JP5259747B2 - Magnetic resonance imaging apparatus and magnetic resonance imaging method - Google Patents

Description

The present invention relates to an imaging method for imaging a blood vessel image or CSF (cerebrospinal fluid) of a subject in medical magnetic resonance imaging .

  In magnetic resonance imaging, the nuclear spin of a subject placed in a static magnetic field is magnetically excited with a high-frequency signal of Larmor frequency, and an image is generated from an FID (free induction decay) signal or echo signal generated by this excitation. It is a technique to obtain.

  As one category of this magnetic resonance imaging, MR angiography (MRA) for imaging blood dynamics has attracted attention.

  In this MRA, in general, a contrast medium having the property of greatly changing the signal intensity in MRI is administered inside the blood vessel, scanning under the same conditions is continuously performed, and the movement of blood flow is imaged. MR angiography (hereinafter referred to as “CE-DMRA”) is adopted (for example, see Non-Patent Document 1).

  This CE-DMRA imaging procedure is conceptually shown in FIG. First, a contrast medium is injected into a vein, and scanning is continuously performed from the time when the contrast medium reaches a blood vessel in the imaging region. A curve CB in FIG. 5A shows a time change of the signal intensity at the position of one point in the imaging target. As shown in FIG. 6B, the arrival point of the contrast agent crosses the imaging region from the contrast agent injection time t0, and all blood vessels are drawn depending on the size of the region and the imaging region. Although it cannot be defined, it is about 30 seconds to 2 minutes. In FIG. 7B, periods PD1, PD2,... Represent first, second,. In the scan periods PD1, PD2,..., A desired, for example, three-dimensional pulse sequence is executed, and echo signals generated in response to the execution are collected. The echo signal is reconstructed for each scan, and is generated, for example, as three-dimensional image data D1, D2,... As conceptually shown in FIG. These image data D1, D2,... Are subjected to, for example, a process of projecting a maximum value when viewed from a certain viewpoint (maximum value projection process), and as shown conceptually in FIG. , IMmax2, ... are processed and displayed.

The scan method used in the CE-DMRA is a pulse sequence mainly based on the FE (field echo) method. An example of this is shown in FIG. As shown in the figure, the harmonic excitation pulse P _ext is applied together with the slice selective excitation gradient magnetic field Gs _sel , and the echo signal S _echo is received together with the application of the read direction gradient magnetic field Gr. In the figure, a gradient magnetic field Gs _rew indicates a rewind gradient magnetic field in the slice direction. This series of excitation and acquisition is repeated a predetermined number of times for each repetition time TR until echo data necessary for image reconstruction is completed while changing, for example, the intensity of the phase encoding gradient magnetic field Ge. The repetition time TR is usually about 3-10 ms.

Note that FIG. 13 illustrates the pulse sequence necessary for image reconstruction based on the two-dimensional Fourier method, but image reconstruction based on the three-dimensional Fourier method may be used depending on the imaging purpose. In that case, when a series of data is collected by changing the intensity of the phase encoding gradient magnetic field Ge by repetition of each excitation, the intensity of the rewind gradient magnetic field Gs _{rew in} the slice direction is changed. Then, the operation of collecting a series of data associated with the intensity change of the phase encoding gradient magnetic field Ge is performed again for the number of matrices in the slice direction. As a result, all data necessary for image reconstruction based on the three-dimensional Fourier method is collected.

Thus, in the CE-DMRA, the images D ₁ , D ₂ ,... Along the reconstructed time series, or the images IM _max1 , IM _max2,. By doing so, it is possible to grasp the dynamic behavior of the blood BD flowing through the blood vessel BV. This method can be applied to imaging of a moving object in the imaging target, for example, a CSF (cerebrospinal fluid) when the imaging target is a human body, and the behavior can be observed through similar processing. In addition, when CSF is taken as an imaging target, it is called hydrography.

On the other hand, Non-Patent Document 2 proposes a conventional method for obtaining a blood vessel image by labeling a locally moving spin by an inversion (IR) pulse without administering a contrast agent. An outline of the angiography according to this conventional method is shown in FIG. FIG. 6A shows a pulse sequence when the ECG (electrocardiogram) synchronization method is used together, FIG. 6B shows a time change state of longitudinal magnetization of spins in each part to be imaged, and FIG. The positional relationship between the cross section and the region RG _A excited by the labeling (tag) inversion pulse P _inv-A is shown.

As shown in FIG. _{6A, an} inversion pulse P _inv-A having a flip angle of 180 degrees is applied after a lapse of a certain time from the R wave of the ECG signal (however, immediately after the R wave in the same figure). Is done. At this time, the RF frequency of the inversion pulse P _inv-A is offset from the center frequency by the offset amount Df so that the region RG _A considered to be the source of the flow into the imaging section CS of the blood vessel of interest is selectively excited. The selective excitation gradient magnetic field Ge is applied together with the inversion pulse P _inv-A . After the inversion pulse P _inv-A is applied, after a certain time of about 300 to 1000 ms, a pulse sequence P _seq for collecting echo signals is executed. This sequence is constituted by, for example, the SE (spin echo) method. This series of operations is repeated until all echo data necessary for reconstruction of one screen can be collected. The echo data is reconstructed and generated into a blood vessel image. The pulse sequence that can be used for this angiography is not limited to the SE method, but may be a segmented FE method. This segmented FE method is proposed in Non-Patent Document 3 as an example.

Non-Patent Document 2 _discloses a method of collecting a plurality of images in which the position and width of the partial region RG _A excited by the inversion pulse P _inv-A are changed, and creating a difference image from each image. It is stated. By this difference calculation, signals other than the blood vessel are suppressed, and the blood vessel rendering ability is improved.

Further, as another example of angiography that does not use a contrast agent, a technique described in FIGS. 15A to 15C is also known. The technique shown in FIG. 14 is a combination of the technique shown in FIG. 14 described above and the technique described in Non-Patent Document 4. As the scan pulse sequence P _seq for obtaining the echo signal, for example, a fast SE (FSE) method is used. The method shown in FIG. 15 is the same as that shown in FIG. 14, but differs in the application of an inversion pulse. That is, the inversion pulse P _inv-A that excites the entire cross section CS to be imaged is first selectively applied, and immediately after this (for example, after 2 to 10 ms), it is considered that the inflow source of the blood vessel of interest is the same as in FIG. The second inversion pulse P _inv-B is applied so that the partial region RG _A is selectively excited. Since the time between the first and second inversion pulses P _inv-A and P _inv-B is extremely short compared to the blood flow velocity, it is considered to be almost the same when viewed from the nuclear spin of the blood vessel. be able to. Therefore, since the nuclear spin of the blood vessel of interest receives the application of the 180-degree pulse twice within a very short time, as shown in FIG. 5B, the longitudinal magnetization is partially returned to the initial state. Since it flows from the region RG _A to the imaging section CS, it is rendered as a portion having a higher signal than the tissue. Note that the above-described method of FIG. 14 is symmetric to that the blood vessel signal is imaged as a value lower than that of the tissue.

M.M. Prince, Radiology 1994; 191: 144-164 Paper “Considations of Magnetic Resonance Angiography by Selective Inversion Recovery”, D. G. Nishimura et al., Magnetic Resonance in Med. The paper “Fast Angiography Using Selective Inversion Recovery”, Samuel J. et al. Wang et al. , Magnetic Resonance in Medicine, Vol. 23, 109-121, 1992 " Papers “D. Chien et al.,“ High Speed black blood imaging of vessel stenosis in the presence of pulsatile flow, ”J. Magn. Reson. “Simonetti OP, et al., Radiology, 199, 49, 1996”

  However, in the case of the conventional CE-DMRA method using the above-described contrast agent, since the contrast agent can be injected only once (or twice) during one examination, the signal intensity depends on the injected contrast agent. All scans must be completed within a limited time of 30 seconds to 2 minutes, where the change is. In principle, in order to ensure a sufficient time resolution, it is necessary to shorten a scan time as much as possible. On the other hand, since the S / N of the image is proportional to the square root of the scanning time, the shorter the scanning time, the lower the S / N. For this reason, according to the conventional method, the temporal resolution and the spatial resolution of the scan are in a trade-off relationship, and both cannot be increased dramatically.

  On the other hand, in the case of MR angiography without administration of the contrast agent, the difference between a plurality of blood vessel images obtained through the execution of the pulse sequence shown in FIG. 14 or FIG. Suppressing is stated. Thereby, the ability to depict blood vessels can be improved, but no display or observation technique for dynamically capturing the dynamics of blood flow has been presented. In the case of blood flow, in addition to its ability to depict, information on how it behaves over time is extremely important.

The present invention has been made in view of the conventional problems described above, without the administration of contrast medium, raising the time resolution and spatial resolution to a high level co, provide images that enable the dynamic observation of moving objects The purpose is to do.

Magnetic resonance imaging method according to the present invention, after a series of labels pulses applied with selective excitation gradient magnetic field in order to label the imaging object in motion in the subject is applied, until the pulse sequence is started as the traveling path of the imaging target proceeds do it imaging region is an exhaustive and imaged during, the labeling pulse condition on which the selectable application number or selective excitation width of said label pulse An echo signal from the imaging target by starting a pulse sequence after a lapse of a predetermined time after continuously applying the marker pulse for which a condition is set in the first step a plurality of times, a second step of collecting, using the echo signals, after a plurality of images of the imaging region where the imaging target is labeled, or the series of labeled pulse is applied, the Parusushike Scan and having a third step of generating an image travel path is covered in the imaging target advances do it imaging region until the start.

Magnetic resonance imaging apparatus of the present invention, until after a series of labels pulses applied with selective excitation gradient magnetic field in order to label the imaging object in motion in the subject is applied, the pulse sequence is started as the traveling path of the imaging area's imaging target advances do is be exhaustive and imaged during, setting the conditions of the labeled pulse on you can select the application number or selective excitation width of said label pulse Means for performing the first step, and starting the pulse sequence after elapse of a predetermined time after continuously applying the marker pulse for which the condition is set in the first step a plurality of times, from the imaging target means for performing a second step of acquiring echo signals, using the echo signals, a plurality of images of the imaging region where the imaging target is labeled, or the series of labeled pulse is applied , Characterized by comprising a means for performing a third step of generating an image travel path is covered in the imaging area's imaging target proceeds do until the pulse sequence is started.

  According to the MR imaging of the present invention, both temporal resolution and spatial resolution, which have been problems in conventional MRA, can be achieved, and both can be maintained at a high level. Information can be obtained.

  Furthermore, the MR imaging method of the present invention eliminates the need for administration of a contrast agent, which is essential in conventional CE-DMRA, so that it is non-invasive and significantly reduces the mental and physical burden on the subject. be able to. Moreover, the troublesomeness associated with the recognition of the imaging timing, such as when a contrast agent is administered, is unnecessary, and the preparation and labor of the examination are greatly reduced. In addition, since no contrast agent is used, it is possible to easily cope with re-inspection.

  Furthermore, according to the MR imaging method of the present invention, the position of the region to be tagged with the inversion pulse can be set freely, so that the inflowing blood vessel can be limited and the inspection can be performed with high accuracy and certainty. It becomes possible.

1 is a block diagram showing a schematic configuration of an MRI apparatus according to an embodiment of the present invention. The pulse sequence which has one inversion pulse for tags used in the first embodiment. The figure explaining the positional relationship of the imaging area | region and tag area | region in 1st Embodiment, and the production | generation procedure of an MRA image. A pulse sequence having a plurality of tag inversion pulses used in the second embodiment. The figure explaining the positional relationship of the imaging area | region and tag area | region in 2nd Embodiment, and the production | generation procedure of an MRA image. The pulse sequence used in the third embodiment. The figure explaining the positional relationship of an imaging area | region and a tag area | region regarding the arteriovenous separation in 3rd Embodiment, and the production | generation procedure of MRA image. The figure explaining the positional relationship of an imaging area | region and a tag area | region regarding the arteriovenous separation in 3rd Embodiment, and the production | generation procedure of MRA image. The pulse sequence which has one inversion pulse for tags used in the pre-scan according to the fourth embodiment. The figure explaining the positional relationship of an imaging area | region and a tag area | region, and the production | generation procedure of MRA image in the pudding scan which concerns on 4th Embodiment. The figure which shows the pulse sequence and image example which concern on 5th Embodiment. The figure explaining CE-DMRA as a prior art. The figure which illustrates the pulse sequence used for CE-DMRA. The figure explaining an example of conventional MRA with a pulse sequence. The figure explaining another example of conventional MRA with a pulse sequence.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
An MRI (magnetic resonance imaging) apparatus according to the first embodiment will be described with reference to FIGS.

  Characteristically, this MRI apparatus is a non-contrast MR angiography that presents, for example, a cine-mode image as a quasi-dynamic image representing the dynamics of blood flow as a moving object in a subject without using a contrast agent. It has a function of executing the graphic (MRA). The pulse sequence for performing this non-contrast MRA uses a harmonic inversion recovery (IR) pulse of selective excitation.

  A schematic configuration of this MRI apparatus is shown in FIG. This apparatus configuration can be used in common in each embodiment described later.

  This MRI apparatus includes a bed unit on which a patient P as a subject is placed, a static magnetic field generating unit for generating a static magnetic field, a gradient magnetic field generating unit for adding position information to the static magnetic field, and transmission and reception for transmitting and receiving high-frequency signals. Unit, a control / arithmetic unit responsible for overall system control and image reconstruction, an electrocardiogram measurement unit that measures an ECG signal as a signal representing the cardiac time phase of the subject P, and commands the patient P to hold his / her breath And a breath-hold command unit.

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 an axial direction of a cylindrical opening (diagnostic space) into which the subject P is loosely inserted. (Z-axis direction) to generate a static magnetic field _{H 0.} 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 also includes a gradient magnetic field power supply 4 that supplies current to the x, y, and z coils 3x to 3z. The 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 5 described later.

By controlling the pulse current supplied from the gradient magnetic field power source 4 to the x, y, z coils 3x to 3z, the gradient magnetic fields in the three axes X, Y, and Z, which are physical axes, are synthesized and slices orthogonal to each other. The logical axis directions of the direction gradient magnetic field Gs, the phase encoding direction gradient magnetic field Ge, and the readout direction (frequency encoding direction) gradient magnetic field Gr can be arbitrarily set and changed. Slice direction, phase encoding direction, and gradient magnetic fields in 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 1, and a transmitter 8T and a receiver 8R connected to the coil 7. The transmitter 8T and the receiver 8R operate under the control of the sequencer 5 described later. The transmitter 8T supplies the RF coil 7 with an RF current pulse having a Larmor frequency for causing nuclear magnetic resonance (NMR). The receiver 8R takes in an echo signal (high frequency signal) received by the RF coil 7, and performs various signal processing such as preamplification, intermediate frequency conversion, phase detection, low frequency amplification, filtering, etc. A digital amount of echo data (original data) corresponding to the echo signal is generated by / D conversion.

  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, an input device 13, and a sound generator 16. 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.

  The host computer 6 performs an imaging scan based on the pulse sequence shown in FIG. 2 following a preparatory operation such as a positioning scan. This imaging scan is a scan that collects a set of echo data necessary for image reconstruction, and is set to a two-dimensional scan here. The imaging scan is performed using an ECG gate method based on an ECG signal. This ECG gate method may not be used in some cases.

  This pulse sequence is a three-dimensional (3D) scan or a two-dimensional (2D) scan. The pulse trains include SE (spin echo) method, FSE (fast SE) method, FASE (fast asymmetric SE) method (that is, imaging method combining the fast SE method with the half Fourier method), EPI (echo planar imaging). ) Method, etc. are used.

  The sequencer 5 includes a CPU and a memory, stores pulse sequence information sent from the host computer 6, controls the operations of the gradient magnetic field power source 4, the transmitter 8T, and the receiver 8R according to this information, The echo data output from the receiver 8R is once input and transferred to the arithmetic unit 10. 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.

  The arithmetic unit 10 inputs echo data (original data or raw data) output from the receiver 8R through the sequencer 5, and arranges the echo data in the Fourier space (also referred to as k space or frequency space) in the internal memory. Then, the echo data is subjected to two-dimensional or three-dimensional Fourier transform for each group to reconstruct the image data in real space. Further, the arithmetic unit can perform a data synthesizing process, a difference arithmetic process, and the like as necessary.

  In this synthesis process, two-dimensional image data of a plurality of frames are added for each corresponding pixel, and maximum value projection (MIP) or minimum for selecting the maximum value or minimum value in the line-of-sight direction for three-dimensional data Value (MIP) projection processing and the like are included. As another example of the synthesis process, the axes of a plurality of frames may be matched in the Fourier space and synthesized into one frame of echo data as it is. The addition processing includes simple addition processing, addition averaging processing, weighted addition processing, and the like.

  The storage unit 11 can store not only the reconstructed image data but also the image data that has been subjected to the above-described combining process and difference process. The display device 12 displays an image. In addition, information relating to imaging conditions, pulse sequences, image synthesis, and difference calculation desired by the operator can be input to the host computer 6 via the input unit 13.

  Moreover, the sound generator 16 is provided as an element of the breath-hold command unit. The voice generator 16 can emit a breath holding start message and a breath holding end message as voice when instructed by the host computer 6.

  Further, the electrocardiogram measurement unit attaches to the body surface of the subject 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 electrocardiogram measurement unit is used by the sequencer 5 when executing an imaging scan. Thereby, the synchronization timing by the ECG gate method (electrocardiogram synchronization method) can be set appropriately, and the ECG gate method imaging scan based on this synchronization timing can be performed to collect data.

Next, the operation of the MRI apparatus according to the present embodiment will be described with reference to FIGS.
FIG. 2 shows a pulse sequence used in non-contrast-enhanced MR angiography according to this embodiment, and FIG. 3 shows a diagram for explaining a processing process from scanning to display image generation. In order to facilitate understanding, the non-contrast MR angiography performed in this embodiment performs three two-dimensional scans to obtain three consecutive final images and displays them in cine display. Further, although the actual image signal values are displayed darker lower pixel, in FIG. 3 (b) ~ (d) , expressed in dark hatching as portion to be rendered to a high signal, rendering region of the low signal thin housing Represented by

First, the pulse sequence will be described. The pulse sequence shown in FIGS. 2A to 2C is a pulse train based on the above-described method of FIG. 15 in which two inversion pulses are applied in a very short time (2 to 10 ms). Specifically, in synchronization with the R wave of the ECG signal (the delay time with respect to the R wave is arbitrary), the first inversion pulse P _inv-A includes a region CS (see FIG. 3A) to be imaged. Applied non-selectively.

Thereafter, when viewed from the blood flow velocity, the second inversion pulse P _inv-B is applied together with the selective excitation gradient magnetic field Ge after an extremely short time that can be regarded as simultaneous. Thereafter, when a predetermined TI time (for example, 600 ms) elapses, an imaging scan based on a pulse sequence based on, for example, the FSE method is performed on the imaging region CS.

Each of the pulse sequences in FIGS. 2A to 2C is a selective excitation position based on the second inversion pulse P _inv-B , that is, the spatial area of the tag region RG _A (spin inversion region) with respect to the imaging region CS. They are different from each other in that they are configured to change positions. Specifically, the carrier frequency offset amount Df of the inversion pulse P _inv-B is mutually changed.

Therefore, the tag region RG _A (: RG _{A1 to} RG _A3 ) selectively excited by the second inversion pulse P _inv-B is first adjusted by adjusting the selective excitation gradient magnetic field Ge and the frequency offset amount Df. As shown by the dotted line in the left column of FIG. 3 (a), it is set in the upstream portion of the blood BD flowing into the imaging region CS (for example, a cross section) in the patient (subject) to be imaged.

During imaging, the host computer 6 sends the pulse sequence information includes information for setting the position of such tag area RG _A sequencer 5. In response to this, the sequencer 5 drives the gradient magnetic field power supply 4 and the transmitter 8T according to the given pulse sequence information. Thereby, the pulse which comprises the pulse sequence of the pulse sequence of Fig.2 (a) is applied in time series.

Accordingly, as described with reference to FIG. 15 described above, the spin of the entire imaging region CS is inverted by 180 degrees by the first inversion pulse P _inv-A . However, by the second inversion pulse P _inv-B applied immediately thereafter, only the spin of the selected tag region RG _A is inverted 180 degrees again (tagging), and almost returned to the initial state (FIG. 15). (See (b)). Based on the return of the flip angle of the spin, that is, the tagging, as schematically shown in FIG. 15C, the blood of the portion excited by both inversion pulses P _inv-A and P _inv-B is shown. The echo signal is generated with the highest intensity.

  The entire echo signal including the echo signal from the blood is received by the receiver 8R via the RF coil 7 and sent to the arithmetic unit 10 via the sequencer 5 as echo data.

  The arithmetic unit 10 applies this echo data to appropriate processing and places it in a two-dimensional k-space. When the entire k space is filled with echo data, the arithmetic unit 10 performs a two-dimensional Fourier transform on the echo data to obtain a two-dimensional reconstructed image IMrec1 as shown in the left column of FIG.

As can be seen from this reconstructed image IM _rec1, the blood BD that was in the tag region RG _A when the second inversion pulse P _inv-B was applied has almost returned to its initial state in the magnetization spin. Therefore, on the imaging area CS, after applying the second inversion pulse P _inv-B , the high signal partially flows from the tag area until the imaging pulse sequence P _seq is applied. It is drawn to. Further, in the tag region RG _A , the portion of the tissue that does not move as a background is almost in the initial state spin after receiving the second inversion pulse P _inv-B , so the first inversion pulse P _{The image} is drawn with a contrast different from that of the non-moving part to which _inv-A is applied.

When the reconstruction is completed, the arithmetic unit 10 performs a masking process on a portion of the reconstructed image IM _rec1 having a different contrast. In the figure, the cross-hatched portion MG ₁ shows the masking area. The masking process is a process of rewriting a certain range of image values on the image to a certain pixel value. By the masking process, an intermediate image IM _int1 represented as shown in the left column of FIG. _3C is obtained.

Similarly to the first scan described above, the second and third scans are also performed. The echo signals obtained by these scans are processed in the same manner, and intermediate images IM _int2 and IM _int3 subjected to masking processing are obtained as shown in the middle and right columns of FIG.

However, in the case of the second and third scans, the application position of the inversion pulse P _inv-B selectively applied for the second time is the middle column and the right column in FIGS. As shown in FIG. 4, the offset amount of the carrier frequency (high frequency) of the selective excitation gradient magnetic field Ge and the inversion pulse P _inv-B is changed so as to move little by little along the blood flow direction, and the above-described pulse sequence is changed. Executed.

  Note that the timing of the intermediate image generation processing by the image reconstruction and masking processing executed in the arithmetic unit 10 may be arbitrary.

When the intermediate images IM _int1 , IM _int2 , and IM _int3 are obtained in this way, the arithmetic unit 10 executes a maximum value projection process by appropriately combining these images, and a plurality of final images IM _fin1 , IM _fin2 , IM _fin3 is generated. During the maximum value projection processing, the first intermediate image IM _int1 is removed as it is and is stored again as the first final image IM _fin1 , and the first and second intermediate images IM _int1 and IM _int2 are _stored . The corresponding two pixels between the images are compared with each other and the larger one is _taken to generate the second final image IM _fin2 , and further, the first, second, and third intermediate images IM _int1 , For IM _int2 and IM _int3 , the corresponding three pixels are compared with each other to obtain the maximum value, thereby generating the third final image IM _fin3 .

The three final images IM _fin1 , IM _fin2 , and IM _fin3 are continuously displayed as moving images under the cine mode by the display 12. Thereby, the inflow situation (dynamics) of the blood flowing into the region of interest can be dynamically observed and grasped.

In particular, even when the dynamics of blood are shorter in time, the same dynamic observation can be performed. In this case, the entire scan time becomes long, but the amount of movement of the spatial position of the tag region RG _A to which the inversion pulse P _inv-B is applied may be reduced to collect more images. Furthermore, when it is desired to further improve the spatial resolution of each image, scanning may be repeated without changing the spatial position of the tag region RG _A to which the inversion pulse P _inv-B is applied. As a result, an image having a large number of matrices, that is, a high spatial resolution can be obtained. Further, when it is desired to obtain an image with a high S / N, the scan may be repeated without changing the spatial position to which the inversion pulse P _inv-B is applied, and a scan with a large number of additions may be performed.

That is, in the case of the above-described conventional CE-DMRA (see FIG. 12), since the signal change time in the region of interest due to the contrast agent is constant, changing the imaging conditions such as the number of scan repetitions, There is a problem that the time resolution is lowered. However, according to the present embodiment, the inversion excitation by the inversion pulse can be repeatedly executed, and thus there is no restriction as in the prior art. Therefore, the spatial resolution and the temporal resolution can be freely changed within the allowable time, and both can be improved.
This embodiment can be variously modified as follows.

For example, as another example of the above-described dynamic display method, the final image IM _fin1 , IM _fin2 , and IM _fin3 are simply displayed simultaneously on the display device 12 and the image _reader visually compares the images with each other. You may do it. Thereby, observation of hemodynamics by visual observation becomes possible.

  Moreover, although this embodiment demonstrated MRA which images the blood, it can image similarly about the object which has another motion as an imaging target, for example, CSF. In the case of this CSF, the time width from the application of the inversion pulse to the imaging scan may be changed as appropriate.

In addition, in the pulse sequence shown in FIG. 2, fat suppression that suppresses signals from fat in the cross section to be imaged between the second inversion pulse P _inv-B and the imaging scan P _seq as necessary. A pulse may be applied.

  Furthermore, in the present embodiment, an embodiment based on a technique using two inversion pulses as in the technique of FIG. 15 described above has been described, but instead of this, as shown in FIG. The above-described embodiment may be performed on the basis of a method using only one. In this case, post-processing may be performed by performing minimum value projection processing instead of the above-described maximum value projection processing.

  Further, the pulse sequence usable in the present embodiment is not limited to the example using the FSE method as described above, and various methods such as the FE method, the segmented FE method, the SE method, and the echo planar method can be adopted. Further, data collection and image reconstruction are not limited to the above-described two-dimensional scan and two-dimensional reconstruction, and they may be performed in three dimensions.

Furthermore, in the embodiment described above it has been to generate a final image _IM fin1 _{to IM FIN3} by performing maximum value projection processing from the intermediate image _IM int1 _{to IM int3,} which will be also various modifications. For example, blood flow dynamics can be observed even if a plurality of intermediate images are displayed in order in the cine mode without executing the maximum value projection process. Further, the masking process for creating the intermediate image may be omitted.

(Second Embodiment)
An MRI apparatus according to the second embodiment will be described with reference to FIGS. In the following embodiments, the same or equivalent components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted or simplified.

The MRI apparatus according to this embodiment performs MRA based on the technique shown in FIG. 15 described above, and in particular, within the time from the application of the inversion pulse to the scan, that is, the time until the scan for imaging is executed. It is characterized by collecting vascular images or cine images representing blood flow dynamics in a wider range than the distance traveled by blood.
The hardware configuration of this MRI apparatus is the same as that of the first embodiment.

  FIG. 4 shows a pulse sequence used in non-contrast-enhanced MR angiography according to the present embodiment, and FIG. 5 shows a diagram for explaining a processing process from scanning to display image generation. In the non-contrast MR angiography performed in this embodiment, three final two-dimensional scans are performed to obtain a single wide-range final blood vessel image.

  Note that in FIGS. 5B to 5D, the magnitude of the pixel value is represented by the hatching density, and the portion rendered as a high signal is represented by the darker hatching.

First, the pulse sequence will be described. The pulse sequence shown in FIGS. 4A to 4C applies four inversion pulses at very short time intervals (2 to 10 ms). Specifically, in synchronization with the R wave of the ECG signal (the delay time with respect to the R wave is arbitrary), the first inversion pulse P _inv-A includes the region CS (see FIG. 5A) to be imaged. Applied non-selectively. Thereafter, when viewed from the blood flow velocity, the second to fourth inversion pulses P _{inv-B to} P _inv-D can be sequentially selected at extremely short time intervals, which can be regarded as simultaneous. Applied with magnetic field Ge. The application positions of the inversion pulses P _{inv-B to} P _inv-D are arranged at regular intervals in the downstream direction from the upstream portion of the blood flowing into the imaging region CS as shown in the left column of FIG. Further, an offset amount Df of the selective excitation gradient magnetic field Ge and the frequency of those pulses is set. Unlike the case of the first embodiment, the space interval between the tag regions in the direction of blood flow is slightly longer than the distance traveled by blood after the inversion pulse is applied until the scan is started. It is set to be. In addition, since the time interval between inversion pulses is very short, these four inversion pulses can be regarded as simultaneous when viewed from the blood flow.

  When a predetermined fixed TI time (for example, 600 ms) elapses after the application of the series of inversion pulses, an imaging scan based on a pulse sequence based on, for example, the FSE method is performed on the imaging region CS.

  In each pulse sequence shown in FIGS. 4A to 4C, the frequency offset amount Df is adjusted for each sequence. Thereby, three selective excitation positions based on the second to fourth inversion pulses Pinv-B to Pinv-D, that is, the spatial positions of the tag areas RGA to RGC with respect to the imaging area CS are shown in FIGS. As shown in the left column, middle column, and right column of c), they are mutually changed.

When imaging is started, the pulse sequence shown in FIG. 4A is executed by the sequencer 5 according to the given pulse sequence information, as in the first embodiment. As a result, as described above, the blood echo signal of the portion excited by any one of the first inversion pulse P _inv-A and the second to fourth inversion pulses P _{inv-B to} P _inv-D is _equalized. Occurs at high strength. This echo signal is sent to the arithmetic unit 10 as echo data. The arithmetic unit 10 applies this echo data to appropriate processing and places it in a two-dimensional k-space, and performs two-dimensional Fourier transform on this data. As a result, a two-dimensional reconstructed image IM _rec1 is obtained as shown in the left column of FIG.

The reconstruction as seen from the image _{IM rec1,} blood BD was in the tag area _RG A _{~RG C} when applying the second to fourth th inversion pulse _{P inv-B ~P inv-D} , its Since the magnetization spin is almost returned to the initial state, after applying the second to fourth inversion pulses P _{inv-B to} P _inv-D on the imaging region CS, the imaging pulse sequence P _seq A portion corresponding to the flow out of the tag area before applying is partially rendered as a high signal. Also, among the tag area _RG A _{~RG C,} without tissue motion of the background portion, to 4-th second inversion pulse _{P inv-B ~P inv-D} or receiving most of the initial state of the Since it is in a spin, the image is depicted with a contrast different from that of the non-motion portion where the first inversion pulse P _inv-A is applied.

When the reconstruction is completed, the arithmetic unit 10 performs a masking process on a portion of the reconstructed image IM _rec1 having a different contrast. In the figure, cross-hatched portions MG _{11 to} MG ₂₁ indicate masking regions. By this masking process, an intermediate image IM _int1 represented as shown in the left column of FIG. _5C is obtained.

Similarly to the first scan described above, the second and third scans are also performed. The echo signals obtained by these scans are processed in the same manner, and intermediate images IM _int2 and IM _int3 subjected to the masking process are obtained as shown in the middle column and the right column of FIG. _5C .

However, in the case of the second and third scans, the application positions of the inversion pulses P _{inv-B to} P _inv-D selectively applied for the second to fourth times are shown in FIGS. As shown in the middle column and the right column of c), the frequency offset amount of the selective excitation gradient magnetic field Ge and the inversion pulses P _{inv-B to} P _inv-D so as to move gradually along the blood flow direction. Df is changed and the above-described pulse sequence is executed.

  Note that the timing of the intermediate image generation processing by the image reconstruction and masking processing executed in the arithmetic unit 10 may be arbitrary.

The thus obtained intermediate image _{IM int1, IM int2, IM int3} is by arithmetic unit 10, subjected to the maximum value projection processing, one of the final image _{IM fin} is generated. This final image IM _fin is displayed by the display 12. Thereby, the inflow situation (dynamics) of the blood flowing into the region of interest can be observed.

Thus, in each round of scanning a plurality of times, and detects the moving amount of the second to fourth th inversion pulse blood lies at a plurality of tag area RG _A ~RG _C upon application of the same time, inversion pulse A blood vessel image in a wider range than the distance that the blood flow moves between the application and the scan can be obtained. Accordingly, conditions such as the number of a plurality of tag areas set in one scan (that is, the number of inversion applied after the second time), its width (selective excitation width), and the total number of scans are appropriately selected. As a result, even when the blood flow velocity is low, a fine blood vessel image can be provided over a wide area covering the entire blood flow traveling path with a small number of scans.
This embodiment can be modified as follows.

  From the plurality of intermediate images IMint1 to IMint3 obtained in the above-described embodiment, the remaining images R1 to R9 that are not subjected to the masking process may be cut out and displayed, for example, in this order.

  Further, as shown in FIG. 3D described above, while increasing the original image (here, the intermediate image) to be subjected to the maximum value projection processing, a plurality of maximum value projection images are created and displayed in an appropriate order. You may make it do. Thereby, a dynamic image of blood flow dynamics can be provided in a pseudo manner, and blood flow behavior can be easily grasped.

  Furthermore, although the present embodiment has been described with respect to MRA for imaging blood, other moving objects such as CSF can be similarly imaged as imaging targets. In the case of this CSF, the time width from the application of the inversion pulse to the imaging scan may be appropriately changed.

In the pulse sequence shown in FIG. 4, a fat suppression pulse may be applied between the fourth inversion pulse P _inv-D and the imaging scan P _seq as necessary.

  Furthermore, although this embodiment demonstrated embodiment based on the method of FIG. 15 mentioned above, it may replace with this and may perform above-mentioned embodiment based on the method shown in FIG. 14 mentioned above. In this case, instead of the above-described maximum value projection process, a minimum value projection process may be performed.

  On the other hand, in the present embodiment, various methods such as the FE method, the segmented FE method, the SE method, and the echo planar method can be employed for the imaging pulse sequence. Furthermore, data collection and image reconstruction may be performed in three dimensions.

(Third embodiment)
Next, the 3rd Embodiment of this invention is described based on FIGS. The MRI apparatus according to this embodiment is characterized by the function of displaying a blood vessel image representing the flow direction separately.

FIG. 6 shows a pulse sequence used in this MRA, FIG. 7 shows a technique for rendering a blood flow flowing upward (for example, vein BD _V ), and FIG. 8 shows a blood flow flowing downward (for example, an artery). BD _A ) are depicted respectively.

The pulse sequence shown in FIG. 6 is set in the same manner as that in FIG. 2 described above, except for the setting of the frequency offset amount Df of the inversion pulse P _inv-B applied for the second time. That is, the offset amount Df of the second inversion pulse P _inv-B applied in a total of three scans as an example is set to a predetermined value of + polarity, zero, and a predetermined value of −polarity. As a result, the spatial positions of the tag regions RG _{A1 to} RG _A3 selectively excited by the three scans are shown in FIG. 7A and FIG. Are symmetrically positioned in the upper, middle, and lower predetermined portions and are set a predetermined distance apart from each other.

  Now, as shown in FIGS. 7 and 8, it is assumed that MR images obtained by performing arterial and vein separation of the imaging region CS including two blood vessels flowing in the opposite directions in the vertical direction one by one on the left and right are obtained.

First, based on FIGS explaining a case of imaging a vein BD _V. Each of the pulse sequences shown in FIGS. 6A to 6C is executed. As a result, as shown in the left column, the central column, and the right in FIG. 7A, by the selective excitation based on the second inversion pulse P _inv-B , they are separated equidistantly in the direction of blood flow and symmetrical. The tag regions RG _{A1 to} RG _{A3 in position} are excited (tagged). Each echo signal reflecting this selective excitation is collected.

This echo signal is processed into digital amount of echo data and reconstructed by the arithmetic unit 10 as described above. This reconstructed image is shown as images IM _rec1 , IM _rec2 , and IM _{rec3 in FIG} .

The reconstructed image _{IM rec1, IM rec2,} as can be seen from the _{IM rec3,} 2 nd inversion pulse _{P inv-B} arteries were in the tag area _RG A1 _{~RG A3} when applying the BD _A and veins BD _V Since the magnetization spin is almost returned to the initial state, after applying the second inversion pulse P _inv-B on the imaging region CS, until applying the imaging pulse sequence P _seq A part corresponding to the flow from the tag area in between (see reference signs A1 to A3 and V1 to V3) is partially rendered as a high signal. At this time, the flow-out distance varies depending on the flow velocity of the artery and vein.

Further, in the tag areas RG _{A1 to} RG _A3 , the tissue portion without background movement is almost in the initial state after receiving the second inversion pulse P _inv-B , so the first inversion is performed. The image is depicted with a contrast different from that of the non-moving part to which the pulse _Pinv-A is applied.

When this reconstruction is completed, the arithmetic unit 10 performs a masking process on portions of the reconstructed images IM _rec1 , IM _rec2 , and IM _rec3 that have different background contrasts. That is, as shown in FIG. 7 (c), and the boundary of each of the tag area _RG A1 _{~RG A3} bisecting the imaging region CS, the vein upstream of the portion including the respective tag area _RG A1 _{(~RG A3)} Each is masked. In the figure, cross-hatched portions MG _{1 to} MG ₃ represent masking regions. By this masking processing, intermediate images IM _{int1 to} IM _int3 represented as in the left column, the center column, and the right column in FIG. _7C are obtained.

The thus obtained intermediate image _{IM int1, IM int2, IM int3} is by arithmetic unit 10, subjected to the maximum value projection processing, one of the final image _{IM fin-V} is as shown in FIG. 7 (d) generating Is done. This final image IM _fin-V is displayed by the display 12. Thus, it is possible to obtain MRA images of the vein BD _V through the region of interest.

On the other hand, the case where the artery BD _A is imaged will be described with reference to FIGS. Also at this time, the pulse sequences shown in FIGS. 6A to 6C are executed. Thereby, reconstructed image images IM _rec1 , IM _rec2 , and IM _rec3 are obtained as in the case of the vein BD _V (FIG. 8B), and then subjected to masking processing. In the masking process in this case, contrary to the case of veins, as shown in FIG. 8C, the tag areas RG _{A1 to} RG _A3 that bisect the imaging area CS are used as boundaries, and the tag areas RG _{A1 are} separated. The upstream part of the artery including (˜RG _A3 ) is masked.

The intermediate images IM _int1 , IM _int2 , and IM _{int 3 thus created} are then subjected to maximum value projection processing, and an MRA image in which only the artery BD _A appears can be displayed.

  As described above, according to the present embodiment, an MRA image obtained by separating the arteriovenous vein can be easily provided by a simple method of changing the position of the masking process in the post-processing after collecting the echo signals. In addition, by using this MRA image, it is possible to simply check the running direction of the arteriovenous vein.

Even in this embodiment, the remaining arteriovenous images R1, R2, and R3 that have been masked may be sequentially displayed in sequence, or the reconstructed images IM _rec1 , IM _rec2 , and IM _rec3 may be sequentially _displayed . You may display continuously. Thereby, a pseudo dynamic image of the arterial vein can be observed.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIGS. The MRI apparatus according to this embodiment sets the thickness (slice thickness or slab thickness) that is selectively excited from the inversion (IR) used for the pulse sequence when performing an imaging scan (main scan) to an optimum value. This relates to scanning (pre-scan).

  When the MR angiography according to FIGS. 4 and 5 according to the second embodiment described above or FIGS. 14 and 15 described above is performed, the blood flow of the blood flow depending on the blood vessel to be observed is observed. Since the inflow speed changes, the distance of the high signal portion due to the inversion pulse is short, or on the contrary, the high signal portion remains in the tag area excited by another inversion, and image synthesis or It may not be suitable for cine image display. In the present embodiment, a pre-scan technique that can reliably eliminate such a situation is taught.

  In this pre-scan, the optimum excitation thickness and excitation position are obtained by continuously scanning while changing the excitation thickness by the inversion pulse stepwise.

  FIG. 9 schematically shows an example of a pulse sequence used for this prescan, and FIG. 10 schematically shows a prescan procedure.

9A to 9C show pulse sequences used for three scans from the first to the third time, respectively. In these pulse sequences, at each scan, at least one of the carrier frequency offset amount Df and the intensity of the selective excitation gradient magnetic field Ge of the second inversion pulse P _inv-B is adjusted. Accordingly, as shown in the left column, the central column, and the right column in FIG. 10A, the thickness of the tag region RG _A (RG _{A1 to} RG _A3 ) set for the imaging region CS is gradually increased. At the same time, in any of the first to third scans, the position of the band-like tag regions RG _{A1 to} RG _A3 is selected so that the boundary positions on the downstream side of the blood flow are the same. That is, as the number of scans increases, the excitation position is set so that only the boundary position on the bloodstream upstream side of the tag regions RG _{A1 to} RG _A3 changes and becomes thicker. In the pulse sequences of FIGS. 9A to 9C, the other pulse trains are the same as described above.

  Note that conditions such as the number of scans in this pre-scan and the fluctuation range of the boundary position on the upstream side of the blood flow are determined in consideration of conditions including the blood flow velocity at the imaging region and the desired value of the change width.

By sequentially executing these pulse sequences as a pre-scan, reconstructed images IM _{rec1 to} IM _rec3 are obtained for each sequence as shown in _FIGS .

Therefore, for example, the operator, the series of image IM _rec1 to IM _rec3 by visual observation, seems to be ideal for imaging sites of interest, determines the excitation thickness and spatial position by inversion pulse. In this case, such determinations to facilitate, may be continuously displaying a series of images _IM rec1 _{to IM rec3} in the order of the thickness of the tag area. The above-described determination may be automatically performed using an appropriate algorithm such as a blood flow extraction method in addition to a method based on an artificial judgment by an operator.

The information on the excitation thickness and spatial position obtained by the above pre-scan is obtained by using the carrier frequency of the second inversion pulse P _inv-B applied in the pulse sequence of the main scan and the selective excitation gradient applied at the same time. This is reflected, for example, in the strength of the magnetic field. As a result, in the MRA image obtained by the main scan, the relationship between the imaging length of the blood flow portion tagged with the inversion pulse P _inv-B and the blood flow velocity is appropriate, and accurate image synthesis and cine image display are performed. It can be performed.

  In the above-described embodiment, MRA that images blood is described. However, other moving objects such as CSF can be similarly imaged. In the case of this CSF, the time width from the application of the inversion pulse for tagging to the imaging scan may be appropriately changed.

In the pulse sequence shown in FIG. 9, a fat suppression pulse may be applied between the second inversion pulse P _inv-B and the imaging scan P _seq as necessary.

  Furthermore, although this embodiment demonstrated embodiment based on the method of FIG. 15 mentioned above, it may replace with this and may perform above-mentioned embodiment based on the method shown in FIG. 14 mentioned above. In this case, instead of the above-described maximum value projection processing, the minimum value projection processing may be performed as post-processing.

  On the other hand, in the present embodiment, the imaging pulse sequence is not limited to the FSE method, and various methods such as the FE method, the segmented FE method, the SE method, and the echo planar method can be employed. Furthermore, data collection and image reconstruction may be performed in three dimensions.

(Fifth embodiment)
An MRI apparatus according to the fifth embodiment of the present invention will be described. This embodiment relates to another example of a tagging region that relies on selective excitation.

  FIG. 11A shows an example of a pulse sequence used in the MRI apparatus, and FIG. 11B shows an example of a reconstructed image.

According to this pulse sequence, only one pulse P _inv-O is used as the inversion pulse. The carrier frequency of this pulse and the selective excitation gradient magnetic field Ge are set so that the region RG _A excited by the inversion pulse P _inv-O is the same as the region CS to be imaged as shown in FIG. . In other words, this inversion pulse P _inv-O has a function of tagging by reversing the spin by 180 degrees, but this tagging adds contrast to the high signal due to the new blood flow that flows during scanning. This is a reverse tagging function that lowers the spin of the region RG _A. As shown in FIG. 11A, only the tagging pulse P _inv-O is applied alone as the inversion pulse. Other pulse trains are the same as those of the above-described embodiments.

An echo signal is collected by executing this pulse sequence, and a reconstructed image IM _rec illustrated in FIG. 11B is obtained from the echo signal.

Therefore, the same region RG _A as the imaging region CS is reverse-tagged by the inversion pulse P _inv-O , and then the scan is executed after the inversion time TI.

For this reason, at the time of scanning, for example, the artery BD _A and the vein BD _V flow from the region that is not selectively excited by the inversion pulse P _inv-O into the imaging region CS as spins that are not saturated. Therefore, a high signal can be obtained from the artery BD _A and the vein BD _V , and they can be reliably depicted.

In particular, since there is a speed difference in the flow velocity in the arteriovenous vein, the length of the portion that flows into the imaging region CS during scanning is usually different. For this reason, for example, by setting to selectively excite the region that has entered the vein upstream side of the imaging region CS by the inflow length L of the vein BD _V , an image displaying only the artery BD _A is presented. Can do.

  As a modification common to all the embodiments described above, there is a synchronization method. That is, each of the above-described embodiments has described MR imaging based on the electrocardiographic synchronization method, but instead of this synchronization method, an electroencephalogram synchronization method, a respiratory synchronization method, or the like may be used. Further, even with the same electrocardiographic synchronization method, the pulse wave synchronization method (PPG) can be used.

  Further, in each of the above-described embodiments, a method for displaying the dynamics of blood or CSF by changing the excitation position by the inversion pulse for tagging has been taught. However, a series of inversions are generated from generation of a trigger used in the synchronization method. Scanning may be performed while appropriately changing the time width (delay time) until the application of the version pulse. By displaying the images thus obtained in an appropriate order or by creating and displaying a plurality of maximum value projection images, it is possible to observe the periodic movement of the imaging target synchronized with the heartbeat and respiration.

  Furthermore, each embodiment described above can be developed in various forms. First, since the transposition of the blood flow portion imaged with the application of the tagging inversion pulse varies depending on the blood flow velocity, the blood flow velocity can be measured based on this correspondence. .

  Second, by appropriately varying the offset amount of the carrier frequency of the tagging inversion pulse and the intensity of the selective excitation gradient magnetic field, the tag region can be arbitrarily sliced (slab position), slice thickness (slab thickness), or The oblique excitation position can be set.

  Third, by varying the slice thickness (slab thickness) by the tagging inversion pulse, a blood vessel having an arbitrary slice thickness (slab thickness) can be depicted.

  Fourth, a suitable example of the flip angle of the tagged inversion pulse is 180 degrees, but the flip angle is not necessarily limited thereto. By setting this angle to an appropriate value of less than 180 degrees, it is possible to collect the signal of the signal-reduced region in a shorter TI time and shorten the entire scan time.

  It should be noted that the present invention is not limited to the above-described exemplary embodiments and modifications, which are representatively exemplified, and those skilled in the art will be within the scope of the gist of the present invention based on the content of the claims. Various modifications can be made and these are also within the scope of the present invention.

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 Host computer 7 RF coil 8T Transmitter 8R Receiver 10 Arithmetic unit 11 Storage unit 12 Display 13 Input device

Claims (11)

After a series of labels pulses applied with selective excitation gradient magnetic field in order to label the imaging object in motion in the subject it is applied, but the imaging target progresses I until the pulse sequence is started A first step of setting a condition of the labeling pulse after making it possible to select an application number or a selective excitation width of the labeling pulse so that a traveling path in the imaging region is covered and imaged;
A second step of collecting the echo signals from the imaging target by starting the pulse sequence after a predetermined time has elapsed since the marker pulse having the condition set in the first step is continuously applied a plurality of times; When,
Using the echo signals, after a plurality of images of the imaging area where the imaging target is labeled, or the series of labeled pulse is applied, the imaging target until the pulse sequence is started magnetic resonance imaging method characterized by a third step of generating a travel path image covered in but proceeds in the imaging area I. The magnetic resonance imaging method according to claim 1.
A magnetic resonance imaging method, comprising: measuring an imaging target based on a plurality of images of the imaging region. The magnetic resonance imaging method according to claim 1.
A magnetic resonance imaging method, comprising: measuring a flow velocity of the imaging target based on a plurality of images of the imaging region. The magnetic resonance imaging method according to claim 1.
The magnetic resonance imaging method, wherein the pulse sequence is a fast spin echo method. The magnetic resonance imaging method according to claim 1.
A magnetic resonance imaging method, wherein a fat suppression pulse is applied to the imaging region before the start of the pulse sequence. The magnetic resonance imaging method according to claim 1.
A magnetic resonance imaging method, comprising applying a fat suppression pulse to the imaging region after applying the series of marker pulses and before starting the pulse sequence. The magnetic resonance imaging method according to claim 1.
A magnetic resonance imaging method, wherein the echo signal is repeatedly collected without changing a spatial position of a tag region to which the marker pulse is applied. The magnetic resonance imaging method according to claim 1.
In the second step, the process of collecting the echo signal by starting the pulse sequence after the predetermined time has elapsed after the marker pulse is continuously applied a plurality of times, and the time width of the predetermined time is increased. It is a process that is repeated multiple times while changing,
The third step is a step of creating a plurality of images respectively corresponding to the different time widths using the echo signals collected at each repetition of the processing. . The magnetic resonance imaging method according to claim 1.
Said label pulse is applied multiple tag area wherein the selective excitation gradient magnetic field and by changing the spatial position of the marker pulse a plurality of times to be applied, the pulse sequence after the elapse of the predetermined time every time the application A magnetic resonance imaging method characterized in that, when executed, a plurality of images are generated based on the echo signals generated in response to the pulse sequence performed each time application is performed. The magnetic resonance imaging method according to claim 1.
The first step is a step of setting a selective excitation width of the labeling pulse and the number of the tag regions. A magnetic resonance imaging method, wherein: After a series of labels pulses applied with selective excitation gradient magnetic field in order to label the imaging object in motion in the subject it is applied, but the imaging target progresses I until the pulse sequence is started Means for performing a first step of setting a condition of the labeling pulse after enabling selection of the number of label pulses applied or a selective excitation width so that the travel path in the imaging region is covered and imaged; ,
A second step of collecting the echo signals from the imaging target by starting the pulse sequence after a predetermined time has elapsed since the marker pulse having the condition set in the first step is continuously applied a plurality of times; Means for
Using the echo signals, after a plurality of images of the imaging area where the imaging target is labeled, or the series of labeled pulse is applied, the imaging target until the pulse sequence is started magnetic resonance imaging apparatus characterized by comprising means for performing a third step of generating an image travel path is covered in but I proceeds the imaging area.

Images