JP2012143467A - Magnetic resonance imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic resonance imaging apparatus capable of performing cinematic imaging such as dynamic or synchronizing imaging with regard to a wider region.SOLUTION: The magnetic resonance imaging apparatus includes a data collection means, an image reconstitution means and an image processing means. The data collection means is constituted so as to move a bed to a plurality of mutually different positions to collect a plurality of magnetic resonance signals at every position of the bed from the subject set to the bed. The image reconstitution means forms a plurality of image data at every position of the bed by the image reconstitution processing of a plurality of magnetic resonance signals and the image processing means performs stitching processing for stitching a plurality of the image data corresponding to a plurality of the positions between a plurality of the positions to form cinematic imaging data.

Description

  Embodiments described herein relate generally to a magnetic resonance imaging (MRI) apparatus.

  MRI magnetically excites a nuclear spin of a subject placed in a static magnetic field with a radio frequency (RF) signal of Larmor frequency, and nuclear magnetic resonance (NMR) generated by this excitation. This is an imaging method for reconstructing an image from a signal.

  Conventionally, in MRI, synchronous imaging in which NMR data is collected in synchronization with biological signals such as dynamic imaging for sequentially collecting and imaging time-series NMR data and electrocardiogram (ECG electrocardiogram) signals is performed. If dynamic imaging or synchronous imaging is performed, the blood flow in the blood vessel can be visualized.

JP 2010-253256 A JP 2005-270213 A JP 2007-117669 A JP 2008-246006 A

  When imaging blood in a peripheral blood vessel away from the heart, it is desired to collect images using the entire body of the subject or at least a wide site as an imaging site. That is, it is desirable to perform dynamic imaging or synchronous imaging over a wider area.

  An object of the present invention is to provide a magnetic resonance imaging apparatus capable of performing cine imaging such as dynamic imaging and synchronous imaging over a wider area.

  A magnetic resonance imaging apparatus according to an embodiment of the present invention includes data collection means, image reconstruction means, and image processing means. The data collection means moves the bed to a plurality of different positions and collects a plurality of magnetic resonance signals for each position of the bed from the subject set on the bed. The image reconstruction means generates a plurality of image data for each position of the bed by image reconstruction processing on the plurality of magnetic resonance signals. The image processing means generates cine image data by a stitching process for joining a plurality of image data corresponding to the plurality of positions between the plurality of positions.

1 is a configuration diagram of a magnetic resonance imaging apparatus according to an embodiment of the present invention. The functional block diagram of the computer shown in FIG. The flowchart which shows the flow at the time of performing the synchronous imaging by the stepping-table method of a test object with the magnetic resonance imaging apparatus shown in FIG. The figure which shows the example which set the imaging condition which collects NMR data in several time phases synchronizing with ECG signal for every station of a bed as the imaging condition of the synchronous imaging shown in FIG. The figure which shows an example of the original image data and processed image data of the stitching process shown in FIG. 4 is a flowchart showing an example of a detailed flow of the stitching process shown in FIG. 3. The flowchart which shows the flow at the time of performing the dynamic imaging by the stepping-table method of a test object with the magnetic resonance imaging apparatus shown in FIG. The figure which shows the example of a setting of the imaging conditions of the dynamic imaging shown in FIG. The figure which shows an example of the original image data and processed image data of the stitching process shown in FIG. 4 is a flowchart showing an example of a detailed flow of the stitching process shown in FIG. 3.

  A magnetic resonance imaging apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

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

  The magnetic resonance imaging apparatus 20 includes a cylindrical static magnetic field magnet 21 that forms a static magnetic field, a shim coil 22, a gradient magnetic field coil 23, and an RF coil 24 provided inside the static magnetic field magnet 21.

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

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

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

  The gradient magnetic field coil 23 includes an X-axis gradient magnetic field coil 23 x, a Y-axis gradient magnetic field coil 23 y, and a Z-axis gradient magnetic field coil 23 z, and is formed in a cylindrical shape inside the static magnetic field magnet 21. A bed 37 is provided inside the gradient magnetic field coil 23 as an imaging region, and the subject P is set on the bed 37. The RF coil 24 includes a whole body coil (WBC) for transmitting and receiving an RF signal built in the gantry, a bed 37 and a local coil for receiving an RF signal provided near the subject P.

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

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

  The RF coil 24 is connected to at least one of the transmitter 29 and the receiver 30. The transmission RF coil 24 has a function of receiving an RF signal from the transmitter 29 and transmitting it to the subject P, and the reception RF coil 24 is accompanied by excitation of the nuclear spin inside the subject P by the RF signal. It has a function of receiving the NMR signal generated in this way and giving it to the receiver 30.

  On the other hand, the sequence controller 31 of the control system 25 is connected to the gradient magnetic field power supply 27, the transmitter 29 and the receiver 30. The sequence controller 31 is control information necessary for driving the gradient magnetic field power supply 27, the transmitter 29, and the receiver 30, for example, operation control information such as the intensity, application time, and application timing of the pulse current to be applied to the gradient magnetic field power supply 27. And the gradient magnetic field power supply 27, the transmitter 29 and the receiver 30 are driven according to the stored predetermined sequence to drive the X-axis gradient magnetic field Gx, the Y-axis gradient magnetic field Gy, and the Z-axis gradient magnetic field. It has the function of generating Gz and RF signals.

  The sequence controller 31 is configured to receive raw data, which is complex data obtained by detection of an NMR signal and A / D (analog to digital) conversion in the receiver 30, and supply the received raw data to the computer 32. The

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

  Further, the magnetic resonance imaging apparatus 20 includes an ECG unit 38 that acquires an ECG signal of the subject P. The ECG signal acquired by the ECG unit 38 is configured to be output to the computer 32 via the sequence controller 31.

  Note that a pulse wave synchronization (PPG) signal or a respiratory signal representing pulsation as pulse wave information can be acquired instead of an ECG signal representing pulsation as heart rate information. The PPG signal is, for example, a signal obtained by detecting a fingertip pulse wave as an optical signal. In the case of acquiring a PPG signal, a PPG signal detection unit is provided. Hereinafter, a case where an ECG signal is acquired will be described.

  In addition, the bed 37 includes a bed driving device 39. The bed driving device 39 is connected to the computer 32 and configured to move the table of the bed 37 under the control of the computer 32 so as to perform imaging by the stepping-table method. The stepping-table method is a technique for imaging by moving the top plate of the bed 37 step by step for each station. This technique is used when imaging a wide area that cannot be captured at a time, such as whole body imaging. A plurality of images collected by moving the bed 37 can be connected to each other by a stitching process in the computer 32.

  Further, the computer 32 is provided with various functions by executing the program stored in the storage device 36 of the computer 32 by the arithmetic unit 35. However, a specific circuit having various functions may be provided in the magnetic resonance imaging apparatus 20 instead of at least a part of the program.

  FIG. 2 is a functional block diagram of the computer 32 shown in FIG.

  The computing device 35 of the computer 32 functions as an imaging condition setting unit 40, an image reconstruction unit 41, and an image processing unit 42 by executing a program stored in the storage device 36. The storage device 36 functions as a k-space data storage unit 43 and an image data storage unit 44.

  The imaging condition setting unit 40 has a function of setting an imaging condition including a pulse sequence based on instruction information from the input device 33 and controlling the drive by giving the set imaging condition to the sequence controller 31. In particular, the imaging condition setting unit 40 has a function of setting imaging conditions by a stepping-table method in which imaging is performed by moving the bed 37 to a plurality of different positions.

  The imaging condition setting unit 40 has a function of setting imaging conditions for synchronous imaging in the stepping-table method or imaging conditions for dynamic imaging in the stepping-table method. Synchronous imaging in the stepping-table method is imaging in which a plurality of NMR signals corresponding to a plurality of different time phases are collected for each position of the bed 37 in synchronization with a biological signal such as an ECG signal. The dynamic imaging in the stepping-table method is imaging in which a plurality of NMR signals corresponding to a plurality of different time phases at the same or different positions of the bed 37 are dynamically acquired. Therefore, in the case of synchronous imaging, the time phase corresponds to the delay time from the trigger of the synchronization signal, and in the case of dynamic imaging, the time phase corresponds to the data acquisition timing.

  Furthermore, the imaging condition setting unit 40 is also provided with a function of setting imaging conditions for contrast imaging that involves injection of a contrast agent into the subject P.

  The image reconstruction unit 41 receives raw data from the sequence controller 31 and arranges it as k-space data in the k-space formed in the k-space data storage unit 43, and takes in the k-space data from the k-space data storage unit 43. It has a function of reconstructing image data by performing an image reconstruction process including a Fourier transform (FT) and a function of writing the image data in the image data storage unit 44.

  When the NMR signal is collected in synchronization with the biological signal by the stepping-table method, a plurality of image data corresponding to a plurality of time phases is generated for each position of the bed 37. When NMR signals are dynamically acquired by the stepping-table method, a plurality of time-series image data corresponding to a plurality of different time phases are generated for each position of the bed 37.

  The image processing unit 42 has a function of acquiring a plurality of image data corresponding to a plurality of positions of the bed 37 from the image data storage unit 44, and an image including a stitching process for joining the acquired plurality of image data between the plurality of positions. It has a function of generating cine image data by processing, a function of writing the generated cine image data in the image data storage unit 44, and a function of causing the display device 34 to display cine image data.

  In the case of synchronous imaging by the stepping-table method, cine image data can be generated by stitching processing in which a plurality of corresponding time-phase image data are connected between a plurality of positions on the bed 37. Desirably, a stitching process for connecting a plurality of image data corresponding to the same time phase is executed. However, when image data corresponding to the same time phase is not collected, the stitching process is executed using the image data corresponding to the closest time phase. Therefore, a single image data may be used for stitching processing a plurality of times.

  On the other hand, in the case of dynamic imaging by the stepping-table method, cine image data is obtained as dynamic image data by stitching processing in which a plurality of image data corresponding to closer time phases of NMR signals are connected between a plurality of positions of the bed 37. Can be generated. Therefore, even in the case of dynamic imaging by the stepping-table method, a single image data may be used for the stitching process a plurality of times.

  When the image data is three-dimensional (3D) image data, MPR (multi planar reconstructions) processing or maximum intensity projection (MIP) processing is performed as pre-processing or post-processing of stitching processing. 2D (two dimensional) processing of 3D data such as is performed.

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

  First, the case where synchronous imaging by the stepping-table method is performed by the magnetic resonance imaging apparatus 20 will be described.

  FIG. 3 is a flowchart showing a flow when the magnetic resonance imaging apparatus 20 shown in FIG. 1 performs synchronous imaging of the subject P by the stepping-table method.

  First, the RF coil 24 for receiving NMR signals corresponding to the subject P and the imaging region is set on the bed 37 in advance, and the static magnetic field magnet 21 (superconducting magnet) excited by the static magnetic field power source 26 is statically imaged. A magnetic field is formed. Further, a current is supplied from the shim coil power supply 28 to the shim coil 22, and the static magnetic field formed in the imaging region is made uniform.

  In step S <b> 1, the imaging condition setting unit 40 sets the imaging conditions for synchronous imaging by the stepping-table method based on the instruction information from the input device 33. For example, imaging conditions such as a plurality of station positions on the top plate of the bed 37, time phase and number of image data, slice position of image data, and number of slices are set.

  FIG. 4 is a diagram illustrating an example in which imaging conditions for collecting NMR data in a plurality of time phases are set for each station of the bed 37 as the imaging conditions of the synchronous imaging shown in FIG.

  In FIG. 4, the horizontal axis indicates time. As shown in FIG. 4, synchronous imaging conditions for collecting NMR data can be set in different cardiac phases T1, T2, T3,... After a predetermined delay time has elapsed from the R wave of the ECG signal. Since the imaging is based on the stepping-table method, NMR data corresponding to each cardiac phase T1, T2, T3,... is collected for each station of the bed 37.

FIG. 4 shows an example in which NMR data is collected at two station positions (STATION1, STATION2). That is, NMR data D _S1TI , D _S1T2 , D _S1T3 ,... In cardiac phase T1, T2, T3, ... after a delay time from a certain R wave with the top plate of bed 37 positioned at _STATION1 . Are collected sequentially. Further, in a state where the top plate of the bed 37 is positioned at _STATION2 , NMR data D _S2TI , D _S2T2 , D _S2T3 ,... In cardiac phase T1, T2, T3 _,. Are collected sequentially. The same applies when there are three or more station positions.

  Next, in step S2, the constituent elements of the magnetic resonance imaging apparatus 20 for executing the scan of the sequence controller 31, the static magnetic field magnet 21 and the like collect data according to the set imaging conditions.

  That is, when an imaging scan start instruction is given from the input device 33 to the imaging condition setting unit 40, the imaging condition setting unit 40 gives imaging conditions including a pulse sequence to the sequence controller 31. The sequence controller 31 drives the gradient magnetic field power source 27, the transmitter 29, and the receiver 30 in synchronization with the ECG signal acquired from the ECG unit 38 in accordance with the pulse sequence, thereby causing a gradient magnetic field in the imaging region in which the subject P is set. And an RF signal is generated from the RF coil 24.

  Therefore, an NMR signal generated by nuclear magnetic resonance inside the subject P is received by the RF coil 24 and given to the receiver 30. The receiver 30 receives the NMR signal from the RF coil 24, performs necessary signal processing, and then performs A / D conversion to generate raw data that is an NMR signal of digital data. The receiver 30 gives the generated raw data to the sequence controller 31. The sequence controller 31 provides the raw data to the image reconstruction unit 41, and the image reconstruction unit 41 arranges the raw data as k-space data in the k-space formed in the k-space data storage unit 43.

  Next, in step S <b> 3, the image reconstruction unit 41 reconstructs image data by taking k-space data from the k-space data storage unit 43 and performing image reconstruction processing. The image data is written into the image data storage unit 44 as necessary.

  Next, in step S4, the image processing unit 42 acquires image data for a plurality of frames corresponding to a plurality of cardiac time phases for each position of the bed 37 from the image reconstruction unit 41 or the image data storage unit 44, Image processing including stitching processing is performed.

  FIG. 5 is a diagram illustrating an example of original image data and processed image data of the stitching process illustrated in FIG. 3.

  FIG. 5A is a diagram showing a relative positional relationship between the imaging region of the subject P set on the bed 37 and the station position (STATION1, STATION2) of the bed 37. FIG. As shown in FIG. 5A, for example, two station positions (STATION1, STATION2) are set so as to cover an imaging region of a wide area of the subject P. The two station positions (STATION1, STATION2) are provided with overlapping portions so that smooth image data can be generated by stitching processing.

FIG. 5B shows original image data for stitching processing. The original image data are NMR data (D _S1TI , D _S1T2 , D) in a plurality of time phases (T1, T2, T3,...) Collected at each station position ( _STATION1 , _STATION2 ) in _FIG . _S1T3 , ..., D _S2TI , D _S2T2 , D _S2T3 , ...) (I _S1TI , I _S1T2 , I _S1T3 , ..., I _S2TI , I _S2T2 , I _S2T3 , ..) .) In FIG. 5B, the horizontal axis direction is the station direction, and the vertical axis direction is the time phase direction.

FIG. 5C shows processed image data of the stitching process. The processed image data is cine image data generated by stitching processing using the image data of FIG. 5B as original image data. In FIG. 5C, the vertical axis direction is the time phase direction. Extract image data having the same time phase from a plurality of image data (I _S1TI , I _S1T2 , I _S1T3 , ..., I _S2TI , I _S2T2 , I _S2T3 , ...) shown in FIG. When the stitching process is performed for each phase, as shown in FIG. 5C, wide area cine image data (I _TI ) for a plurality of frames corresponding to a plurality of time phases (T1, T2, T3,...). , I _T2 , I _T3 , ...) are generated.

  FIG. 5 shows an example in which the number of slices is one. However, when a plurality of slice image data are collected for a plurality of station positions and a plurality of time phases, respectively, each time phase and each slice are shown. By performing the stitching process, it is possible to generate cine image data of a wide area for a plurality of frames corresponding to a plurality of time phases and a plurality of slices.

  FIG. 6 is a flowchart showing an example of a detailed flow of the stitching process shown in FIG.

  First, in step S41, the image processing unit 42 acquires a plurality of image data corresponding to a plurality of station positions and a plurality of time phases, which are original image data for stitching processing. In step S42, the image processing unit 42 substitutes 1 as an initial value for T indicating the order of time phases.

  Next, in step S43, the image processing unit 42 determines whether or not the value of T indicating the order of time phases is equal to or less than the total number of time phases NT of the collected data. If it is determined that the value of T is equal to or less than the number of time phases NT, in step S44, the image processing unit 42 outputs image data collected in the same time phase as the T-th time phase for each station. Search and obtain from image data. When there is no time phase image data to be searched, the image processing unit 42 acquires image data collected in the time phase closest to the T-th time phase as substitute image data.

  In step S45, the image processing unit 42 performs a stitching process between a plurality of image data corresponding to the T-th time phase obtained by the search. The stitching process is a known process in which a plurality of image data corresponding to adjacent stations are connected to each other to generate wide area image data. As a result, image data corresponding to adjacent stations having the same or equivalent time phases are connected to each other. That is, cine image data for one frame is generated for each time phase and slice.

  In step S46, the image processing unit 42 substitutes T + 1 for T indicating the order of time phases. Thereby, the next time phase T is selected. The processing from step S44 to step S46 is repeated until it is determined in step S43 that the value of T is equal to or less than the number of time phases NT. As a result, wide area cine image data for a plurality of frames corresponding to all time phases is generated.

  Next, in step S5 of FIG. 3, the image processing unit 42 continuously outputs a plurality of frames of wide area cine image data to the display device 34 in order of time phase. Thereby, on the display device 34, an image of a wide area in which an observation target such as blood changes in order of time is displayed in cine. Then, the user can observe the cine-displayed wide area image.

  Next, the case where dynamic imaging by the stepping-table method is performed by the magnetic resonance imaging apparatus 20 will be described.

  FIG. 7 is a flowchart showing a flow when the magnetic resonance imaging apparatus 20 shown in FIG. 1 performs dynamic imaging of the subject P by the stepping-table method.

  First, the RF coil 24 for receiving NMR signals corresponding to the subject P and the imaging region is set on the bed 37 in advance, and the static magnetic field magnet 21 (superconducting magnet) excited by the static magnetic field power source 26 is statically imaged. A magnetic field is formed. Further, a current is supplied from the shim coil power supply 28 to the shim coil 22, and the static magnetic field formed in the imaging region is made uniform.

  In step S <b> 11, the imaging condition setting unit 40 sets the imaging conditions for dynamic imaging by the stepping-table method based on the instruction information from the input device 33. For example, a plurality of station positions on the top plate of the bed 37, the number of frames of image data continuously collected at the same station position, the number of times the top plate of the bed 37 is intermittently moved to the same station position, and slices of image data Imaging conditions such as the position and the number of slices are set.

  FIG. 8 is a diagram illustrating an example of setting the imaging conditions of the dynamic imaging illustrated in FIG.

  In FIG. 8, the horizontal axis indicates time. As shown in FIG. 8, it is possible to set an imaging condition for dynamically collecting NMR data while changing the top plate of the bed 37 to a plurality of station positions. Because of dynamic imaging, the data collection timing of each NMR data corresponds to the time phases T1, T2, T3,. In addition, an arbitrary number of segments can be set as the number of times the top plate of the bed 37 is repeatedly arranged at the same station position. In each segment, the number of frames of image data collected continuously and repeatedly at the same station position can be set to a desired number.

  FIG. 8 shows that the number of station positions is STATION1, STATION2, STATION3, the number of image data frames in segment 1 is 1, the number of image data frames in segment 2 is 2, and the number of image data frames in segment n is i. An example of the case is shown. That is, in segment 1, the station position of the top plate of the bed 37 is sequentially moved to STATION1, STATION2, and STATION3, and NMR data for one frame of image data is collected at each station position. In segment 2, the station position of the top plate of the bed 37 is sequentially moved to STATION1, STATION2, and STATION3, and NMR data for two frames of image data is collected at each station position.

  Note that the number of frames of image data collected at each station position in the same segment may be changed. For example, if the number of frames of image data continuously collected at each station position is set in accordance with the movement of the contrast agent injected into the subject P, image data for monitoring the arrival part of the contrast agent is obtained. be able to.

  Next, in step S12, the constituent elements of the magnetic resonance imaging apparatus 20 for executing the scan of the sequence controller 31, the static magnetic field magnet 21 and the like perform dynamic acquisition of NMR data in accordance with the set imaging conditions. That is, the raw data is sequentially arranged in the k space formed in the k space data storage unit 43 in the same flow as in the synchronous imaging.

  Next, in step S13, the image reconstruction unit 41 sequentially reconstructs image data by taking k-space data from the k-space data storage unit 43 and performing image reconstruction processing. The image data is written into the image data storage unit 44 as necessary. As a result, time-series image data corresponding to a plurality of station positions is generated.

  Next, in step S14, the image processing unit 42 acquires image data for a plurality of frames in time series corresponding to a plurality of station positions from the image reconstruction unit 41 or the image data storage unit 44, and performs a stitching process. Including image processing.

  FIG. 9 is a diagram illustrating an example of the original image data and the processed image data of the stitching process illustrated in FIG.

  FIG. 9A is a diagram showing a relative positional relationship between the imaging region of the subject P set on the bed 37 and the station position (STATION1, STATION2, STATION3) of the bed 37. FIG. As shown in FIG. 9A, for example, three station positions (STATION1, STATION2, STATION3) are set so as to cover an imaging region of a wide area of the subject P. The three station positions (STATION1, STATION2, STATION3) are provided with overlapping portions so that smooth image data can be generated by stitching processing.

FIG. 9B shows original image data for stitching processing. The original image data is obtained by NMR data (D _S1TI , D _S2T2 , D _S3T3 , D _S1T4 , D _S1T5 , D _S2T6 , D _S2T6 , collected at any of the plurality of station positions ( _STATION1 , _STATION2 , _STATION3) in _FIG . Image data (I _S1TI , I _S2T2 , I _S3T3 , I _S1T4 , I) in the time series (T1, T2, T3, ...) generated from D _S2T7 , D _S3T8 , D _S3T9 , ...) _S1T5 , _IS2T6 , _IS2T7 , _IS3T8 , _IS3T9 , ...). In FIG. 9B, the horizontal axis direction is the station direction, and the vertical axis direction is the segment direction.

Image data (I _S1TI , I _S2T2 , I _S3T3 , I _S1T4 , I _S1T5 , I _S2T6 , I _S2T7 , I _S3T8 , I _S3T9 , ...) for each station position ( _STATION1 , _STATION2 , _STATION3 ) When the are aligned, the data shown by the solid line in FIG. 9B is obtained. Image data (I _S1TI , I _S2T2 , I _S3T3 , I _S1T4 , I _S1T5 , I _S2T6 , I _S2T7 , I _S3T8 , I _S3T9 , ...) are collected dynamically at different data collection timings, so each other Corresponds to different time phases.

Therefore, each image data (I _S1TI , I _S2T2 , I _S3T3 , I _S1T4 , I _S1T5 , I _S2T6 , I _S2T7 , I _S3T8 , I _S3T9 , ...) Image data collected at the position is used as substitute image data. Image data indicated by a dotted line in FIG. 9B is data used as original image data for repeated stitching processing as substitute image data. That is, each image data (I _S1TI , I _S2T2 , I _S3T3 , I _S1T4 , I _S1T5 , I _S2T6 , I _S2T7 , I _S3T8 , I _S3T9 , ...) The image data collected at the position is subjected to stitching processing. Thereby, it is possible to maintain the time resolution while avoiding the time order of the image data being reversed between the stations.

FIG. 9C shows processed image data of stitching processing. The processed image data is cine image data generated by stitching processing using the image data of FIG. 9B as original image data. In FIG. 9C, the vertical axis direction is the time phase direction. From the plurality of image data (I _S1TI , I _S2T2 , I _S3T3 , I _S1T4 , I _S1T5 , I _S2T6 , I _S2T7 , I _S3T8 , I _S3T9 , ...) _shown in FIG. When similar image data is extracted and stitching processing is performed for each corresponding time phase, as shown in FIG. 9C, a wide range of multiple frames in the order of dynamic time phases (T1, T2, T3,...). Cine image data (I _T3 , I _T4 , I _T5 ,...) Of the area is generated.

  FIG. 9 shows an example in which the number of slices is one. However, when a plurality of time-series slice image data is dynamically acquired at any of a plurality of station positions, the time phase and slices are shown. By performing the stitching process every time, it is possible to generate cine image data of a wide area for a plurality of time-series frames corresponding to a plurality of slices.

  FIG. 10 is a flowchart showing an example of a detailed flow of the stitching process shown in FIG.

  First, in step S51, the image processing unit 42 acquires a plurality of pieces of time-series image data dynamically collected at any of a plurality of station positions, which are original image data for stitching processing.

In step S52, the image processing unit 42 substitutes T0 as an initial value for T indicating the order of time phases. T0 may be the earliest time phase at which collection of image data for at least one frame is completed at all station positions. In the example shown in FIGS. 8 and 9, since the collection of image data (I _S1TI , I _S2T2 , I _S3T3 ) at the three station positions ( _STATION1 , _STATION2 , _STATION3 ) is completed in the third time phase T3, T0 = 3

  Next, in step S53, the image processing unit 42 determines whether or not the value of T indicating the order of time phases is equal to or less than the total number of time phases NT of the collected data. When it is determined that the value of T is equal to or less than the number of time phases NT, in step S54, the image processing unit 42 acquires the image data collected in the closest time phase before the T-th time phase for each station. Retrieve from multiple image data.

  In step S55, the image processing unit 42 performs a stitching process between a plurality of image data corresponding to the T-th time phase obtained by the search. As a result, the image data corresponding to stations that are close in time and adjacent to each other are connected to each other. That is, cine image data for one frame is generated for each time phase and slice.

  In step S56, the image processing unit 42 substitutes T + 1 for T indicating the order of time phases. Thereby, the next time phase T is selected. Then, the processing from step S54 to step S56 is repeated until it is determined in step S53 that the value of T is equal to or less than the number of time phases NT. As a result, cine image data of a wide area for a plurality of time-series frames is generated.

  Next, in step S15 in FIG. 7, the image processing unit 42 continuously outputs a plurality of frames of wide area cine image data to the display device 34 in the order of dynamic time phases. Thereby, on the display device 34, an image of a wide area in which an observation target such as blood changes in order of dynamic time phase is displayed as a cine. Then, the user can observe the cine-displayed wide area image.

  That is, the magnetic resonance imaging apparatus 20 as described above moves the bed 37, collects a plurality of image data for each position of the bed 37, and performs stitching processing on the image data based on the time phase information of the collected image data. Thus, cine image data of a wide area is generated.

  For this reason, according to the magnetic resonance imaging apparatus 20, when imaging the temporal change of the imaging region as in synchronous imaging or dynamic imaging, a wider region of the imaging region can be displayed in cine. For this reason, the user can perform dynamic observation on an imaging region in a wide area.

  In the case of dynamic imaging, temporal continuity can be maintained well by repeatedly using the image data collected at each position of the bed 37 as substitute image data for stitching processing.

  Although specific embodiments have been described above, the described embodiments are merely examples, and do not limit the scope of the invention. The novel methods and apparatus described herein can be implemented in a variety of other ways. Various omissions, substitutions, and changes can be made in the method and apparatus described herein without departing from the spirit of the invention. The appended claims and their equivalents include such various forms and modifications as are encompassed by the scope and spirit of the invention.

20 Magnetic Resonance Imaging Device 21 Magnet for Static Magnetic Field 22 Shim Coil 23 Gradient Magnetic Field Coil 24 RF Coil 25 Control System 26 Static Magnetic Field Power Supply 27 Gradient Magnetic Field Power Supply 28 Shim Coil Power Supply 29 Transmitter 30 Receiver 31 Sequence Controller 32 Computer 33 Input Device 34 Display Device 35 arithmetic device 36 storage device 37 bed 38 ECG unit 39 bed driving device 40 imaging condition setting unit 41 image reconstruction unit 42 image processing unit,
43 k space data storage unit 44 Image data storage unit P Subject

Claims (5)

Data collection means for collecting a plurality of magnetic resonance signals for each position of the bed from a subject set on the bed by moving the bed to a plurality of different positions;
Image reconstruction means for generating a plurality of image data for each position of the bed by image reconstruction processing for the plurality of magnetic resonance signals;
Image processing means for generating cine image data by stitching processing for joining a plurality of image data corresponding to the plurality of positions between the plurality of positions;
A magnetic resonance imaging apparatus comprising: The data collection means is configured to collect a plurality of magnetic resonance signals corresponding to a plurality of different time phases for each position of the bed in synchronization with the biological signal of the subject,
2. The magnetic resonance imaging apparatus according to claim 1, wherein the image processing unit is configured to generate the cine image data by stitching processing in which a plurality of corresponding time-phase image data are joined between the plurality of positions. The data collection means is configured to dynamically collect the plurality of magnetic resonance signals;
The said image processing means is comprised so that the said cine image data may be produced | generated as dynamic image data by the stitching process which joins several image data corresponding to the near time phase between these several positions. Magnetic resonance imaging device.   The magnetic resonance imaging apparatus according to claim 2, wherein the image processing unit is configured to use a single image data for the stitching process a plurality of times. The data collection means outputs a plurality of magnetic resonance signals corresponding to the number of image data continuously collected for each position of the bed set in accordance with the movement of the contrast agent injected into the subject. The magnetic resonance imaging apparatus according to claim 3, wherein the magnetic resonance imaging apparatus is configured to continuously collect each position.

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