here, as shown in the figure, two ROIs (ROI1, ROI2) are displayed at predetermined positions on the positioning image. The operator sets each position and width so that ROI1 and ROI2 are located on both sides of the target slice.

  The preceding pulse setting unit 422 reads the width from each ROI 1 and ROI 2 set by the operator on the positioning image, and displays the width in the individual parameter input area 614 as a numerical value.

  The operator sets the FA and the number of times in the individual parameter input area 614. Here, FA is set to 90 degrees for both ROI1 and ROI2. The number of times is set to 2 times. At this time, the size (width) may be finely adjusted.

  The preceding pulse setting unit 422 displays the set FA in the second input area 620.

  When a presati is input as a pulse type, initial values of parameters such as the corresponding shape, size, FA, and number of times are displayed in the type-specific parameter input area 615 from a database stored in the storage device 72 in association with the pulse. Then, the initial excitation area corresponding thereto may be displayed in the second input area 620.

  With the above procedure, the setting of two types of preceding pulses that are different in excitation area is completed. The preceding pulse synthesizing unit 423 synthesizes the set preceding pulse and reflects it in the pulse sequence.

  When the preceding pulse parameter is set as described above, the blood flow signal flowing into the imaging slice from the portion excited by the preceding pulse is suppressed during the main imaging, and the artifact due to the blood flow is suppressed. Furthermore, in this embodiment, two RF pulses are synthesized and irradiated, but the same RF pulse is irradiated twice at the same position. Therefore, the suppression effect of about twice is obtained with the same application time of the preceding pulse as before.

<Example 4>
A description will be given of an embodiment in which parameters of a preceding pulse (labeling preceding pulse) for labeling for examining the blood flow inflow paths and the like in imaging of the right and left arteries of the head and the renal artery are described.

  Here, the operator inputs 1 as the number of preceding pulse types and labeling as the pulse type. The shape is set to be circular.

  An example of the ROI indicator 621 displayed in the second input area 620 at this time is shown in FIG. Here, as shown in the figure, two ROIs (ROI1, ROI2) are displayed at predetermined positions on the positioning image. Here, as shown in FIG. 15, the positions of ROI1 and ROI2 are set at the roots of two blood vessels to be labeled, respectively. Also, the size of each is adjusted so as to excite only the root of the target blood vessel.

  The preceding pulse setting unit 422 reads the width from each ROI 1 and ROI 2 set by the operator on the positioning image, and displays the width in the individual parameter input area 614 as a numerical value.

  The operator sets the FA and the number of times in the individual parameter input area 614. Here, the FA is set to 180 degrees for both ROI1 and ROI2. The number of times is set to 2 times. At this time, the size (width) may be finely adjusted.

  The preceding pulse setting unit 422 displays the set FA in the second input area 620.

  When labeling is input as a pulse type, initial values of parameters such as the corresponding shape, size, FA, and number of times are displayed in a parameter input area 615 for each type from a database stored in the storage device 72 in association with the labeling. Then, the initial excitation area corresponding thereto may be displayed in the second input area 620.

  With the above procedure, the setting of two types of preceding pulses that are different in excitation area is completed. The preceding pulse synthesizing unit 423 synthesizes the set preceding pulse and reflects it in the pulse sequence. At this time, the TI is set so that the time from the preceding pulse to the excitation RF pulse for main imaging becomes the null point of the magnetization of the blood flow reversed by the preceding pulse.

  When the preceding pulse is set as described above, an image in which the signal has dropped is obtained by the amount of blood flow excited by the preceding pulse during the time until the excitation of the main imaging. That is, it is possible to obtain an image capable of grasping how much blood has flowed from the root of the labeled blood vessel. Conventionally, since RF pulses cannot be applied simultaneously, there has been a shift in the labeling of blood for the application time of the left and right RF pulses. However, by synthesizing and applying the RF pulse, two preceding pulses can be applied simultaneously, and an image with a uniform effect of the preceding pulse can be acquired. Further, at this time, since the two RF pulses are synthesized and irradiated, the time taken for the preceding pulse is about half that of the conventional one, and the imaging time is shortened.

  In the above-described embodiment, the imaging condition setting unit is configured to be realized by the control processing system 70 of the MRI apparatus 10, but is not limited thereto. For example, it may be configured on an independent information processing apparatus capable of transmitting / receiving data to / from the MRI apparatus 10.

  10: MRI apparatus, 11: subject, 20: static magnetic field generation system, 30: gradient magnetic field generation system, 31: gradient magnetic field coil, 32: gradient magnetic field power supply, 40: sequencer, 50: transmission system, 51: transmission coil, 52: synthesizer, 53: modulator, 54: high frequency amplifier, 60: reception system, 61: reception coil, 62: signal amplifier, 63: quadrature phase detector, 64: A / D converter, 70: control processing system, 71: CPU, 72: storage device, 73: display device, 74: input device, 201: RF pulse, 202: RF pulse, 203: RF pulse, 300: pulse sequence, 310: main imaging sequence, 311: excitation RF pulse 312: Imaging slice selection gradient magnetic field, 313: Encode gradient magnetic field, 314: Encode gradient magnetic field, 315: Echo signal, 320: Previous pulse sequence 321: preceding pulse, 410: imaging unit, 420: imaging condition setting unit, 421: basic condition setting unit, 422: preceding pulse setting unit, 423: preceding pulse synthesis unit, 500: imaging condition setting initial screen, 510: positioning image Display area, 520: basic condition setting button, 530: preceding pulse condition setting button, 540: imaging button, 600: preceding pulse setting screen, 601: first preceding pulse setting screen, 602: second preceding pulse setting screen, 603: third preceding pulse setting screen, 610: first input area, 611: preceding pulse type input area, 612: pulse type input area, 613: shape input area, 614: individual parameter input area, 615: seed Each parameter input area, 620: second input area, 621: ROI indicator, 630: OK button

Claims (6)

A magnetic resonance imaging apparatus comprising an imaging means for reconstructing an image from echo signals acquired by operating each unit according to an imaging condition set via an imaging condition setting means and a preset pulse sequence,
The imaging condition setting means includes
A preceding pulse setting means for receiving an input of a parameter specifying each of the plurality of preceding pulses;
A preceding pulse synthesizing unit that synthesizes a plurality of preceding pulses received by the preceding pulse setting unit and generates a combined preceding pulse;
The imaging means controls to apply the combined preceding pulse before execution of the main imaging,
The magnetic resonance imaging apparatus, wherein the preceding pulse setting means accepts the input of the parameter on a preceding pulse setting screen capable of independently grasping each excitation region of each preceding pulse. The magnetic resonance imaging apparatus according to claim 1,
The preceding pulse setting screen includes a first input area for receiving input of the parameter by text data, and a second input area for receiving input of the parameter on a positioning image,
The preceding pulse setting means includes
Each time an input of the parameter is received via one of the first input area and the second input area, the received parameter is reflected on the other. The magnetic resonance imaging apparatus according to claim 2,
The first input area is
A pulse type setting area that accepts input of the number of types of preceding pulses to be used;
A pulse type setting region for receiving input of preceding pulse types of the number of types of the preceding pulses;
For each of the preceding pulse types, a shape setting area for receiving shape input;
A magnetic resonance imaging apparatus comprising: a parameter setting area for each pulse for receiving an input of FA, width, and number of times of application for each preceding pulse. The magnetic resonance imaging apparatus according to claim 3,
When the preceding pulse setting means receives the number of pulse types, it generates and displays the received number of the pulse type setting region and the shape setting region, and the two parameter setting regions for each pulse. Magnetic resonance imaging apparatus. A magnetic resonance imaging apparatus according to any one of claims 2 to 4,
The preceding pulse setting means displays the region excited by the preceding pulse for each preceding pulse in the input area on the image in a different display mode. The magnetic resonance imaging apparatus according to any one of claims 2 to 5,
When the FA is input in the direct input area, the preceding pulse setting means displays the FA in a predetermined display manner so that the FA can be identified for each preceding pulse.

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