JP2006087825A - Magnetic resonance imaging apparatus, and control signal generating method for the apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic resonance imaging apparatus for suppressing a signal intensity from a fat component without using a pre-pulse to suppress fat, so as to obtain a blood stream image in excellent contrast, and to provide a control signal generating method for the magnetic resonance imaging apparatus. <P>SOLUTION: The magnetic resonance imaging apparatus comprises a photographing area setting means 46 for setting a photographing area and the power of an ISCE (spacilly changed excited) pulse so as to allow the area with the many fat components to be contained in a part with the less power of the ISCE pulse; a pulse sequence setting means 45 for setting a pulse sequence having an imaging sequence for collecting a magnetic resonance signal by impressing the ISCE pulse and a pre-pulse sequence for impressing the pre-pulse to obtain an MT (magnetization transfer) effect; a raw data collecting means for receiving the magnetic resonance signal in response to a photographing condition stipulated by the pulse sequence and digitizing the signal, so as to generate raw data; and blood stream generation means 42, 44 for generating three-dimensional image data as a blood stream image from the raw data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention magnetically excites a nuclear spin of a subject with an RF signal having a Larmor frequency, and reconstructs an image from a magnetic resonance signal generated by the excitation, and a control signal for the magnetic resonance imaging apparatus The magnetic resonance imaging apparatus and the control of the magnetic resonance imaging apparatus that can suppress the signal intensity from the fat component and obtain a blood flow image with better contrast without using a prepulse for fat suppression, in particular. The present invention relates to a signal generation method.

  Magnetic resonance imaging (MRI) magnetically excites a subject's nuclear spin placed in a static magnetic field with a radio frequency (RF) signal of a Larmor frequency, and is generated along with this excitation. This is an imaging method in which an image is reconstructed from a magnetic resonance (MR) signal.

  In the field of magnetic resonance imaging, MRA (magnetic resonance angiography) is known as a technique for obtaining a blood flow image at a desired site such as the head, lung field, or abdomen. MRA includes a contrast MRA that performs imaging by administering a contrast agent to a subject and a non-contrast MRA that does not use a contrast agent. One of typical MRAs is the time of flight (TOF) method.

  TOF is MRA that utilizes the fact that blood flows into the imaging region. That is, the TOF excites the imaging region with a repetition time (TR: repetition time) shorter than the longitudinal relaxation time (T1), which is a time constant at the time of recovery of longitudinal magnetization in the tissue. The MR signal from the blood flow component flowing into the imaging region is collected with a high signal strength.

  According to the TOF, MR signals from blood flow components can be obtained with high signal intensity, so that an MR image in which a blood vessel portion is shined can be obtained. However, when fat is present in still tissue, there is a drawback that it is difficult to distinguish MR signals from fat and MR signals from blood flow components because T1 of fat is short.

  For example, in three-dimensional TOF non-contrast MRA imaging for obtaining a blood flow image at the subject's head, MR signals from fat in the orbit obstruct blood flow image generation.

  Therefore, in order to obtain a blood flow image in MRA other than TOF as well as TOF, at least MR signals from fat are suppressed, while water signals that are components of blood flow and MR signals from the substantial part are excited. Thus, it is important to obtain sufficient contrast between the blood flow portion and the substantial portion other than the blood flow portion.

  Therefore, a fat suppression method that suppresses MR signals (fat signals) from fat by using a difference (chemical shift) between resonance frequencies of fat protons and water protons is conventionally used. One of the fat suppression methods is a prepulse method. In the fat suppression method using the prepulse method, a fat saturation pulse for suppressing a fat signal is applied to the subject as a prepulse prior to blood flow imaging, and only fat is selectively excited by frequency. This is an imaging method in which imaging of a blood flow image is started after saturating the protons.

  In addition, when a predetermined frequency region is selectively excited with an RF pulse, the MR signal level from the polymer and water, which are substantial components, respectively decreases, and a contrast image corresponding to the proportion of the polymer present is obtained. An MT (magnetization transfer) effect that an image can be taken is obtained. Therefore, in order to obtain such an MT effect, a technique is proposed in which an RF pulse called an MTC (magnetization transfer contrast) pulse is applied as a prepulse to a subject prior to a blood flow image scan.

  Further, a SORS pulse (slice-selective off-resonance sinc pulse) that is applied with a slice gradient magnetic field pulse for selective excitation of the MTC excitation surface at substantially the same timing as the MTC pulse is used for imaging a blood flow image. Prior to this scanning, a technique of applying a prepulse to a subject is devised (see, for example, Patent Document 1).

  FIG. 10 is a diagram showing an imaging region in conventional three-dimensional TOF non-contrast MRA imaging using a SORS pulse for obtaining a blood flow image at the head of a subject, and FIG. 11 is a diagram showing the subject shown in FIG. It is a figure which shows the pulse sequence for applying a fat suppression pulse with the SORS pulse to the head of a sample prior to the imaging pulse for blood-flow image imaging.

  As shown in FIG. 10, when obtaining a blood flow image in the head of a subject, a three-dimensional region composed of a plurality of slice sections perpendicular to the body axis is taken as an imaging region A1. Then, the three-dimensional imaging region A1 is set so as to include a large number of fine blood vessels existing near the center of FIG. However, in this imaging region A1, since fat exists in the orbit, it is necessary to suppress MR signals from the fat.

  Therefore, as shown in FIG. 11, prior to an imaging sequence for obtaining a blood flow image, fat suppression (Fat-Suppress) in which a fat suppression pulse for suppressing MR signals from fat is applied to the head of the subject. ) A pulse sequence is created so that the sequence is executed.

  Further, prior to the fat suppression sequence, a SORS pulse composed of an MTC pulse and a slice gradient magnetic field pulse for selective excitation of the MTC excitation plane in order to adjust the contrast between the blood flow component in the head and the parenchyma of the brain. A SORS sequence is provided for applying.

  At this time, the MTC excitation surface by the slice gradient magnetic field pulse of the SORS pulse is a surface included in the region A2 indicated by the dotted frame in FIG. That is, the MTC excitation surface is set so as to be farther from the heart than the imaging region A1. If the MTC excitation plane is set in this manner, the blood flow in the artery flowing into the imaging region A1 from the heart side does not pass through the MTC excitation plane, so that an MR signal with high signal intensity is generated from the blood flow in the artery. Since the venous blood flow that flows out of the imaging region A1 and returns to the heart passes through the MTC excitation surface, the signal intensity is suppressed from the blood flow in the vein and an MR signal is generated.

  For this reason, MRA using SORS pulses can enhance MR signals from blood flow in arteries that are clinically useful, while suppressing MR signals from blood flow in veins.

  It should be noted that the greater the angle at which magnetization is reversed by the SORS pulse (the flip angle), the smaller the intensity of the MR signal from the substantial part of the brain, while the intensity of the MR signal from fat and blood flow components includes the flip of the SORS pulse. Angle has the property of not affecting. Therefore, the larger the intensity of the MR signal from fat, the larger the flip angle of the SORS pulse is set, and the intensity of the MR signal from the substantial part is relative to the intensity of the MR signal from the blood flow component and fat. It is desirable that the acquisition is performed so that the MR signal is reduced, that is, the intensity of the MR signal from the blood flow component is relatively larger than the intensity of the MR signal from a portion other than the blood flow.

  Then, three-dimensional data such as an MIP image is obtained from image data such as maximum intensity projection (MIP) processing from three-dimensional data collected by executing a scan with a contrast improvement technique such as application of a SORS pulse or fat suppression pulse. Image data is created and used for diagnosis.

  12 shows a MIP image in the body axis direction of the head obtained by executing a scan according to the pulse sequence as shown in FIG. 11 on the imaging region A1 in the head of the subject shown in FIG. FIG.

  By executing scanning under the imaging conditions shown in FIGS. 10 and 11, a MIP image in the body axis direction (axial sectional direction) of the head as shown in FIG. 12 is created for diagnosis. That is, after a SORS pulse and a fat saturation pulse are applied as pre-pulses, MR signals are collected from a plurality of slice cross sections perpendicular to the body axis by application of an imaging pulse, and are used to create an MIP image.

  Note that the flip angle of the SORS pulse in the scan for obtaining the MIP image shown in FIG. 12 was set to 350 °.

  Although it can be seen from FIG. 12 that blood vessels are imaged together with the substantial part in the head, it can be confirmed that fat in the eye socket is conspicuous.

  Furthermore, in addition to the contrast improvement method using the prepulse method such as SORS pulse and fat suppression pulse, ISCE (inclined slab) in which the power of the excitation pulse in the imaging sequence is changed according to the distance from the heart to the slice cross section to be excited. For contrast enhancement), a technique using a pulse for improving contrast is devised (for example, see Patent Document 2).

  In this technique, when the imaging region is excited by an ISCE pulse in which the excitation pulse power is smaller in the slice cross section closer to the heart and the excitation power is larger in the slice cross section farther from the heart, the imaging sequence is closer to the heart. While the flip angle in the slice cross section can be reduced while the flip angle in the slice cross section far from the heart can be increased, it is possible to compensate for a decrease in the intensity of the MR signal from the imaging region away from the heart.

Note that the MIP image shown in FIG. 12 is obtained not by the ISCE pulse but by the execution of an imaging sequence in which the ratio of the excitation pulse power in the slice cross sections at both ends of the imaging region is 1: 1.
JP-A-6-319715 JP-A-11-104106

  In a conventional method for improving contrast in MRA, it is necessary to apply a fat suppression pulse to a subject prior to an imaging excitation pulse in order to suppress MR signals from fat. For this reason, it takes time to apply the fat suppression pulse to the subject, which leads to an increase in imaging time.

  Also, there are cases where components obtained from MR signals from fat still exist in the three-dimensional data obtained by scanning, and when MIP images are generated from such three-dimensional data, blood vessels are displayed with sufficient contrast. There is a risk of being lost.

  For example, FIG. 12 shows a MIP image obtained by generating a blood flow image in the head of a subject as a MIP image obtained by MIP processing three-dimensional data in the axial cross-sectional direction. According to the MIP image shown in FIG. It can be confirmed that fat in the orbit is still conspicuous. For example, when an MIP image in the coronal cross-sectional direction is created from such three-dimensional data, the image of the blood vessel disappears from the MIP image in the coronal cross-sectional direction because the pixel value of the fat region is large, or the fat and blood vessels are identified. There is a problem that becomes difficult.

  For this reason, when creating a MIP image in the coronal cross-sectional direction or in another direction, region extraction processing such as threshold processing is performed from the three-dimensional data to extract the three-dimensional data excluding the fat component, and the extracted 3 A technique of performing MIP processing using the dimension data is required. Therefore, region extraction processing is newly required, which leads to complication of data processing.

  The present invention has been made to cope with such a conventional situation, and can suppress a signal intensity from a fat component without using a prepulse for fat suppression, and obtain a blood flow image with a better contrast. An object of the present invention is to provide a magnetic resonance imaging apparatus and a control signal generation method for the magnetic resonance imaging apparatus.

  In order to achieve the above-mentioned object, the magnetic resonance imaging apparatus according to the present invention, as described in claim 1, provides power in the imaging region for capturing a three-dimensional blood flow image of the subject. An imaging region setting means for setting the imaging region and the power of the ISCE pulse so that a region where the fat component is large is included in a portion where the power of the ISCE pulse, which is an excitation pulse that has been changed, is small, and the imaging region setting An imaging sequence for collecting the magnetic resonance signal by applying the ISCE pulse to create the blood flow image in the imaging region set by the means, and a pre-pulse for obtaining the MT effect prior to the application of the ISCE pulse Pulse sequence setting means for setting a pulse sequence having a pre-pulse sequence to be applied; and the pulse sequence The gradient magnetic field is applied to the subject in the static magnetic field and the high-frequency signal is transmitted in accordance with the imaging condition defined by the pulse sequence set by the event setting means, while the ISCE pulse in the subject is used. Raw data collection means for generating raw data by receiving and digitizing the magnetic resonance signal generated along with nuclear magnetic resonance of the nucleus, and the blood flow from the raw data generated by the raw data collection means It has blood flow image generation means for generating three-dimensional image data as an image.

  In order to achieve the above object, the magnetic resonance imaging apparatus according to the present invention provides a three-dimensional blood flow image of a subject on a blood vessel portion that requires clinical imaging as described in claim 2. The direction of each slice cross-section included in the imaging region is set so that the region containing a large amount of fat components while being included in the imaging region for imaging can be a portion where the power of the ISCE pulse that is an excitation pulse in which the power is spatially changed is small. Of the imaging region formed by the oblique cross-section setting means to be set and each slice cross-section in the direction set by the oblique cross-section setting means, the region where the power of the ISCE pulse is small includes a region where the fat component is large The imaging area setting means for setting the imaging area and the power of the ISCE pulse, and the imaging area setting means An imaging sequence for collecting the magnetic resonance signal by applying the ISCE pulse to create the blood flow image in the imaging region, and a prepulse sequence for applying a prepulse for obtaining the MT effect prior to the application of the ISCE pulse. A pulse sequence setting means for setting a pulse sequence, and an application of a gradient magnetic field and a high-frequency signal to the subject in a static magnetic field according to an imaging condition defined by the pulse sequence set by the pulse sequence setting means Raw data collection means for generating raw data by receiving and digitizing the magnetic resonance signal generated along with nuclear magnetic resonance of the nucleus by the ISCE pulse inside the subject, The raw data generated by the data collecting means It is characterized in that it has a blood flow image generating unit configured to generate three-dimensional image data as the blood flow image from.

  Moreover, in order to achieve the above-mentioned object, the magnetic resonance imaging apparatus according to the present invention includes, as described in claim 3, a power in an imaging region for capturing a three-dimensional blood flow image of a subject. An imaging region setting means for setting the imaging region and the power of the ISCE pulse so that a region having a large amount of fat component is included in a portion where the power of the ISCE pulse which is an excitation pulse in which the power is spatially changed is included. Prior to the application of the ISCE pulse for creating the blood flow image in the imaging region set by the region setting means, the prepulse flip angle applied to obtain the MT effect is set to an excitation pulse other than the ISCE pulse. Using the ISCE pulse to determine whether the fat component is smaller than the flip angle set when performing a scan using A flip angle setting means for setting a larger value than the flip angle when the contrast between the blood flow and the substantial part becomes a required contrast when the MR signal is reduced, and the flip angle setting means A pulse sequence setting means for setting a pulse sequence having a pre-pulse sequence for applying a pre-pulse so as to have a flip angle and an imaging sequence for applying the ISCE pulse to collect magnetic resonance signals, and the pulse sequence setting means While applying a gradient magnetic field and transmitting a high-frequency signal to the subject in a static magnetic field according to the imaging conditions defined by the pulse sequence, the nuclear magnetic resonance of the nucleus by the ISCE pulse inside the subject is performed. Occurred Raw data collection means for generating raw data by receiving and digitizing magnetic resonance signals, and blood for generating three-dimensional image data as the blood flow image from the raw data generated by the raw data collection means And a flow image generating means.

  In order to achieve the above object, a magnetic resonance imaging apparatus according to the present invention provides a magnetic resonance imaging apparatus for imaging a blood flow image of a head of a subject as described in claim 4. A region setting means for setting a pre-pulse region to which a pre-pulse for obtaining an MT effect is applied to the region of the subject that is closer to the top of the subject than the imaging region, and sets a photographing region in a region including the eye socket of the sample; A pulse sequence setting means for setting a pre-pulse sequence for applying the pre-pulse to the pre-pulse region, and an imaging sequence for applying an ISCE pulse having a greater power on the parietal side than the orbital side to the imaging region after applying the pre-pulse. And applying the pre-pulse sequence and the imaging sequence Collecting means for collecting gas resonance signal, and characterized by having an image generating means for generating an MIP image from a magnetic resonance signal obtained by the acquisition means.

  According to another aspect of the present invention, there is provided a method for generating a control signal of a magnetic resonance imaging apparatus, as set forth in claim 7, for capturing a three-dimensional blood flow image of a subject. Setting the imaging region and the power of the ISCE pulse so that a region having a large amount of fat component is included in a portion of the region where the power of the ISCE pulse, which is an excitation pulse whose power is spatially changed, is small; An imaging sequence for collecting the magnetic resonance signals by applying the ISCE pulse to create the blood flow image in the imaging region, and a prepulse sequence for applying a prepulse for obtaining the MT effect prior to the application of the ISCE pulse. And a step of setting a pulse sequence having.

  According to another aspect of the present invention, there is provided a method for generating a control signal of a magnetic resonance imaging apparatus. Each region included in the imaging region so that the power of the ISCE pulse, which is an excitation pulse in which the power is spatially changed, can be made a portion including a large amount of fat component while being included in the imaging region for capturing a blood flow image of A step of setting a direction of a slice cross section, and the imaging area and the imaging area formed by each slice cross section so that the area where the power of the ISCE pulse is small includes an area where the fat component is large Setting the power of the ISCE pulse and applying the ISCE pulse to generate a magnetic resonance signal in order to create the blood flow image in the imaging region Is characterized in that a step of setting a pulse sequence with a pre-pulse sequence that applies a pre-pulse for obtaining the MT effect prior to the application of the imaging sequence and the ISCE pulse current.

  According to another aspect of the present invention, there is provided a method for generating a control signal of a magnetic resonance imaging apparatus, as set forth in claim 9, for capturing a three-dimensional blood flow image of a subject. Setting the imaging region and the power of the ISCE pulse so that a region having a large amount of fat component is included in a portion of the region where the power of the ISCE pulse, which is an excitation pulse whose power is spatially changed, is small; Prior to the application of the ISCE pulse for creating the blood flow image in the imaging region, the pre-pulse flip angle applied to obtain the MT effect is scanned using an excitation pulse other than the ISCE pulse. MR signal from the fat component is reduced by using the ISCE pulse which is smaller than the flip angle set in the case A step of setting a value larger than a flip angle when the contrast between the blood flow and the substantial part is a required contrast, a pre-pulse sequence for applying a pre-pulse so as to be the set flip angle, and the ISCE And setting a pulse sequence having an imaging sequence for applying a pulse and collecting a magnetic resonance signal.

  In the magnetic resonance imaging apparatus and the control signal generation method of the magnetic resonance imaging apparatus according to the present invention, the signal intensity from the fat component is suppressed without using a prepulse for fat suppression, and a blood flow image is obtained with better contrast. be able to.

  Embodiments of a magnetic resonance imaging apparatus according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram showing an embodiment of a magnetic resonance imaging apparatus according to the present invention.

  The magnetic resonance imaging apparatus 20 includes a cylindrical static magnetic field magnet 21 that forms a static magnetic field, a shim coil 22, a gradient magnetic field coil unit 23, and an RF coil 24 provided inside the static magnetic field magnet 21 in a gantry (not shown). It is a built-in configuration.

  In addition, the magnetic resonance imaging apparatus 20 includes a control system 25. The control system 25 includes a static magnetic field power supply 26, a gradient magnetic field power supply 27, a shim coil power supply 28, a transmitter 29, a receiver 30, a sequence controller 31, and a computer 32. The gradient magnetic field power source 27 of the control system 25 includes an X-axis gradient magnetic field power source 27x, a Y-axis gradient magnetic field power source 27y, and a Z-axis gradient magnetic field power source 27z. In addition, the computer 32 includes an input device 33, a display device 34, an arithmetic device 35, and a storage device 36.

  The static magnetic field magnet 21 is connected to a static magnetic field power supply 26 and has a function of forming a static magnetic field in the imaging region by a current supplied from the static magnetic field power supply 26. In many cases, the static magnetic field magnet 21 is composed of a superconducting coil, and is connected to the static magnetic field power supply 26 at the time of excitation and supplied with current. It is common. In some cases, the static magnetic field magnet 21 is composed of a permanent magnet and the static magnetic field power supply 26 is not provided.

  A cylindrical shim coil 22 is coaxially provided inside the static magnetic field magnet 21. The shim coil 22 is connected to the shim coil power supply 28, and is configured such that a current is supplied from the shim coil power supply 28 to the shim coil 22 to make the static magnetic field uniform.

  The gradient magnetic field coil unit 23 includes an X-axis gradient magnetic field coil 23 x, a Y-axis gradient magnetic field coil 23 y, and a Z-axis gradient magnetic field coil 23 z, and is formed in a cylindrical shape inside the static magnetic field magnet 21. A bed 37 is provided inside the gradient coil unit 23 as an imaging region, and the subject P is set on the bed 37. The RF coil 24 may not be built in the gantry but may be provided near the bed 37 or the subject P.

  The gradient magnetic field coil unit 23 is connected to a gradient magnetic field power supply 27. The X axis gradient magnetic field coil 23x, the Y axis gradient magnetic field coil 23y, and the Z axis gradient magnetic field coil 23z of the gradient magnetic field coil unit 23 are respectively an X axis gradient magnetic field power source 27x, a Y axis gradient magnetic field power source 27y, and a Z axis. It is connected to the gradient magnetic field power supply 27z.

  The X-axis gradient magnetic field power source 27x, the Y-axis gradient magnetic field power source 27y, and the Z-axis gradient magnetic field power source 27z are supplied with currents supplied to the X-axis gradient magnetic field coil 23x, the Y-axis gradient magnetic field coil 23y, and the Z-axis gradient magnetic field coil 23z, respectively. In the imaging region, a gradient magnetic field Gx in the X-axis direction, a gradient magnetic field Gy in the Y-axis direction, and a gradient magnetic field Gz in the Z-axis direction can be formed, respectively.

  The RF coil 24 is connected to the transmitter 29 and the receiver 30. The RF coil 24 receives the RF signal from the transmitter 29 and transmits it to the subject P, and receives the MR signal generated along with the excitation of the nuclear spin inside the subject P by the RF signal to the receiver 30. Has the function to give.

  On the other hand, the sequence controller 31 of the control system 25 is connected to the gradient magnetic field power source 27, the transmitter 29, and the receiver 30. The sequence controller 31 has control information necessary for driving the gradient magnetic field power supply 27, the transmitter 29, and the receiver 30, for example, operation control information such as the intensity, application time, and application timing of the pulse current to be applied to the gradient magnetic field power supply 27. And a gradient magnetic field power source 27, a transmitter 29, and a receiver 30 by driving the gradient magnetic field power source 27, the transmitter 29, and the receiver 30 according to the imaging conditions defined by the stored predetermined pulse sequence. It has a function of generating a magnetic field Gy, a Z-axis gradient magnetic field Gz, and an RF signal.

  The sequence controller 31 is configured to receive raw data, which is complex data obtained by detection of the MR signal and A / D conversion in the receiver 30, and supply the raw data to the computer 32.

  For this reason, the transmitter 29 has a function of applying an RF signal to the RF coil 24 based on the control information received from the sequence controller 31, while the receiver 30 detects the MR signal received from the RF coil 24. Then, by executing required signal processing and A / D conversion, a function of generating raw data that is digitized complex data and a function of supplying the generated raw data to the sequence controller 31 are provided.

  That is, the static magnetic field magnet 21, shim coil 22, gradient magnetic field coil unit 23, RF coil 24, and control system 25 make the magnetic resonance imaging apparatus 20 in accordance with each imaging condition set as a pulse sequence. Applying a gradient magnetic field and transmitting an RF signal to the subject P in the magnetic field, and receiving and digitizing MR signals generated by nuclear magnetic resonance of the nuclei by the RF signal in the subject P Thus, a function as raw data collecting means for generating raw data is provided.

  Further, the computer 32 is provided with various functions by executing the program stored in the storage device 36 of the computer 32 by the arithmetic unit 35. However, the computer 32 may be configured by providing a specific circuit regardless of the program.

  FIG. 2 is a functional block diagram of the computer 32 in the magnetic resonance imaging apparatus 20 shown in FIG.

  The computer 32 includes a sequence controller control means 40, a raw data database 41, an image reconstruction means 42, an image data database 43, a projection image creation means 44, a pulse sequence setting means 45, an imaging area setting means 46, and a flip angle setting means. 47, which functions as an oblique cross-section setting means 48. Among these, the pulse sequence setting unit 45, the imaging region setting unit 46, the flip angle setting unit 47, and the oblique section setting unit 48 can be constructed by reading the control signal generation program into the computer 32.

  The sequence controller control means 40 receives the raw data from the sequence controller 31 and the function of controlling the drive by giving the sequence controller 31 the required pulse sequence based on the information from the input device 33 or other components. And a function of arranging in the k space (Fourier space) formed in the raw data database 41.

  For this reason, each raw data generated in the receiver 30 is stored in the raw data database 41, and the raw data is arranged in the k space formed in the raw data database 41.

  The image reconstruction unit 42 reconstructs the three-dimensional image data of the subject P by taking the raw data from the raw data database 41 and performing a predetermined image reconstruction process such as a three-dimensional (3D) Fourier transform process. A function of writing to the image data database 43. However, 3D image data may be reconstructed after intermediate data such as 2D image data is once created by processing such as 2D Fourier transform processing.

  Therefore, 3D image data of the subject P is stored in the image data database 43.

  The projected image creation means 44 has a function of creating MIP image data by performing MIP processing on 3D image data stored in the image data database 43, and providing the created MIP image data to the display device 34. It has a function to display MIP images.

  However, the image reconstructing unit 42 may be omitted, and the projection image creating unit 44 may create the MIP image data directly from the raw data read from the raw data database 41. Further, if clinically useful, not only MIP image data but also an SVR (Shaded volume rendering) image or other three-dimensional image may be created as a blood flow image by various image processing.

  That is, the magnetic resonance imaging apparatus 20 has a function as a blood flow image generation unit that generates a blood flow image from raw data. When the blood flow image is an MIP image, the image reconstruction unit 42 or the projection is used. A blood flow image generating means is formed by the image creating means 44.

  The pulse sequence setting unit 45 has a function of setting a pulse sequence and a function of enabling the execution of scanning by giving the set pulse sequence to the sequence controller control unit 40.

  FIG. 3 is a diagram showing an example of a pulse sequence created by the magnetic resonance imaging apparatus 20 shown in FIG. 1 and used for executing a scan.

  As shown in FIG. 3, the pulse sequence set by the pulse sequence setting means 45 is obtained by applying an MR signal from a slice cross section having an arbitrary angle by applying an ISCE pulse which is one of excitation pulses for generating a blood flow image. An imaging sequence to be collected and a pre-pulse sequence for applying an MTC pulse or SORS pulse as a pre-pulse for obtaining the MT effect prior to the application of the ISCE pulse during the execution of the imaging sequence are provided. Further, the fat suppression sequence for applying the fat suppression pulse is not provided in the pulse sequence.

  FIG. 3 is a diagram illustrating an example in which a pulse sequence is set with a prepulse sequence as a SORS sequence so that a SORS pulse is applied as a prepulse instead of an MTC pulse. Therefore, an MTC sequence in which an MTC pulse is applied as a pre-pulse instead of the SORS sequence may be used.

RF indicates an RF pulse transmitted from the RF coil 24 to the subject P, and echo indicates an MR signal generated in the subject P and collected for creating a blood flow image. Gs (G _SE ) represents a gradient magnetic field in the slice encoding direction (SE), G _PE represents a gradient magnetic field in the phase encoding direction, and G _RO represents a gradient magnetic field in the readout direction.

Then, the slice cross section is selected by the gradient magnetic field in the slice encode direction, and the position information in the two-dimensional direction in the slice cross section is converted into the phase and frequency by the gradient magnetic field _GPE in the phase encode direction and the gradient magnetic field _{GRO in the} readout direction. The

  Note that the imaging sequence can be a sequence using any technique such as a spin echo (SE) method or a field echo (FE) method as long as it is a sequence that can be used for scanning by three-dimensional MRA.

  Here, TOF is mentioned as an example of MRA. In MRA using three-dimensional TOF (3DTOF-MRA), the intensity of MR signals from stationary tissue is reduced by exciting the imaging region with a repetition time (TR) shorter than the longitudinal relaxation time (T1) in the tissue. A sequence that collects MR signals from blood flow components flowing into the imaging region with high signal intensity is used as the imaging sequence. According to this 3DTOF-MRA, MR signals from blood flow components can be obtained with high signal intensity, so that an MR image in which a blood vessel portion is illuminated can be obtained.

  On the other hand, the MTC pulse is a pulse applied to the subject P as a pre-pulse prior to the application of the excitation pulse during the execution of the imaging sequence in order to obtain the MT effect.

  FIG. 4 is a diagram for explaining the concept of the MT effect.

  In FIG. 4, the solid line is the spectrum of protons contained in water and the polymer before the MT effect is obtained, and the alternate long and short dash line is the spectrum of protons contained in water and the polymer after the MT effect is obtained. is there. As shown in FIG. 4, when a frequency shifted from the resonance frequency of water proton of 64 MHz by about 500 Hz is selectively excited by the MTC pulse, the MR signal level from the proton of the polymer and the MR signal from the proton of water. The MT effect that the level decreases is obtained.

  If MR signals are collected by using the MT effect by application of such an MTC pulse and an MR image is reconstructed, an MRA image having a contrast corresponding to the proportion of macromolecules that are substantial components is obtained. An image can be taken. Therefore, this is particularly effective when an MRA image that involves extraction of a thin blood vessel is taken.

  The SORS pulse is a pulse in which the slice gradient magnetic field pulse is applied at substantially the same timing as the MTC pulse. Then, by applying the slice gradient magnetic field pulse, the MTC excitation surface for obtaining the MT effect is selectively excited.

  FIG. 5 is a diagram for explaining an arrangement example of the MTC excitation surface by the SORS pulse and the effect by the application of the SORS pulse.

For example, as shown in FIG. 5, when the imaging region S1 is set to the head P _H of the subject P and a blood flow image of the blood flow X in the head P _H is captured, the MTC excitation surface S2 is the imaging region. It is set to be further from the heart than S1.

  In FIG. 5, the slice cross section and the MTC excitation surface S2 constituting the imaging region S1 are set in a direction perpendicular to the body axis for the sake of simplification. However, the slice cross section and the MTC excitation surface S2 are perpendicular to the body axis. The orientation can be any angle.

Setting this manner MTC excitation surface S2, blood X1 flowing in arteries extending from unillustrated heart head P _H, after flowing through the artery at the inflow and shooting areas S1 to the imaging regions S1, MTC excitation Guided to surface S2. Further, the blood flow X2 guided into the vein from the MTC excitation surface S2 via the peripheral blood vessel flows out from the MTC excitation surface S2, and then flows again toward the heart via the imaging region S1.

  Therefore, since the blood flow X1 in the artery flowing from the heart side into the imaging region S1 does not pass through the MTC excitation surface S2, an MR signal having a high signal intensity is generated from the blood flow X1 in the artery. On the contrary, the blood flow X2 in the vein that flows out from the imaging region S1 and returns to the heart passes through the MTC excitation surface S2. Therefore, the signal intensity is suppressed from the blood flow X2 in the vein by the MT effect, and the MR signal is output. appear.

Further, if the MTC excitation surface S2 is set in the vicinity of the imaging region S1 and the MTC pulse is applied, the intensity of the MR signal from the blood flow component can be relatively increased rather than the intensity of the MR signal from the substantial part. since it makes it possible to image the peripheral blood vessels there are many in the central portion of the head P _H with high accuracy.

  It should be noted that the strength of the MR signal from the parenchyma of the brain decreases as the flip angle by the SORS pulse including the MTC pulse increases, and the strength of the MR signal from the parenchyma of the brain decreases as the flip angle of the SORS pulse decreases. It has the property of becoming larger. At this time, the intensity of the MR signal from the fat and blood flow components is not affected by the flip angle of the SORS pulse.

  Therefore, the larger the intensity of the MR signal from fat, the larger the flip angle of the SORS pulse is set, and the intensity of the MR signal from the substantial part is relative to the intensity of the MR signal from the blood flow component and fat. It is important to collect so that the MR signal from the blood flow component becomes relatively small, that is, the strength of the MR signal from the portion other than the blood flow is relatively large.

  On the other hand, when the intensity of MR signal from fat is sufficiently small, setting the flip angle of the SORS pulse to a small value and increasing the intensity of the MR signal from the substantial part results in a difference between the blood flow component and the substantial part. A distinction can be made clear.

  The application of the SORS pulse for selectively exciting the MTC excitation surface S2 enhances the MR signal from the blood flow in the artery that is clinically useful, while suppressing the MR signal from the blood flow in the vein. it can.

  On the other hand, the ISCE pulse is an excitation pulse in which the power is changed according to the position of the slice cross section excited in the imaging region.

  FIG. 6 is a diagram comparing the power profile of the ISCE pulse with the power profile of a general excitation pulse.

  FIG. 6A is a diagram showing a power profile of a general excitation pulse. That is, for example, in the MRA in the head of the subject P, the slice cross section constituting the imaging region is set perpendicular to the body axis Z. The power of the excitation pulse applied to the head of the subject P is constant regardless of the position in the body axis Z direction. Then, a blood flow image D1 is generated from the MR signals collected by applying the excitation pulse with a constant power regardless of the position of the slice cross section.

  On the other hand, FIG. 6B is a diagram showing the power profile of the ISCE pulse. That is, in the MRA in the head of the subject P similar to FIG. 6A, for example, the slice cross section constituting the imaging region is set perpendicular to the body axis Z. The power of the ISCE pulse applied to the head of the subject P is changed depending on the position in the body axis Z direction, for example. That is, the power of the ISCE pulse is set such that the slice section set closer to the heart has a lower power and the slice section set farther from the heart has a higher power.

  The slice cross section is set not to be perpendicular to the body axis Z, but to have a certain angle with respect to the body axis Z, and depending on the position of the slice cross section in the normal direction, the ISCE pulse The power may be changed.

The slope of the power profile of the ISCE pulse can be expressed by the ratio between the maximum value P _MAX and the minimum value P _{MIN of} power. For example, when the minimum power value P _MIN in the slice cross section set at the position closest to the heart is ½ of the maximum power value P _MAX in the slice cross section set at the position farthest from the heart, 1 : 2 In this case, the flip angle in the slice cross section set at the position closest to the heart is also ½ of the flip angle in the slice cross section set at the position farthest from the heart.

  Therefore, for example, when an ISCE pulse having a nominal flip angle of 20 ° and a power profile slope of 1: 2 is applied to the subject P, the flip angle in the slice cross section set at the closest position from the heart is The flip angle in the slice cross section set at a position farthest from the heart is about 27 °.

  When the power profile slope is 1: 1, a general excitation pulse that is not an ISCE pulse is obtained.

  If a scan for imaging a blood flow image is executed using such an ISCE pulse, it is possible to compensate for a decrease in the intensity of the MR signal from an imaging region away from the heart. That is, when the blood flow passes through the imaging region, the MR signal intensity decreases, but the flip angle in the slice cross section close to the heart can be reduced while the flip angle in the slice cross section far from the heart can be increased. It is possible to obtain a blood flow image D2 with higher uniformity by suppressing the decrease in signal.

  Furthermore, the intensity of the MR signal from fat can be reduced by utilizing the power difference of the ISCE pulse. That is, the imaging area and the power of the ISCE pulse are set so that the imaging area where the power of the ISCE pulse is small includes a part with a large amount of fat components (a part where the fat component is substantially larger than other parts). For example, the intensity of the MR signal from the blood flow as described above can be adjusted, and the intensity of the MR signal from fat can be adjusted to the blood in the imaging region where the power of the ISCE pulse is farther from the heart than fat. It can be made smaller than the intensity of the MR signal from the stream.

  Therefore, the imaging region and the power of the ISCE pulse are set so that the pulse sequence created by the pulse sequence setting unit 45 includes a region having a large amount of fat component in the imaging region where the power of the ISCE pulse used for the imaging sequence is small. Pulse sequence. In other words, the pulse sequence created by the pulse sequence setting unit 45 can be used for scanning when a blood flow image is generated in an imaging region in which many fat components are present in a region near the heart.

  An example of such an imaging region is the head. That is, in the head, since many of the peripheral blood vessels are located farther from the heart than the fat portion in the orbit, the target of scanning for blood flow image creation using the pulse sequence created by the pulse sequence setting means 45 can do.

  The imaging region setting means 46 has a function of setting the imaging region and the power of the ISCE pulse so that the region having a large amount of fat component is included in the imaging region where the power of the ISCE pulse is small based on the information received from the input device 33. A function of giving the set imaging region and the power of the ISCE pulse to the pulse sequence setting means 45; The imaging region can be set by the position and number of each slice cross section.

  In addition, the imaging region setting unit 46 has a function of setting the MTC excitation surface together with the setting of the imaging region and giving the pulse sequence setting unit 45 when the SORS pulse is used. The setting of the MTC excitation plane may be performed based on information received from the input device 33, or may be automatically set from the imaging region according to a predetermined geometric relationship.

  The flip angle setting means 47 has a function of setting the flip angle of the SORS pulse or MTC pulse based on the information received from the input device 33, and a function of giving the flip angle of the set SORS pulse or MTC pulse to the pulse sequence setting means 45. And have. As described above, the flip angle of the SORS pulse and the MTC pulse is desirably set to be smaller as the intensity of the MR signal from fat becomes smaller, so as to increase the intensity of the MR signal from the substantial part.

  Here, the intensity of the MR signal from fat is set so that the imaging region and the power of the ISCE pulse are set so that the imaging region where the power of the ISCE pulse is small includes a region having a large amount of fat components. This is considered to be smaller than when scanning is performed using pulses. For this reason, the flip angle of the SORS pulse or MTC pulse set by the flip angle setting means 47 is set smaller than the flip angle set when scanning is performed using a general excitation pulse that is not an ISCE pulse. The

  However, if the flip angle is made too small, the intensity of the MR signal from the substantial part becomes large, and the MR signal from the blood flow component becomes relatively small, which may reduce the contrast between the blood flow and the substantial part. . For this reason, the flip angle of the SORS pulse or MTC pulse set by the flip angle setting means 47 requires a contrast between the blood flow and the substantial part when the MR signal from fat is reduced using the ISCE pulse. It is set larger than the flip angle at which contrast is achieved.

  The oblique section setting unit 48 has a function of setting the direction of the slice section based on the information received from the input device 33 and a function of giving the set direction of the slice section to the pulse sequence setting unit 45. That is, by adjusting the direction of the slice cross section, the region containing a large amount of fat components while including the blood vessel portion that needs to be clinically imaged in the imaging region becomes an imaging region where the power of the ISCE pulse is low, or It is possible to prevent the imaging region from including a region that does not require clinical imaging and includes a large amount of fat components.

  For this reason, the oblique cross-section setting unit 48 includes a blood vessel portion that needs to be clinically imaged in the imaging region so that a portion containing a large amount of fat component can be an imaging region with a low ISCE pulse power, or a clinical image. There is a function of setting the orientation of the slice cross section so that the region that does not need to be converted and contains a large amount of fat components is not included in the imaging region.

  Next, the operation of the magnetic resonance imaging apparatus 20 will be described.

  FIG. 7 is a flowchart showing an example of a flow when an MRA image on the head of the subject P is picked up by the magnetic resonance imaging apparatus 20 shown in FIG. 1, and reference numerals with numerals in FIG. Each step is shown.

  First, in step S1, imaging conditions such as an imaging region of a blood flow image using an ISCE pulse, an orientation of a slice section, a flip angle of a SORS pulse or an MTC pulse, and the like are set as an imaging region setting unit 46, an oblique section setting unit 48, and a flip angle. Set by the setting means 47. In addition, a SORS pulse is applied together, and an MTC excitation surface is set.

  The imaging region of the blood flow image is, for example, a head in which a region with a large amount of fat components exists in a region close to the heart.

  FIG. 8 is a diagram showing an example of the imaging region and the MTC excitation surface set by the magnetic resonance imaging apparatus 20 shown in FIG.

  As shown in FIG. 8, in the head of the subject P, many peripheral blood vessels are located farther from the heart than the fat portion in the orbit. For this reason, the power of the imaging region S1 and the ISCE pulse is set to the imaging region setting means 46 so that the fat portion in the orbit becomes a region where the power of the ISCE pulse is small, while many peripheral blood vessels become regions where the power of the ISCE pulse is large. Is set by

  In addition, it is desirable to reduce the MR signal from the fat part in the orbit, and conversely, since the blood vessel part near the central part of the head needs to be clinically imaged, the blood vessel part that needs to be clinically imaged is taken. The direction of the slice cross section is set by the oblique cross section setting means 48 so that the portion containing a large amount of fat components in the area S1 becomes an imaging area where the power of the ISCE pulse is small. Then, the imaging region setting means 46 sets the MTC excitation surface S2 to be farther from the heart than the imaging region S1.

  As a result, as shown in FIG. 8, the power profile of the ISCE pulse is an inclined power profile in which the power P increases as the distance from the heart increases depending on the position in the normal direction Z ′ of the slice cross section.

  Also, the flip angle setting means 47 sets the flip angle of the SORS pulse. The flip angle is smaller than the flip angle set when scanning is performed using a general excitation pulse that is not an ISCE pulse, and the blood flow is reduced when the MR signal from fat is reduced using the ISCE pulse. Is set to a value larger than the flip angle, for example, 300 °, when the required contrast with the substantial part is obtained.

  Information necessary for setting these imaging conditions is given from the input device 33 to the imaging area setting means 46, the oblique cross-section setting means 48, and the flip angle setting means 47, respectively. The imaging region setting unit 46, the oblique section setting unit 48 and the flip angle setting unit 47 give the imaging region S 1 of the blood flow image, the direction of the slice section, and the flip angle of the SORS pulse to the pulse sequence setting unit 45. .

  Next, in step S <b> 2, the pulse sequence setting unit 45 creates a pulse sequence so that scanning is executed according to the imaging conditions received from the imaging region setting unit 46, the oblique section setting unit 48 and the flip angle setting unit 47. The pulse sequence is a pulse sequence composed of a SORS sequence that applies a SORS pulse as a pre-pulse as shown in FIG. 3 and an imaging sequence that applies an ISCE pulse for imaging. The imaging sequence is a sequence for executing a scan by TOF, for example.

  Then, the pulse sequence setting unit 45 gives the created pulse sequence to the sequence controller control unit 40.

  At this time, the subject P is set on the bed 37 and a static magnetic field is formed in the imaging region of the static magnetic field magnet 21 (superconducting magnet) excited by the static magnetic field power supply 26. Further, a current is supplied from the shim coil power supply 28 to the shim coil 22, and the static magnetic field formed in the imaging region is made uniform.

  In step S3, when a scan start command is given from the input device 33 to the sequence controller control means 40, the pulse sequence is output from the sequence controller control means 40 to the sequence controller.

  For this reason, in step S4, TOS-3DMRA imaging is performed on the head of the subject P according to the pulse sequence, and raw data is collected.

  That is, the sequence controller 31 drives the gradient magnetic field power source 27, the transmitter 29, and the receiver 30 in accordance with the pulse sequence received from the sequence controller control means 40, so that the X-axis gradient magnetic field Gx is set in the imaging region where the subject P is set. The Y-axis gradient magnetic field Gy and the Z-axis gradient magnetic field Gz are formed, and an RF signal is generated.

  At this time, an X-axis gradient magnetic field Gx, a Y-axis gradient magnetic field Gy, and a Z-axis gradient magnetic field Gz formed by the gradient magnetic field coil are used to cause a phase encoding (PE) gradient magnetic field, a read (RO) gradient magnetic field, and a slice according to a pulse sequence. A gradient magnetic field for (SL) is formed.

  For this reason, regularity appears in the spin rotation direction of the nucleus inside the subject P, and the normal Z ′ having a constant inclination with respect to the Z axis that is the body axis direction by the gradient magnetic field for SL in each slice section. The dimensional positional information is converted into the phase change amount and the frequency change amount of the spin of the nucleus in the subject P by the PE gradient magnetic field and the RO gradient magnetic field, respectively.

  On the other hand, the transmitter 29 sequentially applies an RF signal to the RF coil 24 in accordance with the pulse sequence, and the RF coil 24 transmits the RF signal to the subject P. That is, prior to an imaging sequence for transmitting an ISCE pulse for creating a blood flow image, a SORS sequence is executed and a SORS pulse is transmitted. As a result, the MT effect is obtained at the MTC excitation surface S2 selectively excited by the transmission of the SORS pulse.

  Next, when an imaging sequence is executed and an ISCE pulse is transmitted in a state where the MT effect is obtained, an MR signal for creating a blood flow image is generated from the imaging region S1. The transmission of the ISCE pulse is performed at a TR shorter than T1 in the tissue in accordance with the scanning imaging conditions by TOF, so that the intensity of the MR signal from the stationary tissue is reduced, while the blood flow component flowing into the imaging region S1 The intensity of the MR signal becomes relatively high.

  Further, since the MTC excitation surface S2 is set farther from the heart than the imaging region S1, a high signal intensity is obtained from the blood flow in the artery flowing into the imaging region S1 from the heart side without passing through the MTC excitation surface S2. On the other hand, from the blood flow in the vein that flows out of the imaging region S1 and returns to the heart via the MTC excitation surface S2, the signal intensity is suppressed by the MT effect and the MR signal is generated.

  In addition, since the excitation pulse is an ISCE pulse whose power increases as the distance from the heart increases, even if the blood flow passes through the imaging region and the intensity of the MR signal decreases, the slice cross section is from the heart. Since the flip angle gradually increases as the distance increases, the decrease in MR signal from the blood flow is suppressed.

  Furthermore, a slice is so formed that the blood vessel portion in the central portion of the head that needs clinical imaging is included in the imaging region S1, and the imaging region S1 in which the power of the ISCE pulse is small includes the region having a large fat component in the orbit. The direction of the cross section is adjusted, and the imaging area S1 and the power of the ISCE pulse are set. For this reason, the intensity of MR signals from fat is suppressed while acquiring MR signals from blood vessel portions that need clinical imaging.

  Since the MR signal intensity from fat can be suppressed and reduced, the flip angle of the SORS pulse is set to be small, so that the MR signal intensity from the substantial part is increased and the blood flow component and the substantial part are reduced. MR signals can be generated with such intensity that distinction can be made clear.

  MR signals generated under such imaging conditions are received by the RF coil 24. When the MR signal from each slice cross section is received by the RF coil 24, the receiver 30 receives the MR signal from the RF coil 24 and performs preamplification, intermediate frequency conversion, phase detection, low frequency amplification, filtering, and the like. Various signal processing is executed. Further, the receiver 30 performs A / D conversion on the MR signal to generate raw data that is an MR signal of digital data. The receiver 30 gives the generated raw data to the sequence controller 31.

  The sequence controller 31 gives the raw data received from the receiver 30 to the sequence controller control means 40, and the sequence controller control means 40 arranges the raw data in the k space formed in the raw data database 41. As a result, in the raw data database 41, raw data collected from each slice cross section in the head of the subject P is accumulated.

  Next, in step S5, a blood flow image is generated and displayed using the raw data accumulated in the raw data database 41 as original data.

  That is, the image reconstruction means 42 reconstructs the 3D image data of the subject P by taking in the raw data from the raw data database 41 and performing a predetermined image reconstruction process such as a three-dimensional Fourier transform process. Write to the data database 43. Then, the projection image creating unit 44 creates MIP image data as blood flow image data by performing MIP processing on the 3D image data stored in the image data database 43, and displays the created MIP image data on the display device 34. To give. As a result, a MIP image in the axial direction, for example, in the head of the subject P is displayed on the display device 34 as a blood flow image.

  FIG. 9 shows the head of the subject P created as a blood flow image based on the data collected from the imaging region S1 by executing a scan according to the pulse sequence as shown in FIG. 3 according to the imaging conditions shown in FIG. It is a figure which shows the MIP image to the axial direction in a part.

  According to FIG. 9, it can be seen that blood vessels are imaged together with the substantial part in the head, but it can be confirmed that MR signals from fat in the orbit are suppressed and fat in the orbit is inconspicuous. The substantial part and blood vessels are imaged with good contrast.

  If three-dimensional image data reconstructed by suppressing MR signals from fat components in the eye socket is used in this way, for example, even if a MIP image in the coronal section direction or other directions is created, the blood vessel and the substantial part are separated. It can be confirmed separately. Therefore, complicated data processing such as performing region extraction processing such as threshold processing from three-dimensional image data to exclude fat components in order to create an MIP image is unnecessary.

  That is, in the magnetic resonance imaging apparatus 20 as described above, 3DMRA imaging is performed using an ISCE pulse having a spatial inclination in the power profile, and a region where the fat component is large is included in a region where the power of the ISCE pulse is small. By setting the imaging region as described above, the MR signal from fat can be reduced.

  Further, the magnetic resonance imaging apparatus 20 adjusts the direction of the slice cross section so that a region having a large amount of fat components is not included in the imaging region, or is applied prior to a scan for creating a blood flow image. A blood flow image can be obtained with good contrast by devising imaging conditions such as setting the flip angle of the SORS pulse and MTC pulse as small as possible.

  For this reason, according to the magnetic resonance imaging apparatus 20, it is not necessary to apply a fat suppression pulse, which is conventionally required, and the imaging time can be shortened. Moreover, MR signals from fat can be suppressed without applying a fat suppression pulse, and a blood flow image can be obtained with the required contrast.

  In particular, when creating a blood flow image in the head, it is possible to suppress MR signals from fat in the orbit and obtain a blood flow image that is easier to observe. For this reason, it becomes possible to create an MIP image from an arbitrary direction, and an area extraction process such as excluding an image of a fat area for creating an MIP image can be made unnecessary.

  Note that some functions and processing of the magnetic resonance imaging apparatus 20 may be omitted, and the processing order may be changed.

1 is a configuration diagram showing an embodiment of a magnetic resonance imaging apparatus according to the present invention. The functional block diagram of the computer in the magnetic resonance imaging apparatus shown in FIG. The figure which shows an example of the pulse sequence produced by the magnetic resonance imaging apparatus shown in FIG. 1, and used for execution of a scan. The figure explaining the concept of MT effect. The figure explaining the example of arrangement | positioning of the MTC excitation surface by a SORS pulse, and the effect by the application of a SORS pulse. The figure which compared the power profile of the ISCE pulse with the power profile of the general excitation pulse. 2 is a flowchart showing an example of a flow when an MRA image on the head of a subject is taken by the magnetic resonance imaging apparatus shown in FIG. The figure which shows an example of the imaging | photography area | region and MTC excitation surface which were set by the magnetic resonance imaging apparatus shown in FIG. By executing the scan according to the pulse sequence as shown in FIG. 3 according to the imaging conditions shown in FIG. 8, the head direction of the subject created as a blood flow image based on the data collected from the imaging region in the axial direction The figure which shows a MIP image. The figure which shows the imaging | photography area | region in the three-dimensional TOF non-contrast MRA imaging using the SORS pulse for obtaining the blood-flow image in the conventional subject's head. FIG. 11 is a diagram showing a pulse sequence for applying a fat suppression pulse together with a SORS pulse to the head of the subject shown in FIG. 10 prior to an imaging pulse for imaging a blood flow image. The figure which shows the MIP image to the body-axis direction of the head obtained by performing the scan according to a pulse sequence as shown in FIG. 11 with respect to the imaging region in the head of the subject shown in FIG.

Explanation of symbols

20 Magnetic Resonance Imaging Device 21 Magnet for Static Magnetic Field 22 Shim Coil 23 Gradient Magnetic Field Coil Unit 24 RF Coil 25 Control System 26 Static Magnetic Field Power Supply 27 Gradient Magnetic Field Power Supply 28 Shim Coil Power Supply 29 Transmitter 30 Receiver 31 Sequence Controller 32 Computer 33 Input Device 34 Display Device 35 Computing device 36 Storage device 37 Bed 40 Sequence controller control means 41 Raw data database 42 Image reconstruction means 43 Image data database 44 Projected image creation means 45 Pulse sequence setting means 46 Imaging area setting means 47 Flip angle setting means 48 Oblique section setting means P subject _{P H} head X, X1, X2 blood flow S1 imaging area S2 MTC excitation surface

Claims (9)

Of the imaging region for capturing a three-dimensional blood flow image of the subject, a region with a large amount of fat components is included in the portion where the power of the ISCE pulse, which is an excitation pulse whose power is spatially changed, is small. Imaging area setting means for setting the imaging area and the power of the ISCE pulse;
An imaging sequence that collects magnetic resonance signals by applying the ISCE pulse to create the blood flow image in the imaging region set by the imaging region setting means, and an MT effect prior to the application of the ISCE pulse. Pulse sequence setting means for setting a pulse sequence having a pre-pulse sequence for applying a pre-pulse for
In accordance with the imaging conditions specified by the pulse sequence set by the pulse sequence setting means, the gradient magnetic field is applied to the subject in a static magnetic field and a high-frequency signal is transmitted, while the ISCE inside the subject. Raw data collection means for generating raw data by receiving and digitizing the magnetic resonance signal generated along with the nuclear magnetic resonance of the nucleus by a pulse;
Blood flow image generating means for generating three-dimensional image data as the blood flow image from the raw data generated by the raw data collecting means;
A magnetic resonance imaging apparatus comprising: An ISCE pulse that is an excitation pulse that includes a blood vessel portion that requires clinical imaging in an imaging region for capturing a three-dimensional blood flow image of a subject while spatially changing the power of a region having a large amount of fat components. Oblique cross-section setting means for setting the orientation of each slice cross-section included in the imaging region so that the power can be a small portion,
Among the imaging areas formed by the slice sections in the direction set by the oblique section setting means, the imaging area and the imaging area and the area where the fat component is high are included in a portion where the power of the ISCE pulse is small An imaging region setting means for setting the power of the ISCE pulse;
An imaging sequence that collects magnetic resonance signals by applying the ISCE pulse to create the blood flow image in the imaging region set by the imaging region setting means, and an MT effect prior to the application of the ISCE pulse. Pulse sequence setting means for setting a pulse sequence having a pre-pulse sequence for applying a pre-pulse for
In accordance with the imaging conditions specified by the pulse sequence set by the pulse sequence setting means, the gradient magnetic field is applied to the subject in a static magnetic field and a high-frequency signal is transmitted, while the ISCE inside the subject. Raw data collection means for generating raw data by receiving and digitizing the magnetic resonance signal generated along with the nuclear magnetic resonance of the nucleus by a pulse;
Blood flow image generating means for generating three-dimensional image data as the blood flow image from the raw data generated by the raw data collecting means;
A magnetic resonance imaging apparatus comprising: Of the imaging region for capturing a three-dimensional blood flow image of the subject, a region with a large amount of fat components is included in the portion where the power of the ISCE pulse, which is an excitation pulse whose power is spatially changed, is small. Imaging area setting means for setting the imaging area and the power of the ISCE pulse;
Prior to the application of the ISCE pulse for creating the blood flow image in the imaging region set by the imaging region setting means, the pre-pulse flip angle applied to obtain the MT effect is not the ISCE pulse. The contrast between the blood flow and the substantial part is required when the MR signal from the fat component is reduced using the ISCE pulse, which is smaller than the flip angle set when the scan is performed using the pulse. A flip angle setting means for setting a value larger than the flip angle at the time of contrast;
Pulse sequence setting means for setting a pulse sequence having a pre-pulse sequence for applying a pre-pulse so as to have a flip angle set by the flip angle setting means and an imaging sequence for collecting the magnetic resonance signals by applying the ISCE pulse;
In accordance with the imaging conditions specified by the pulse sequence set by the pulse sequence setting means, the gradient magnetic field is applied to the subject in a static magnetic field and a high-frequency signal is transmitted, while the ISCE inside the subject. Raw data collection means for generating raw data by receiving and digitizing the magnetic resonance signal generated along with the nuclear magnetic resonance of the nucleus by a pulse;
Blood flow image generating means for generating three-dimensional image data as the blood flow image from the raw data generated by the raw data collecting means;
A magnetic resonance imaging apparatus comprising: In a magnetic resonance imaging apparatus for imaging a blood flow image of the head of a subject,
An area setting means for setting an imaging area in an area including the eye socket of the subject, and for setting a pre-pulse area that is closer to the top of the subject than the imaging area and to which a pre-pulse for obtaining an MT effect is applied; ,
A pulse sequence setting for setting a pre-pulse sequence for applying the pre-pulse to the pre-pulse region, and an imaging sequence for applying an ISCE pulse having a greater power on the parietal side than the orbital side to the imaging region after applying the pre-pulse. Means,
Collecting means for collecting magnetic resonance signals obtained by applying the pre-pulse sequence and the imaging sequence;
Image generating means for generating a MIP image from the magnetic resonance signal obtained by the collecting means;
A magnetic resonance imaging apparatus comprising: An oblique for setting the direction of each slice cross section included in the imaging region so that a region having a large amount of fat component can be a portion where the power of the ISCE pulse is low while the blood vessel portion requiring clinical imaging is included in the imaging region Cross-section setting means is provided, and the imaging area setting means is configured to set the imaging area formed by each slice section in the direction set by the oblique section setting means, while the flip angle of the prepulse is set to When a scan is performed using an excitation pulse that is not an ISCE pulse, it is smaller than the flip angle that is set, and when the MR signal from the fat component is reduced using the ISCE pulse, the blood flow and the substantial part Set to a value larger than the flip angle when the required contrast is achieved. Flip angle setting means is provided, and the pulse sequence setting means sets the prepulse sequence for applying the prepulse so as to be the flip angle set by the flip angle setting means. Item 2. The magnetic resonance imaging apparatus according to Item 1. 4. The magnetism according to claim 1, wherein the imaging region is a head of the subject, and a region having a large amount of the fat component is a region of a fat component in the eye socket of the subject. Resonance imaging device. Of the imaging region for capturing a three-dimensional blood flow image of the subject, a region with a large amount of fat components is included in the portion where the power of the ISCE pulse, which is an excitation pulse whose power is spatially changed, is small. Setting power of the imaging region and the ISCE pulse;
An imaging sequence for collecting the magnetic resonance signals by applying the ISCE pulse to create the blood flow image in the imaging region, and a prepulse sequence for applying a prepulse for obtaining the MT effect prior to the application of the ISCE pulse. Setting a pulse sequence comprising:
A control signal generation method for a magnetic resonance imaging apparatus. An ISCE pulse that is an excitation pulse that includes a blood vessel portion that requires clinical imaging in an imaging region for capturing a three-dimensional blood flow image of a subject while spatially changing the power of a region having a large amount of fat components. Setting the orientation of each slice cross-section included in the imaging region so that it can be a small power portion;
Setting the imaging region and the power of the ISCE pulse so that a region having a large amount of the fat component is included in a portion where the power of the ISCE pulse is small in the imaging region formed by each slice section;
An imaging sequence for collecting the magnetic resonance signals by applying the ISCE pulse to create the blood flow image in the imaging region, and a prepulse sequence for applying a prepulse for obtaining the MT effect prior to the application of the ISCE pulse. Setting a pulse sequence comprising:
A control signal generation method for a magnetic resonance imaging apparatus. Of the imaging region for capturing a three-dimensional blood flow image of the subject, a region with a large amount of fat components is included in the portion where the power of the ISCE pulse, which is an excitation pulse whose power is spatially changed, is small. Setting power of the imaging region and the ISCE pulse;
Prior to the application of the ISCE pulse for creating the blood flow image in the imaging region, the pre-pulse flip angle applied to obtain the MT effect is scanned using an excitation pulse other than the ISCE pulse. Than the flip angle that is smaller than the flip angle set in this case, and when the MR signal from the fat component is reduced using the ISCE pulse, the contrast between the blood flow and the substantial part is the required contrast. The step of setting to a larger value,
Setting a pulse sequence having a pre-pulse sequence for applying a pre-pulse so as to have the set flip angle and an imaging sequence for collecting the magnetic resonance signal by applying the ISCE pulse;
A control signal generation method for a magnetic resonance imaging apparatus.

Images