JP4777372B2 - Magnetic resonance imaging system - Google Patents

Description

  The present invention relates to a magnetic resonance imaging apparatus that visualizes blood flow without using a contrast agent by applying a flow pulse.

  Magnetic resonance imaging is an imaging method in which a nuclear spin of a subject placed in a static magnetic field is magnetically excited with a high-frequency signal of its Larmor frequency, and an image is reconstructed from the magnetic resonance signal generated by this excitation. is there. One imaging method that has recently attracted attention in the field of magnetic resonance imaging is non-contrast angiography.

  Non-contrast angiography controls the signal intensity from a specific blood flow by dephasing or rephasing the magnetization of the blood flow in the subject by applying a flow pulse without administering a contrast agent to the subject. Actually, the pulse sequence is individually executed in the diastole and the systole to generate the diastole image and the systole image, and the arteries / veins are separated by subtracting them. For example, if the artery is the target blood flow, the intensity difference between the diastolic signal and the systolic signal from the vein is enlarged, and at the same time, the intensity difference between the diastolic signal and the systolic signal from the vein is reduced. It is important to set such conditions.

  However, even in the same region, the blood flow velocity is not only different among individuals, but is also considerably different only between a healthy person and a patient. For this reason, it is very difficult to optimize the strength of the gradient magnetic field as a flow pulse. In addition, the flow pulse is normally applied using the readout gradient magnetic field pulse for frequency encoding. Therefore, in order to avoid the extension of the echo interval, the time margin for applying the flow pulse is small and the flow pulse is applied. At present, there are few degrees of freedom given to pulses.

An object of the present invention is to improve the extractability of a target blood flow in a scan using flow pulses.

The present invention provides means for repeatedly executing a prep scan including a flow pulse for dephasing or rephasing the magnetization of blood flow in a subject a plurality of times while changing the type of the flow pulse, and the prep scan repeatedly performed a plurality of times. It means for determining a type of the scanning of the flow pulses based on data obtained by scanning, and means for performing a main scan that includes the determined type of flow pulses, based on data obtained by the main scan And means for generating a blood flow image.

ADVANTAGE OF THE INVENTION According to this invention, the extractability of the target blood flow can be improved in the scan using a flow pulse.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a schematic configuration of a magnetic resonance imaging apparatus according to the present embodiment. This magnetic resonance imaging apparatus includes a bed part on which a patient P as a subject is placed, a static magnetic field generation part for generating a static magnetic field, a gradient magnetic field generation part for adding position information to the static magnetic field, and RF (high frequency) A transmission / reception unit for transmitting / receiving signals, a control / calculation unit responsible for overall system control and image reconstruction, an electrocardiogram measurement unit for measuring an ECG (electrocardiogram) signal as a signal representing the cardiac phase of the patient P, and a patient A breath-hold command unit that commands P to hold the breath is functionally provided.

  The static magnetic field generation unit includes, for example, a superconducting magnet 1 and a static magnetic field power supply 2 that supplies current to the magnet 1, and a longitudinal axis of a cylindrical opening (diagnostic space) into which the subject P is loosely inserted. A static magnetic field H0 is generated in the direction (Z-axis direction). In addition, the shim coil 14 is provided in this magnet part. The shim coil 14 is supplied with a current for homogenizing a static magnetic field from a shim coil power supply 15 under the control of a host computer to be described later. The couch portion can removably insert the top plate on which the subject P is placed into the opening of the magnet 1.

  The gradient magnetic field generator includes a gradient magnetic field coil unit 3 incorporated in the magnet 1. The gradient coil unit 3 includes three sets (types) of x, y, and z coils 3x to 3z for generating gradient magnetic fields in the X, Y, and Z axis directions orthogonal to each other. The gradient magnetic field unit further includes a gradient magnetic field power supply 4 that supplies current to the x, y, z coils 3x to 3z. This gradient magnetic field power supply 4 supplies a pulse current for generating a gradient magnetic field to the x, y, z coils 3x to 3z under the control of a sequencer described later.

  By controlling the pulse current supplied to the x, y and z coils 3x to 3z from the gradient magnetic field power source 4, the gradient magnetic fields in the three-axis X, Y and Z directions are synthesized, and the slice direction gradient magnetic field Gs and the phase encoding are synthesized. Each direction of the direction gradient magnetic field Gpe and the frequency encoding direction (lead-out direction) gradient magnetic field Gro can be set and changed arbitrarily. The gradient magnetic fields in the slice direction, the phase encoding direction, and the readout direction are superimposed on the static magnetic field H0.

  The transmission / reception unit includes an RF (high frequency) coil 7 disposed in the vicinity of the patient P in the imaging space in the magnet 1, and a transmitter 8T and a receiver 8R connected to the RF coil 7. Under the control of a sequencer described later, the transmitter 8T supplies an RF current pulse having a Larmor frequency for exciting magnetic resonance (NMR) to the RF coil 7, while the receiver 8R receives the RF coil 7. The received MR signal (high frequency signal) is received, and various received signal processing is performed on the received signal to form corresponding digital data.

  The control / arithmetic unit further includes a sequencer (also referred to as a sequence controller) 5, a host computer 6, an arithmetic unit 10, a storage unit 11, a display device 12, and an input device 13. Among these, the host computer 6 has a function of commanding the pulse sequence information to the sequencer 5 according to the stored software procedure and overseeing the operation of the entire apparatus including the sequencer 5.

  The sequencer 5 includes a CPU and a memory, stores pulse sequence information sent from the host computer 6, and controls a series of operations of the gradient magnetic field power source 4, the transmitter 8T, and the receiver 8R according to this information. . Here, 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, for example, x, y, z coils 3x to 3z. Includes information on the intensity, application time, application timing, and the like of the pulse current applied to. In addition, the sequencer 5 inputs digital data (MR signal) output from the receiver 8 </ b> R and transfers this data to the arithmetic unit 10.

  This pulse sequence may be a two-dimensional (2D) scan or a three-dimensional (3D) scan as long as the Fourier transform method can be applied. Also, the pulse train forms include SE (spin echo) method, FE (field gradient echo) method, FSE (fast SE) method, EPI (echo planar imaging) method, Fast asymmetry SE (FASE: half of FSE method). A method that combines the Fourier method) can be applied.

  Further, the arithmetic unit 10 inputs the digital data of the MR signal sent from the receiver 8R via the sequencer 5, and the original data (also called raw data) to the Fourier space (also called k space or frequency space). And a two-dimensional or three-dimensional Fourier transform process for reconstructing the original data into a real space image, while performing an image data synthesis process. The Fourier transform process may be assigned to the host computer 6.

  The storage unit 11 can store not only original data and reconstructed image data, but also image data that has been subjected to various types of processing. The display device 12 displays an image. In addition, information such as the type of parameter desired by the operator, the scanning condition, the type and parameter of the pulse sequence, the desired image processing method, and the like can be input to the host computer 6 via the input unit 13.

  Moreover, the audio | voice generator 19 is provided as a breath-hold command part. This voice generator 19 can emit, for example, messages indicating the start and end of breath holding as voice when instructed by the host computer 6.

  Further, the electrocardiogram measurement unit attaches to the body surface of the patient P and detects an ECG signal as an electrical signal, and performs various processing including digitization processing on the sensor signal to perform the host computer 6 and the sequencer. And an ECG unit 18 for outputting to the PC. The measurement signal from the electrocardiograph is used by the host computer 6 and the sequencer 5 when executing the prep scan scan and the imaging scan based on the electrocardiogram synchronization method.

  Next, the operation of this embodiment will be described. In this embodiment, as shown in FIG. 2, a prep scan (preparation scan) is executed before the main scan (imaging scan) in order to optimize the scan conditions of the main scan by using the breath holding method together. . First, the main scan will be described, and then the prep scan will be described.

  As shown in FIGS. 3 and 4, the main scan is executed twice in the systole and the diastole using electrocardiogram synchronization. Then, as shown in FIG. 5, the arithmetic unit 10 makes a difference between the image Isys generated from the magnetic resonance signal collected in the systole and the image Idia generated from the magnetic resonance signal collected in the diastole. By this difference, for example, an artery is extracted as the target blood flow, and the static part and the vein can be reduced. Conditions suitable for extraction of the target blood flow are determined by prep scan.

  Here, for example, when an artery is used as an example of the target blood flow, the optimum condition is that the difference in the arterial signal is as large as possible between the systole and the diastole, and conversely the difference in the venous signal is as small as possible. Specifically, as the flow pulse, there are a rephase type that compensates the blood flow signal and a dephase type that suppresses the blood flow signal, either of them, or the original pulse sequence without using the flow pulse. If the main scan is performed as it is or if a flow pulse is used, the degree of rephase / dephase, that is, the intensity of the gradient magnetic field pulse as the flow pulse is determined.

  6 and 7 show two typical pulse sequences of the main scan to which the FASE method is applied. FIG. 6 shows a flow-compensation (flow-comp.) Consisting of a pair of gradient magnetic field pulses of opposite polarity and the same intensity as a rephase type flow pulse, and FIG. 7 shows 180 as a dephase type flow pulse. A flow-spoiled pulse composed of a pair of gradient magnetic field pulses having opposite polarities, ie, substantially the same polarity and the same intensity, is shown by hatching.

  As is well known, the FASE method applies half-Fourier reconstruction to the high-speed SE method that collects a plurality of echoes by one nuclear magnetic excitation, and arranges an echo signal near the center (zero encoding) of k-space. Thus, the echo time is shortened. That is, a high-frequency magnetic field pulse (excitation pulse) having a flip angle of 90 ° is applied together with the slice selection gradient magnetic field pulse Gs, and then a high-frequency magnetic field pulse (phase inversion pulse) having a flip angle of 180 ° is repeatedly applied. The echo signal is repeatedly collected in the presence of the encoding (reading) gradient magnetic field pulse Gro. Since three-dimensional imaging is employed here, phase encoding is given to the echo signal by the gradient magnetic field pulse Gpe, and slice encoding is given to the echo signal by the gradient magnetic field pulse Gs.

  Here, as shown in FIG. 8, the phase encoding direction PE is set substantially parallel to the direction of the target blood flow (artery AR in the figure). Thereby, compared with the case where the phase encoding direction PE is set to a direction orthogonal to the blood flow direction, it is possible to capture more clearly without missing or dropping the running direction of the artery AR. In general, it is known that the blood flow represented by pulmonary blood vessels and liver blood vessels (portal veins) has a slightly shorter T2 time. It has been found that the half-width of the signal is widened in the short blood flow of T2 time compared to CSF and joint fluid having a long T2 time. Compared with CSF and synovial fluid with a long T2, blood (arteries) with a short T2 is apparently equivalent to an increase in the width of the phase encoding direction per pixel. Therefore, blood (arteries) indicates that the entire image is more blurred in the phase encoding direction than CSF and synovial fluid.

  Therefore, by making the phase encoding direction PE substantially coincide with the blood flow direction, the degree of spread (blurring) on the pixel of the signal value in the phase encoding direction PE of blood with a short T2 time is greater than that with a long T2 time. This can be used positively and blood flow is emphasized. Therefore, as described above, when selecting an optimal MRA image (that is, optimal delay time) for ECG synchronization, the selection is facilitated.

  Further, the flow pulse, that is, the flow compensation pulse flow-comp. Of FIG. 6 or the flow-spoil pulse flow-spoiled of FIG. 7 needs to be set in the direction of the target blood flow, but it is phase-encoded in the blood flow direction. By arranging PE, it can be formed by the phase encoding gradient magnetic field Gpe.

  By forming the flow pulse with the phase encoding gradient magnetic field Gpe, the flow pulse can be made longer than when the flow pulse is formed with the frequency encoding gradient magnetic field Gro as in the prior art, and the echo interval can be shortened. It can be applied with sufficient intensity necessary for vein separation.

  In the above description, the flow pulse is applied in the phase encoding direction to visualize the blood flow in that direction. However, as indicated by the oblique lines in FIGS. 9 and 10, the flow pulse is combined with the phase encoding direction Gpe and the frequency encoding direction Gro. It is also possible to visualize the blood flow in that direction.

  In the main scan as described above, the systolic image Isys and the diastolic image Idia are acquired, and by simple or weighted difference between them, for example, an artery is extracted as the target blood flow, and the static part and the vein are reduced. An image is obtained. Conditions suitable for extraction of the target blood flow are determined by prep scanning. As described above, the optimum condition is defined as a condition in which the difference in signal from the target blood flow is as large as possible between the systole and the diastole, and conversely, the difference in signal from the target blood flow is as small as possible. The

  FIG. 11 shows a case where a flow pulse is applied in a rephase type (flow-comp.), A case where a flow pulse is applied in a dephase type (flow-spoiled), and a case where a flow pulse is not applied (original). The general tendency of the signal strength of each artery and vein is shown for each systole and diastole.

  As described above, the optimum condition for arteriovenous separation is that the difference in signal from the target blood flow is as large as possible between the systole and the diastole, and conversely the difference in signal from the target blood flow is as small as possible. It is determined depending on whether the target blood flow is an artery or a vein, and also on the blood flow velocity.

  In this embodiment, as shown in FIG. 12, a prep scan is actually executed under various conditions before the main scan, and a difference image between the systolic image and the diastolic image is generated for each condition. The operator (examiner) visually selects and selects an image having the best separation between the target blood flow and the non-target blood flow from the difference image. The same flow pulse conditions as the pulse sequence that collected the original signal of the selected image, that is, no rephase type, dephase type, or flow pulse, and the same setting as the intensity of the gradient magnetic field pulse as the flow pulse. The main scan is executed.

  FIGS. 13 and 14 show simple prep scans, and FIGS. 15 and 16 show examples of prep scans for detailed condition setting. The simple prep scan is made for the purpose of selecting one of application of a rephase type flow pulse (flow-comp.), Application of a dephase type flow pulse (flow-spoiled), and non-application of a flow pulse (original). A detailed prep scan can be selected from applying a rephase flow pulse (flow-comp.), Applying a dephase flow pulse (flow-spoiled), or not applying a flow pulse (original). This is done for the purpose of selecting a suitable strength. Either type of prep scan is preselected by the operator.

Regardless of the type, the prep scan is performed in the same manner as the main scan, here in the FASE method, but with two-dimensional imaging. That is, a high-frequency magnetic field pulse (excitation pulse) having a flip angle of 90 ° is applied together with the slice selection gradient magnetic field pulse Gs, and then a high-frequency magnetic field pulse (phase inversion pulse) having a flip angle of 180 ° is repeatedly applied. The echo signal is repeatedly collected in the presence of the encoding (reading) gradient magnetic field pulse Gro. However, unlike the main scan, the prep scan employs two-dimensional imaging in order to shorten the prep scan time, and therefore, the echo signal is given a phase encoding by the gradient magnetic field pulse Gpe, but the slice encoding is not applied. In the prep scan, as in the main scan, the phase encoding direction PE is set substantially parallel to the direction of the target blood flow (artery AR in the figure).

  In the simple type, as shown in FIGS. 13 and 14, a two-dimensional FASE pulse sequence in which rephase-type flow pulses (flow-comp.) Are applied in systole and diastole using electrocardiogram synchronization, and A two-dimensional FASE method pulse sequence to which a dephase type flow pulse (flow-spoiled) is applied, and a two-dimensional FASE method pulse sequence to which a flow pulse is not applied (original) are executed.

  Images reconstructed based on echoes collected in a two-dimensional FASE pulse sequence with rephase flow pulses (flow-comp.) Applied during systole and rephase flow pulses (flow-comp.) During diastole The image reconstructed based on the echoes collected in the two-dimensional FASE method pulse sequence to which is applied is simply or weighted and the difference image is displayed.

  Similarly, an image reconstructed based on echoes collected in a two-dimensional FASE pulse sequence with a dephasing flow-spoiled applied during systole and a dephasing flow-pulse (flow-spoiled during diastole) ) Is applied to the image reconstructed based on the echo collected by the two-dimensional FASE method pulse sequence applied with a simple or weighted difference, and the difference image is displayed.

  Similarly, an image reconstructed based on echoes collected in a two-dimensional FASE pulse sequence that does not apply a flow pulse during systole and a two-dimensional FASE pulse sequence that does not apply a flow pulse during diastole The image reconstructed based on the echo that has been reconstructed is simply or weighted differenced, and the difference image is displayed.

  The operator visually recognizes these three types of images, and selects an image in which a target blood flow, for example, an artery is extracted most clearly.

  The host computer 6 and the sequencer 5 set the main scan condition to the same flow condition as that of the selected image. In other words, an image reconstructed based on echoes collected by a two-dimensional FASE pulse sequence to which a rephase flow pulse (flow-comp.) Is applied, and a rephase flow pulse (flow-comp.) In the diastole When a difference image from an image reconstructed based on echoes collected in the applied two-dimensional FASE pulse sequence is selected, this scan condition applies rephase type flow pulses (flow-comp.) 3 Dimensional FASE method pulse sequence is set.

  In addition, an image reconstructed based on echoes collected by a two-dimensional FASE pulse sequence that applies a dephasing flow pulse (flow-spoiled) during systole, and a dephasing flow pulse (flow-spoiled) during diastole When a difference image from an image reconstructed based on echoes collected in a two-dimensional FASE method pulse sequence to which the image is applied is selected, this scan condition applies a dephase-type flow pulse (flow-spoiled) 3 Dimensional FASE method pulse sequence is set.

  Furthermore, similarly, an image reconstructed based on echoes collected in a two-dimensional FASE pulse sequence that does not apply a flow pulse during systole and a two-dimensional FASE pulse sequence that does not apply a flow pulse during diastole When a difference image from an image reconstructed based on the echoes selected is selected, the main scan condition is set to a three-dimensional FASE method pulse sequence to which no flow pulse is applied.

  On the other hand, when the detailed setting type prep scan is selected, as shown in FIGS. 15 and 16, the rephasic flow pulse (flow flow effect) in the systole has a flow compensation effect of +3, that is, the gradient magnetic field strength is three times the reference strength. -comp.) applied image reconstructed based on echoes collected in a 2D FASE pulse sequence and flow compensation effect +3 in systole during diastole, that is, gradient magnetic field strength is 3 times the reference strength The image reconstructed based on the echo collected by the two-dimensional FASE pulse sequence to which the rephase type flow pulse (flow-comp.) Is applied is subjected to simple or weighted difference, and the difference image is displayed.

  It is reconstructed based on echoes collected in a two-dimensional FASE pulse sequence that applies a rephase flow pulse (flow-comp.) With a flow compensation effect of +2 during the systole, that is, the gradient magnetic field strength is twice the reference strength. And a two-dimensional FASE pulse sequence that applied a rephasing flow pulse (flow-comp.) With a flow compensation effect of +2 in the systole during diastole, that is, the gradient magnetic field strength is twice the reference strength. The image reconstructed based on the echo is simply or weighted differenced, and the difference image is displayed.

  An image reconstructed based on echoes collected in a two-dimensional FASE pulse sequence applying a rephase flow pulse (flow-comp.) With a flow compensation effect of +1 in the systole, that is, a gradient magnetic field strength of a reference strength, and Reconstruction based on echoes collected in a two-dimensional FASE pulse sequence using a rephasing flow pulse (flow-comp.) With a flow compensation effect of +1 in the diastole and in the systole, that is, the gradient magnetic field strength is the reference strength The obtained image is simply or weighted differenced, and the difference image is displayed.

  In addition, images reconstructed based on echoes collected in a two-dimensional FASE pulse sequence without applying a flow pulse during systole and echoes collected with a two-dimensional FASE pulse sequence without applying a flow pulse in diastole The image reconstructed based on the above is simply or weighted differenced, and the difference image is displayed.

  Based on echoes collected in a two-dimensional FASE pulse sequence applying a dephasing flow pulse (flow-spoiled) with a flow compensation effect of -1 (a flow suppression effect of +1), that is, a gradient magnetic field strength of a reference strength during systole Two-dimensional FASE method pulse applying a rephased flow pulse (flow-spoiled) with a flow compensation effect of -1 (flow suppression effect of +1), that is, a gradient magnetic field strength of a reference strength in the diastole The image reconstructed based on the echoes collected in the sequence is simply or weighted differenced, and the difference image is displayed.

  Collected in a two-dimensional FASE pulse sequence with a flow compensation effect of −2 (flow suppression effect of +2) during the systole, that is, applying a dephasing flow pulse (flow-spoiled) whose gradient magnetic field strength is twice the reference strength Image reconstructed based on echo and dephasing flow pulse (flow-spoiled) with flow compensation effect -2 (flow suppression effect +2) in diastole, that is, gradient magnetic field strength is twice the reference strength The image reconstructed based on the echoes collected in the two-dimensional FASE pulse sequence is simply or weighted and the difference image is displayed.

  Collected in a two-dimensional FASE pulse sequence using a dephasing flow pulse (flow-spoiled) with a flow compensation effect of −3 (flow suppression effect +3), that is, a gradient magnetic field strength of 3 times the reference strength in the systole Reconstructed image based on echo and dephasing flow pulse (flow-spoiled) with flow compensation effect -3 (flow suppression effect +3), that is, gradient magnetic field strength is 3 times the reference strength in diastole The image reconstructed based on the echo collected by the two-dimensional FASE pulse sequence is simply or weighted and the difference image is displayed.

  The operator visually recognizes these seven types of images, and selects an image in which the target blood flow, for example, an artery is extracted most clearly.

  The host computer 6 and the sequencer 5 set the main scan condition to the same flow condition as that of the selected image. That is, when a difference image corresponding to a two-dimensional FASE pulse sequence to which any of the rephasing flow pulses (flow-comp.) Having flow compensation effects is applied is selected, this scan condition has the same flow compensation effect. In other words, it is set to a three-dimensional FASE method pulse sequence to which a rephase type flow pulse (flow-comp.) Having the same gradient magnetic field strength is applied.

  When a difference image corresponding to a two-dimensional FASE method pulse sequence to which no flow pulse is applied is selected, the main scan condition is set to a three-dimensional FASE method pulse sequence to which no flow pulse is applied.

Furthermore, when a difference image corresponding to a two-dimensional FASE pulse sequence to which any one of the flow suppression effects is applied is applied to the two-dimensional FASE method pulse sequence, this scan condition has the same flow suppression effect. That is, it is set to a three-dimensional FASE pulse sequence to which a dephase type flow pulse (flow-spoiled) having the same gradient magnetic field strength is applied.

  Note that the number of stages of the flow compensation effect and the flow suppression effect executed in this detailed type of prep scan can be arbitrarily set by the operator.

  As described above, according to the present embodiment, at the time of the main scan, the phase encoding pulse Gpe is applied almost in the direction of the target blood flow, and the flow pulse is applied in the phase encoding direction, thereby enhancing blood flow. The effect can be realized, and the flow pulse can be applied with sufficient time and sufficient intensity for arteriovenous separation along with shortening the echo interval by giving a time margin.

(Modification)
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation. Furthermore, the above embodiment includes various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, some constituent requirements may be deleted from all the constituent requirements shown in the embodiment.

The functional block diagram which shows an example of a structure of the magnetic resonance imaging apparatus which concerns on embodiment of this invention. The figure which shows the temporal relationship of the prep scan and this scan in this embodiment. The figure which shows the systolic procedure of the main scan of FIG. The figure which shows the expansion period procedure of the main scan of FIG. Explanatory drawing of the difference process of this embodiment. The figure which shows an example of the flow compensation type (flow-comp.) Pulse sequence of the main scan of FIG. FIG. 3 is a diagram illustrating an example of a flow-spoiled pulse sequence of the main scan in FIG. 2. The figure which shows the relationship between the direction of the phase encoding (PE) of FIG. 6, FIG. 7, and the direction of a blood flow. The figure which shows the modification of the flow compensation type (flow-comp.) Pulse sequence of the main scan of FIG. The figure which shows the modification of the spoil type (flow-spoiled) pulse sequence of the main scan of FIG. The figure which shows the correspondence of the general signal strength with respect to the diastole and systole of each of an original, a flow compensation type, and a spoil type in this embodiment. The flowchart which shows the whole flow of this embodiment. The figure which shows the basic pulse sequence of the prep scan (systole) of FIG. The figure which shows the basic pulse sequence of the prep scan (expansion period) of FIG. FIG. 13 is a diagram showing an evolution pulse sequence of the prep scan (systole) in FIG. 12. FIG. 13 is a diagram showing an advanced pulse sequence of the prep scan (expansion period) of FIG. 12.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Magnet 2 ... Static magnetic field power supply 3 ... Gradient magnetic field coil unit 4 ... Gradient magnetic field power supply 5 ... Sequencer 6 ... Controller 7 ... RF coil 8T ... Transmitter 8R ... Receiver 10 ... Arithmetic unit 11 ... Storage unit 12 ... Display 13 ... Input device 17 ... ECG sensor 18 ... ECG unit 19 sound generator

Claims (8)

Means for repeatedly executing a prep scan including a flow pulse for dephasing or rephasing the magnetization of the blood flow in the subject a plurality of times while changing the type of the flow pulse;
Means for determining the type of flow pulse of the main scan based on data obtained by the prep scan repeatedly executed a plurality of times;
Means for performing a main scan including the determined type of flow pulse;
Means for generating a blood flow image based on the data obtained by the main scan. Wherein the means for determining the type of the scanning of the flow pulses, as well as the type of the flow pulses, the magnetic resonance imaging apparatus according to claim 1, wherein the determining the strength of the gradient magnetic field waveform as the flow pulses.   The magnetic resonance imaging apparatus according to claim 1, wherein the flow pulse is applied in a phase encoding direction. Wherein the means for determining the type of flow pulses of the scan, the type of flow pulses used to obtain the image selected by the operator from the difference image between the diastole image and the displayed systolic image for each of the types 4. The magnetic resonance imaging apparatus according to claim 1, wherein the type of flow pulse of the main scan is determined.   5. The magnetic resonance imaging apparatus according to claim 4, wherein the prep scan has a rephase type flow pulse.   6. The magnetic resonance imaging apparatus according to claim 1, wherein the prep scan is a pulse sequence of the same type as the main scan.   The magnetic resonance imaging apparatus according to claim 1, wherein the prep scan is a two-dimensional scan, and the main scan is a three-dimensional scan. The main scan includes a first scan based on a three-dimensional FASE pulse sequence that collects magnetic resonance signals during the systole of the subject and a second scan based on the three-dimensional FASE pulse sequence that collects magnetic resonance signals during the diastole of the subject. It consists of a scan,
In the first and second scans , the determined type of flow pulse is applied in the phase encoding direction ,
The first image of the subject generated based on the magnetic resonance signal obtained by the first scan, and the second image of the subject generated based on the magnetic resonance signal obtained by the second scan. The magnetic resonance imaging apparatus according to claim 1, wherein the blood flow image is generated based on a difference from the image.

Images