JP2016189979A - Magnetic-resonance imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic-resonance imaging apparatus enabled to improve the image quality of an MRI image by changing the collection sequence of data of a k-space in accordance with the attainment degree of contrast medium.SOLUTION: A magnetic-resonance imaging apparatus comprises: attainment degree judging parts 20 and 61 for judging the attainment degree of a contrast medium in an analyte; and a judging order determining part 61 for determining the collection order of data on a frequency space in a scan for acquiring a diagnostic image on the basis of the judged attainment degree of the contrast medium, and executes the scan for acquiring a diagnostic image in accordance with the collection sequence of the determined data.SELECTED DRAWING: Figure 2

Description

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

  There is a method of imaging an image of a wide area of a subject while moving a bed using a magnetic resonance imaging (Magnetic_Resonance_Imaging: MRI) apparatus. The collection order of k-space data includes an Interleave method, a Centric method, a Sequential method, and the like. The collection order is also called a collection method. An MRI image with better image quality can be obtained by changing the collection order of k-space data. However, it is difficult to set an optimal collection order in advance due to factors such as the speed at which the contrast agent advances depending on the patient, and conditions such as the imaging region and scan time.

JP 2004-57237 A

  An object of the present invention is to provide a magnetic resonance imaging apparatus capable of improving the image quality of an MRI image by changing the collection order of k-space data according to the degree of arrival of a contrast agent.

  The magnetic resonance imaging apparatus according to the present embodiment includes a reach determination unit that determines the reach of the contrast medium in the subject, and a scan for acquiring a diagnostic image based on the determined reach of the contrast medium. A collection order determination unit that determines a data collection order on a frequency space; and a scan execution unit that executes a scan for acquiring the diagnostic image according to the determined data collection order. It is characterized by.

The figure which shows an example of a structure of the magnetic resonance imaging apparatus which concerns on this embodiment 2 is a diagram showing an example of a configuration of a host computer and an arithmetic unit according to the present embodiment. The flowchart figure which showed the flow of the scan accompanying a bed movement which concerns on this embodiment It is a figure for demonstrating the prior scan which concerns on this embodiment, and is the figure which illustrated three imaging regions (R1, R2, R3) set in the imaging range R and the said imaging range R FIG. 3 is a flowchart showing a contrast medium reachability determination / data collection order determination and a main scan subroutine performed under the control of the control unit 63 according to FIG. The figure for demonstrating the data collection order in the case of acquiring preferentially from the data of the center area | region in k space in a two-dimensional scan. The figure for demonstrating the data collection order in the case of acquiring preferentially from the data of the edge area | region in k space in a two-dimensional scan. The figure which shows TIC in time t1 The figure which shows TIC in time t2 The figure which shows TIC in time t3 The figure which shows TIC in time t4 The figure which shows TIC in time t5 The figure for demonstrating the data collection order in the case of acquiring preferentially from the data of the center area | region in k space in a three-dimensional scan. Diagram showing Interleave method in 3D scanning The figure which shows the Sequential method in a three-dimensional scan

  Hereinafter, the present embodiment will be described with reference to the drawings. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

  FIG. 1 is a diagram illustrating an example of a configuration of a magnetic resonance imaging apparatus according to the present embodiment. As shown in FIG. 1, the magnetic resonance imaging apparatus 100 includes an imaging unit 110, a host computer 6, a temporary storage unit 9, an arithmetic unit 10, a storage unit 11, a display unit 12, an input unit 13, And an audio generator 16.

  The imaging unit 110 includes a bed, a static magnetic field generation unit, a gradient magnetic field generation unit, a transmission / reception unit, and a sequencer 5. A subject P is placed on the bed. The sequencer 5 is also called a sequence controller, a scan execution unit, an imaging control unit, or the like. The couch can be removably inserted into the opening (diagnostic space) of the magnet unit 1 with the top plate on which the subject P is placed.

The static magnetic field generating unit includes, for example, a superconducting magnet unit 1 and a static magnetic field power source 2 that supplies current to the magnet unit 1. The static magnetic field generator generates a static magnetic field H ₀ in the axial direction (Z-axis direction) of the cylindrical opening into which the subject P is inserted. The magnet unit 1 is provided with a shim coil 14. The shim coil 14 is supplied with a current for homogenizing the static magnetic field from the shim coil power supply 15 under the control of the host computer 6 described later.

  The gradient magnetic field generation unit includes a gradient magnetic field coil unit 3. The gradient magnetic field coil unit 3 includes three sets of coils 3x, 3y, and 3z for generating gradient magnetic fields in the X, Y, and Z axis directions orthogonal to each other. The gradient magnetic field generator has a gradient magnetic field power supply 4 that supplies current to the coils 3x, 3y, and 3z. The gradient magnetic field power supply 4 supplies a pulse current for generating a gradient magnetic field to the coils 3x, 3y, and 3z under the control of the sequencer 5.

By adjusting the pulse current supplied from the gradient magnetic field power source 4 to the coils 3x, 3y, and 3z, the gradient magnetic fields of the X, Y, and Z directions, which are three orthogonal axes, are synthesized, and the slice directions orthogonal to each other The respective logical axis directions of the gradient magnetic field Gs, the phase encode direction gradient magnetic field Ge, and the readout direction (also referred to as lead-out encode, frequency encode direction) gradient magnetic field Gr can be arbitrarily set. Slice direction, gradient magnetic fields in the phase encoding direction and the readout direction are superimposed on the static magnetic field H _0.

  The transmission / reception unit includes an RF coil 7 disposed in the vicinity of the subject P in the imaging space in the magnet unit 1, and a transmitter 8T and a receiver 8R connected to the RF coil 7. The transmitter 8T and the receiver 8R operate under the control of the sequencer 5. The transmitter 8T supplies the RF coil 7 with RF pulses having a Larmor frequency for causing nuclear magnetic resonance (Nuclear_Magnetic_Resonance: NMR). The receiver 8R takes in the high-frequency signal received by the RF coil 7, performs various signal processing such as pre-amplification, intermediate frequency conversion, phase detection, low-frequency amplification, and filtering, and then performs A / D conversion. Thus, digital reception data (raw (RAW) data) corresponding to the high frequency signal is generated.

  The sequencer 5 includes a memory that stores information (hereinafter referred to as pulse sequence information) related to various pulse sequences output from the host computer 6, and a CPU that controls the transmission / reception unit based on the stored pulse sequence information. In MRI imaging, based on the principle, RF pulses and gradient magnetic field pulses in the X, Y, and Z-axis three directions are controlled as a time-series waveform (sequence). The time series of these four pulses to be controlled is called a pulse sequence. Examples of the pulse sequence include SE (spin echo) method, FSE (fast spin echo) method, FASE (fast asymmetry spin echo) method, EPI (echo planar imaging) method, gradient echo (Gradient_Echo: GRE, GE) method and the like. .

  The pulse sequence information is all information necessary for operating the gradient magnetic field power source 4, the transmitter 8T, and the receiver 8R according to a series of pulse sequences. The pulse sequence information includes information on the intensity, application time, application timing, and the like of the pulse current applied to each of the coils 3x, 3y, 3z, and the RF coil 7, for example.

  The sequencer 5 stores, for example, various pulse sequence information sent from the host computer 6, and controls the operations of the gradient magnetic field power source 4, the transmitter 8T, and the receiver 8R according to this information.

  The host computer 6 has a function of inputting pulse sequence information to the sequencer 5 according to the stored software procedure and supervising the operation of the entire apparatus.

  The temporary storage unit 9 temporarily stores the raw data output by the receiver 8R and outputs the raw data to the arithmetic unit 10.

  The arithmetic unit 10 inputs the raw data output from the receiver 8 </ b> R via the temporary storage unit 9. The arithmetic unit 10 arranges raw data in k space (also called Fourier space or frequency space) on the internal memory. The arithmetic unit 10 performs inverse Fourier transform on the arranged raw data and reconstructs it into real space image data. The arithmetic unit 10 can perform data composition processing, difference calculation processing, and the like as necessary.

  Here, the relationship between the host computer 6 and the arithmetic unit 10 will be described. FIG. 2 is a diagram illustrating an example of a configuration of the host computer 6 and the arithmetic unit 10 according to the present embodiment. As shown in FIG. 2, the host computer 6 includes a collection order determination unit 61 and a control unit 63. The collection order determination unit 61 determines the degree of arrival of the contrast agent in the imaging region of the subject, and determines the data collection order in the frequency space in the main scan based on the degree of arrival of the contrast agent in the imaging region. . The imaging region is a region used for the pre-contrast confirmation scan and the post-contrast confirmation scan for determining the contrast agent arrival degree. Details of the pre-contrast confirmation scan and the post-contrast confirmation scan will be described later. The control unit 63 functions as the center of the magnetic resonance imaging apparatus 100 according to the present embodiment. The control unit 63 reads the imaging program according to the present embodiment from the storage unit 11 and controls various components according to the imaging program. Thereby, the control unit 63 controls various components, and executes MRI imaging and image processing for generating an image such as a cross-sectional image according to the present embodiment in the determined order.

  As shown in FIG. 2, the arithmetic unit 10 includes a time signal intensity curve (Time-signal_Intensity_Curve: TIC) calculation unit (hereinafter referred to as a TIC calculation unit) 20. The TIC calculation unit 20 refers to the reconstructed image of the pre-contrast confirmation scan data with reference to the reconstructed image of the pre-contrast confirmation scan data in the region of interest preset by the operator via the input unit 13. The TIC relating to the difference image from the reconstructed image is calculated.

  The storage unit 11 stores reconstructed image data, image processed image data, various pal sequence information, an imaging program, various programs, and the like. The storage unit 11 stores the type and concentration of the contrast agent used in the reach determination described later in association with the first threshold value and the second threshold value. The display device 12 displays various images under the control of the host computer 6. The input device 13 is an interface (I / F) for inputting information relating to imaging conditions desired by the operator, pulse sequence, image synthesis, and difference calculation to the host computer 6. Under the control of the host computer 6, the voice generator 16 can emit a breath holding start message and a breath holding end message as voices.

(Scan sequence according to this embodiment)
Next, an example of a scan sequence according to the present embodiment will be described. FIG. 3 is a flowchart showing the flow of scanning with couch movement according to the present embodiment. In the present embodiment, for the sake of specific explanation, a case where a plurality of (for example, 10) coronal images are captured is taken as an example.

[Step S11: Advance scan]
As shown in FIG. 3, the control unit 63 controls the sequencer 5 in response to an instruction from the operator via the input device 13, and executes a pre-scan on the subject before contrast agent injection (step). S11). Here, the pre-scan according to the present embodiment is a scan for calibrating the magnetic resonance imaging apparatus, which is executed prior to a scan for imaging a diagnostic image. Sensitivity map creation scan), shimming, positioning scan (positioning scan) and precontrast confirmation scan. Here, the pre-contrast confirmation scan is a scan executed in order to acquire pre-contrast data that is used as a reference in the determination of the contrast agent arrival level described later.

  FIG. 4 is a diagram for explaining pre-scanning according to the present embodiment, and is a diagram illustrating an imaging range R and three imaging regions (R1, R2, R3) set in the imaging range R. . First, the control unit 63 performs a sensitivity map creation scan for the imaging region R1, and performs coil tuning, center frequency setting, transmission output adjustment, and reception sensitivity adjustment based on the result. Further, the control unit 63 performs shimming, calculates the magnetic field intensity necessary for correction from the obtained image, and supplies the current corresponding to each shim coil to perform correction for making the magnetic field uniform. Further, the control unit 63 performs a positioning scan according to a predetermined sequence, and displays an image obtained as a result on the display 12. Based on the displayed image, the operator sets the position of the two-dimensional section to be imaged in the main scan via the input device 13. In the present embodiment, for the sake of specific explanation, it is assumed that a plurality of (ten) coronal sections are set in the imaging region R1 as the two-dimensional section in the main scan.

  The operator sets the imaging area A1 for the pre-contrast confirmation scan upstream of the imaging area R1. In the present embodiment, it is assumed that at least one body axis section is set as the imaging region A1 of the pre-contrast confirmation scan for the sake of specific explanation. Moreover, it is preferable that the imaging region of the pre-contrast confirmation scan includes at least an imaging region of the post-contrast confirmation scan described later. When the imaging area A1 is set, the control unit 63 executes a pre-contrast confirmation scan in the imaging area A1.

  Further, the operator sets a region of interest (Region_of_Interest: ROI) via the input device 13 based on the reconstructed image (pre-contrast confirmation image) obtained by the pre-contrast confirmation scan in the imaging region A1. This region of interest is set, for example, in a part of a blood vessel in order to determine the reach of the contrast agent (details will be described later). The pre-contrast confirmation image in which the region of interest is set is stored in the storage unit 11.

  Similarly, a pre-scan is executed for each of the imaging regions R2 and R3 shown in FIG.

[Step S12: Injection of contrast medium]
When step S11 is performed, the operator injects a contrast medium into the subject (step S12). The operator injects the contrast agent from the imaging region A1 to the imaging region A3 and the upstream of the imaging region R1 to the imaging region R3 in the vein of the subject.

[Step S13: Determination of Contrast Agent Reaching / Determination of Data Collection Order and Main Scan]
When step S12 is performed, the control unit 63 causes the sequencer 5 to execute a post-contrast confirmation scan, and uses the post-contrast confirmation image and the pre-contrast confirmation image obtained as a result to cause the collection order determination unit 61 to provide a contrast agent. The degree of achievement is determined and the data collection order is determined. Further, the control unit 63 causes the sequencer 5 to execute a main scan based on the determined data collection order (step S13). Here, the main scan is a scan for capturing a diagnostic image according to a predetermined pulse sequence. Further, the post-contrast confirmation scan is to capture in real time an imaging region (for example, A1 in FIG. 4) set on the upstream side of the imaging region of the main scan immediately before the main scan.

  Note that the processing in step S13 will be described in detail later as a contrast medium reachability determination / data collection order determination and main scan subroutine.

[Steps S14, S15, S16: Scan of all imaging regions with couch movement]
The controller 63 controls the sequencer 5 until the number of cross-sectional images acquired in the main scan in step S13 reaches a predetermined value (S_MAX), and repeats the main scan in step S13 (step S14). In this embodiment, S_MAX = 10.

  When the number of cross-sectional images acquired in the main scan (S_MAX) is reached in step S14, the control unit 63 controls the bed mechanism to move the bed and move the imaging field of view (Field_Of_View: FOV) to the next (downstream) imaging area. (In the example of FIG. 4, it is set to the imaging region R2).

  The controller 63 controls the sequencer 5 until the number of bed movements in step S15 reaches a predetermined value (T_MAX), and repeats the bed movement in step S15 (step S16). When the number of bed movements reaches a predetermined value (T_MAX) in step S16, the scan sequence ends. FIG. 4 illustrates T_MAX = 2.

(Contrast agent arrival determination, data collection order determination and main scan subroutine)
Next, an example of the contrast medium reachability determination / data collection order determination and the main scan subroutine according to the present embodiment will be described. FIG. 5 is a flowchart showing the flow of this subroutine, which is performed under the control of the control unit 63.

  As shown in FIG. 5, the control unit 63 causes the sequencer 5 to execute a post-contrast confirmation scan (step S31). In step S31, the sequencer 5 performs a post-contrast confirmation scan on the imaging region A1 (described in FIG. 4). The arithmetic unit 10 reconstructs scan data obtained by the post-contrast confirmation scan and generates a post-contrast confirmation image.

  When step S31 is performed, the control unit 63 causes the TIC calculation unit 20 to calculate the TIC (step S32). The TIC calculation unit 20 calculates the TIC based on the signal intensity of the difference image between the region of interest in the pre-contrast confirmation image and the region of interest in the post-contrast confirmation image. In addition, for the calculation of TIC, a differential value or a change rate related to the signal intensity of the difference image in the region of interest may be used.

  When step S32 is performed, the control unit 63 causes the collection order determination unit 61 to determine whether the signal strength is equal to or greater than the first threshold value b (step S33). Here, the first threshold value b is a threshold value for determining that the contrast effect by the currently used contrast agent is sufficient (for example, the contrast effect is close to the peak).

  When the signal strength is greater than or equal to the first threshold value b in step S33, the control unit 63 causes the collection order determination unit 61 to determine the data collection order so that the data corresponding to the low frequency component is prioritized (step S34). Here, the low frequency component indicates a central region in the k space. The low frequency component is a frequency component mainly indicating the shape of a blood vessel or an organ.

  FIG. 6 is a diagram for explaining the data collection order in the case of acquiring preferentially from the data of the central region in the k space in the two-dimensional scan. This collection order is called the Interleave method or the Centric method. The sequencer 5 executes the main scan according to the data collection order determined by changing the gradient magnetic field of phase encoding (Phase_Encode). Specifically, preferential acquisition from the data of the central region in the k space can be realized by gradually changing the phase encoding gradient magnetic field from 0 to a positive value and a negative value. In the present embodiment, the pulse sequence uses a gradient echo method. Other pulse sequences may be used.

  When the signal strength is less than the first threshold value b in step S33, the control unit 63 causes the collection order determination unit 61 to determine whether the signal strength is equal to or greater than the second threshold value a (step S35). Here, the second threshold value a is a threshold value for determining that the contrast effect by the contrast agent currently used is equal to or greater than a certain level and that it is time to execute the main scan.

  When the signal strength is greater than or equal to the second threshold value a in step S35, the control unit 63 causes the collection order determination unit 61 to determine the data collection order so as to preferentially acquire data corresponding to the high frequency components (step S36). . Here, the high frequency component indicates an end region in the k space. FIG. 7 is a diagram for explaining a data collection order in the case of acquiring preferentially from end region data in the k space in the two-dimensional scan. This collection order is sometimes called a sequential method. The sequencer 5 executes the main scan according to the determined data collection order by changing the phase encoding gradient magnetic field. Specifically, the phase acquisition gradient magnetic field is gradually changed from the maximum value and the minimum value to the zero value direction, so that preferential acquisition from the data of the end region in the k space can be realized.

  The determination of the signal strength in steps S33 and S35 and the determination of the data collection order in steps S34 and S36 will be specifically described with reference to FIGS.

  FIG. 8 is a diagram showing the TIC at time t1. At time t1, the signal intensity is less than the second threshold value a. That is, NO is determined in step S33 and NO in step S35. Therefore, in step S35, the collection order determination unit 61 determines not to collect data until the next determination is made from the time.

  FIG. 9 is a diagram illustrating the TIC at time t2. At time t2, the signal strength is greater than or equal to the second threshold value a and less than the first threshold value b. That is, NO is determined in step S33 and YES is determined in step S35. Therefore, in step S35, the collection order determination unit 61 determines to collect high frequency component data from the time until the next determination is made.

  FIG. 10 is a diagram illustrating the TIC at time t3. At time t3, the signal strength is greater than or equal to the first threshold value b. That is, YES is determined in step S33. Therefore, in step S33, the collection order determination unit 61 determines to collect low frequency component data from the time until the next determination is made.

  FIG. 11 is a diagram illustrating the TIC at time t4. At time t4, the signal strength is greater than or equal to the second threshold value a and less than the first threshold value b. That is, NO is determined in step S33 and YES is determined in step S35. Therefore, in step S35, the collection order determination unit 61 determines to collect low frequency component data from the time until the next determination is made.

  FIG. 12 is a diagram showing the TIC at time t5. At time t5, the signal strength is less than the second threshold value a. That is, NO is determined in step S33 and NO in step S35. Therefore, in step S35, the collection order determination unit 61 determines not to collect data until the next determination is made from the time.

  If the signal strength of the contrast agent is less than the second threshold value a in step S35 as shown in FIGS. 8 and 12, the processing returns to step S31 and the determination of the signal strength is repeated. In other words, when the signal strength of the contrast agent is less than the second threshold value a, the determination of the signal strength is repeated until the signal strength becomes a or more after a lapse of time.

  When the data acquisition order is determined, the control unit 63 controls the sequencer 5 to execute the main scan on the subject after the contrast agent injection (step S37). After the pre-contrast confirmation scan and the post-contrast confirmation scan are performed on the imaging region A1 (described in FIG. 4), the main scan is performed on the imaging region R1. At least one post-contrast confirmation scan is performed in the body axis direction with respect to the imaging region. A plurality of (10) main scans are performed on the imaging region in the coronal direction as set by the operator via the input device 13.

  When the data of all the areas collected and set in the k-space are acquired, the contrast medium reachability determination and the main scanning subroutine are finished.

  Although the above-described main scan has been described as being performed on a plurality of two-dimensional sections, the main scan may be performed on a three-dimensional region. The three-dimensional region is, for example, the entire imaging region R1 (described in FIG. 4). FIG. 13 is a diagram for explaining the data collection order in the case of acquiring preferentially from the data of the central region in the k space in the three-dimensional scan. The collection order of FIG. 11 is realized by the Centric method or the Swirl method. The sequencer 5 realizes the main scan according to the determined acquisition order by changing the gradient magnetic fields of the phase encoding (Phase_Encode) and the slice encoding (Slice_Encode). For example, in the Centric method, the sequencer 5 collects data in a centric manner in both the phase encoding direction and the slice direction. Specifically, first, data in a row in the reading direction when the gradient magnetic field in phase encoding and slice encoding is set to 0 is acquired. Thereafter, the gradient magnetic field of one of phase encoding and slice encoding is gradually changed to a positive value and a negative value to acquire data for each column in the reading direction. By repeating the above operation, preferential acquisition from the data of the central region in the k space can be realized.

  In addition, there is an Interleave method shown in FIG. 14 as another k-space data collection method in the three-dimensional scan. In the Interleave method, the sequencer 5 collects data with the phase encoding direction as “centric” and the slice direction as “sequential”. Specifically, collection of data in one column in the reading direction at the center of the left end in the k space shown in FIG. When the collection of data in one reading direction at the first code position is completed, the gradient magnetic field of the phase encoding is added as indicated by one arrow in the phase encoding direction, and the data in the reading direction one row in the second code is added. Perform a collection. When the collection of data in one reading direction at the second code position is completed, the gradient magnetic field of the phase encoding is subtracted as indicated by the other arrow in the phase encoding direction, and the data in the first reading line in the third code is stored. Perform a collection. When acquisition of data regarding all values of the phase encoding gradient magnetic field is completed, the slice encoding gradient magnetic field is added, and the phase encoding gradient magnetic field is changed in the same manner as described above to acquire data for each column in the readout direction. By repeating the above operation up to the slice encode minimum value, data acquisition by the Interleave method can be realized.

  As another k-space data collection method in the three-dimensional scan, there is a Sequential method shown in FIG. In the Sequential method, the sequencer 5 collects data sequentially in both the phase encoding direction and the slice direction. Specifically, data collection in one column in the reading direction at the lower left end in the k space shown in FIG. When the collection of data in one reading direction at the first code position is completed, the phase encoding gradient magnetic field is added as indicated by the arrow in the phase encoding direction, and the data in the first reading line is collected at the second code. Run. When the collection of data in one reading direction at the second code position is completed, the phase encoding gradient magnetic field is further added as indicated by the arrow in the phase encoding direction, and the data in the first reading direction is collected at the third code. Execute. Similarly, the phase-encoding gradient magnetic field is gradually added to acquire data for each column in the readout direction. When acquisition of data regarding all values of the phase encoding gradient magnetic field is completed, the slice encoding gradient magnetic field is added, and the phase encoding gradient magnetic field is changed in the same manner as described above to acquire data for each column in the readout direction. By repeating the above operation up to the slice encode minimum value, data acquisition by the sequential method can be realized.

  In addition, although the Centric method, the sequential method, the interleave method, and the swirl method are shown as the k-space data collection method, other methods may be used.

(Modification)
In the embodiment, the TIC calculation unit 20 calculates the TIC based on the pre-contrast confirmation scan data and the post-contrast confirmation scan data. Based on the calculated TIC, the data collection order in k-space was determined. However, the magnetic resonance imaging apparatus according to the present embodiment is not limited thereto. The magnetic resonance imaging apparatus according to the modification calculates the TIC based on the pre-contrast confirmation scan data and the main scan data in the upstream imaging region in the direction in which the contrast agent flows.

  In the main scan targeting the imaging region R1 according to the modification, there is no imaging region of the main scan upstream of the imaging region R1, so the TIC calculation unit 20 performs the pre-contrast check in the imaging region A1 as in the above embodiment. Calculated based on scan data and post-contrast confirmation scan data. Here, the pre-contrast confirmation scan data and the post-contrast confirmation scan data for the imaging region A1 are executed on at least one body axis section. The collection order determination unit 61 determines the data collection order in the k space of the imaging region R1 based on the calculated TIC. In order to make the description concrete, at least one coronal section is set in the imaging region R1 as in the above embodiment.

  In the modification, the post-contrast confirmation scan is not necessary for the TIC calculation in the main scan subsequent to the imaging region R1. Specifically, the main scan data of the coronal section from the upstream imaging region is used instead of the post-contrast confirmation scan data. The imaging area of the pre-contrast confirmation scan includes at least the imaging area of the main scan as the post-contrast confirmation scan.

  In order to determine the data collection order in the imaging region R2 in the modification, the TIC calculation unit 20 performs the pre-contrast confirmation scan data in the imaging region R1 located upstream of the imaging region R2 in the direction in which the contrast agent flows and the imaging region R1. The TIC is calculated from the main scan data.

  In order to determine the data collection order in the imaging region R3 in the modification, the TIC calculation unit 20 performs the pre-contrast confirmation scan data in the imaging region R2 positioned upstream of the imaging region R3 and the imaging region R2 in the direction in which the contrast agent flows. The TIC is calculated from the main scan data. Note that the TIC calculation unit 20 may calculate the TIC based on the pre-contrast confirmation scan data in the imaging region R1 positioned upstream of the imaging region R3 and the main scan data in the imaging region R1 in the direction in which the contrast agent flows.

  As described above, according to the magnetic resonance imaging apparatus according to the present embodiment, the confirmation scan of the contrast agent is performed by performing the confirmation scan before and after contrasting in the imaging region upstream of the imaging region of the main scan in the direction in which the contrast agent flows. Reachability can be determined. The collection order of k-space data can be determined based on the determined degree of reach of the contrast agent. Data corresponding to a low frequency component in the k space, that is, a frequency component indicating the shape of a blood vessel or an organ can be acquired when the signal intensity is high. Thus, the image quality of the MRI image can be improved.

  Moreover, according to the magnetic resonance imaging apparatus according to the present embodiment, the data collection order is automatically determined according to the degree of arrival of the contrast agent. Therefore, data collection at the optimal timing can be easily realized regardless of factors such as individual differences, imaging regions, and scan time conditions.

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

  DESCRIPTION OF SYMBOLS 1 ... Magnet part, 2 ... Static magnetic field power supply, 3 ... Gradient magnetic field coil unit, 4 ... Gradient magnetic field power supply, 5 ... Sequencer, 6 ... Host computer, 7 ... RF coil, 8R ... Receiver, 8T ... Transmitter, 9 ... Temporary storage unit, 10 ... arithmetic unit, 11 ... storage unit, 12 ... display, 13 ... input device, 14 ... shim coil, 15 ... shim coil power supply, 16 ... sound generator, 20 ... TIC calculation unit, 61 ... determination of collection order , 63 ... control unit, 100 ... magnetic resonance imaging apparatus, 110 ... imaging unit

Claims (8)

A reach determination unit for determining the reach of the contrast medium in the subject;
A collection order determination unit that determines the collection order of data on a frequency space in a scan for acquiring a diagnostic image based on the determined reach of the contrast agent;
A scan execution unit that executes a scan for acquiring the diagnostic image according to the determined data collection order;
A magnetic resonance imaging apparatus comprising: The scan execution unit obtains pre-contrast confirmation scan data by executing a scan before the contrast agent is injected into the subject, and executes the scan after the contrast agent is injected into the subject. Acquire post-contrast confirmation scan data,
The reach determination unit determines the reach of the contrast agent based on the pre-contrast confirmation scan data and the post-contrast confirmation scan data,
2. The magnetism according to claim 1, wherein the acquisition order determination unit determines an acquisition order of data on a frequency space in a scan for acquiring the diagnostic image based on the determined reach of the contrast agent. Resonance imaging device. In the case of acquiring diagnostic images for a plurality of imaging regions with bed movement,
The reach determination unit is obtained for the pre-contrast confirmation scan data acquired by executing a scan before the contrast medium is injected into the subject and the imaging region located upstream of the imaging region. The magnetic resonance imaging apparatus according to claim 1, wherein the reach of the contrast agent is determined based on scan data for acquiring a diagnostic image.   The acquisition order determination unit uses signal intensity in a predetermined region of the subject as an indicator of the degree of reach of the contrast agent, and prioritizes data corresponding to a low frequency component when the signal intensity is equal to or higher than a predetermined first threshold value. The magnetic resonance imaging apparatus according to claim 1, wherein the data collection order is determined so as to be acquired.   The acquisition order determination unit uses the signal intensity in the predetermined area as an index of the degree of arrival of the contrast agent in the predetermined area, and is high when the signal intensity is less than a predetermined first threshold and not less than a predetermined second threshold. The magnetic resonance imaging apparatus according to claim 4, wherein the data collection order is determined so as to preferentially acquire data corresponding to frequency components.   6. The scan execution unit executes a scan for acquiring the diagnostic image according to the determined data collection order by changing the intensity of a phase encoding gradient magnetic field. 6. The magnetic resonance imaging apparatus described.   The scan execution unit executes a scan for acquiring the diagnostic image according to the determined data collection order by changing a phase encode gradient magnetic field and a slice encode gradient magnetic field. A magnetic resonance imaging apparatus according to claim 1.     The scan execution unit executes the scan before the contrast medium is injected into the subject in a pre-scan for calibration of the magnetic resonance imaging apparatus. Magnetic resonance imaging device.