JP2020010972A - Magnetic resonance imaging apparatus and blood vessel separation display apparatus - Google Patents

Abstract

To provide a magnetic resonance imaging apparatus capable of distinguishing a plurality of blood vessels that supply blood to an imaging region.SOLUTION: A magnetic resonance imaging apparatus includes: a setting unit for setting a first sequence for applying a labelling pulse (A) to an inflow blood vessel α for supplying blood to an imaging region, and collecting a first magnetic resonance signal a predetermined delay time after the application of the labelling pulse (A), and a second sequence for applying a labelling pulse (B) to an inflow blood vessel β different from the inflow blood vessel α, and collecting a second magnetic resonance signal from the imaging region; a generation unit for generating a first image and a second image from the first and second magnetic resonance signals collected by the application of the first and second pulse sequences respectively; and a processing unit for dividing a plurality of blood vessels in the imaging region into a first blood vessel derived from the inflow blood vessel α and a second blood vessel derived from the inflow blood vessel β by a difference between the first image and the second image.SELECTED DRAWING: Figure 5

Description

  Embodiments of the present invention relate to a magnetic resonance imaging apparatus and a blood vessel separation and display apparatus.

  The magnetic resonance imaging apparatus excites a nuclear spin of a subject placed in a static magnetic field with a radio frequency (RF) signal having a Larmor frequency, and generates a magnetic resonance signal (MR (Magnetic) generated from the subject with the excitation. Resonance) signal to generate an image.

  In the field of magnetic resonance imaging, there is an imaging method called ASL (Arterial Spin Labeling) method. In the ASL method, after labeling the longitudinal magnetization of a fluid such as intravascular blood or cerebrospinal fluid (CSF) with a labeling pulse, an imaging sequence accompanied by an excitation pulse is applied after a predetermined waiting time, and an MR signal is applied. This is the imaging method to collect. The ASL method can generate an image in which the position of the labeled fluid after a predetermined waiting time is correctly depicted. Further, by performing a plurality of images with different waiting times, it is possible to correctly track the change in the position of the labeled fluid, that is, the movement of the labeled fluid.

  In the conventional ASL method, for example, when an imaging region is set on the head and a blood vessel of the head is imaged, a labeling pulse is applied to a slab crossing the neck, which is an upstream side of the head blood vessel. . Although blood flows into the head from a plurality of blood vessels, in the conventional ASL method, all of the plurality of flowing blood vessels are simultaneously labeled, so from which blood vessel the blood flowing into the imaging region flows. Could not be distinguished.

US Pat. No. 6,564,080

Markus Oelhafen et.al, “Calibration of Echo-Planar 2D-Selective RF Excitation Pulses”, Mag. Res. In Medicine 52: 1136-1145 (2004).

  The problem to be solved by the present invention is to make it possible to easily distinguish from which inflow blood vessel the blood in the imaging area flows in a situation where blood flows into the imaging area from a plurality of inflow blood vessels. is there.

  The magnetic resonance imaging apparatus according to one embodiment includes a setting unit, a generation unit, and a processing unit. The setting unit locally applies a first labeling pulse to a first inflow blood vessel that supplies blood to the imaging region, and after a predetermined delay time from the application of the first labeling pulse, sets the imaging region. A first pulse sequence for collecting a first magnetic resonance signal from a first inflow vessel, and a second labeling pulse for a second inflow vessel different from the first inflow vessel for supplying blood to the imaging region. And a second pulse sequence for collecting a second magnetic resonance signal from the imaging region. The generation unit generates a first image and a second image from the first and second magnetic resonance signals collected by applying the first and second pulse sequences, respectively. The processing unit determines a plurality of blood vessels in the imaging region from a first blood vessel derived from the first inflow blood vessel and a second inflow blood vessel, based on a difference between the first image and the second image. From the second blood vessel derived from

1 is a configuration diagram illustrating an example of the entire configuration of a magnetic resonance imaging apparatus according to an embodiment. FIG. 2 is a schematic explanatory view of a conventional ASL method. FIG. 2 is a functional block diagram of a processing circuit in the magnetic resonance imaging apparatus of the embodiment. 5 is a flowchart illustrating a processing example of the magnetic resonance imaging apparatus according to the first embodiment. FIG. 3 is a diagram illustrating a pulse sequence set in the first embodiment. The figure which shows an example of the sequence for data collection in a pulse sequence. The figure which shows the time change of the longitudinal magnetization in the data collected by execution of pulse sequence (A), (B). FIG. 3 is a conceptual explanatory diagram of an operation flow according to the first embodiment. FIG. 4 is a diagram illustrating an example of a difference image generated in the first embodiment. FIG. 3 is a conceptual explanatory diagram of a MIP process and a minIP process in the first embodiment. FIG. 3 is a first diagram illustrating a first modification of the first embodiment. FIG. 2 is a second diagram illustrating a first modification of the first embodiment. FIG. 6 is a diagram illustrating a pulse sequence according to a second modification of the first embodiment. FIG. 9 is a diagram illustrating a pulse sequence according to a third modification of the first embodiment. FIG. 9 is a diagram illustrating a pulse sequence according to a fourth modification of the first embodiment. FIG. 9 is a diagram illustrating a pulse sequence according to the third embodiment. FIG. 13 is a conceptual explanatory diagram of an operation flow according to the third embodiment. The figure which modeled the situation where several inflow blood vessels flow into an imaging area. FIG. 1 is a block diagram illustrating a configuration example of a blood vessel separation display device according to an embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a block diagram showing the overall configuration of the magnetic resonance imaging apparatus 1 according to the first embodiment. The magnetic resonance imaging apparatus 1 according to the embodiment includes a magnet gantry 100, a control cabinet 300, a console 400, a bed 500, and the like.

  The magnet mount 100 has a static magnetic field magnet 10, a gradient magnetic field coil 11, a WB (Whole Body) coil 12, and the like, and these components are housed in a cylindrical housing. The bed 500 has a bed main body 50 and a top plate 51. Further, the magnetic resonance imaging apparatus 1 has an array coil 20 disposed close to the subject.

  The control cabinet 300 includes a gradient magnetic field power supply 31 (31x for the X axis, 31y for the Y axis, 31z for the Z axis), an RF receiver 32, an RF transmitter 33, and a sequence controller 34.

  The static magnetic field magnet 10 of the magnet mount 100 has a substantially cylindrical shape, and generates a static magnetic field in a bore (space inside the cylinder of the static magnetic field magnet 10) which is an imaging region of a subject (for example, a patient). The static magnetic field magnet 10 has a built-in superconducting coil, and the superconducting coil is cooled to extremely low temperature by liquid helium. In the excitation mode, the static magnetic field magnet 10 generates a static magnetic field by applying a current supplied from a static magnetic field power supply (not shown) to the superconducting coil. Is cut off. Once in the permanent current mode, the static magnetic field magnet 10 continues to generate a large static magnetic field for a long time, for example, over one year. The static magnetic field magnet 10 may be configured as a permanent magnet.

  The gradient magnetic field coil 11 also has a substantially cylindrical shape, and is fixed inside the static magnetic field magnet 10. The gradient magnetic field coil 11 applies a gradient magnetic field to the subject in the X-axis, Y-axis, and Z-axis directions by a current supplied from a gradient magnetic field power supply (31x, 31y, 31z).

  The bed main body 50 of the bed 500 can move the top board 51 in the vertical direction, and moves the subject placed on the top board 51 to a predetermined height before imaging. Thereafter, at the time of imaging, the subject is moved into the bore by moving the top board 51 in the horizontal direction.

  The WB coil 12 is fixed in a substantially cylindrical shape inside the gradient magnetic field coil 11 so as to surround the subject. The WB coil 12 transmits an RF pulse transmitted from the RF transmitter 33 toward the subject, and receives a magnetic resonance signal emitted from the subject due to excitation of hydrogen nuclei.

  The array coil 20 is an RF coil and receives a magnetic resonance signal emitted from the subject at a position near the subject. The array coil 20 is composed of, for example, a plurality of element coils. There are various types of array coils 20 for the head, chest, spine, lower limbs, and whole body, depending on the imaging region of the subject. FIG. 1 illustrates the array coil 20 for the chest. ing.

  The RF transmitter 33 transmits an RF pulse to the WB coil 12 based on an instruction from the sequence controller 34. On the other hand, the RF receiver 32 detects a magnetic resonance signal received by the WB coil 12 or the array coil 20, and sends raw data obtained by digitizing the detected magnetic resonance signal to the sequence controller.

  The sequence controller 34 scans the subject under the control of the console 400 by driving the gradient magnetic field power supply 31, the RF transmitter 33, and the RF receiver 32, respectively. Then, when the sequence controller 34 performs scanning and receives raw data from the RF receiver 32, the sequence controller 34 sends the raw data to the console 400.

  The sequence controller 34 includes a processing circuit (not shown). This processing circuit is configured by, for example, a processor that executes a predetermined program, or hardware such as an FPGA (Field Programmable Gate Array) and an ASIC (Application Specific Integrated Circuit).

  The console 400 is configured as a computer having a processing circuit 40, a storage circuit 41, a display 42, and an input device 43.

  The storage circuit 41 is a storage medium including an external storage device such as a hard disk drive (HDD) and an optical disk device in addition to a read only memory (ROM) and a random access memory (RAM). The storage circuit 41 stores various information and data, and also stores various programs executed by a processor included in the processing circuit 40.

  The display 42 is a display device such as a liquid crystal display panel, a plasma display panel, and an organic EL panel. The input device 43 is, for example, a mouse, a keyboard, a trackball, a touch panel, or the like, and includes various devices for an operator to input various information and data.

  The processing circuit 40 is a circuit including, for example, a CPU and a dedicated or general-purpose processor. The processor realizes various functions to be described later by executing various programs stored in the storage circuit 41. The processing circuit 40 may be configured by hardware such as an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). Various functions described later can also be realized by these hardware. Further, the processing circuit 40 can also realize various functions by combining software processing with a processor and a program and hardware processing.

  With these components, the console 400 controls the entire magnetic resonance imaging apparatus 1. Specifically, an imaging condition and other various information and instructions are received by an operator such as a laboratory technician operating the mouse, keyboard, or the like (input device 42). Then, the processing circuit 40 causes the sequence controller 34 to execute scanning based on the input imaging conditions, and reconstructs an image based on the raw data transmitted from the sequence controller 34. The reconstructed image is displayed on the display 43 or stored in the storage circuit 41.

  Further, in the magnetic resonance imaging apparatus 1 of the embodiment, an image is reconstructed from an MR signal in an imaging region obtained by executing a scan according to a predetermined pulse sequence described later, and from this image, the blood flowing into the imaging region is determined. Processing for discriminating whether the blood is flowing from a blood vessel is performed.

  Before describing the operation of the magnetic resonance imaging apparatus 1 of the present embodiment, a conventional ASL method will be schematically described with reference to FIG. In the conventional ASL method, two pulse sequences of a pulse sequence (L) having a labeling pulse and a pulse sequence (C) having a control pulse are generally used as a pair.

  FIG. 2A is a diagram schematically showing a relationship between an application region of a labeling pulse and a control pulse in a conventional ASL method and an imaging region. As the imaging region, for example, a head is set, and a cerebral blood vessel is an imaging target. Blood flows into the head from a plurality of arteries such as a right internal carotid artery, a left internal carotid artery, a right vertebral artery, and a left vertebral artery. Hereinafter, these arteries will be referred to as inflow vessels. FIG. 2A illustrates only two inflow vessels α and β among a plurality of inflow vessels.

  As shown in FIG. 2A, the application region of the labeling pulse is usually set on the upstream side of the blood vessel flowing into the imaging region. The conventional labeling pulse application region is set as a slab (flat plate) defined by a predetermined thickness and a center position in the thickness direction. Therefore, when the imaging region is the head, for example, a slab that is substantially parallel to the axial section of the neck and crosses the entire neck is set as the imaging region.

  On the other hand, the control pulse application region is set as a slab having the same thickness as the slab of the labeling pulse application region, for example, in a region outside the imaging region, for example, at a position further above the head.

  FIG. 2B is a diagram illustrating a pair of two pulse sequences (L) and (C) used in the conventional ASL method. The labeling pulse and the control pulse are RF pulses having a predetermined flip angle. Although the labeling pulse and the control pulse have different application areas as shown in FIG. 2A, the flip angles are set to substantially the same value.

  A pulse sequence for data collection is applied in each pulse sequence after a predetermined delay time PLD (Post Labeling Delay) from the application time of the labeling pulse or the control pulse. Then, the data acquired by the pulse sequence (L) is reconstructed to generate a labeling image, and the data acquired by the pulse sequence (C) is reconstructed to generate a control image.

  Thereafter, as shown in FIG. 2C, the control image and the labeling image are subtracted to generate a blood vessel image. By the difference processing, the background in the imaging region is canceled and reduced to a value close to zero, so that a blood vessel image having a large contrast with the background can be generated.

  However, in the blood vessel image generated by the conventional ASL method, when blood flows from a plurality of inflow vessels into the imaging region, it is not possible to distinguish from which inflow blood the blood in the imaging region flows. In other words, it is not possible to associate a blood vessel in the imaging region with each inflowing blood vessel.

  The magnetic resonance imaging apparatus 1 of the present embodiment addresses such a problem. Hereinafter, the configuration and operation of the magnetic resonance imaging apparatus 1 will be described more specifically.

  FIG. 3 shows a functional block diagram of the processing circuit 40 of the magnetic resonance imaging apparatus 1. As shown in FIG. 3, the processing circuit 40 of the magnetic resonance imaging apparatus 1 realizes each of an imaging condition setting function 401, a first image generation function 402, a second image generation function 403, and an image processing function 410. . Here, the image processing function 410 includes a difference processing function 411, a MIP processing function 412, a minIP processing function 413, and a fusion image generation function 414. As described above, each of these functions is realized, for example, by the processor of the processing circuit 40 executing a predetermined program.

  In addition, in the configuration of the magnetic resonance imaging apparatus 1 shown in FIG. 1, components other than the console 40 (the control cabinet 300, the magnet mount 100, and the bed 500) constitute the collection unit 600.

  Among the above components, the imaging condition setting function 401 sets the imaging conditions such as the type of pulse sequence used in imaging and various parameters in the pulse sequence in the sequence controller 34. These imaging conditions are input by the operator via the input device 42, for example. Alternatively, the operator can change the already stored imaging conditions by operating the input device 42.

  FIG. 4 is a flowchart illustrating a processing example of the magnetic resonance imaging apparatus 1 according to the first embodiment. Hereinafter, specific processing of the magnetic resonance imaging apparatus 1 according to the first embodiment will be sequentially described with reference to this flowchart and FIGS. 5 to 10.

  In step ST100 of FIG. 4, a first pulse sequence and a second pulse sequence used in the first embodiment are set. Step ST100 is processing performed by the imaging condition setting function 410 in FIG. Step ST100 includes setting of the application area of the first labeling pulse included in the first pulse sequence and the application area of the second labeling pulse included in the second pulse sequence.

  FIG. 5 is a diagram illustrating a pulse sequence set in the first embodiment. In the first embodiment, a first labeling pulse is locally applied to a first inflow blood vessel that supplies blood to an imaging region, and imaging is performed after a predetermined delay time from the application of the first labeling pulse. A first pulse sequence for acquiring a first magnetic resonance signal from the region and a second labeling pulse for a second inflow vessel different from the first inflow vessel that supplies blood to the imaging area. And then a second pulse sequence for acquiring a second magnetic resonance signal from the imaging region.

  FIG. 5B illustrates a pulse sequence (A) as a first pulse sequence and a pulse sequence (B) as a second pulse sequence.

  The pulse sequence (A) includes a labeling pulse (A) as a first labeling pulse and a data collection sequence (Post Labeling Delay) applied after a predetermined delay time PLD (Post Labeling Delay) from the application time of the labeling pulse (A). 5 (b), the sequence is shown as “data (A) collection”.

  Similarly, the pulse sequence (B) includes a labeling pulse (B) as a second labeling pulse and a sequence for data collection applied after a predetermined delay time PLD from the application time of the labeling pulse (B) (FIG. 5). (B), a sequence indicated by “data (B) collection”).

  FIG. 5A is a diagram showing an example of the respective application areas of the labeling pulse (A) and the labeling pulse (B). As in FIG. 2A, it is assumed that blood flows from a plurality of inflow vessels into the imaging region. For example, assuming a head as an imaging region and cerebral blood vessels as an imaging target, the head includes a plurality of inflow blood vessels such as a right internal carotid artery, a left internal carotid artery, a right vertebral artery, and a left vertebral artery. Blood is flowing. In the example shown in FIG. 5A, two inflow vessels, an inflow vessel α and an inflow vessel β, are shown among the plurality of inflow vessels. The inflow blood vessel α is, for example, a right internal carotid artery, and the inflow blood vessel β is, for example, a left internal carotid artery.

  In the following, a first embodiment that uses a method for distinguishing from which of the inflow blood vessels α and the inflow blood vessels β the blood flowing into the imaging region flows, that is, a first embodiment that uses a method for identifying two inflow blood vessels will be described. As will be described below, the number of identifiable inflow vessels can easily be expanded to three or more.

  As is clear from FIG. 5A, in the magnetic resonance imaging apparatus 1 of the first embodiment (the same applies to other embodiments), two labeling pulses are applied only to different inflow vessels. I have. For example, the labeling pulse (A) is locally applied only to the inflow blood vessel α, and the labeling pulse (B) is locally applied only to the inflow blood vessel β.

  Here, “locally applying a labeling pulse only to a specific inflow blood vessel” means that by applying the labeling pulse, only the longitudinal magnetization of the blood of the specific inflow blood vessel is defeated at a certain flip angle, and the longitudinal direction is reduced. This means that the magnitude of the magnetization component is changed, and the longitudinal magnetization component of the blood in the inflow blood vessel other than the specific inflow blood vessel is not changed by the application of the labeling pulse. Therefore, it can be paraphrased as "the labeling pulse is applied exclusively to a specific inflow blood vessel".

  The “local application of a labeling pulse to a specific inflow blood vessel” will be further described by comparing the conventional ASL method (FIG. 2A) with the present embodiment (FIG. 5A).

  The application area of the labeling pulse in the conventional ASL method is a slab (flat) area, and as shown in FIG. 2A, when the thickness direction of the slab is the head-foot direction of the subject, Is determined by the center frequency and band of the labeling pulse (RF pulse) and the magnitude of the gradient magnetic field in the slice direction. However, in the width direction of the slab (for example, the lateral direction of the subject) and the depth direction (for example, the dorso-ventral direction of the subject), there is no restriction as to the spatial region defined by the pulse sequence, and the width of the slab is not changed. The labeling pulse is applied over a wide range in the direction and the depth direction. In other words, the labeling pulse according to the conventional ASL method is applied to a region where only the thickness direction of the slab is one-dimensionally selected. For this reason, in the conventional ASL method, a labeling pulse is simultaneously applied to all of a plurality of inflow blood vessels passing through the neck and the like.

  On the other hand, in the present embodiment, as shown in FIG. 5A, a labeling pulse is applied to a region in which the thickness direction and the width direction of the slab are selected two-dimensionally. That is, in the present embodiment, the labeling pulse is applied to a local region defined two-dimensionally in the thickness direction and the width direction of the slab. As a result, in the present embodiment, even when blood from a plurality of inflow vessels flows into one imaging region, it is possible to separate each of the plurality of inflow vessels and apply a labeling pulse. .

  A method of applying a labeling pulse to a local region defined two-dimensionally in a thickness direction and a width direction of a slab is disclosed in, for example, Non-Patent Document 1 and the like. It can be realized by using a known technique such as configuring as an RF pulse.

  The labeling pulses (A) and (B) may have a flip angle of 180 degrees, for example, and may be configured as inversion pulses for inverting the longitudinal magnetization of blood in each inflowing blood vessel. However, the flip angle need not necessarily be 180 degrees. Absent. For example, the flip angles of the labeling pulses (A) and (B) may be between 180 ° and 90 °, may be 90 °, or may be less than 90 °. The flip angle of the labeling pulse (A) and the flip angle of the labeling pulse (B) need not be the same, and may be different from each other.

  On the other hand, there is no particular limitation on the sequence for data collection applied after the labeling pulse (A) or (B). As a sequence for data collection, for example, a pulse sequence of a GRE (Gradient Echo) system such as a SSFP (steady-state free precision) method or an SE (Spin Echo) method such as a FASE (Fast Asymmetric Spin Echo) method may be used. ) -Based pulse sequence may be used. Alternatively, a GRE or SE EPI (Echo Planar Imaging) method or DWI (Diffusion Weighted Imaging) may be used.

  FIG. 6 is a diagram showing an example of a data collection sequence for collecting data (A) in the pulse sequence (A). The lower part of FIG. 6 illustrates a GRE pulse sequence corresponding to one phase encoding amount. In the data collection sequence, the k-space data (data (A) MR signal is collected while updating the phase encoding amount as PE1, PE2, PE3. As shown in FIG. Strictly speaking, the time PLD is defined as a period from the time at which the labeling pulse is applied to the time at which k-space data (ky = 0) whose phase encoding amount is zero is collected.

  If not all of the phase encoding amounts required to form an image can be collected by one pulse sequence, an image is formed by a plurality of segments obtained by dividing the phase encoding direction using a plurality of pulse sequences. May be collected.

  In step ST100 of FIG. 4, the above-described pulse sequences (A) and (B) are set. The process of step ST100 includes setting the application area of the above-described labeling pulses (A) and (B).

  Next, in step ST101 of FIG. 4, the above-described pulse sequence (A), that is, the first pulse sequence is executed, and data (A), that is, a first MR signal is collected. In step ST102, the above-described pulse sequence (B), that is, the second pulse sequence is executed to collect data (B), that is, a second MR signal. The processing in step ST101 and step ST102 is performed by the collection unit 600 in FIG.

  In the next step ST103, the first MR signal is reconstructed to generate a first image (absolute value image). Similarly, in step ST104, the second MR signal is reconstructed to generate a second image (absolute value image). The process of step ST103 is a process performed by the first image generation function 402 in FIG. 3, and the process of step ST104 is a process performed by the second image generation function 403.

  7 and 8 are diagrams for explaining the concept of the processing from step ST101 to step ST104.

  FIG. 7A is a diagram showing a temporal change of longitudinal magnetization in data (A) collected by executing the pulse sequence (A). Specifically, the longitudinal magnetization of the data (A) is imaged from: a) longitudinal magnetization of blood of a blood vessel group (hereinafter referred to as α-system blood vessel group) flowing into the imaging region from the inflow blood vessel α; Longitudinal magnetization of blood of a blood vessel group (hereinafter referred to as β-system blood vessel group) flowing into the region, and c) longitudinal magnetization of a background (region other than α-system blood vessel group and β-system blood vessel group) of the imaging region. FIG.

  Similarly, FIG. 7B is a diagram showing a temporal change of longitudinal magnetization in data (B) collected by execution of the pulse sequence (B). As in FIG. FIG. 3 is a diagram showing the longitudinal magnetization of (a) divided into (a) longitudinal magnetization of blood in the α-system blood vessel group, (a) longitudinal magnetization of blood in the β-system blood vessel group, and (c) longitudinal magnetization of the background.

  As can be seen from FIGS. 7A and 7B, the value of the longitudinal magnetization of the background of the imaging region is the same between data (A) and data (B), and does not change with time. This is because neither the labeling pulse (A) nor the labeling pulse (B) is applied to the imaging region.

  On the other hand, the longitudinal magnetization of the blood in the inflow blood vessel α is depressed by the application of the labeling pulse (A). When the flip angle of the labeling pulse (A) is larger than 90 °, the value of the longitudinal magnetization of the blood of the inflowing blood vessel α immediately after the application of the labeling pulse (A), as shown by the solid line in FIG. It becomes negative, and then recovers toward the original positive value in the process of flowing into the imaging region as an α-system blood vessel group.

  On the other hand, since the labeling pulse (A) is not applied to the inflow blood vessel β, the value of the longitudinal magnetization of the blood of the inflow blood vessel β is equal to that of the labeling pulse (A) as shown by a broken line in FIG. It does not change even after the application, and the value of the longitudinal magnetization of the β-system blood vessel group in the imaging region also shows a constant value.

  On the other hand, the longitudinal magnetization of the blood in the inflow blood vessel β is degraded by the application of the labeling pulse (B). When the flip angle of the labeling pulse (B) is larger than 90 °, the value of the longitudinal magnetization of the blood of the inflowing blood vessel β immediately after the application of the labeling pulse (B), as shown by the broken line in FIG. After that, it becomes negative, and then recovers toward the original positive value in the process of flowing into the imaging region as a β-system blood vessel group.

  On the other hand, since the labeling pulse (B) is not applied to the inflow blood vessel α, the value of the longitudinal magnetization of the blood in the inflow blood vessel α is equal to that of the labeling pulse (B) as shown by the solid line in FIG. The value does not change even after the application, and the value of the longitudinal magnetization of the α-system blood vessel group in the imaging region also shows a constant value.

  8, an image A is generated from data (A) collected by executing the pulse sequence (A), while an image A is generated from data (B) collected by executing the pulse sequence (B). FIG. 9 is a diagram illustrating the concept of processing from generation of image B to generation of a difference image between image B and image A.

  As is well known, the value of the pixel value of an image is approximately proportional to the value of the data (i.e., MR signal) collected. The value of the acquired MR signal is substantially proportional to the value of the transverse magnetization of each tissue, and the value of the transverse magnetization is substantially proportional to the value of the longitudinal magnetization when the excitation pulse is applied. Therefore, the pixel value of the image is approximately proportional to the value of the longitudinal magnetization of each tissue at the time of data collection.

  The pixel value of an image obtained by reconstructing the collected MR signals by inverse Fourier transform is a complex number as it is, but as an image for display, the absolute value of the complex number is calculated for each pixel, and the absolute value is calculated. Generally, an image is displayed on the display 42 or the like. Therefore, here, it is assumed that both the image A generated based on the execution of the pulse sequence (A) and the image B generated based on the execution of the pulse sequence (B) are absolute value images.

Further, here, the pixel value of the α-system blood vessel group of the image A is expressed as | S _A (α) |, and the pixel value of the β-system blood vessel group of the image A is expressed as | S _A (β) | Is described as | S _A (back) |.

Similarly, the pixel value of the α-system blood vessel group of the image B is expressed as | S _B (α) |, the pixel value of the β-system blood vessel group of the image B is expressed as | S _B (β) | the pixel value of the background | shall be denoted as | S _{B (back).}

Then, the following relationships (Equation 1) to (Equation 3) are established between the pixel values.
Pixel value of α-system blood vessel group: | S _B (α) |> | S _A (α) | (Equation 1)
Pixel value of β-system blood vessel group: | S _A (β) |> | S _B (β) | (Equation 2)
Background pixel value: | S _A (back) | = | S _B (back) | (Equation 3)

  The relations of (Equation 1) to (Equation 3) correspond to the longitudinal magnetization of the α-system blood vessel group, the longitudinal magnetization of the β-system blood vessel group, and the longitudinal magnetization of the background in FIGS. Can be easily derived from the size relationship.

  The above is the description of the processing from step ST101 to step ST104 in FIG. In the next step ST105, a difference image is generated from the second image and the first image. For example, a difference image is generated by subtracting the pixel value of the first image from the pixel value of the second image. The processing of step ST105 is performed by the difference processing function 411 in FIG.

By the processing of step ST105, the difference image is configured by substantially positive pixel values, substantially negative pixel values, and substantially zero pixel values, as shown in the following (Equation 4) to (Equation 6). .
alpha-based vascular group of pixel _{values: | S B (α) |} - | S A (α) |> 0: positive (Equation 4)
Pixel value of β-system blood vessel group: | S _B (β) | − | S _A (β) | <0: negative (Equation 5)
Background pixel value: | S _A (back) | − | S _B (back) | = 0: zero (Equation 6)
FIG. 9B is a diagram illustrating an example of the difference image generated as described above. Note that FIG. 9A is shown for comparison with FIG. 9B, and is the same as FIG. 5A.

  In the present embodiment, in addition to the effect that the background can be suppressed by setting the pixel value of the background to zero by the above-described difference processing, the blood of a plurality of blood vessel groups in the imaging region can be set in the plurality of inflow blood vessels. It is possible to identify from which inflowing blood vessel the inflow is based not only on the magnitude relationship between the pixel values of the difference image but also on the basis of only the sign of the pixel value.

  For example, as is apparent from the above (Equation 4) and (Equation 5), when the sign of the pixel value is positive, the pixel is a pixel of the α-system blood vessel group, that is, a pixel of blood flowing from the inflow blood vessel α. It can be determined that there is. Similarly, when the sign of the pixel value is negative, it can be determined that the pixel is a pixel of the β-system blood vessel group, that is, a pixel of blood flowing from the inflow blood vessel β.

  In the example described above, the difference image is obtained by subtracting the pixel value of the image A from the pixel value of the image B. Conversely, the difference image is obtained by subtracting the pixel value of the image B from the pixel value of the image A. An image may be obtained. In this case, as can be understood from (Equation 4) and (Equation 5), the sign of the pixel value of the α-system blood vessel group is negative and the sign of the pixel value of the β-system blood vessel group is positive. Even in this case, it is still possible to separate and identify the α-system blood vessel group and the β-system blood vessel group only by the sign of the pixel value of the difference image.

  Referring back to FIG. 4, in step ST106, MIP (Maximum Intensity Projection) processing is performed on the difference image to generate a first blood vessel image derived from a first inflow vessel (for example, inflow vessel α). In step ST107, the difference image is subjected to minIP (minimum Intensity Projection) processing to generate a second blood vessel image derived from the second inflow blood vessel (for example, inflow blood vessel β).

  MIP processing, that is, maximum value projection processing, performs projection processing on data constructed in three dimensions (in this example, three-dimensional difference images) in an arbitrary viewpoint direction, and calculates the maximum value in the projection path. Is a process for generating an image by extracting On the other hand, the minIP process, that is, the minimum value projection process, is a process of performing projection processing on data constructed three-dimensionally in an arbitrary viewpoint direction, extracting a minimum value in a projection path, and generating an image. is there.

  The right part of FIG. 8 and FIG. 10 are views for explaining the processing of steps ST106 and 107 described above. FIG. 10A is the same diagram as FIG. 9A, and is a diagram schematically illustrating the difference image generated in the process of step ST105. Also in the difference image shown in FIG. 10A, it is possible to distinguish the α-system blood vessel group and the β-system blood vessel group by the magnitude of the pixel value or the sign of the pixel value.

  Steps ST106 and ST107 are processes in which the MIP process and the minIP process are performed on the difference image to more clearly distinguish the α-system blood vessel group and the β-system blood vessel group. As described above, the pixel value of the α-system blood vessel group in the difference image is positive, and the pixel value of the β-system blood vessel group is negative. This means that the pixel value of the α-system blood vessel group is always larger than the pixel value of the β-system blood vessel group. Therefore, by performing MIP processing on the difference image, an α-system blood vessel group can be extracted from the difference image, and an α-system blood vessel group image as illustrated in FIG. 10B can be generated. Similarly, by performing minIP processing on the difference image, a β-system blood vessel group can be extracted from the difference image, and a β-system blood vessel group image as illustrated in FIG. 10C can be generated.

  As the process of extracting the α-system blood vessel group, the process of extracting only pixels having a positive pixel value from the difference image may be performed instead of the MIP process, or may be performed in addition to the MIP process. . Similarly, as the process of extracting the β-system blood vessel group, the process of extracting only pixels having a negative pixel value from the difference image may be performed instead of the minIP process, or may be performed in addition to the minIP process. Good. The processing of step ST106 in FIG. 4 is performed by the MIP processing function 412 of FIG. 3, and the processing of step ST107 is performed by the minIP processing function 413.

  In the above description, a difference image is generated from the image A and the image B, and MIP processing and minIP processing are performed on the generated difference image to separate and identify the α-system blood vessel group and the β-system blood vessel group. As described above, the processing for generating a difference image, the MIP processing, or the minIP processing can be omitted. For example, an α-system blood vessel group and a β-system blood vessel group may be separated and identified based on a difference value including a sign of each pixel value of the image A and the image B.

  Thereafter, the process of step ST108 in FIG. 4 may be performed. In step ST108, a fusion image is generated by synthesizing a first blood vessel image (for example, α-system blood vessel group image) and a second blood vessel image (for example, β-system blood vessel group image) so as to be distinguishable from each other. For example, the α-system blood vessel group image and the β-system blood vessel group image are processed so as to have different chromatic colors, or are processed so as to have different brightness achromatic colors, so that both can be easily identified. The fusion image of various aspects is generated. The process of step ST108 is performed by the fusion image generation function 414 in FIG.

  In step ST109, the generated fusion image is displayed on the display 42. The image displayed on the display 42 is not limited to the fusion image, but may be, for example, the first blood vessel image or the second blood vessel image generated in steps ST106 and ST107, or may be the difference image generated in step ST105.

  According to the magnetic resonance imaging apparatus 1 according to the above-described first embodiment, for example, in a situation where blood flows into the imaging region from two inflow blood vessels, it is possible to determine from which inflow blood vessel the blood in the imaging region flows. It can be easily distinguished. Further, it is possible to easily identify which inflow blood vessel the blood in the imaging region is derived from.

(First Modification of First Embodiment)
Hereinafter, some of the modifications of the first embodiment will be described. In some modified examples described below, in the process of step ST100, some parameters of the pulse sequence set by the imaging condition setting function 401 are different from those of the above-described first embodiment. Therefore, also in each modification, the configuration itself of the magnetic resonance imaging apparatus 1 is the same as the configuration shown in FIGS. 1 and 3, and the flow of processing is basically the same as that of the flowchart shown in FIG. is there.

  FIG. 11 is a diagram illustrating the concept of a first modification of the first embodiment. FIG. 12 is a diagram for explaining a so-called MT (Magnetic Transfer) effect in relation to the first modification of the first embodiment.

  FIG. 12 is a spectrum distribution diagram of the MR signal, in which the horizontal axis represents the frequency and the vertical axis represents the MR signal spectrum intensity. Since the spectrum of the free water signal in the living body has a narrow band, the spectrum of the free water signal is indicated by a thick black arrow in FIG. On the other hand, the spectrum of bound water that is bound to proteins and the like in a living body has a broad band, and spreads around the spectrum of the free water signal.

  As described so far, the labeling pulse is applied to an area different from the imaging area. This means that the frequency of the labeling pulse, which is an RF pulse, is in an off-resonant state with respect to the magnetic resonance frequency of free water in the imaging region, and the labeling pulse is applied to the combined water spectrum in the imaging region. I have. As a result, magnetic transfer occurs from the combined water in the imaging region to the free water, and a phenomenon occurs in which the free water signal is attenuated. This free water decay is called the MT effect.

  In the above-described first embodiment, as shown in FIG. 5A, the application region of the labeling pulse (A) and the application region of the labeling pulse (B) are set to regions close to each other. As a result, as shown in FIG. 12, the off-resonant frequencies Δf of the labeling pulse (A) and the labeling pulse (B) are almost the same, and the MT effect by applying the labeling pulse (A) and the labeling pulse (B) is also reduced. It is about the same. Therefore, the magnitude of the background signal in the imaging region that has undergone the MT effect is substantially the same between the image A and the image B, and the background signal can be favorably canceled in the difference image.

  On the other hand, there may be a case where the positions of two inflow vessels (inflow vessel α and inflow vessel β) to be distinguished from each other are distant. For example, as illustrated in FIG. 11, when the inflowing blood vessel α is the right internal carotid artery and the inflowing blood vessel β is the left vertebral artery, the application regions of the labeling pulse (A) and the labeling pulse (B) must be kept apart. I will not get it. As a result, the MT effect by the labeling pulse (A) is different from the MT effect by the labeling pulse (A). Therefore, in a first modification of the first embodiment, as shown in the lower part of FIG. 11, the control pulse (B) is applied immediately after the labeling pulse (A) of the pulse sequence (A), and the pulse sequence (B ), Pulse sequences (A) and (B) for applying the control pulse (A) immediately after the labeling pulse (B) are set.

  The control pulse (B) is an RF pulse applied to cancel the MT effect of the labeling pulse (A). For this reason, the control pulse (B) is applied to a region that does not affect the imaging region (in the example of FIG. 11, above the head), and on the frequency axis, as shown in FIG. Is set at a position symmetrical to the off-resonant frequency Δf of the labeling pulse (A).

  Similarly, the control pulse (A) is an RF pulse applied to cancel the MT effect of the labeling pulse (B). Therefore, the control pulse (A) is applied to a region that does not affect the imaging region (in the example of FIG. 11, in front of the nose), and on the frequency axis, as shown in FIG. The magnetic resonance frequency is set at a position symmetrical to the off-resonant frequency Δf of the labeling pulse (B).

  In other words, in the first modified example of the first embodiment, in the pulse sequence (A), the MT effect combining the labeling pulse (A) and the control pulse (B), and in the pulse sequence (B), the labeling pulse The control pulse (A) and the control pulse (B) are set so that the MT effect obtained by combining the control pulse (B) and the control pulse (A) becomes equal.

(Second Modification of First Embodiment)
FIG. 13 is a diagram illustrating pulse sequences (A) and (B) according to a second modification of the first embodiment. In the pulse sequences (A) and (B) of the second modified example of the first embodiment, data (A) with different delay times PLD (A) and PLD (B) are respectively obtained from the labeling pulses (A) and (B). ) And (B) are collected. Except for the delay time PLD, it is the same as the first embodiment. The pulse sequence (A) or (B) can also identify whether the blood in the imaging region is flowing from the inflow blood vessel α or the inflow blood vessel β.

(Third Modification of First Embodiment)
FIG. 14 is a diagram illustrating pulse sequences (A) and (B) of a third modification of the first embodiment. In the pulse sequences (A) and (B) of the third modification of the first embodiment, a plurality of data are collected at a plurality of different delay times PLD, in other words, at a plurality of different time phases. For example, as illustrated in FIG. 14, in the pulse sequence (A), from the labeling pulse (A), the data (A1), the data (A1), and the delay time PLD (1), PLD (2), and PLD (3), respectively, Data (A2) and data (A3) are collected. Similarly, in the pulse sequence (B), data (B1), data (B2), and data (B) are obtained from the labeling pulse (B) with three delay times PLD (1), PLD (2), and PLD (3), respectively. B3) is collected. Then, by generating a difference image for each corresponding time phase, it is determined for each of the plurality of delay times PLD whether the blood in the imaging region is flowing from the inflow blood vessel α or the inflow blood vessel β. Phase by phase).

(Fourth Modification of First Embodiment)
FIG. 15 is a diagram illustrating pulse sequences (A) and (B) of a fourth modification of the first embodiment. In the pulse sequences (A) and (B) of the fourth modified example of the first embodiment, as shown in FIG. 15A, the application region of the labeling pulses (A) and (B) is the first embodiment. And different. In the example shown in FIG. 15, the inflow blood vessel γ is interposed between the inflow blood vessel α and the inflow blood vessel β. In such an arrangement state of blood vessels, the application region of the labeling pulse (A) may include an inflow blood vessel γ other than the inflow blood vessel β to be identified, in addition to the inflow blood vessel α. In such a case, in the pulse sequences (A) and (B) of the fourth modification of the first embodiment, the application region of the labeling pulse (B) is set so as to include the inflow blood vessel γ in addition to the inflow blood vessel β. Set. In other words, the inflow blood vessel γ is commonly included in the respective application regions of the labeling pulse (A) and the labeling pulse (B). By setting such an application region, the influence of the inflow blood vessel γ is offset in the difference image, and it is possible to identify whether the blood in the imaging region flows from the inflow blood vessel α or the inflow blood vessel β. .

(Second embodiment)
In the first embodiment and each of the modifications described above, the image A and the image B are respectively generated as absolute value images, and the pixel values (absolute values) of the image A and the image B are differentiated to obtain the difference. The difference method of generating an image is used. On the other hand, in the magnetic resonance imaging apparatus 1 of the second embodiment, a modified example of the difference method that is different from the above-described difference method is used.

  For example, as a first modified example of the difference method, in step ST103 and step ST104 in FIG. 4, the image A (first image) and the image B (second image) are replaced with the real part (real part) whose pixel value is a complex number. ) Is generated as a real image. Then, in step ST105, a difference image as a real image is generated by subtracting each pixel value (real part of a complex number) of the image A and the image B. Thereafter, the MIP process in step ST106 and the minIP process in step ST107 are performed on the difference image as the real image.

  In addition, as a second modification of the difference method, the difference processing may be performed on the raw data (that is, k-space data) before reconstructing the images A and B. That is, data (A) and data (B) as k-space data collected by executing the pulse sequences (A) and (B) are subtracted to generate differential k-space data. Then, the difference k-space data is reconstructed by inverse Fourier transform to generate a difference image as a complex image. Thereafter, the MIP processing in step ST106 and the minIP processing in step ST107 are performed on the difference image as the complex image or the difference image as a real image using the real part of each pixel value.

  According to the magnetic resonance imaging apparatus 1 of the second embodiment described above, it is possible to identify whether blood in the imaging region is flowing from the inflow blood vessel α or the inflow blood vessel β.

(Third embodiment)
In the above-described first embodiment and its modified example, or in the second embodiment, when blood flows from two inflow vessels (for example, inflow vessel α and inflow vessel β) into the imaging area, the imaging area A method has been described for identifying whether blood in the blood flows from the inflow blood vessel α or the inflow blood vessel β. However, there may be a case where blood flows into the imaging region from three or more inflow blood vessels.

  In the magnetic resonance imaging apparatus 1 according to the third embodiment, even when blood flows into the imaging region from three or more inflow blood vessels, the blood in the imaging area is in the plurality of inflow blood vessels. A method is provided for identifying from which inflowing blood vessel the blood flows.

  FIGS. 16 and 17 are diagrams for explaining the operation concept of the magnetic resonance imaging apparatus 1 according to the third embodiment. In the following description using FIGS. 16 and 17, a case where blood from three inflow vessels (inflow vessel α, inflow vessel β, and inflow vessel γ) flows into the imaging region is used, but loses generality. Without any limitation, it can be extended to four or more inflow vessels.

  In the third embodiment, as illustrated in FIG. 16A, when blood from the inflow blood vessel α, the inflow blood vessel β, and the inflow blood vessel γ flows into the imaging region, the state illustrated in FIG. The three pulse sequences (A), (B), and (C) are executed, and three data (data (A), data (B), and data (C)) are collected from the imaging region.

  Then, similarly to the first embodiment, the labeling pulse (A) of the pulse sequence (A) is locally or exclusively applied to the upstream region of the inflowing blood vessel α. That is, the labeling pulse (A) is applied only to the inflow blood vessel α without applying to the region of the inflow blood vessel β or the inflow blood vessel γ. As a result, by the application of the labeling pulse (A), only the blood flowing into the imaging region from the inflowing blood vessel α changes the magnitude of its longitudinal magnetization component, as in FIG. The longitudinal magnetization component of the blood in the inflow blood vessel γ is maintained at the same value without any change.

  Similarly, the labeling pulses (B) and (C) of the pulse sequences (B) and (C) are also applied locally or exclusively to the upstream region of the inflow blood vessel β and the inflow blood vessel γ, respectively. .

  FIG. 17 is an explanatory diagram in which FIG. 8 illustrating the operation concept of the first embodiment using two pulse sequences is extended to the operation concept of the third embodiment using three pulse sequences. In the third embodiment, an image A, an image B, and an image C are generated from each data collected by executing the pulse sequences (A), (B), and (C). Each image is, for example, an absolute value image.

Here, similarly to the description of FIG. 8, the pixel value of the α-system blood vessel group of the image A is denoted as | S _A (α) |, and the pixel value of the β-system blood vessel group of the image A is | S _A (β) |, And the pixel value of the γ-system blood vessel group is expressed as | S _A (γ) |. The pixel value of the background of the image A is represented as | S _A (back) |.

Similarly, alpha-based vascular group of images B, beta-based vascular group, and the pixel value of the γ-based vascular group, _{respectively, | S B (α) |} , | S B (β) |, and | S _B (gamma) | and represented, the image B pixel values of the background | shall be denoted as | S _{B (back).}

Similarly, the pixel values of the α-system blood vessel group, the β-system blood vessel group, and the γ-system blood vessel group of the image C are respectively expressed as | S _C (α) |, | S _C (β) |, and | S _C (γ) |, and the pixel value of the background of the image C is written as | S _C (back) |.

Then, the following relationship similar to the above-described (Equation 1) to (Equation 3) is established between the pixel values.
Pixel value of α-system blood vessel group: | S _B (α) | = | S _C (α) |> | S _A (α) | (Equation 7)
Pixel value of β-system blood vessel group: | S _A (β) | = | S _C (β) |> | S _B (β) | (Equation 8)
Pixel value of γ-system blood vessel group: | S _A (γ) | = | S _B (γ) |> | S _C (γ) | (Equation 8)
Background pixel value: | S _A (back) | = | S _B (back) | = | S _C (back) | (Equation 10)

Next, a difference image (1) is generated from the image A and the image B, for example, by calculating (image B-image A). Then, the pixel values of the α-system blood vessel group, the β-system blood vessel group, the γ-system blood vessel group, and the pixel value of the background in the difference image (1) are as follows.
alpha-based vascular group of pixel _{values: | S B (α) |} - | S A (α) |> 0: positive (11)
beta-based vascular group of pixel _{values: | S B (β) |} - | S A (β) | <0: Negative (12)
gamma-based vascular group of pixel _{values: | S B (γ) |} - | S A (γ) | = 0: zero (equation 13)
Background pixel value: | S _A (back) | − | S _B (back) | = 0: zero (Equation 14)

  As can be seen from the above equations, if the influence of noise or the like is ignored, the pixel value of the α-system blood vessel group in the difference image (1) is positive, and the pixel value of the β-system blood vessel group is negative, while γ The pixel values of the system blood vessel group and the background are zero. Therefore, similarly to the first embodiment, by performing MIP processing on the difference image (1), it is possible to extract the α-system blood vessel group from the difference image (1). By performing minIP processing on (1), a β-system blood vessel group can be extracted from the difference image (1).

Similarly, a difference image (2) is generated from the image B and the image C by, for example, calculating (image C-image B). Then, the pixel values of the α-system blood vessel group, the β-system blood vessel group, the γ-system blood vessel group, and the pixel value of the background in the difference image (2) are as follows.
Pixel value of α-system blood vessel group: | S _C (α) | − | S _B (α) | = 0: zero (Equation 15)
Pixel value of β-system blood vessel group: | S _C (β) | − | S _B (β) |> 0: positive (Equation 16)
Pixel value of γ-system blood vessel group: | S _C (γ) | − | S _B (γ) | <0: negative (Equation 17)
Background pixel value: | S _C (back) | − | S _B (back) | = 0: zero (Equation 18)

  As can be seen from the above equations, if the influence of noise or the like is ignored, the pixel value of the β-system blood vessel group in the difference image (2) is positive, and the pixel value of the γ-system blood vessel group is negative, while α The pixel values of the system blood vessel group and the background are zero. Therefore, by performing the MIP processing on the difference image (2), it is possible to extract the β-system blood vessel group from the difference image (2). Similarly, the minIP processing is performed on the difference image (2). By performing this, the γ-system blood vessel group can be extracted from the difference image (2).

  As described above, even when blood from the inflow blood vessel α, the inflow blood vessel β, and the inflow blood vessel γ flows into the imaging region, the α-system blood vessel group and the β-system blood Groups and γ-system blood vessels can be extracted and identified by a simple method.

  FIG. 18 is a diagram modeling a situation in which a plurality of inflow vessels flow into the imaging region, and illustrates that the above-described third embodiment can be applied to four or more inflow vessels. FIG.

  For example, it is assumed that blood from eight inflow vessels of the inflow vessel α, the inflow vessel β,..., The inflow vessel θ flows into the imaging region in the center of FIG. In such a case, the image A is generated by the pulse sequence (A) having the labeling pulse (A) whose application region is exclusively set to the inflow blood vessel α, and the application region is exclusively set to the inflow blood vessel β. An image B is generated by a pulse sequence (B) having a labeling pulse (B), and an image C is generated by a pulse sequence (C) having a labeling pulse (C) whose application area is set exclusively to the inflow blood vessel γ. , An image D is generated by a pulse sequence (D) having a labeling pulse (D) whose application region is exclusively set to the inflow blood vessel δ, and so on, eight images (images A to H) are generated. .

  Then, from the difference image of the two images selected from these images, it is possible to distinguish two bloods (blood vessel groups) in the imaging region derived from the two inflow vessels corresponding to the two images. For example, from the difference image between the image A and the image B, it is possible to distinguish between the blood derived from the inflow blood vessel α and the blood derived from the inflow blood vessel β in the imaging region. Further, the blood derived from the inflow blood vessel β and the blood derived from the inflow blood vessel γ can be distinguished from the difference image between the image B and the image C. The blood derived from the blood flowing from the inflow blood vessel δ can be distinguished. Further, from the difference image obtained by subtracting the image A and the image D, it is possible to distinguish the blood derived from the inflow blood vessel α and the blood derived from the inflow blood vessel δ.

(Vessel separation display device)
FIG. 19 is a block diagram illustrating a configuration example of a blood vessel separation display device 800 according to another embodiment of the present invention. As shown in FIG. 19, the blood vessel separation display device 800 is configured as a device having a processing circuit 80, a storage circuit 81, a display 82, an input device 83, and an input interface 801 such as a computer.

  The processing circuit 80, the storage circuit 81, the display 82, and the input device 83 have functions similar to those of the processing circuit 40, the storage circuit 41, the display 42, and the input device 43 in the console 400 described above. Omitted.

  The input interface 801 of the blood vessel separation display device 800 inputs data via a wired or wireless network, a dedicated or general-purpose communication line, or inputs data via a storage medium such as an optical disk or a USB memory. Interface circuit. In the blood vessel separation display device 800 of the present embodiment, the image A (that is, the first image) and the image B (that is, the second image) generated by the above-described magnetic resonance imaging apparatus 1 are input via the input interface 801. A first image input function 802 and a second image input function 803 of the processing circuit 80 are input.

  The processing performed by the image processing function 410 of the processing circuit 80 is the same as that of the magnetic resonance imaging apparatus 1 described above, and a description thereof will be omitted. According to the blood vessel separation and display device 800 of the embodiment, it is possible to easily distinguish from which inflow blood vessel the blood in the imaging region is flowing in by processing the input images A and B.

  As described above, the magnetic resonance imaging apparatus and the blood vessel separation and display apparatus of each embodiment are designed such that, in a situation where blood flows from a plurality of inflow vessels into the imaging area, blood in the imaging area flows from any inflow vessel. Can be easily distinguished.

  Note that the imaging condition setting function described in each embodiment is an example of a setting unit described in the claims. Further, the first image generation function and the second image generation function in the description of each embodiment are examples of the generation unit in the description of the claims. Further, the image processing function in the description of each embodiment is an example of a processing unit in the description of the claims.

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

Reference Signs List 1 magnetic resonance imaging apparatus 40, 80 processing circuit 41, 81 storage circuit 42, 82 display 43, 83 input device 400 console 401 imaging condition setting function 402 first image generation function 403 second image generation function 410 image processing function 411 difference processing Function 412 MIP processing function 413 minIP processing function 414 Fusion image generation function 600 Collection unit 800 Vascular separation display device 801 Input interface 802 First image input function 803 Second image input function

Claims (11)

A first labeling pulse is locally applied to a first inflow blood vessel that supplies blood to an imaging region, and after a predetermined delay time from the application of the first labeling pulse, a first labeling pulse is applied from the imaging region to a first inflowing blood vessel. A first pulse sequence for acquiring a magnetic resonance signal, and a second labeling pulse is locally applied to a second inflow vessel different from the first inflow vessel for supplying blood to the imaging region. A setting unit for setting a second pulse sequence for collecting a second magnetic resonance signal from the imaging region,
A generation unit configured to generate a first image and a second image from the first and second magnetic resonance signals collected by applying the first and second pulse sequences, respectively;
Based on a difference between the first image and the second image, a plurality of blood vessels in the imaging region are derived from a first blood vessel derived from the first inflow blood vessel and a plurality of blood vessels derived from the second inflow blood vessel. A processing unit for distinguishing the second blood vessel from the second blood vessel;
A magnetic resonance imaging apparatus comprising: The generating unit generates the first image and the second image as absolute value images, respectively.
The processing unit sets a plurality of blood vessels in the imaging region to the first inflow blood vessel based on a difference value including a sign of each pixel value of the first image and the second image. Distinguishing the first blood vessel derived from the second blood vessel derived from the second inflow blood vessel,
The magnetic resonance imaging apparatus according to claim 1. The generating unit generates the first image and the second image as absolute value images, respectively.
The processing unit applies a MIP (Maximum Intensity Projection) method to a difference image obtained by subtracting the first image from the second image to obtain a first image from a plurality of blood vessels in the imaging region. While extracting the first blood vessel derived from the inflowing blood vessel, the difference image is subjected to minIP (minimum Intensity Projection) to obtain the second inflowing blood vessel from a plurality of blood vessels in the imaging region. Extracting the second blood vessel
The magnetic resonance imaging apparatus according to claim 1. The generating unit generates the first image and the second image as absolute value images, respectively.
The processing unit applies a MIP (Maximum Intensity Projection) method to a difference image obtained by subtracting the second image from the first image to obtain a second image from a plurality of blood vessels in the imaging region. While extracting the second blood vessel derived from the inflowing blood vessel, the difference image is subjected to minIP (minimum Intensity Projection) to obtain the first inflowing blood vessel from a plurality of blood vessels in the imaging region. Extracting the first blood vessel,
The magnetic resonance imaging apparatus according to claim 1. The processing unit synthesizes the extracted first blood vessel and the second blood vessel so that they can be distinguished from each other, and a plurality of blood vessels in the imaging region are combined with the first blood vessel derived from the first inflowing blood vessel. Generating a fusion image distinguished from the second blood vessel derived from the second inflow vessel;
The magnetic resonance imaging apparatus according to claim 3. The setting unit cancels the first MT (Magnetic Transfer) effect generated by applying the first labeling pulse and the second MT effect generated by applying the second labeling pulse by the difference. And setting an application area of the first labeling pulse and an application area of the second labeling pulse.
The magnetic resonance imaging apparatus according to claim 1. The setting unit may be configured to set a first labeling pulse application area and a second labeling pulse application area to a first MT (Magnetic Transfer) effect generated by applying the first labeling pulse, When the second MT effect generated by the application of the second labeling pulse is set at a position that is not canceled by the difference, the second MT effect is used to cancel the second MT effect immediately after the first labeling pulse. Applying a first control pulse, and applying a second control pulse for canceling the first MT effect immediately after the second control pulse;
The magnetic resonance imaging apparatus according to claim 1. The setting unit may be configured such that the application region of the first labeling pulse includes, in addition to the first inflow vessel, a third inflow vessel other than the first inflow vessel and the second inflow vessel. Sets an application area of the second labeling pulse so as to include the third inflow blood vessel in addition to the second inflow blood vessel.
The magnetic resonance imaging apparatus according to claim 1. The setting unit includes:
Applying the first labeling pulse to the right internal carotid artery and collecting the first magnetic resonance signal from the head;
Applying the second labeling pulse to the left internal carotid artery and collecting the second magnetic resonance signal from the head;
Set,
The magnetic resonance imaging apparatus according to claim 1. A labeling pulse, a pulse sequence for collecting data after a predetermined delay time from the application of the labeling pulse, for a plurality of inflow vessels supplying blood to an imaging region, the labeling pulse is applied to a plurality of inflow vessels, respectively. A setting unit for setting a plurality of pulse sequences to be applied locally;
From a set of a plurality of magnetic resonance signals collected by the application of the plurality of pulse sequences, a generating unit that respectively generates a plurality of images,
By a difference between the plurality of images, a processing unit that distinguishes a plurality of blood vessels in the imaging region into respective blood vessels derived from the plurality of inflow blood vessels,
A magnetic resonance imaging apparatus comprising: A first labeling pulse is locally applied to a first inflow blood vessel that supplies blood to an imaging region, and after a predetermined delay time from the application of the first labeling pulse, a first labeling pulse is applied from the imaging region to a first inflowing blood vessel. A first pulse sequence for acquiring a magnetic resonance signal, and a second labeling pulse is locally applied to a second inflow vessel different from the first inflow vessel for supplying blood to the imaging region. And then generating a first image generated from the first and second magnetic resonance signals acquired by applying a second pulse sequence for acquiring a second magnetic resonance signal from the imaging region And an input unit for inputting a second image and
Based on a difference between the first image and the second image, a plurality of blood vessels in the imaging region are derived from a first blood vessel derived from the first inflow blood vessel and a plurality of blood vessels derived from the second inflow blood vessel. A processing unit for separating into a second blood vessel;
A display unit that displays at least one of the separated first blood vessel and the second blood vessel;
A blood vessel separation display device comprising: