JP2022109798A - Image processing apparatus, magnetic resonance imaging apparatus, and image processing system - Google Patents

Abstract

To determine the height of a coil installed on an analyte.SOLUTION: An image processing apparatus of one embodiment comprises first acquisition means, second acquisition means, and determination means. The first acquisition means successively acquires an image including a coil disposed on an analyte. The second acquisition means acquires a first time when the coil passes through a first reference point as a result of the movement of a top plate with the analyte placed thereon and a second time when the coil passes through the second reference point as a result of the movement, on the basis of the images successively acquired by the first acquisition means. The determination means determines the height of the coil on the basis of the first time and the second time.SELECTED DRAWING: Figure 3

Description

The embodiments disclosed in the specification and drawings relate to an image processing apparatus, a magnetic resonance imaging apparatus, and an image processing system.

A magnetic resonance imaging apparatus excites the nuclear spins of a subject placed in a static magnetic field with a radio frequency (RF) signal of the Larmor frequency, and emits a magnetic resonance signal (MR (Magnetic It is an imaging device that reconstructs the resonance (resonance) signal) to generate an image. A magnetic resonance imaging apparatus can noninvasively acquire magnetic resonance signals from a subject.

There is also a technique for analyzing an image acquired by an optical camera in a system that includes a magnetic resonance imaging apparatus and an optical camera. The system identifies the progress of a series of procedures based on workflow information indicating a series of procedures related to imaging and the analysis results of images, and notifies information on the next procedure. According to the system, it is possible to more appropriately present the procedure for imaging.

JP 2018-183525 A

One of the problems to be solved by the embodiments disclosed in the specification and drawings is determining the height of the coil placed on the subject. However, the problems to be solved by the embodiments disclosed in this specification and drawings are not limited to the above problems. A problem corresponding to each effect of each configuration shown in the embodiments described later can be positioned as another problem.

An image processing apparatus according to one embodiment includes a first acquisition unit, a second acquisition unit, and a determination unit. The first acquiring means sequentially acquires images including the coils arranged on the subject. The second acquisition means acquires a first time when the coil passes through the first reference position and a second time when the coil passes through the second reference position due to movement of the top plate on which the subject is placed. Acquired based on the images sequentially acquired by The determining means determines the height of the coil based on the first time and the second time.

1 is a configuration diagram showing an example of the overall configuration of an image processing system according to an embodiment; FIG. 4A to 4C are diagrams showing images acquired in the process of moving the bed top plate into the bore of the magnet pedestal of the image processing system according to the embodiment; FIG. 2 is a block diagram showing functions of the image processing system according to the embodiment; FIG. 4 is a flowchart showing the operation of the image processing system according to the embodiment; FIG. 4 is a diagram for explaining a method of determining the height of the chest coil in the image processing system according to the embodiment; FIG. 4 is a diagram for explaining a method of determining the height of the chest coil in the image processing system according to the embodiment; FIG. 11 is a diagram for explaining a method of determining the height of the chest coil in the image processing system according to the modification;

Hereinafter, embodiments of an image processing apparatus, a magnetic resonance imaging apparatus, and an image processing system will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of an image processing system S according to the embodiment. An image processing system S of the embodiment includes a magnetic resonance imaging (MRI) device 1 and an optical camera 8 . The magnetic resonance imaging apparatus 1 includes a magnet pedestal 100, a control cabinet 300, an image processing device (for example, a console) 400, a bed 500, and the like.

The magnet pedestal 100 and bed 500 are usually placed in a shield room. On the other hand, the control cabinet 300 is arranged, for example, in a room called a machine room, and the console 400 is arranged in an operation room.

The magnet mount 100 has a static magnetic field magnet 10, a gradient magnetic field coil 11, a WB (Whole Body) coil 12, etc., and these components are housed in a cylindrical housing. The bed 500 has a bed body 50 and a bed top plate 51 . The magnetic resonance imaging apparatus 1 also has an RF coil 20 arranged close to the subject. In the following description, the RF coil 20 is one component of the magnetic resonance imaging apparatus 1 , but the RF coil 20 may not be included in the configuration of the magnetic resonance imaging apparatus 1 . In this case, although the RF coil 20 is not included in the configuration of the magnetic resonance imaging apparatus 1, the RF coil 20 and the magnetic resonance imaging apparatus 1 are configured to be connectable to each other. More specifically, the RF coil 20 and the bed top plate 51 of the magnetic resonance imaging apparatus 1 are configured to be connectable to each other.

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

The static magnetic field magnet 10 of the magnet pedestal 100 has a substantially cylindrical shape, and generates a static magnetic field in a bore (a 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 incorporates a superconducting coil, and the superconducting coil is cooled to an extremely low temperature by liquid helium. 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 in the excitation mode, and then, when shifting to the persistent current mode, the static magnetic field power supply is separated. Once transferred to the persistent 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. Note that 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 . This gradient magnetic field coil 11 is composed of three gradient magnetic field coils for the X-axis, the Y-axis, and the Z-axis. Gradient magnetic field currents are supplied to the respective gradient magnetic field coils from gradient magnetic field power sources (31x, 31y, 31z) to generate gradient magnetic fields in the X-, Y-, and Z-axis directions and apply them to the subject.

The bed main body 50 of the bed 500 can move the bed top plate 51 vertically and horizontally, and moves the subject placed on the bed top plate 51 to a predetermined height before imaging. After that, during imaging, the patient is moved into the bore by moving the bed top plate 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 magnetic resonance signals (that is, MR signals) emitted from the subject by excitation of hydrogen nuclei.

The RF coil 20 receives MR signals emitted from the subject at a position close to the subject. The RF coil 20 includes, for example, multiple element coils. There are various types of RF coils 20, such as for the head, for the chest, for the spine, for the legs, or for the whole body, depending on the imaging region of the subject. A plurality of RF coils 20 can be placed on the subject at the same time. FIG. 1 illustrates a state in which a chest RF coil (hereinafter referred to as a "chest coil") 20 is placed.

The RF transmitter 33 transmits RF pulses to the WB coil 12 based on instructions from the sequence controller 34 . A coil selection circuit 36 selects the MR signal received by the WB coil 12 or the MR signal received by the RF coil 20 and transmits it to the RF receiver 32 . The RF receiver 32 detects MR signals received by the WB coil 12 or the RF coil 20 and sends raw data obtained by digitizing the detected MR signals to the sequence controller 34 .

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

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

Console 400 is configured as a computer having processing circuitry 40 , memory circuitry 41 , display 42 and input device 43 .

The storage circuit 41 is a storage medium including a ROM (Read Only Memory), a RAM (Random Access Memory), and an external storage device such as a HDD (Hard Disk Drive) and an optical disk device. The storage circuit 41 stores various kinds of information and data, as well as various programs executed by the processor included in the processing circuit 40 .

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

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

The console 400 controls the entire magnetic resonance imaging apparatus 1 by these components. The processing circuit 40 causes the sequence controller 34 to perform scanning based on the input imaging conditions, while reconstructing an image based on raw data input from the sequence controller 34, that is, digitized MR signals. The reconstructed image is displayed on display 42 or stored in memory circuit 41 .

The optical camera 8 is installed, for example, on the ceiling of the imaging room in which the magnetic resonance imaging apparatus 1 is installed. The optical camera 8 includes a lens, an image sensor, an amplifier, an A/D (Analog to Digital) converter (not shown), and the like. A lens is an optical element for refracting and focusing light. The image sensor images an RF coil to be imaged, for example, the chest coil 20 placed on the subject placed on the bed top plate 51 via an objective optical system (not shown). An amplifier amplifies the output video signal from the image sensor. The A/D converter converts the analog video signal output from the amplifier into a digital signal. The optical camera 8 is connected to the processing circuit 40 and outputs the captured image to the processing circuit 40 as a digital signal.

The optical camera 8 photographs all or part of the bed top plate 51 from above before entering the magnet pedestal 100, and obtains an image of the chest coil 20 placed on the subject placed on the bed top plate 51. do. For example, optical camera 8 can acquire a moving image as an image of chest coil 20 .

The lens of the optical camera 8 may be a standard lens, or may be a so-called wide-angle lens having a wider angle of view than the standard lens. The optical camera 8 is not limited to being installed on the ceiling, and may be fixed to a cover (including the inside of the bore) that covers the magnet pedestal 100 or an end of the magnet pedestal 100. , the magnet mount 100 or a wall around the magnet mount 100 . Furthermore, the case where the object to be imaged is the chest coil 20 will be described, but the object is not limited to that case, and may be, for example, an abdominal RF coil, a shoulder joint RF coil, or the like.

FIGS. 2A to 2C are diagrams showing images acquired during the process of moving the bed top plate 51 into the bore of the magnet pedestal 100. FIG.

FIG. 2A shows an image frame Gt0 acquired by the optical camera 8 at time t0. The image frame Gt0 includes an image of the subject placed on the bed top plate 51 and an image of the chest coil 20 placed on the subject. The image of the chest coil 20 includes an end Pe farther from the magnet pedestal 100 and an end Ps closer to the magnet pedestal 100 . When the bed top plate 51 starts moving, the optical camera 8 acquires an image frame Gt1 at time t1 (see FIG. 2B). In FIG. 2B, compared to FIG. 2A, the bed top plate 51, the subject, and the chest coil 20 are moved in the z-axis negative direction (the direction toward the magnet pedestal 100). .

Further, as the movement of the bed top plate 51 progresses, the optical camera 8 acquires an image frame Gt2 at time t2 (see FIG. 2(C)). In FIG. 2(C), the bed top plate 51, the subject, and the chest coil 20 are moved in the negative z-axis direction compared to FIG. 2(B).

FIG. 3 is a block diagram showing functions of the image processing system S. As shown in FIG.

As shown in FIG. 3, the processing circuit 40 reads and executes a computer program stored in the storage circuit 41 or directly incorporated in the processing circuit 40 to obtain the first acquisition function F1 and the second acquisition function F1. It implements an acquisition function F2, a determination function F3, and an imaging function F4. In the following, the functions F1 to F4 will be explained as an example in which the functions F1 to F4 function in software by executing a computer program, but all or part of the functions F1 to F4 may be realized by a circuit such as an ASIC. . Also, the functions F1 to F3 may be provided in a computer different from the console 400 having the imaging function F4, such as a doublet computer.

The first acquisition function F1 includes a function of sequentially acquiring, by the optical camera 8, images including the RF coil placed on the subject, for example, the chest coil 20 placed on the subject placed on the bed top plate 51. . Note that the first acquisition function F1 is an example of a first acquisition unit.

The second acquisition function F2 acquires a first time at which the chest coil 20 passes through the first reference position and a second time at which the chest coil 20 passes through the second reference position as the bed 51 on which the subject is placed moves. , a function of obtaining based on the images sequentially obtained by the first obtaining function F1. Note that the second acquisition function F2 is an example of a second acquisition unit.

The determination function F3 includes a function of determining the height of the chest coil 20 based on the first time and the second time acquired by the second acquisition function F2. The chest coil 20 is placed on the chest of the subject lying on the bed top plate 51 . Therefore, the height of the chest coil 20, that is, the height of the chest coil 20 from the bed top 51 corresponds to the width of the subject lying on the bed top 51 in the y-axis direction (for example, dorsal-abdominal direction). It will be. The decision function F3 is an example of decision means.

The imaging function F4 has a function of setting an FOV (Field Of View), which is an imaging range, based on the height of the chest coil 20 determined by the determination function F4, and performs MR imaging of the subject based on the FOV. Including functions. If the height of the chest coil 20 can be determined, the width of the FOV to be imaged can be appropriately set, at least in the y-axis direction. Note that the imaging function F4 is an example of imaging means.

Next, the operation of the image processing system S will be explained.

FIG. 4 is a flow chart showing the operation of the image processing system S. As shown in FIG.

First, in step ST<b>11 , the subject is placed on the bed top plate 51 of the bed 500 . In step ST11, the subject is placed on the bed top plate 51 at the lowered position, and the height of the bed top plate 51 is adjusted by raising the bed top plate 51 on which the subject is placed. be.

Subsequently, in step ST12, an RF coil, for example, the chest coil 20 is installed on the subject placed on the bed top plate 51. FIG. In step ST12, the chest coil 20 is placed on the chest of the subject, the cable of the chest coil 20 is connected to the coil port, and the chest coil 20 is fixed to the subject.

Subsequently, in step ST13, the first obtaining means F1 starts photographing, for example, moving image photographing by the optical camera 8. FIG. As a result, the first acquisition function F1 finishes capturing the image frame including the RF coil placed on the subject, for example, the chest coil 20 placed on the subject placed on the bed top plate 51 (step ST22). can be obtained sequentially. Further, in step ST14, the imaging function F4 starts moving the bed top plate 51 into the bore of the magnet pedestal 100. As shown in FIG. The first acquisition function F1 acquires an image frame including the chest coil 20 placed on the subject (step ST15).

The second acquisition function F2 detects the chest coil 20 (the end part Pe of the chest coil 20 described later) based on the image frame acquired in step ST15 while the bed 51 on which the subject is placed is moving, It is determined whether or not the chest coil 20 has reached the first reference position (step ST16). If the determination in step ST16 is NO, that is, if it is determined that the chest coil 20 has not reached the first reference position, the second acquisition function F2 acquires the chest coil based on the image frame corresponding to the next frame. 20 has reached the first reference position (step ST16). That is, the second acquisition function F2 repeats the determination in step ST16 until the chest coil 20 reaches the first reference position.

On the other hand, if the determination in step ST16 is YES, that is, if it is determined that the chest coil 20 has reached the first reference position, the second acquisition function F2 sets the time at which the frame was acquired to the first reference position. It is obtained as the first passing time (step ST17).

Subsequently, the first acquisition function F1 acquires an image frame including the chest coil 20 placed on the subject for the next frame (step ST18). The second acquisition function F2 detects the chest coil 20 (the end part Pe of the chest coil 20 described later) based on the image frame acquired in step ST18 while the bed 51 on which the subject is placed is moving, It is determined whether or not the chest coil 20 has reached the second reference position (step ST19). If the determination in step ST19 is NO, that is, if it is determined that the chest coil 20 has not reached the second reference position, the second acquisition function F2 acquires the chest coil based on the image frame corresponding to the next frame. 20 has reached the second reference position (step ST19). That is, the second acquisition function F2 repeats the determination in step ST19 until the chest coil 20 reaches the second reference position.

On the other hand, if the determination in step ST19 is YES, that is, if it is determined that the chest coil 20 has reached the second reference position, the second acquisition function F2 sets the time at which the frame was acquired to the second reference position. It is acquired as the second time to pass through (step ST20).

The determination function F3 determines the height of the chest coil 20 based on the first time acquired in step ST17 and the second time acquired in step ST20 (step ST21). A method of determining the height of the chest coil 20 in step ST20 will be described later with reference to FIGS. 5 and 6. FIG.

5 and 6 are diagrams for explaining how the determination function F3 determines the height of the chest coil 20. FIG. FIG. 5 is an external side view showing the image processing system S. As shown in FIG.

The image processing system S shown in FIG. Here, the half angle of the field angle of the optical camera 8 is defined as "θ", the distance from the focal point of the optical camera 8 to the upper surface of the bed top plate 51 is defined as "H0", and the distance from the optical camera 8 to the chest coil 20 is defined as "θ". is "H'", the length of the bed top plate 51 in the z-axis direction is "L0", and the visual range of the height of the chest coil 20 is "L'". The distance H′ from the optical camera 8 to the chest coil 20 is the distance from the optical camera 8 to the center of the thickness of the chest coil 20, but is considered synonymous with the distance from the optical camera 8 to the upper surface of the chest coil 20. be able to.

The determining function F3 can determine the height H of the chest coil 20 from the bed top plate 51 (simply referred to as "the height of the chest coil 20") from "H0-H'". In other words, since the distance H0 from the focal point of the optical camera 8 to the upper surface of the bed top plate 51 is known, the determination function F3 can determine the distance H' from the optical camera 8 to the chest coil 20. can be obtained from "H0-H'".

Here, using the angle θ of the optical camera 8, the following equation (1) can be derived. Based on the equation (1), the distance H' from the optical camera 8 to the chest coil 20 can be obtained from the following equation (2).

Then, the determination function F3 obtains the movement range L' of the chest coil 20 within the visual field range determined by the angle θ of the optical camera 8. FIG. The method will be described with reference to FIG.

The determination function F3 obtains the time required for the characteristic point of the chest coil 20 to pass through the first reference position and the second reference position due to the movement of the bed top plate 51 as follows. For example, as shown in the upper part of FIG. 6 (time t0), the end Pe of the chest coil 20 farther from the magnet mount 100 is set as a feature point. Further, for example, the first reference position is assumed to be the center of the image frame in the movement direction (ie, z-axis direction) of the bed top plate 51 (the optical camera 8 is attached perpendicularly to the bed top plate 51). ), and the second reference position is the end of the image frame in the moving direction of the bed top plate 51 (on the magnet gantry 100 side).

When the bed top plate 51 moves at the speed v, the end Pe of the chest coil 20 reaches the position of the chest coil 20 when it passes the first reference position, as shown in the middle part of FIG. When the second acquisition function F2 determines that the end Pe of the chest coil 20 has reached the first reference position (image center) based on the image frame, the end Pe of the chest coil 20 passes through the first reference position. A first time t1 is stored.

Further, when the bed top plate 51 moves at the speed v, as shown in the lower part of FIG. 6, the end Pe of the chest coil 20 reaches the position of the chest coil 20 when it passes the second reference position. When the second acquisition function F2 determines that the end Pe of the chest coil 20 has reached the second reference position (image end) based on the image frame, the end Pe of the chest coil 20 reaches the second reference position. A passing second time t2 is stored.

A first time t1 when the end Pe of the chest coil 20 passes the first reference position (image center) and a second time t1 when the end Pe of the chest coil 20 passes the second reference position (image end) Using t2, the following equation (3) can be derived. Then, based on the equation (3), the visual field range L' of the height of the chest coil 20 can be obtained from the following equation (4). Further, by substituting the visual field range L' of the height of the chest coil 20 in the formula (4) into the above formula (2), the following formula (5) can be obtained.

The above equation (5) defines the distance H′ from the focal point of the optical camera 8 to the chest coil 20 as the moving speed v of the bed top plate 51, the first time t1, the second time t2, and the angle of the optical camera 8. It shows that it can be formulated with θ. Since the moving speed v of the bed top plate 51 and the angle θ of the optical camera 8 are known (because the angle of view is known), if the first time t1 and the second time t2 are obtained based on the image frame, , the distance H' from the optical camera 8 to the chest coil 20 can be determined. Thereby, the height H of the chest coil 20 can be obtained from "H0-H'".

The end Pe of the chest coil 20 farther from the magnet pedestal 100 is set as a feature point, the first reference position is set as the center of the image of the optical camera 8, and the second reference position is set as the image edge on the magnet pedestal 100 side. It is not limited to those cases. However, it is preferable to use the first reference position as the center of the angle of view, because detection accuracy of the end Pe of the chest coil 20 based on the image frame is better when the first reference position is the center of the angle of view. Therefore, it is preferable to set the image end portion on the side of the magnet gantry 100 where the end portion Pe of the chest coil 20 passes after the center of the angle of view as the second reference position.

Returning to the description of FIG. 4, the first acquisition function F1 ends the optical photography started in step ST13, and the imaging function F4 ends the movement of the bed top 51 started in step ST14 (step ST22). The imaging function F4 sets the FOV as the imaging range, for example, the FOV in the y direction, based on the height H of the chest coil 20 determined in step ST21 (step ST23).

The imaging function F4 determines imaging conditions such as the step amount and number of steps of phase encoding in the y direction based on the FOV set in step ST23, and executes MR imaging of the subject (step ST24). After imaging is completed, the bed top plate 51 is pulled out from the bore of the magnet pedestal 100 and retracted, and the chest coil 20 is removed from the subject. Then, the subject placed on the bed top plate 51 is withdrawn from the bed top plate 51 .

Note that the optical imaging in step ST13 may be started before the chest coil 20 is installed in step ST12, or after the movement of the bed board 51 is started in step ST14. Further, the end of optical imaging in step ST22 may be after the end of MR imaging in step ST24. Further, the optical imaging is not limited to starting and ending before one MR imaging, and optical imaging may be continuously performed over a plurality of MR imagings.

As described above, according to the console 400, the magnetic resonance imaging apparatus 1, and the image processing system S, it is possible to acquire the height H of the RF coil, for example, the chest coil 20 placed on the subject. That is, according to the console 400, the magnetic resonance imaging apparatus 1, and the image processing system S, it is possible to acquire the body type information (for example, thickness in the ventral-dorsal direction) of the subject on which the FR coil, for example, the chest coil 20 is installed. .

For example, when setting the FOV of the axial section, if the size of the FOV in the y direction is set smaller than the thickness of the subject in the y direction (the ventral-back direction), folding distortion (that is, aliasing) occurs in the y direction of the image. do. In order to avoid this, the size of the FOV in the y-direction is usually set to be larger than the thickness of the subject in the y-direction (ventral-dorsal direction) by, for example, about 50 mm, taking into consideration the movement of the subject. For this reason, conventionally, for example, it was necessary to measure the thickness in the ventral-dorsal direction of the subject in advance, but according to the present embodiment, such work becomes unnecessary.

Moreover, from the viewpoint of safety, information on the body weight of the subject may be required when setting the upper limit of the SAR (Specific Absorption Rate). According to this embodiment, since information on the thickness of the subject in the y direction (ventral-dorsal direction) can be obtained, the weight of the subject can be estimated, and the user does not need to measure the weight or set the device. becomes.

(Modification)
So far, the description has been made on the assumption that the chest coil 20 is horizontally placed on the subject. However, there are cases where the chest coil 20 is placed on the subject so as to be inclined according to the shape of the subject. In that case, if a feature point is set at the lower end of the tilted chest coil 20 (the end closer to the bed top plate 51), the height of the chest coil 20 is determined to be lower. The FOV for imaging is set narrow. Therefore, this modification is characterized in that the height of the chest coil 20 is determined based on the characteristic point of the tilted upper end of the chest coil 20 (the end farther from the bed top plate 51). As a result, the FOV for MR imaging can be appropriately set when the chest coil 20 is placed on the subject with an inclination.

When the chest coil 20 is installed tilted by rotating about the x-axis, the height of the chest coil 20 is determined when the predetermined feature point is one point, so the height of the chest coil 20 is determined. Unable to detect location. Since the height is the highest on the side closer to or farther from the magnet mount 100, the chest coil 20 is considered as a flat plate, and in addition to the end Pe of the chest coil, the end Ps on the side closer to the magnet mount 100 is defined as a feature point. set as

In addition to the first time and the second time, the second acquisition function F2 shown in FIG. It includes a function of acquiring the third time to be set based on the images sequentially acquired by the first acquisition function F1. The determination function F3 includes a function of determining the height of the chest coil 20 based on the first time, the second time, and the third time acquired by the second acquisition function F2.

FIG. 7 is a diagram for explaining how the determination function F3 determines the height of the chest coil 20. FIG.

For example, the end Pe of the chest coil 20 farther from the magnet pedestal 100 and the end Ps closer to the magnet pedestal 100 are defined as feature points (see the uppermost part of FIG. 7). Further, for example, the first reference position can be set to the center of the image of the optical camera 8 (assuming that the optical camera 8 is attached perpendicularly to the bed top plate 51), and the second reference position can be set to It can be the image edge of the optical camera 8 (the side closer to the magnet mount 100).

The second row from the top in FIG. 7 shows the position of the chest coil 20 when the end Pe of the chest coil 20 passes through the first reference position. When the second acquisition function F2 determines that the end Pe of the chest coil 20 has reached the first reference position (image center) based on the image frame, the end Pe of the chest coil 20 passes through the first reference position. A first time t1 is stored. Note that the first time t1 is equivalent to the first time t1 described using the middle part of FIG.

The third row from the top in FIG. 7 shows the position of the chest coil 20 when the end Ps of the chest coil 20 passes through the second reference position. When the second acquisition function F2 determines that the end Ps of the chest coil 20 has reached the second reference position (image end) based on the image frame, the end Ps of the chest coil 20 reaches the second reference position. The passing third time t3 is stored.

7 shows the position of the chest coil 20 when the end Pe of the chest coil 20 passes through the second reference position. When the second acquisition function F2 determines that the end Pe of the chest coil 20 has reached the second reference position (image end) based on the image frame, the end Pe of the chest coil 20 reaches the second reference position. A passing second time t2 is stored. Note that the second time t2 is equivalent to the second time t2 described using the lower part of FIG.

The third stage from the top of FIG. 7 will be described. If the chest coil 20 is not tilted, the third time when the end Ps of the chest coil 20 passes the image end of the optical camera 8 is "t30". The third time t30 is represented by the following equations (6) to (7). Note that W is the length of the chest coil 20 .

Since the length W of the chest coil 20 is known, it represents the third time t30 from the second time t2 when the end Pe of the chest coil 20 passes the second reference position to the third time t30 when the end Ps passes the second reference position. be able to.

On the other hand, when the chest coil 20 is tilted, the time at which the end Ps of the chest coil 20 passes through the second reference position changes. Specifically, when the height of the chest coil 20 is lower at the end Ps than at the end Pe, the time to pass the second reference position is delayed, while the height of the chest coil 20 is higher than at the end Pe. When the part Ps is higher, the time to pass the second reference position is hastened.

If these are formulated, (a) when the actual passing time t of the second reference position is compared with the passing time t30 when the chest coil 20 is not tilted and "t>t30", the following equation (8 ) to (10). On the other hand, in the case of (b) "t<t30", the following equations (11) to (12) can be defined. Note that equations (10) and (12) are equivalent.

As described above, according to the modification of the console 400, the magnetic resonance imaging apparatus 1, and the image processing system S, the inclination of the chest coil 20 is considered based on the two characteristic points Pe and Ps of the chest coil 20. The height H of the thoracic coil 20 can be determined.

(detection accuracy)
The detection accuracy of the height of the chest coil 20 with respect to the movement speed of the bed top plate 51 will be described. For example, assume that the moving speed of the bed top plate 51 is 400 [mm/sec]. On the other hand, if the frame rate of the optical camera 8 is 20 [fps] (20 frames per second), the moving bed top 51, that is, the chest coil 20 is detected with an accuracy of 20 [mm/frame]. be able to. This numerical value means that the image acquired by the optical camera 8 may be shifted horizontally by 2 [mm].

Convert the horizontal displacement into height accuracy. Assuming that the optical camera 8 is installed at a ceiling height of 3 m, the height of the bed top plate 51 from the floor surface is 1 m, and the length of the bed top plate 51 is 2 m, the bed top plate The angle of the optical camera 8 with respect to 51 is 45°. Therefore, if the displacement in the horizontal direction is ΔL, the displacement in the height direction ΔH is represented by the following equation (13).

As shown in (13) above, the displacement ΔH in the height direction is approximately 20 [mm]. As described above, in normal MR imaging, the FOV is set to be about 50 [mm] wider than the body shape of the subject, considering the movement of the subject and the folding back of the image. can be considered acceptable.

As described above, according to the console 400, the magnetic resonance imaging apparatus 1, and the image processing system S, the height H of the RF coil, for example, the chest coil, placed on the subject can be obtained. That is, according to the console 400, the magnetic resonance imaging apparatus 1, and the image processing system S, it is possible to acquire the body type information (for example, thickness in the ventral-dorsal direction) of the subject on which the FR coil, for example, the chest coil 20 is installed. .

According to at least one embodiment described above, the height of the coil placed on the subject can be determined.

Note that the first acquisition function F1 is an example of a first acquisition unit. The second acquisition function F2 is an example of a second acquisition means. The decision function F3 is an example of decision means. The imaging function F4 is an example of imaging means.

While several embodiments 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 various other forms, and various omissions, replacements, changes, and combinations of embodiments can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

1 Magnetic Resonance Imaging Device 8 Optical Camera 20 Chest Coil 40 Processing Circuit 51 Bed F1 First Acquisition Function F2 Second Acquisition Function F3 Decision Function F4 Imaging Function S Image Processing System

Claims (8)

a first acquisition means for sequentially acquiring images including the coils placed on the subject;
A first time at which the coil passes through the first reference position and a second time at which the coil passes through the second reference position as the table on which the subject is placed moves, are sequentially obtained by the first obtaining means. a second acquiring means for acquiring based on the obtained image;
determining means for determining the height of the coil based on the first time and the second time;
Image processing device. the first reference position is the center of the image in the moving direction of the tabletop;
wherein the second reference position is an edge of the image in the moving direction of the tabletop;
The image processing apparatus according to claim 1. using the time at which the end of the coil farther from the cradle passes through a reference position;
The image processing apparatus according to claim 1 or 2. The second acquisition means obtains, in addition to the first time and the second time, a third time when the coil passes through a third reference position due to movement of the top plate on which the subject is placed. , based on the images sequentially acquired by the first acquisition means,
The determination means determines the height of the coil based on the first time, the second time, and the third time.
The image processing apparatus according to any one of claims 1 to 3. The second obtaining means obtains the first time when the far end of the coil passes the first reference position, and the near end of the coil passes the second reference position. Acquiring a third time of passing and the second time of passing the end portion through the second reference position based on the images sequentially acquired by the first acquiring means;
The image processing apparatus according to any one of claims 1 to 4. Based on the height of the coil determined by the determining means, the FOV (Field Of View) is set as an imaging range, and imaging means for performing MR imaging of the subject based on the FOV.
The image processing apparatus according to any one of claims 1 to 5. a magnet mount;
The image processing device according to any one of claims 1 to 6;
A magnetic resonance imaging apparatus comprising. an optical camera for acquiring the image by optical photography;
The magnetic resonance imaging apparatus according to claim 7;
An image processing system comprising

Images