CN100570393C

CN100570393C - MR imaging apparatus and MR imaging method

Info

Publication number: CN100570393C
Application number: CNB2007100067834A
Authority: CN
Inventors: 油井正生; 葛西由守; 久原重英
Original assignee: Toshiba Corp; Toshiba Medical Systems Corp
Current assignee: Canon Medical Systems Corp
Priority date: 2006-02-06
Filing date: 2007-02-06
Publication date: 2009-12-16
Anticipated expiration: 2027-02-06
Also published as: JP5106697B2; JP2012183431A; CN101017196A

Abstract

A kind of MRI device comprises imaging signal acquisition unit, motor message acquiring unit, motion amount determination unit, motion correction unit and image reconstruction unit.Imaging signal acquisition unit is obtained the MR signal as imaging signal.The motor message acquiring unit repeat to obtain the PE amount less than the MR signal of the PE amount of imaging signal as motor message.Motion amount determination unit utilizes described motor message to obtain an amount of exercise.Motion correction unit is carried out treatment for correcting according to described amount of exercise to imaging signal.Image reconstruction unit utilizes the imaging signal after the treatment for correcting to come reconstructed image.

Description

MR imaging apparatus and MR imaging method

Technical field

The present invention relates to MR imaging apparatus and MR imaging method, generate gradient magnetic on its imaging area that in a static magnetic field, forms, make the nuclear spin generation magnetic resonance of the object set that is arranged in described imaging area by emitting radio frequency signal, and by using the NMR signal that generates owing to excitation to rebuild the image of described target, more particularly, relate to a kind of MR imaging apparatus and a kind of MR imaging method, wherein reduced the influence of target travel image by correction.

Background technology

MRI (magnetic resonance imaging) device is a kind of like this device: the gradient coil on the imaging area of its object set by being positioned at the cylindrical static field magnet that is used for producing static magnetic field generates gradient magnetic, by making the nuclear spin generation magnetic resonance in the described target from a RF coil transmitting RF (radio frequency) signal, and by using owing to encourage NMR (nuclear magnetic resonance) signal that generates to rebuild the image of described target.

Utilizing the cardiac imaging under the magnetic resonance method of magnetic resonance device to be further developed in recent years.Typical cardiac imaging is used the high-resolution imaging that comprises blood-vessel image coronarius.In to high-resolution imaging coronarius, need reduce the influence of respiratory movement as far as possible to image.

A kind of measure that suppresses the respiratory movement influence is the imaging of holding one's breath, and wherein carries out imaging when holding the breath.Yet in the imaging of holding one's breath, imaging only could be carried out in the process of holding the breath, and there is restriction in resolution.In addition, aspect the degree of stability of holding the breath, there is worry.

The another kind of method that suppresses the respiratory movement influence depends on the technology that adopts synchronous imaging under the condition of freely breathing.The synchronizing signal of using in the synchronous imaging can be obtained by a belly expansion contract sensor or a pressure transducer on every side that is arranged on target.But there is the not enough problem of accuracy in this use by the synchronous imaging method of the synchronizing signal that expansion contract sensor or pressure transducer obtain.

Consider the problems referred to above, replace using the another kind of method of the synchronous imaging method of expanding contract sensor or pressure transducer to be, advised a kind of synchronous imaging method, wherein use based on from transeptate NMR input to the diaphragm position as synchronizing signal (people such as Liu " the Magnetic Resonance In Medicine (magnetic resonance in the medical science) " that deliver for example, 30, the 507-511 page or leaf, (1993)), and a kind of being used for is reflected to a formation method on the controller with the positional information of motion imaging region, be used for the NMR signal of imaging with collection, thereby the slice position that is encouraged is finely tuned.

Figure 22 explains to be used to obtain the synoptic diagram of NMR signal with the zone of detection diaphragm motion in conventional MR imaging apparatus.Figure 23 illustrates to have defined image-forming condition to obtain the synoptic diagram of the conventional pulse train that is used to the data that detect the motion and be used for imaging as shown in figure 22.

Be used for utilizing the synchronous imaging method of diaphragm position a kind of as synchronizing signal, shown in the solid box among Figure 22, different with the data collection zone that is used for imaging that comprises heart, a zone that comprises diaphragm on the right cylinder that illustrates in frame of broken lines is set to the data collection zone that is used to detect motion.

Then, carry out imaging according to pulse train shown in Figure 23.In whole pulse train, the preceding pulse as the fat suppression pulse repeatedly is used in combination, and a sequence that is used to apply preceding pulse was set before being used for the sequence of imaging.Then, a sequence that is used for motion detection was set before being used for the sequence of preceding pulse.

In addition, for obtaining for the data required when the image data or the necessary data of subsequent treatment of information, a sequence that is used to apply dummy argument emission (dummy shot) (it is also referred to as the stability emission) is set at the data acquisition that is used for imaging and begins the place.Usually, the slice direction of dummy argument emission is set on the axial xsect, its objective is in order to realize and the similar spin stabilization of data acquisition that is used for imaging.

Then, on the basis of the sequence that is used for motion detection, be used for data collection zone motion detection, that comprise diaphragm and under a kind of specific condition that is different from the motivational techniques that are used for imaging area, be energized.In addition, obtain the data that are used for motion detection, and generate a signal that is called as " navigation signal " from the acquisition zone that comprises diaphragm.Then, detect transeptate position, and when imaging, determine a kind of hardware controlling method, and draw at the adaptation of the data acquisition that is used for imaging according to the change amount of diaphragm position and to judge by described navigation signal.In addition, be used for imaging data is carried out motion correction with breathe relevant heart displacement and calculate by transeptate displacement and a given ratio are multiplied each other.

In this navigation signal method, the sequence that is used for motion detection is different from the sequence that is used for imaging, and the described sequence that is used for motion detection is used to gather navigation signal, and to obtain synchronizing signal, this method is applied to multiple technologies.

Yet this navigation signal method that is used for gathering navigation signal under a kind of condition that is different from the data acquisition conditions that is used for imaging has two main problems.

First problem be imageable target zone (heart) with breathe relevant displacement and have correlativity by the displacement in the observed zone of navigation signal (diaphragm), but incomplete same each other.Therefore, the displacement of heart estimates from transeptate displacement, and this is a reason that reduces accuracy.In addition, even in identical target, displacement and the ratio transeptate displacement between relevant with breathing of heart also can be different with the personal considerations, and change according to breathing state, therefore are difficult to obtain stable image.

Second problem is to be used to detect from the sequential of transeptate signal and is used to be detected as between the sequential of image signal and be very different.Must carry out the data acquisition that is used for imaging that applies and will after applying preceding pulse, carry out of preceding pulse continuously.Therefore, gather the sequential of navigation signal based on the sequence (navigation sequence) of gathering navigation signal and must separate with come the sequential of image data based on imaging sequence in time, this is very disadvantageous.Like this, under relative short situation of the respiratory cycle of target, the deviation between the sequential that is used to gather the sequential of navigation signal and be used for image-forming data acquisition becomes a reason that reduces accuracy.

On the other hand, act on the another kind of method that is used to detect the diaphragm motion, even proposed a kind of method that during image-forming data acquisition, also can generate navigation signal, it has used the pulse train that is used for imaging (Ehman for example, " Radiology (radiologic medicine) " that Felmee showed, 173, the 255-263 pages or leaves, (1989)).

This technology that is used for during image-forming data acquisition generating navigation signal is included in a spin-echo sequence and generates a plurality of echoed signals, and utilizes in the echoed signal that so generates one as navigation signal.According to this technology, can be observed at the movable information of reading on direction and the phase-encoding direction.In addition, this technology has basically the advantage of gathering navigation signal and imaging signal with identical sequential, also have the observation zone identical with imageable target motion, be the advantage of heart movement.

Yet a problem that generates the routine techniques existence of navigation signal during image-forming data acquisition is to be difficult to observe motion with in fact sufficiently high accuracy.The problem that this accuracy deficiency takes place be because navigation signal be by from target with the data that obtain on data projection to a specific direction.That is to say that navigation signal is the data by being added on the data from the moving region from the stacked data in zone that does not in fact have motion, obtaining as the data for projection on the specific direction.Therefore, navigation signal is subjected to not having the influence in the zone of motion.

For example, in chest abdomen zone, the fat on the body surface, chest wall, muscle of back and similar position do not move.But these zones that do not move are than the zone that moves, as the more close receiving coil of lung, thus these the signal intensity ratio in the moving region is not bigger relatively from the signal intensity of moving region.Therefore, the accuracy of motion detection is easy to be subjected to the not influence of moving region, and particularly under the situation of the imaging that requires high precision, as high-resolution imaging, will not be a problem to the influence of motion detection accuracy in the moving region very much.

Summary of the invention

The present invention considers conventional solution and makes, and an object of the present invention is to provide a kind of MR imaging apparatus and a kind of MR imaging method, it can be proofreaied and correct with the height accurate movement and obtain image by from as the position of imageable target, be enough to observe momental motor message directly to obtain with the data acquisition near-synchronous ground that is used for imaging.

In addition, another object of the present invention provides a kind of MR imaging apparatus and a kind of MR imaging method, and it can be proofreaied and correct with the height accurate movement and obtain image by reducing the influence in the zone that does not move.

For in realizing aspect of this purpose, the invention provides a kind of MR imaging apparatus, comprising: imaging signal acquisition unit is configured to from target obtain magnetic resonance signal as imaging signal; The motor message acquiring unit, be configured to repeat to obtain the phase encoding amount less than the magnetic resonance signal of the phase encoding amount of imaging signal as motor message; Motion amount determination unit is configured to utilize described motor message to obtain an amount of exercise; Motion correction unit is configured to according to described amount of exercise imaging signal be carried out treatment for correcting; And image reconstruction unit, be configured to utilize the imaging signal after the treatment for correcting to come reconstructed image.

For in realizing aspect of this purpose, the present invention also provides a kind of MR imaging apparatus, comprising: imaging signal acquisition unit is configured to from target obtain magnetic resonance signal as imaging signal; The motor message acquiring unit, be configured to obtain the phase encoding amount less than a part of imaging signal of the phase encoding amount of imaging signal and magnetic resonance signal as motor message; Motion amount determination unit is configured to utilize described motor message to obtain an amount of exercise; Motion correction unit is configured to according to described amount of exercise imaging signal be carried out treatment for correcting; And image reconstruction unit, be configured to utilize the imaging signal after the treatment for correcting to come reconstructed image.

For in realizing aspect of this purpose, the present invention also provides a kind of MR imaging apparatus, comprising: imaging signal acquisition unit is configured to from target obtain magnetic resonance signal as imaging signal; The motor message acquiring unit, be configured to repeat to obtain the phase encoding amount less than the magnetic resonance signal of the phase encoding amount of imaging signal as motor message; Motion amount determination unit is configured to utilize described motor message to obtain an amount of exercise; Selected cell is configured to according to the imaging signal in particular range of described amount of exercise selection; And image reconstruction unit, be configured to utilize the imaging signal in the described particular range to come reconstructed image.

For in realizing aspect of this purpose, the present invention also provides a kind of MR imaging apparatus, comprise: the component acquiring unit of reflection motion, be configured to obtain from motor message the component of signal of reflection motion, wherein said motion amount determination unit is configured to obtain described amount of exercise from the component of signal of described reflection campaign.

For in realizing aspect of this purpose, the present invention also provides a kind of MR imaging method, may further comprise the steps: obtain magnetic resonance signal as imaging signal from target; Repeat to obtain the phase encoding amount less than the magnetic resonance signal of the phase encoding amount of imaging signal as motor message; Utilize described motor message to obtain an amount of exercise; According to described amount of exercise imaging signal is carried out treatment for correcting; And utilize the imaging signal after the treatment for correcting to come reconstructed image.

For in realizing aspect of this purpose, the present invention also provides a kind of MR imaging method, may further comprise the steps: obtain magnetic resonance signal as imaging signal from target; Obtain the phase encoding amount less than a part of imaging signal of the phase encoding amount of imaging signal and magnetic resonance signal as motor message; Utilize described motor message to obtain an amount of exercise; According to described amount of exercise imaging signal is carried out treatment for correcting; And utilize the imaging signal after the treatment for correcting to come reconstructed image.

For in realizing aspect of this purpose, the present invention also provides a kind of MR imaging method, may further comprise the steps: obtain magnetic resonance signal as imaging signal from target; Repeat to obtain the phase encoding amount less than the magnetic resonance signal of the phase encoding amount of imaging signal as motor message; Utilize described motor message to obtain an amount of exercise; According to the imaging signal in particular range of described amount of exercise selection; And utilize the imaging signal in the described particular range to come reconstructed image.

Aforesaid MR imaging apparatus and MR imaging method make can be enough to be used for the motor message and the near-synchronous ground of correction of movement amount and obtain the image that imaging data obtains having the correction of height accurate movement by directly obtaining from the position as imageable target.

In addition, the influence that can produce by the position of reducing not motion obtains having the image that the height accurate movement is proofreaied and correct.

Description of drawings

In the accompanying drawings:

Fig. 1 shows the block diagram of the MR imaging apparatus of first embodiment according to the invention;

Fig. 2 is the functional block diagram of computing machine shown in Figure 1;

Fig. 3 shows the diagram that an example of the imaging region that the unit sets is set by image-forming condition shown in Figure 2;

Fig. 4 shows for the imaging region that comprises heart shown in Figure 3 being carried out the diagram of an example of the pulse train that imaging generated;

Fig. 5 shows the diagram of a specific examples of pulse train shown in Figure 4;

Fig. 6 shows the diagram that the image-forming condition that shows is provided with an example of screen on display unit shown in Figure 1;

Fig. 7 shows the influence that is used to reduce the magnetization vibration that occurs owing to the dummy argument emission and by image-forming condition shown in Figure 2 the diagram that magnetization that the unit obtains imaging data influences a specific examples of the pulse train that is provided with is set;

Fig. 8 shows the diagram of an example of the motor message that is positioned at the k space in motion detection signal acquiring unit shown in Figure 2;

Fig. 9 shows the diagram of an example of the imaging signal that is positioned at the k space in imaging signal acquisition unit shown in Figure 2;

Figure 10 shows the diagram in a zone of the motor message that is separated by motor message component separative element shown in Figure 2;

Figure 11 shows the diagram corresponding to an example of the profile in the zone of close heart shown in Figure 10;

Figure 12 is used for explaining the diagram of determining a momental method by motion amount determination unit shown in Figure 2;

Figure 13 is used for explaining the diagram of coming the method for correcting imaging signal by motion correction unit shown in Figure 2;

Figure 14 shows the method flow diagram that utilizes MR imaging apparatus shown in Figure 1 the blood-vessel image of target heart to be carried out imaging;

Figure 15 is a diagram of revising example that is used for explaining the method in the k space that forms in the motion detection signal acquiring unit shown in Figure 2 that motor message is arranged in;

Figure 16 is used for explaining a process flow diagram of revising example that comes the method for disengaging movement signal by motor message component separative element shown in Figure 2;

Figure 17 shows the diagram by an example in the formed zone of image reconstruction process shown in Figure 16;

Figure 18 is the concept map of motive position mask shown in Figure 16;

Figure 19 shows the block diagram according to the MR imaging apparatus of second embodiment of the present invention;

Figure 20 shows the diagram that image-forming condition by MR imaging apparatus shown in Figure 19 is provided with an example of the pulse train that the unit generates;

Figure 21 shows the diagram by the section that pulse train encouraged (slab) position shown in Figure 20;

Figure 22 is used for explaining being used to the motion of detection diaphragm and obtaining the diagram in the zone of NMR signal in the MR imaging apparatus of routine; And

Figure 23 shows the diagram of conventional pulse train that the image-forming condition of the data that are used to detect the motion and are used for imaging shown in Figure 22 is obtained in definition.

Embodiment

MR imaging apparatus and MR imaging method according to an embodiment of the invention will be described with reference to the accompanying drawings.

Fig. 1 shows the block diagram of the MR imaging apparatus of first embodiment according to the invention.

MR imaging apparatus 20 shown in Figure 1 comprises the static field magnet 21 that is used to produce static magnetic field, is arranged on the pad coil 22 of columniform static field magnet 21 inside, gradient coil unit 23 and RF coil 24.Static field magnet 21, pad coil 22, gradient coil unit 23 and RF coil 24 are structured in (unshowned) crane boom (gantry).

MR imaging apparatus 20 also comprises control system 25.This control system 25 comprises static magnetic field power supply 26, gradient power supply 27, pad coil power 28, transmitter 29, receiver 30, sequence controller 31 and computing machine 32.The gradient power supply 27 of control system 25 comprises X-axis gradient power supply 27x, Y-axis gradient power supply 27y and Z axial gradient power supply 27z.Computing machine 32 comprises input equipment 33, display unit 34, operating unit 35 and storage unit 36.

Static field magnet 21 communicates with static magnetic field power supply 26.Static magnetic field power supply 26 offers static field magnet 21 with electric current, to obtain producing the function of static magnetic field in an imaging region.Static field magnet 21 comprises a superconducting coil in many cases.Static field magnet 21 obtains electric current in when excitation from the static magnetic field power supply 26 that communicates with static field magnet 21.Yet, in case finished excitation, 21 common and static magnetic field power supply 26 isolation of static field magnet.Static field magnet 21 can comprise a permanent magnet, and it makes that static magnetic field power supply 26 no longer is essential.

Static field magnet 21 has the coaxial cylindrical spacer coil 22 of portion within it.Pad coil 22 communicates with pad coil power 28.Pad coil power 28 offers pad coil 22 with electric current, thereby makes static magnetic field become even.

Gradient coil unit 23 comprises X-axis gradient coil unit 23x, Y-axis gradient coil unit 23y and Z axis gradient coil unit 23z.Among columniform X-axis gradient coil unit 23x, Y-axis gradient coil unit 23y and the Z axis gradient coil unit 23z each all is arranged on static field magnet 21 inside.Gradient coil unit 23 also has bed 37 in the zone that portion forms within it, and this zone is as imaging region.Bed 37 is supporting target P.RF coil 24 can be arranged on around bed 37 or the target P, rather than is structured in the crane boom.

Gradient coil unit 23 communicates with gradient power supply 27.X-axis gradient coil unit 23x, the Y-axis gradient coil unit 23y of gradient coil unit 23 and Z axis gradient coil unit 23z communicate with X-axis gradient power supply 27x, Y-axis gradient power supply 27y and the Z axial gradient power supply 27z of gradient power supply 27 respectively.

X-axis gradient power supply 27x, Y-axis gradient power supply 27y and Z axial gradient power supply 27z offer electric current X-axis gradient coil unit 23x, Y-axis gradient coil unit 23y and Z axis gradient coil unit 23z respectively, thereby produce gradient magnetic Gx, Gy and Gz on the X in imaging region, Y, the Z direction.

RF coil 24 communicates with transmitter 29 and receiver 30.The function of RF coil 24 is that the RF signal that transmitter 29 provides is sent to target P, and receives owing to the NMR signal that nuclear spin produced in the target P that is subjected to the RF signal excitation, to be given to receiver 30.

The sequence controller 31 of control system 30 communicates with gradient power supply 27, transmitter 29 and receiver 30.The function of sequence controller 31 is to come storage sequence information according to a predefined procedure of being stored, this sequence information is used for describing in order to drive gradient power supply 27, transmitter 29 and receiver 30, and by driving gradient magnetic Gx, Gy and the required control information of Gz that gradient power supply 27, transmitter 29 and receiver 30 generate on X, Y, the Z direction.Control information recited above comprises motion control information, as intensity, action period and the effect sequential that should affact the pulse current on the gradient power supply 27.

Sequence controller 31 also is configured to provide raw data to computing machine 32.Raw data is to be converted to the resulting complex data of detected NMR signal in receiver 30 by detecting NMR signal and A/D.

The function of transmitter 29 is to provide the RF signal according to the control information that provides from sequence controller 3l to RF coil 24.The function of receiver 30 is to generate raw data, and described raw data is to be converted to detected NMR signal and digitized complex data by NMR signal, the processing of execution prearranged signal and the A/D that detects from RF coil 24.

In addition, near target P, be provided with an ECG (cardiogram) unit 38, be used to obtain the ECG signal of target P.Be output to sequence controller 31 by ECG unit 38 detected ECG signals.Therefore, sequence controller 31 is configured to the control signal with the ECG signal Synchronization is sent to gradient power supply 27, transmitter 29 and receiver 30.

Computing machine 32 has obtained multiple function by the program of being carried out in some storage unit 36 that are stored in computing machine 32 by operating unit 35.Computing machine 32 can comprise some special circuits, rather than uses some programs in these programs.

Fig. 2 is the functional block diagram of computing machine 32 shown in Figure 1.

As shown in Figure 2, computing machine 32 is worked as image condition setting unit 40, sequence controller control module 41, motion detection signal acquiring unit 42, image signal acquisition unit 43, motor message component separative element 44, motion amount determination unit 45, motion correction unit 46 and image reconstruction unit 47 by programming.Therefore, the function of these unit is to obtain the NMR signal that is used to detect motion and is used for target P is carried out imaging, and rebuilds the image with motion correction according to the movable information that detects in the MR imaging apparatus 20 from the NMR signal that is used for detecting motion.

The function of image condition setting unit 40 is that image information is offered display unit 34, the image-forming condition that is used for being provided with image-forming condition with demonstration on display unit 34 is provided with screen, and the another one function is to generate the pulse train as image-forming condition according to the information from input block 33.In order to be shown as the input of picture condition setting screen and information, can adopt GUI (graphic user interface) technology.In addition, image-forming condition is provided with the pulse train that unit 40 is configured to will be so generate and offers sequence controller control module 41.

Fig. 3 shows the diagram that an example of the imaging region that unit 40 sets is set by image-forming condition shown in Figure 2.

As shown in Figure 3, zone that comprises heart is set to for example to be used for the pickup area (imaging region) of the NMR signal of imaging, and an image-forming condition that is used for the blood image of heart is carried out imaging can be set.In addition, collection zone of being used to detect the NMR signal (motor message) of heart movement also is set to comprise the zone of heart.Fig. 3 shows pickup area that is used for imaging NMR signal and the pickup area that is used for motor message and is set to a mutually the same example, that is to say that the NMR signal and the motor message that are used for imaging in this example are gathered from same excitation region.

The thing that it should be noted that, the pickup area that is used for imaging NMR signal can be provided with arbitrarily, and the pickup area that is used for motor message is set to such zone: wherein motor message can be gathered from human body and organ as the direct target of motion detection.

Fig. 4 shows for the imaging region that comprises heart shown in Figure 3 being carried out the diagram of an example of the pulse train that imaging generated.

As shown in Figure 4, by image-forming condition pulse train that unit 40 generated is set the sequence that provides one to be used to apply preceding pulse is provided, as be positioned at the fat suppression pulse of the data acquisition pulse front that is used for imaging.In addition, also having generated the sequence that is used to apply the dummy argument emission, serves as to gather required information and the essential data of data of imaging data to obtain for subsequent treatment.The sequence that is used for the dummy argument emission is set in time near the sequence that is used for imaging.In Fig. 4, the sequence that is used for the dummy argument emission is set at the starting point of the data acquisition that is used for imaging.Should be noted in the discussion above that described sequence is so generated, make the zone that must apply dummy argument emission become that wherein motor message can be from the zone of directly gathering as the organ of motion detection target.

The slice direction (cross-sectional direction of excited slice) of dummy argument emission can be set to surface arbitrarily, as axial surface, sagittal surface, crown surface, and the xsect of other inclination, if slice direction is set on the bigger direction of amount of exercise, then can detect motion with the data volume of much less and the degree of accuracy of Geng Gao.Therefore, can reduce data acquisition time to motor message.Like this, on the direction that is read the health axle that (RO) direction (frequency coding direction) is advantageously provided target P.

Fig. 5 shows the diagram of a specific examples of pulse train shown in Figure 4.

In Fig. 5, RF represents radio frequency (RF) signal.Gss represents to be used for section selection, i.e. gradient magnetic pulse on section coding (SE) direction, Gpe is illustrated in the gradient magnetic pulse on phase encoding (PE) direction, Gro is illustrated in the gradient magnetic pulse of reading on the direction, ADC represents a digitized received signal (ACQ), and ECG represents the ECG signal.Should be noted in the discussion above that the coding staff here is to being meant and reading rectangular two axles of direction.

As shown in Figure 5, for example make up pulse train by part A, part B and portion C.Part B is the sequence that is used for the data-signal of imaging, and part A and portion C are the sequences that is used to detect motor message.Then, all be set to comprise the sagittal surface of heart at the slice direction of the dummy argument emission that is used for gathering motor message and the slice direction that is used for the data acquisition of imaging.Should be noted in the discussion above that and have only a sequence that can be set to be used to detect motor message in part A and the portion C.In addition, pulse train can be so arranged, and makes to have only in part A and the portion C one or these two to be repeated to carry out.

That is to say that motor message can be gathered before or after collection is used for the data-signal of imaging.Should be noted in the discussion above that if motor message is used for before the data-signal of imaging and is all gathered afterwards in collection, then can increase the number of the time phase that is used to gather motor message.Then, by interpolation method, can obtain the motor message data over time as interpolation or extrapolation.Consequently, can realize the higher degree of accuracy of motor message data.

Part A, part B and portion C for example all are based on the sequence of the formation method of a kind of SSFP of being called as (steady state free precession).According to SSFP, the RF signal was applied in the extremely short repetition time (TR), and can carry out data acquisition.Therefore we can say that mistiming and the mistiming between part B and the portion C between part A and the part B all are very little.That is to say,, can think that then the data acquisition sequential that is used for imaging and the collection sequential of motor message are simultaneously basically if be used for the data acquisition of imaging and the collection of motor message all is to carry out with the very little sequence of TR.Like this, can think that be identical in the motion of the data acquisition period that is used for imaging basically with motion during the motor message collection.

Part A, part B and portion C are the sequences that is used for the cardiogram synchronous imaging that will repeat, the ECG signal Synchronization that itself and ECG unit 38 are obtained.Part B gathers a three-dimensional imaging signal ACQ (B) as the sequence that is used for imaging by read pulse when continuously changing phase encoding pulse PE (B), and in other words, it is the sequence that is used for the segment imaging.Therefore, between a heart beat period,, obtain to be used for the partial data of imaging a sequence that is used for imaging.Then, repeatedly repeating the data acquisition that is used for imaging between heart beat period, can collect like this for all required data of imaging.That is to say, by gathering the data that are used for imaging repeatedly repeatedly carrying out the segment imaging between heart beat period.

On the other hand, by read pulse when continuously changing phase encoding pulse RE (A) and PE (C), gather motion detection signal ACQ (A) and ACQ (C) as the part A of the sequence that is used to detect motor message and portion C respectively.The motor message collection of carrying out based on the sequence (being part A and portion C in sequence example shown in Figure 5) that detects motor message is to carry out when carrying out the segment imaging based on the sequence of imaging process, during each heartbeat at every turn.Like this, all motor messages of essential encoding amount are gathered by the corresponding sequence that is used to detect motor message when the each heartbeat at every turn.Therefore, the motor message from the same area is repeatedly to obtain with different sequential intermittently.Like this, the motor message that is collected comprises about respirometric more accurate information.Therefore, can more accurately from the motor message that obtains by the same area, find amount of exercise with different sequential.

In addition, in the sequence that is used for detecting motor message, phase encoding amount (number of steps of phase encoding) is set to less than the sequence that is used for imaging, makes required motor message to be gathered selectively in the short time period.Should be noted in the discussion above that the phase encoding amount in being used to detect the sequence of motor message is non-vanishing.In addition, this sequence is so arranged, and making can be obtained under image-forming condition as the information of the initial collection target of dummy argument emission.

For example, in the dummy argument emission, a sequence is set to apply one 45 ° RF pulse, therefore can obtain a signal with specific comparative.Then, the sequence that is used for imaging is set to apply one 90 ° RF pulse, therefore carries out the data acquisition that is used for imaging with the determined comparative of comparative according to the signal that collects in the dummy argument emission.

In addition, the coding staff of the sequence that is used for detecting motor message to be not limited to cut into slices coding staff to two direction of principal axis of phase-encoding direction, described coding staff to also can be the section coding staff to phase-encoding direction in one of the single shaft direction.

Then, image-forming condition is provided with unit 40 and is configured to be shown as picture condition setting screen, is used for such image-forming condition is set on display unit 34, makes that the user can be by input block 33 production burst sequences as image-forming condition.

Fig. 6 shows the diagram that the image-forming condition that shows is provided with an example of screen on display unit 34 shown in Figure 1.

Shown in the top that the image-forming condition among Fig. 6 is provided with screen, in the dummy argument emission of SSEP sequence, shown that is used to open/cut off the button gathering motor message and carry out the motion correction function.When clicking this button such as the input block 33 of mouse, be placed in opening based on the motion correction function of the motor message that in the dummy argument emission, collects by operation.

In addition, the number (dummy argument emission number) of the dummy argument emission in the number of the number of phase encoding (PE matrix), section coding (SE matrix) and the dummy argument emission can be by being provided with arbitrarily such as the such operation of the rolling of scroll bar.

In addition, provide one to be used to specify linearity (SI) button that can be used for the motor pattern of motion correction in the bottom that image-forming condition is provided with screen.When clicking this linearity (SI) button, selected a correction mode, be used to carry out motion correction based on motor pattern, hypothesis detects the zone of target owing to linear deformation takes place in motion as amount of exercise under this motor pattern.Then, can be by setting a coefficient of zero order and a first-order linear expression formula that is used to represent this linear movement pattern arbitrarily such as the such operation of the rolling of scroll bar.The details of motor pattern will be described below.

Incidentally, be included in the interior vortex flow of phase encoding pulse generation of dummy argument emission that is used to detect motor message.Phase encoding pulse is intermittently applied repeatedly with different surfaces and polarity under normal conditions.Therefore, have such worry: i.e. the magnetization vibration meeting that produces owing to the dummy argument emission impacts the data acquisition that is used for imaging, ghost image may occur in the image of rebuilding.

Consider the problems referred to above, by be provided with such pulse train to weaken because the magnetization that dummy argument emission produces is vibrated, and reduce to magnetize the influence of vibration as far as possible to the data acquisition that is used for imaging, can suppress the appearance of ghost image.For this reason, wish to be provided with such sequence, make that the magnetization vibration that produces owing to the dummy argument emission is weakened gradually.In addition, also wish such sequence is set, make that the number of last phase encoding pulse in the dummy argument emission and the ladder (difference of pulse strength) between next first phase encoding pulse that is used for imaging is as far as possible little.

Fig. 7 shows the influence that is used to reduce the magnetization vibration that occurs owing to the dummy argument emission and by image-forming condition shown in Figure 2 the diagram that magnetization that the unit obtains imaging data influences a specific examples of the pulse train that is provided with is set.

As shown in Figure 7, described such a case: the sequence that wherein is used for imaging is set at the sequence back of the dummy argument emission that is used to gather motor message.The thing that it should be noted that, RF represents the RF signal, and Gpe represents phase encoding pulse.

At first, the step direction (applying direction) that is used to detect the phase encoding pulse of motor message is set to identical with the step direction of the phase encoding pulse that is used for imaging.Then, the sequence that is used for dummy argument emission is provided so that the phase encoding pulse that is used to detect motor message changes its polarity selectively in a period of time, and weakens its pulse strength gradually.Consequently, owing to the vibration that intensifies that window pulse produced can be weakened smoothly.

In addition, the sequence that is used for imaging is provided so that the polarity of last phase encoding pulse of dummy argument emission is identical with the polarity of first phase encoding pulse that is used for imaging, and reduces the number of the ladder (difference between the pulse strength Gpe) of phase encoding pulse as far as possible.Consequently, because window pulse produced intensifies vibration and can be inhibited to the influence of image-forming data acquisition.In addition, be used for the data acquisition of imaging, for level and smooth magnetization vibration, this sequence preferably is provided so that when changing polarity selectively as time goes by and increases pulse strength gradually.

Therefore, such pulse train is optimum, be that the polarity of phase encoding pulse is opposite with the polarity of the phase encoding pulse that is used for imaging in the dummy argument emission, and dummy argument launch in the reversed in order that applies the position of the order that applies position (data acquisition position) and the phase encoding pulse that is used for imaging of phase encoding pulse.Then, when imaging condition setting unit 40 is configured to such pulse train is set, can reduce vortex flow and magnetized change, thus the image that acquisition has the stabilized image quality.

In addition, image condition setting unit 40 pulse train that is configured to will be so generate offers sequence controller control module 41.

The function of sequence controller control module 41 is by based on the imaging sign on from input block 33, to the pulse train that unit 40 obtained be set by image-forming condition and offer sequence controller 31, thereby carry out drive controlling to sequence controller 31, other function is to receive motor message from sequence controller 31, thereby motor message is offered motor message acquiring unit 42, and receive from sequence controller 31 and to be used for the raw data of imaging, thereby raw data is offered imaging signal acquisition unit 43.

The function of motor message acquiring unit 42 is to obtain motor message from sequence controller control module 41, and another function is that the motor message that will so obtain is arranged in the k space (wave number space or frequency space) that offers motor message acquiring unit 42.

The function of imaging signal acquisition unit 43 be from sequence controller control module 41 obtain be used for imaging raw data as imaging signal, another function is that the imaging signal that will be so obtains is arranged in the k space that offers imaging signal acquisition unit 43.

Fig. 8 shows the diagram of an example of the motor message that is positioned at the k space in motion detection signal acquiring unit 42 shown in Figure 2.Fig. 9 shows the diagram of an example of the imaging signal that is positioned at the k space in imaging signal acquisition unit shown in Figure 2 43.The transverse axis of every width of cloth figure is represented the phase-encoding direction Kpe in the k space among Fig. 8 and Fig. 9, and its Z-axis young tiger is after death cut into slices coding staff to Kse.In addition, the square mark among Fig. 8 is represented motor message Dm, and the circles mark among Fig. 9 is expressed as image signal Di.As shown in Figure 8, in the dummy argument emission, also apply coded pulse to gather motor message Dm.

As mentioned above, motor message Dm is gathered when each heartbeat, and as wanting data updated.Fig. 8 show by coded pulse is applied to phase-encoding direction and section coding staff to the example of two resulting motor message Dm of axial direction.As mentioned above, motor message Dm can be by applying coded pulse collection on a direction of principal axis.Under the situation of using pulse train shown in Figure 5, gather motor message Dm in part A and portion C.

And under the situation of using pulse train shown in Figure 5, imaging signal Di shown in Figure 9 is gathered at part B.Because imaging signal Di is gathered by the segment imaging, imaging signal Di is partly obtained by a sequence in the heartbeat.Then, the repeatedly data acquisition of being undertaken by a plurality of sequences of repeatedly carrying out between heart beat period has realized the collection of all imaging signal Di.

In addition, as mentioned above, more accurate for the encoding amount that is used in motor message Dm, the number of ladder is set to less than the ladder number that is used for imaging signal Di.On the other hand, the ladder number Sm that is used for motor message Dm can be set to the ladder number Si that is used for imaging signal Di identical or different.Should be noted in the discussion above that near the motor message Dm the central authorities in k space is preferentially gathered in order to detect the motion of big organ with pinpoint accuracy.

Should be noted that, thereby, motor message Dm and imaging signal Di suppress the magnetization vibration and when influencing when so being gathered, be set to central authorities by the position of the last motor message Dm that gathers of the dummy argument on k space emission, and be used for being set to be positioned as close to by the last position of motor message Dm in the k space of gathering of dummy argument emission in the position of back to back first imaging signal Di of imaging on the k space near the k space.In addition, the collection direction of the collection direction of motor message Dm and imaging signal Di is set to opposite each other.

The function of motor message component separative element 44 is to read motor message from motor message acquiring unit 42, and make and to reflect the component of signal of a motion on the whole and not reflect that the component of signal of motion is separated from one another that another function is that the component of signal that reflects motion (component that reflection is moved) by resulting separation is offered motion amount determination unit 45.Motor message component separative element 44 is configured to carry out reconstruction to motor message by the known method for reconstructing that is used for the disengaging movement signal (Fourier transform), and obtains the outline data of (coding staff upwards) on the particular spatial location.

Figure 10 shows the diagram in a zone of the motor message that is separated by motor message component separative element 44 shown in Figure 2.

As shown in figure 10, for example when being used as excited slice, gathers the sagittal surface that comprises heart motor message, left and right directions is set to phase encoding (PE) direction, above-below direction is set to section coding (SE) direction, and the health direction of principal axis perpendicular to paper of target P is set to read direction.That is to say that as mentioned above, in order to reduce data acquisition time, the relatively large health direction of principal axis of amount of exercise is set up reads direction.Therefore, excited slice can be crown surface.

If gather motor message when the coded pulse when 4 * 4 is added on PE direction and the SE direction and rebuild the motor message of being gathered, then on the health direction of principal axis, can obtain to be divided into the profile in 4 * 4 zones.Then, can from profile, only select the component of a respirometric profile near the zone (shadow region) the expression heart as the reflection motion.

An example of the method for the profile of selection expression motion is a profile of selecting a sizable position of reconstructed image data amount distortion.In this case, all profiles compare each other, and variation that can the signal intensity profile that surpasses a pre-set threshold is set to reflect the component of motion.Should be noted that, can select to represent the profile that moves by the following method at an easy rate: specify one rule of thumb may have respirometric zone in the method in advance, and have only a profile to be set to reflect the component of motion in the specified zone.

Figure 11 shows the diagram corresponding to an example of the profile in the zone of close heart shown in Figure 10.

In Figure 11, transverse axis represents to read a position on the direction (health direction of principal axis), and transverse axis is represented the signal intensity of motor message.Then, the solid line among Figure 11 is a profile that is chosen as the component of reflection motion.Carry out the collection of motor message at every turn when carrying out above-mentioned segment imaging in advance, therefore when carrying out the segment imaging process, also obtained the component of reflection campaign shown in Figure 11 at every turn.Then because the segment imaging is the cardiogram synchronous imaging, the component of reflection motion can be considered to intermittently obtain about respirometric information.

Then, extracted to such an extent that reflect that the component of motion is provided for motion amount determination unit 45 by motor message component separative element 44.

The function of motion amount determination unit 45 is according to determining that from the component of the received reflection campaign of motor message component separative element 44 amount of exercise, another function are that determined amount of exercise is offered motion correction unit 46.

Figure 12 is used for explaining the diagram of determining a momental method by motion amount determination unit shown in Figure 2 45.

Shown in the top of Figure 12, carry out the data acquisition that is used to create the baseline profile that reflects the component that moves in advance, in the data acquisition that is used for creating baseline profile, with the ECG signal Synchronization shown in Figure 12 (a), according to having part A, part B and portion C pulse train shown in Figure 12 (b), gathered with the data acquisition that is used for imaging as the motor message of benchmark as unit part.Then, the baseline profile in a profile of the component of the reflection campaign shown in motor message component separative element 44 Figure 12 (c) motor message that is set to be gathered.

Then, when imaging,,, repeatedly gather motor message and be used for the data of imaging according to having part A, part B and portion C pulse train shown in Figure 12 (b) as unit part with the ECG signal Synchronization shown in Figure 12 (a).Then, the profile #N+1 of the component of the profile #N of the component of the n shown in Figure 12 (c) reflection campaign of being gathered and (N+1) individual reflection campaign of gathering is obtained continuously by motor message component separative element 44.

Baseline profile, profile #N and the profile #N+1 of the component of reflection motion are provided for motion amount determination unit 45 from motor message component separative element 44.Consequently, motion amount determination unit 45 has obtained the coherence spectra between the difference of the difference of the baseline profile shown in Figure 12 (d) and profile #N+1.Then, motion amount determination unit 45 detects the peak of each coherence spectra, and the respective amount Δ d (N) of the offset of definite corresponding peaks position and Δ d (N+1), the amount of exercise during as collection of N secondary data and the collection of N+1 secondary data.

When the amount of exercise Δ d (N) that is determined respectively by motion amount determination unit 45 and Δ d (N+1) were indicated in the expression shown in Figure 12 (e) and breathe on the data (dotted line) of grade, shown amount was similar to circles mark.Then, adopt such configuration, promptly the amount of exercise of determining in this way is provided for motion correction unit 46 from motion amount determination unit 45.

The function of motion correction unit 46 is to obtain amount of exercise from motion amount determination unit 45, and obtain imaging signal from imaging signal acquisition unit 43, with according to amount of exercise correcting imaging data, another function is that the imaging signal after proofreading and correct is offered image reconstruction unit 47.

Figure 13 is used for explaining the diagram of coming the method for correcting imaging signal by motion correction unit shown in Figure 2 46.

At first, following situation will be described: wherein the target area is proofreaied and correct in the parallel motion of reading on the direction.Shown in Figure 13 (a), when synchronously using the ECG signal, carry out the data acquisition of being undertaken by the pulse train shown in Figure 13 (b) with part A, part B and portion C with cardiogram.In part B, shown in Figure 13 (c), gather imaging signal, and it is hinted obliquely at the k space that forms in the imaging signal acquisition unit 43 by the segment imaging.A for example segment imaging by in part B, shown in Figure 13 (c), by dotted line around imaging signal gathered, to be arranged on the pre-position in the k space.

Then, the distribution by the imaging signal gathered in the particular sequence imaging of reading on direction and the phase-encoding direction is the distribution shown in Figure 13 (d).

On the other hand, if be Δ d by the amount of exercise of gathering simultaneously basically with imaging signal that motor message calculated, then motion correction unit 46 is created the phase shift function shown in the solid line of Figure 13 (e).In Figure 13 (e), Z-axis is represented a phase place, and transverse axis represents to read a position Kro on the direction.That is to say that motion correction unit 46 has been created one and had the phase shift function that single order distributes, and wherein is directly proportional with amount of exercise Δ d in the phase place of reading on the direction.

Then, imaging signal and the phase shift function that will read on the direction of motion correction unit 46 multiplies each other.Should be noted in the discussion above that when motor message be when being used for the motor message of baseline profile, can suppose that amount of exercise Δ d is 0.(Kse) imaging signal in is that (in the time of Kse), this calculating can be expressed as the conversion shown in the expression formula (1) to S for Kro, Kpe for Kro, Kpe in position on the k space.

S(Kro，Kpe，Kse)？S(Kro，Kpe，Kse)·exp(-？d·Kro)...(1)

In this way, for the parallel motion of reading on the direction, can carry out motion correction to imaging signal.In addition, for being not that parallel motion but linear expansion or contraction also can be proofreaied and correct imaging signal.

When using coefficient of first order α and coefficient of zero order β to be described as expression formula (2-1) along the linear movement of a specified point z of expansion of reading direction and contraction, the expression formula (2-2) that moves through of imaging signal S is represented on the k space.

Z？(1+α)z+β...(2-1)

S(Kro，Kpe，Kse)？S((1+α)Kro，Kpe，Kse)·exp(-βKro)...(2-2)

Be appreciated that when having linear expansion and shrinking by expression formula (2-2), read on the direction the sampling location with do not exist because expansion is compared during with motion that contraction takes place, moved a given ratio α.Therefore, by (((Kro, Kpe Kse), carry out the correction to expansion and contraction to the imaging signal S that Kse) locates for Kro, Kpe to obtain initial sampling location in Kse) for (1+ α) Kro, Kpe from the imaging signal S that move to give fixed-ratio α.Initial sampling location (Kro, Kpe, the imaging signal S that Kse) locates (Kro, Kpe Kse) can find by interpolation method, wherein utilized the imaging signal S that moves to fixed-ratio α ((1+ α) Kro, Kpe, Kse).

Then, the value of α and β can be determined that wherein the value of α and β changes according to amount of exercise Δ d by first-order linear amoeboid movement pattern in the expression formula (2-1).The coefficient of this motor pattern can be determined by actual measurement (actual imaging).Be provided with in the screen at image-forming condition shown in Figure 6, by operating linearity (SI) button, the value of determined α and β can be set to represent the coefficient of first order and the coefficient of zero order of the first-order expression of linear deformation arbitrarily, thereby according to along the motor pattern of the expansion and the linear deformation of shrinking motion correction being made indication.

Then, not only to the expansion and the correction of shrinking, and, can carry out by the phase calculation shown in the expression formula (1) according to the correction of the value of β to parallel motion.In this way, since motion to expansion with shrink and can realize at imaging signal to the correction of parallel motion.Then, the imaging signal after the correction is provided for image reconstruction unit 47 from motion correction unit 46.

The function of image reconstruction unit 47 is by the imaging data after the correction that receives from motion correction unit 46 being carried out the image reconstruction process such as two dimension or three dimensional fourier transform processing, create the view data of target P, it is actual spatial data, and another function is that the view data of being created that will offer display unit 34 is carried out necessary image processing.The example of Flame Image Process comprises that MIP (maximum intensity projection) handles.

Next the operation and the behavior of MR imaging apparatus 20 will be described.

Figure 14 shows the method flow diagram that utilizes MR imaging apparatus shown in Figure 1 the blood-vessel image of the heart of target P to be carried out imaging.Comprise each step in the symbolic representation process flow diagram of a S and a numeral among Figure 14.

In step S1, from obtaining motor message as the zone that is included in the momental detection target the imaging section.In addition, in the step S2 that almost carries out simultaneously with step S1, obtain the NMR signal (imaging signal) that is used for imaging from the imaging section that comprises the target area that is used for imaging.The acquisition process of this imaging signal is very to be performed near the sequential of obtaining motor message on the time.

For this reason, when imaging condition setting unit 40 offered display unit 34 with screen message in advance, image-forming condition shown in Figure 6 was provided with screen and is displayed on the display unit 34.When the user realizes the motion correction function and multiple correcting condition is set by operation input block 33, image-forming condition is provided with unit 40 and according to the image-forming condition of setting an excited slice as shown in Figure 3 is set, and generates as Fig. 4, Fig. 5 or pulse train shown in Figure 7.Then, image-forming condition is provided with the pulse train that unit 40 will so generate and offers sequence controller control module 41.

Sequence controller control module 41 offers sequence controller 31 according to will the pulse train that unit 40 obtained being set from image-forming condition from the imaging sign on of input block 33.Consequently, sequence controller 31 offers gradient power supply 27, transmitter 29 and receiver 30 according to this pulse train respectively with gating pulse.Therefore, electric current is offered X-axis gradient coil 23x, Y-axis gradient coil 23y and Z axis gradient coil 23z respectively from X-axis gradient power supply 27x, Y-axis gradient power supply 27y and the Z axial gradient power supply 27z of gradient power supply 27, thereby forms gradient magnetic Gx, the gradient magnetic Gy on the Y direction on the X-direction and the gradient magnetic Gz on the Z-direction in imaging region.In addition, the RF signal is provided for RF coil 24 from transmitter 29, and RF coil 24 sends to target P with the RF signal.

Then, received by RF coil 24 by the NMR signal that nuclear magnetic resonance produced of the nuclear spin of target P inside, to offer receiver 30.Receiver 30 passes through to generate raw data such as detection and the such predetermined signal processing of A/D conversion to the NMR signal, and the raw data that will so generate offers sequence controller 31.

Here, the sequence that is used for gathering motor message was set at pulse train before the data acquisition that is used for imaging, and the raw data and the motor message that therefore are used for imaging signal all are provided for sequence controller 31.Sequence controller 31 offers sequence controller control module 41 with imaging signal and the motor message of being gathered.

Then, motor message acquiring unit 42 obtains motor message from sequence controller control module 41, and the motor message that is obtained is arranged in the motor message acquiring unit 42 interior formed k spaces.In addition, imaging signal acquisition unit 43 is obtained picture signal from sequence controller control module 41, and the imaging signal that is obtained is arranged in the imaging signal acquisition unit 43 interior formed k spaces.

The collection that should be noted in the discussion above that imaging signal and motor message is to carry out according to ECG signal and the pulse train obtained by ECG unit 38 down synchronously at cardiogram.

Next, in step S3, motor message component separative element 44 reads motor message from motor message acquiring unit 42, and motor message is divided into the component of signal of reflection motion generally and the reflection component of signal of moving.For this reason, motor message component separative element 44 is carried out the image reconstruction process of motor messages, and the number that obtains being divided depends on the outline data that coding staff makes progress in a plurality of zones of encoding amount shown in Figure 10.Then, motor message component separative element 44 for example compares the outline data in the All Ranges mutually, and will change the component that maximum profile is divided into the reflection motion.The component of the reflection campaign of being obtained by motor message component separative element 44 is provided for motion amount determination unit 45 as shown in figure 11.

Next, in step S4, motion amount determination unit 45 is according to determining amount of exercise from the component of the received reflection campaign of motor message component separative element 44.More particularly,, determined a baseline profile by process shown in Figure 12, and the difference of definite baseline profile and calculate coherence spectra between the profile difference at sequential place of target corresponding to amount of exercise.Then, calculate the displacement at peak value place of coherence spectra as amount of exercise.The amount of exercise that motion amount determination unit 45 will so be determined then offers motion correction unit 46.

Next, in step S5, motion correction unit 46 obtains amount of exercise from motion amount determination unit 45, also obtains imaging signal from imaging signal acquisition unit 43, is used for coming the correcting imaging signal according to amount of exercise.For example, by process shown in Figure 13, motion correction unit 46 will have the phase shift function that single order that the phase place of wherein reading on the direction is directly proportional with amount of exercise Δ d distributes and the imaging signal of reading on the direction multiplies each other.That is to say, utilize the conversion shown in the expression formula (1), motion correction unit 46 is at the motion correction in the imaging signal execution parallel motion.

And, for example be provided with in the screen at image-forming condition shown in Figure 6, when clicking linear (SI) button and indication timing is carried out in expansion and contraction, utilize the coefficient of zero order β and the coefficient of first order α of the first-order expression of expression linear movement pattern, except parallel motion is proofreaied and correct, also expansion and contraction are proofreaied and correct.At imaging signal to expansion and the correction of shrinking can be by interpolation processing, use coefficient of first order α to carry out simultaneously based on expression formula (2-2).

Then, motion correction unit 46 offers image reconstruction unit 47 with the imaging signal behind the motion correction.

Next, in step S6, imaging signal after the correction that 47 pairs of image reconstruction unit receive from motion correction unit 46 is carried out the image reconstruction process of handling such as two dimension or three dimensional fourier transform, and to create the view data of target P, it is actual spatial data.In addition, 47 pairs of view data of so creating of image reconstruction unit are carried out the Flame Image Process of handling such as MIP, to offer display unit 34.Consequently, be displayed on the display unit 34 by the image that utilizes the motor message that in the dummy argument emission, obtains to carry out the resulting target P of motion correction.

According to MR imaging apparatus 20 with said structure, obtain motor message in the dummy argument emission near imaging sequence on the time of being set to, can think that therefore detection sequential that is used for motor message and the sequential that is used for the data acquisition of imaging are similar to the mutual while.In addition, according to MR imaging apparatus 20, can comprise such as the section of the organ of heart and directly obtain motor message that these organs are collection targets of motor message by excitation.

In addition, according to MR imaging apparatus 20, not to gather the data be used for imaging, be enough to be used in the motor message that amount of exercise is measured required scope but when each heartbeat, gather, can gather motor message from the same area with different sequential like this.Therefore, in MR imaging apparatus 20, can detect amount of exercise with higher degree of accuracy by using motor message, and utilize detected amount of exercise that imaging data is carried out and proofread and correct from the same area.Then, utilize MR imaging apparatus 20 can obtain saturated image, wherein clear phenomenon or the ghost image of obscure boundary is inhibited.

In addition, in MR imaging apparatus 20, can gather motor message with each zone in the different a plurality of zones of time ordered pair, like this, the component of signal of reflection motion extracts from detected motor message selectively, and can be used for motion correction.Consequently, be suppressed, thereby can obtain having carried out the image of motion correction with higher degree of accuracy from the influence of no moving region.In addition, can also suppress the treatment capacity relevant with motion correction increases.

In addition, when the coding in utilizing dummy argument emission on two direction of principal axis is gathered motor message, the spatial movement signal can be obtained, and when the bigger direction of motion is set to read direction, the movable information of pinpoint accuracy can be obtained with less data acquisition amount.

Next the example of a change of the motor message that is obtained by motor message acquiring unit 42 will be described.

Figure 15 is a diagram of revising example that is used for explaining the method in the k space that forms in the motion detection signal acquiring unit shown in Figure 2 42 that motor message is arranged in.

As shown in figure 15, the part of the motor message that is obtained by motion detection signal acquiring unit 42 can be replaced by imaging signal.In other words, motion detection signal acquiring unit 42 obtains the part of picture signal, and the imaging signal part of so obtaining can be used as motor message.

Square mark among Figure 15 is represented the motor message that obtains in the dummy argument emission, and circles mark represents to replace the employed picture signal of motor message.Have little spatial frequency from motor message, and be motor message, therefore need pinpoint accuracy in many cases from macrostructure near the part of k space central authorities.Consider above-mentioned situation, launch the exercise data that obtains near k space central authorities by dummy argument, and imaging signal is used to remainder.

(between the adjacent R ripple) applies the dummy argument emission when each heartbeat, and motor message is updated when heartbeat at every turn like this.On the other hand, the imaging signal that is replaced is gathered by the segment imaging, so imaging signal is obtained gradually along with the carrying out of segment imaging.Like this, the imaging signal that is replaced always has fixing value, and the part of motor message is not updated.Yet under imaging signal was used to situation away from the motor message of the location in k space, only the motor message from minor structure was not updated.Like this, when the motor message that requires to detect from macrostructure, even can think that the motor message from minor structure is not updated, the influence of this situation can be left in the basket in some cases.

On the other hand, the situation with the zone that does not have the motor message data is equal to the k spatial data is carried out the situation that mask is handled.Therefore, if under the very little state of the quantity of motor message data reconstructed image, then have such danger: promptly may cause interference as artificial affecting from the information that is included in the target in other neighborhood pixels.Consider the problems referred to above, when imaging signal is used to motor message, compare that the generation of artificial affecting is inhibited, and can obtain amount of exercise with pinpoint accuracy with there not being the motor message data conditions.

In this way, when motor message acquiring unit 42 is configured to obtain imaging signal from sequence controller control module 41, thereby when replacing a part of motor message with imaging signal, in fact the collection required time cycle of motor message can be reduced, and can improve the time efficiency of gathering motor message.Therefore, the dirigibility of pulse train design can be improved in the segment imaging.

Should be noted in the discussion above that when the motor message that need to detect from minor structure, gather from launching by dummy argument according to the size of structure, and imaging signal can be replaced the motor message of other parts away from the motor message of k space middle body.That is to say, when the motor message only gathered by dummy argument emission from the specific part in k space, when each heartbeat, upgrade motor message, can gather selectively from constriction motor message, to obtain amount of exercise with the expectation size that is used for short cycle.

The motion correction function that substitutes a part of motor message with imaging signal may be selected correction mode in the above described manner.For example, one is used to open/cut off and is displayed on image-forming condition shown on the display unit 34 with the button of the alternative relevant motion correction function of imaging signal screen is set, thereby the user can be switched correction mode arbitrarily.

Next a modification example by the method for motor message component separative element 44 disengaging movement signals will be described.

Figure 16 is used for explaining a process flow diagram of revising example that comes the method for disengaging movement signal by motor message component separative element 44 shown in Figure 2.Each step that comprises the symbolic representation process flow diagram of a S and a numeral among Figure 16.Figure 17 shows the diagram by an example in the formed zone of image reconstruction process shown in Figure 16.Figure 18 is the concept map of motive position mask shown in Figure 16.

As mentioned above, in the step S10 of Figure 16, motor message component separative element 44 obtains the motor message that is arranged on the k space from motor message acquiring unit 42, to carry out the image reconstruction process to motor message.Consequently, as shown in figure 17, can in depending on a plurality of zones of the encoding amount of dividing on PE direction and SE direction, number obtain reading the outline data on the direction.

Next, in step S11, motor message component separative element 44 is created a motion parts mask, and its weight is according to the motion size based on each regional outline data.That is to say that as shown in figure 16, the motion parts mask that has different weights on direction in PE direction and SE direction or the both direction is created by motor message component separative element 44.Figure 16 shows an example of the motion parts mask that only has different weights on the PE direction, but also different weights can be set on the SE direction.

The weight of motion parts mask is provided with greatlyyer in the pixel of the zone with big motion (being heart in this example), on the other hand, have little motion or do not having that weight is set to less in the pixel in zone (being chest wall or similar position in this example) of signal.Motion size in each pixel can be by obtaining with reference to each outline data.

Next, in step S12, motor message component separative element 44 is carried out weighted by motor message being carried out apply the motion parts mask on the image reconstruction data that image reconstruction process obtains with the data reconstruction at the motor message on PE direction and the SE direction.

Next, in step S13,44 pairs of the motor message component separative elements only data reconstruction after carrying out weighted on PE direction and the SE direction are carried out reverse reconstruction process.

Next, in step S14, motor message component separative element 44 will only convert data addition on PE direction and SE direction of k spatial data on PE direction and the SE direction.

Consequently, can obtain reflecting the outline data of the component of motion on the direction in shown in Figure 11 reading.This equates the separated situation of component of signal of reflection motion.In this way, when handling the component of signal that obtains the reflection motion, can be set to greatlyyer to the SN ratio of the measurement of the component of reflection motion, and can improve the momental degree of accuracy of detection by the relevant signal plus of weighting that makes progress with coding staff.

Should be noted in the discussion above that the separation method that is used for motor message also can elect correction mode as by the user.

Figure 19 shows the block diagram according to the MR imaging apparatus of second embodiment of the present invention.

In MR imaging apparatus 20A shown in Figure 19, the function that image-forming condition is provided with unit 40 and the position that comprises profile generation unit 50 rather than motor message component separative element 44 are different with the situation of MR imaging apparatus 20 shown in Figure 1.Other structures of MR imaging apparatus 20A there is no different with operation with the situation of MR imaging apparatus 20 shown in Figure 1 basically.Therefore, only show a functional block diagram of computing machine 20, represent the parts identical with identical Reference numeral, and omitted its explanation with MR imaging apparatus 20.

The image-forming condition of MR imaging apparatus 20A is provided with unit 40 function that pulse train is set is provided, and can fully comprise the motor message of the component of reflection motion as fundamental component near the dummy argument that data acquisition the applied emission collection that is used for imaging on sequential.

Figure 20 shows the diagram that image-forming condition by MR imaging apparatus 20A shown in Figure 19 is provided with an example of the pulse train that unit 40 generated.

As shown in figure 20, image-forming condition is provided with unit 40 and for example creates portion C, and it is the sequence that is used for dummy argument emission of following as the part B back of the sequence that is used for imaging.Part B is the sequence that is used for the segment imaging, is used for applying the RF signal in extremely short repetition time TR, continuously changes the phase encoding pulse PE (B) that is used to gather three-dimensional imaging signal ACQ (B) simultaneously.In part B, slice direction is set to comprise the sagittal surface direction of heart.

Then, portion C is that collection has the sequence of the component of reflection motion as the motor message of fundamental component.For this reason, the section coding staff of portion C is to being set to section coding staff with part B to different directions, and in portion C, slice direction is set to comprise the crown surface direction of heart.In addition, portion C is the sequence that is used for before slice gradient magnetic field pulse Pc and applies the flow-disturbing pulse afterwards.Then, gather the portion C that has by structure like this and reflect the motor message ACQ (B) of the component of motion as fundamental component.

Figure 21 shows the diagram by the slice position that pulse train encouraged shown in Figure 20.

As shown in figure 21, the section B that is represented by solid line is encouraged by the slice gradient magnetic field pulse Gss among the part B of pulse train shown in Figure 20.Subsequently, the section C that is illustrated by the broken lines is encouraged by the slice gradient magnetic field pulse Pc of portion C.Then, in portion C, motor message ACQ (C) is gathered from the rectangular area that dotted line and solid line centered on, and described rectangular area is encouraged by slice gradient magnetic field pulse Gss and the Pc from part B and portion C.

Then, the slice gradient magnetic field pulse Pc by control section C also regulates the position of the section C that is energized, and the zone that has as the motion of heart is included in the rectangular area without any motion selectively.In this way, when the slice gradient magnetic field pulse Pc of portion C is so controlled, make when the zone with motion is included in the rectangular area, can gather component with reflection motion motor message ACQ (C) as fundamental component.For the part of section C, have by empirical data obtain the method for position, according to the method and the similar approach of the movable information estimated position of gathering in advance in each position.

On the other hand, the function of profile generation unit 50 is based on by image-forming condition the pulse train that unit 40 sets is set, obtain by the resulting motor message of data acquisition from motor message acquiring unit 42, another function is by the motor message carries out image reconstruction process to so obtaining, and obtains the outline data of reading on the direction.In addition, the outline data that profile generation unit 50 is configured to so to obtain offers motion amount determination unit 45, as the component of reflection motion.

Then, in MR imaging apparatus 20A, pulse train shown in Figure 20 is provided with unit 40 by image-forming condition and is created, and makes to comprise having as the section in the zone of the motion of heart and be energized by the sequence that is used to gather motor message.Then, the motor message of gathering after gathering imaging signal is provided for profile generation unit 50.The motor message that is provided for profile generation unit 50 has the component of reflection motion as fundamental component.Consider above-mentioned situation, 50 pairs of motor message carries out image of profile generation unit reconstruction process is to obtain reading the outline data on the direction.Then, profile generation unit 50 outline data that will so obtain offers the component of motion amount determination unit 45 as the reflection motion.In addition, the situation of the MR imaging apparatus 20 shown in the image pattern 1 is the same, and imaging signal is carried out motion correction, thereby can obtain the image behind the motion correction.

The a part of assembly of MR imaging apparatus 20 and 20A and function can be omitted in each embodiment, and on the contrary, the function of MR imaging apparatus 20 and 20A also can make up mutually.For example can adopt such structure, the motor message component separative element 44 of MR imaging apparatus 20 wherein shown in Figure 1 can be omitted, and the profile of all motor messages can be used as the component of reflection motion, to carry out motion correction.In addition, also can adopt such structure, wherein provide motor message component separative element 44 for MR imaging apparatus 20A shown in Figure 19, the component of reflection motion is separated from motor message in addition, and described each motor message has the component of reflection motion respectively as fundamental component.

In addition, in above-mentioned MR imaging apparatus 20 and 20A, described based on amount of exercise and carried out example the treatment for correcting of imaging signal, but MR imaging apparatus 20 and 20A also can be configured to not carry out treatment for correcting, thereby select the imaging signal in the particular range to be used for image reconstruction.In this case, for example for computing machine 32 provides a picture signal selected cell, rather than motion correction unit 46.

Picture signal selected cell basis determined amount of exercise in motion amount determination unit 45, the imaging signal in the particular range in the imaging signal of selecting so to obtain by imaging signal acquisition unit 43.As an example of the method that is chosen to image signal, a kind of method comprises according to amount of exercise creates a screening window, and by using this screening window from imaging signal, to select imaging signal in the particular range.For example, the screening window is created as the imaging signal in the scope of selecting amount of exercise to be no more than a threshold value.Utilize the screening window of so creating, can from imaging signal, remove the imaging signal of the bigger motion of expression, be used for image reconstruction.

Then, image reconstruction unit 47 is utilized and is rebuild piece image by the selected imaging signal of picture signal selected cell.In this way, by the sort out imaging signal, it is very little and more near the image of benchmark image to obtain motion effects.

Claims

1. MR imaging apparatus comprises:

Imaging signal acquisition unit is configured to obtain magnetic resonance signal as imaging signal from target;

The motor message acquiring unit, be configured to repeat to obtain the phase encoding amount less than the magnetic resonance signal of the phase encoding amount of imaging signal as motor message;

Motion amount determination unit is configured to utilize described motor message to obtain an amount of exercise;

Motion correction unit is configured to according to described amount of exercise imaging signal be carried out treatment for correcting; And

Image reconstruction unit is configured to utilize the imaging signal after the treatment for correcting to come reconstructed image.

2. MR imaging apparatus as claimed in claim 1,

The component acquiring unit that also comprises the reflection motion is configured to obtain the component of signal of reflection motion from motor message,

Wherein said motion amount determination unit is configured to obtain described amount of exercise from the component of signal of described reflection campaign.

3. MR imaging apparatus as claimed in claim 1, wherein said motion amount determination unit are configured to utilize with mutual different sequential and obtain described amount of exercise from the motor message that obtains with a part.

4. MR imaging apparatus as claimed in claim 1, wherein said motor message acquiring unit are configured to utilize two codings on the direction of principal axis to obtain described motor message.

5. MR imaging apparatus as claimed in claim 1, wherein said motor message acquiring unit are configured to obtain motor message from the section identical with the imaging section that is used to obtain imaging signal.

6. MR imaging apparatus as claimed in claim 1, wherein said motor message acquiring unit are configured to obtain motor message by the health direction of principal axis of intended target as reading direction.

7. MR imaging apparatus as claimed in claim 1, wherein said motor message acquiring unit is configured to obtain before obtaining imaging signal and afterwards motor message.

8. MR imaging apparatus as claimed in claim 1,

Comprise that also image-forming condition is provided with the unit, be configured to be provided for obtaining the image-forming condition of motor message, this image-forming condition comprises the phase encoding amount.

9. MR imaging apparatus as claimed in claim 1, wherein said motor message acquiring unit is configured to be provided with a sequence that is used to obtain motor message, reducing the ladder number of the coded pulse be used to obtain motor message gradually, and

Described imaging signal acquisition unit is configured to be provided with a sequence that is used to obtain imaging signal, to increase the ladder number of the coded pulse be used to obtain imaging signal gradually.

10. MR imaging apparatus as claimed in claim 1, wherein said motor message acquiring unit is configured to be provided with a section that is used to obtain motor message, thereby a position of detecting target as amount of exercise is included in an imaging that is used to obtain imaging signal by this section and cuts into slices in the formed rectangular area, follow in the sequence that is used to obtain motor message of the sequence back that is used for obtaining imaging signal with utilization and to obtain motor message from described rectangular area, this section is set on the direction different with the imaging section.

11. MR imaging apparatus as claimed in claim 1 is characterized in that, described motion correction unit is configured to utilize linear expansion or shrinks to proofread and correct and carry out treatment for correcting.

12. MR imaging apparatus as claimed in claim 2, the component acquiring unit of wherein said reflection campaign is configured to generate the data of rebuilding by rebuilding motor message on a plurality of zones, thereby obtain the profile of data reconstruction at least one zone in described zone, as the component of signal of reflection motion, it represents respiratory movement.

13. MR imaging apparatus as claimed in claim 2, the component acquiring unit of wherein said reflection campaign is configured to generate the data of rebuilding by rebuilding motor message on a plurality of zones, thereby obtain the profile of data reconstruction, described data reconstruction is to obtain the reverse reconstruction process that described deal with data makes progress through coding staff by the component of signal that the deal with data addition that respectively data reconstruction on the described zone is weighted, also subsequently a coding staff is made progress is moved as reflection.

14. a MR imaging apparatus comprises:

The motor message acquiring unit, be configured to obtain the phase encoding amount less than a part of imaging signal of the phase encoding amount of imaging signal and magnetic resonance signal as motor message;

15. a MR imaging apparatus comprises:

Selected cell is configured to according to the imaging signal in particular range of described amount of exercise selection; And

Image reconstruction unit is configured to utilize the imaging signal in the described particular range to come reconstructed image.

16. a MR imaging method may further comprise the steps:

Obtain magnetic resonance signal as imaging signal from target;

Repeat to obtain the phase encoding amount less than the magnetic resonance signal of the phase encoding amount of imaging signal as motor message;

Utilize described motor message to obtain an amount of exercise;

According to described amount of exercise imaging signal is carried out treatment for correcting; And

Utilize the imaging signal after the treatment for correcting to come reconstructed image.

17. a MR imaging method may further comprise the steps:

Obtain magnetic resonance signal as imaging signal from target;

Obtain the phase encoding amount less than a part of imaging signal of the phase encoding amount of imaging signal and magnetic resonance signal as motor message;

Utilize described motor message to obtain an amount of exercise;

18. a MR imaging method may further comprise the steps:

Obtain magnetic resonance signal as imaging signal from target;

Utilize described motor message to obtain an amount of exercise;

According to the imaging signal in particular range of described amount of exercise selection; And

Utilize the imaging signal in the described particular range to come reconstructed image.