JP2002360532A - Mr data collecting method and mri equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suitably perform continuous collection of MR data in the state of SSFP even when frequency variation is caused by moving metal, etc. SOLUTION: Dividing a space (k) into at least two areas and continuously collecting MR data on a plurality of views belonging to a single area in the state of SSFP are repeated concerning each area in order. Then after continuously collecting MR data on the plurality of views belonging to the single area in the state of SSFP, navigation data is collected. When the navigation data is abnormal, the plurality of MRI data on the area is entirely recollected. Consequently, not only the MR data when detecting frequency variation but also the MR data on the whole area is collected. Thus, improper MR data after the state of the SSFP is broken no longer remains and proper MR data is collected surely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an MR (Magnetic R)
esonance) data collection method and MRI (Magnetic Res
onance Imaging) device, more specifically, even when frequency fluctuation (also referred to as frequency drift) occurs,
The present invention relates to an MR data acquisition method and an MRI apparatus capable of suitably performing continuous acquisition of MR data in an FP state.

[0002]

2. Description of the Related Art During the acquisition of MR data, if there is a movement (moving metal) or a temperature change of a metal block near the MRI apparatus, the size and uniformity of the magnetic field fluctuate due to the influence, so that frequency fluctuation occurs. Some of the collected MR data may be incorrect. Therefore, we collected navigation data to detect frequency fluctuation,
Recollection of MR data when frequency fluctuation is detected and phase correction of MR data when frequency fluctuation is detected are performed.

On the other hand, SSFP (Steady State Free Prec)
Various pulse sequences for continuously acquiring MR data in an ession state are known. For example, FIESTA
(FastImaging Employing STeady state Acqisitio
n), True SSFP, etc. Patent No. 2898
No. 329 is also disclosed.

Conventionally, there is no known MR data acquisition method for continuously acquiring MR data in the SSFP state using navigation data.

[0005]

According to the conventional MR data acquisition method for continuously acquiring MR data in the SSFP state, if there is a frequency fluctuation during the acquisition of MR data, a part of the acquired MR data is inappropriate. However, there is a problem that such MR data is included.

On the other hand, it is conceivable that MR data is continuously collected in the SSFP state, navigation data is also collected, and MR data when frequency fluctuation is detected is collected again. However, during continuous acquisition of MR data in the SSFP state, if there is a frequency fluctuation in a part of the data, the SSFP state will be broken by that, and the MR data after the frequency fluctuation has subsided will be improper. It will be appropriate. Therefore, even if the MR data at the time of detecting the frequency fluctuation is collected again, incorrect MR data remains.

Therefore, an object of the present invention is to provide an MR data acquisition method and an MR data acquisition method capable of suitably performing continuous acquisition of MR data in the SSFP state even when a frequency fluctuation occurs.
An object of the present invention is to provide an RI apparatus.

[0008]

According to a first aspect, the present invention divides k-space into first to M-th (≧ 2) regions, and obtains MR data of a plurality of views included in an m-th region. SSFP
An MR data acquisition method in which continuous acquisition in a state is repeated in order from m = 1 to m = M, wherein navigation data for detecting frequency fluctuation is acquired following acquisition of MR data in a certain area. If no frequency fluctuation is detected in the navigation data and the next MR data uncollected area remains, the M
Proceeding to the collection of R data, if a frequency variation is detected in the navigation data, the region where the latest MR data was collected is regarded as an MR data non-collection region, and the MR data is collected again at an appropriate timing thereafter, and the navigation is performed again. There is provided an MR data acquisition method characterized by terminating the acquisition of MR data if no frequency fluctuation is detected in the data and if there is no next MR data unacquired area. In the MR data collection method according to the first aspect, k
The process of dividing the space into two or more regions and continuously collecting MR data of a plurality of views belonging to one region in the SSFP state is sequentially repeated for each region. Then, after the MR data of a plurality of views belonging to one region are continuously collected in the SSFP state, navigation data is collected, and when a frequency variation is detected in the navigation data, all the MR data of the region is re-collected. That is,
Rather than re-collecting only the MR data at the time of detecting the frequency fluctuation, the MR data of the entire area is re-collected. Thus, incorrect MR after SSFP condition is broken
Data does not remain, and proper MR data can be reliably collected.

According to a second aspect, the present invention provides an M
In the R data collection method, when a frequency fluctuation is detected in the navigation data, the region where the latest MR data is collected is set as the next MR data non-collection region,
M, characterized in that the order of the uncollected areas is reduced.
An R data collection method is provided. M according to the second aspect above
In the R data collection method, the M
Since the re-collection of the R data is performed immediately, the order in which the k space is filled with the MR data is as originally planned.

According to a third aspect, the present invention provides an M
In the R data collection method, when a frequency variation is detected in the navigation data, an area in which the latest MR data is collected is added in order after the last MR data non-collection area. . In the MR data acquisition method according to the third aspect, the reacquisition of the MR data in the area where the frequency fluctuation is detected is postponed and the acquisition of the MR data in the next area is advanced. The timing at which the data fills the k space is as originally planned.

According to a fourth aspect, the present invention provides an M
In the R data collection method, when a frequency fluctuation is detected in the navigation data, an adjustment process is executed before the next data collection. In the MR data collection method according to the fourth aspect, when the frequency fluctuation is detected, the adjustment processing is immediately performed, so that the frequency fluctuation can be positively dealt with.

According to a fifth aspect, the present invention provides an M
In the R data collection method, the adjustment process includes a process of adjusting a current amount of a static magnetic field coil, a process of adjusting a transmission frequency, a process of adjusting a reception frequency, a process of adjusting a transmission phase, and a process of adjusting a reception phase. An MR data acquisition method characterized by any one or a combination of two or more is provided. In the MR data acquisition method according to the fifth aspect, the MRI apparatus can be adjusted according to the frequency fluctuation.

According to a sixth aspect, the present invention provides an M
In the R data collection method, the pulse sequence includes:
An MR data acquisition method is provided, wherein the time integral value of the gradient magnetic field in 1TR is 0, and the sequence is a sequence for simultaneously acquiring an FID signal and an echo signal. In the MR data acquisition method according to the sixth aspect, a pulse sequence called FIESTA can be used.

According to a seventh aspect, the present invention provides a method of continuously collecting MR data of a plurality of views in an SSFP state, collecting navigation data for detecting a frequency variation between views, and using the navigation data. MR data collection method characterized by stopping collection of MR data when frequency fluctuations are detected, repeatedly collecting navigation data, and restarting MR data collection in the SSFP state after frequency fluctuations are no longer detected in the navigation data. I will provide a. In the MR data acquisition method according to the seventh aspect, the MR data of a plurality of views are
If the navigation data is collected during the continuous collection in the state and the frequency fluctuation is detected in the navigation data, the collection of the MR data is stopped. Then, the navigation data is repeatedly collected, and when the frequency fluctuation is not detected, the continuous collection of the MR data in the SSFP state is restarted. As a result, appropriate MR data can be reliably collected.

[0015] In an eighth aspect, the present invention provides a transmission coil for transmitting an RF pulse, a gradient coil for applying a gradient magnetic field, a reception coil for receiving an NMR signal, and the transmission coil. The gradient coil and the receiving coil are driven to divide the k-space into first to M-th (≧ 2) regions, and the MR data of a plurality of views included in the m-th region are converted to S-regions.
Continuous collection in the SFP state means that m = 1 to m =
MR data collecting means that repeats in order up to M, navigation data collecting means for collecting navigation data for detecting frequency fluctuation following collection of MR data in a certain area, and whether or not frequency fluctuation has been detected in the navigation data And a determination unit for determining whether the frequency fluctuation is not detected and the next-order MR data non-collection area remains, and proceeds to the collection of the MR data of the next-order MR data non-collection area. The region where the MR data is collected is regarded as the MR data non-collection region, and the MR data is re-collected again at an appropriate timing thereafter. If the frequency fluctuation is not detected and the next-order MR data non-collection region remains, An MRI apparatus comprising: data acquisition control means for terminating the acquisition of MR data. In the MRI apparatus according to the eighth aspect, the first
The MR data acquisition method according to the aspect described above can be suitably implemented.

According to a ninth aspect, the present invention provides an M
In the RI device, when the data acquisition control unit detects a frequency fluctuation, the data acquisition control unit may set the area where the latest MR data is acquired as the next MR data unacquired area, and move down the order of the original MR data unacquired area. A featured MRI apparatus is provided. In the MRI apparatus according to the ninth aspect, the MR data acquisition method according to the second aspect can be suitably implemented.

According to a tenth aspect, the present invention provides the MRI apparatus having the above-mentioned configuration, wherein the data acquisition control means, when a frequency fluctuation is detected, replaces the latest MR data acquired area with the last MR data unacquired area. The MRI apparatus is characterized in that the MRI apparatus is added in the order of after. The MRI apparatus according to the tenth aspect can suitably implement the MR data collection method according to the third aspect.

According to an eleventh aspect, the present invention is characterized in that the MRI apparatus having the above-mentioned configuration is provided with an adjustment executing means for executing an adjustment process before the next data collection when a frequency fluctuation is detected. An MRI apparatus is provided. The MRI apparatus according to the eleventh aspect can suitably implement the MR data collection method according to the fourth aspect.

According to a twelfth aspect of the present invention, in the MRI apparatus having the above-described configuration, the adjustment processing means adjusts a current amount of the static magnetic field coil, adjusts a transmission frequency, and adjusts a reception frequency. , An MRI apparatus performing one or a combination of two or more of a process of adjusting a transmission phase and a process of adjusting a reception phase. In the MRI apparatus according to the twelfth aspect, the MR data acquisition method according to the fifth aspect can be suitably implemented.

According to a thirteenth aspect, the present invention provides the MRI apparatus having the above-mentioned configuration, wherein the pulse sequence is 1TR.
An MRI apparatus characterized in that the time integration value of the gradient magnetic field in the inside is 0 and the sequence is to collect the FID signal and the echo signal at the same time. MR according to the thirteenth aspect
In the I device, the MR data acquisition method according to the sixth aspect can be suitably implemented.

According to a fourteenth aspect, the present invention provides a transmission coil for transmitting an RF pulse, a gradient coil for applying a gradient magnetic field, a reception coil for receiving an NMR signal, and the transmission coil. MR data collection means for driving the gradient coil and the reception coil to continuously collect MR data of a plurality of views in an SSFP state, and navigation data collection for collecting navigation data for detecting frequency fluctuation between views. Means for judging whether or not a frequency change has been detected in the navigation data, and stopping the collection of the MR data when detecting the frequency change and repeating the collection of the navigation data. Data acquisition control means for resuming the acquisition of MR data in the state. To provide an I device. In the MRI apparatus according to the fourteenth aspect, the MR data acquisition method according to the seventh aspect can be suitably implemented.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited by this.

First Embodiment FIG. 1 is a block diagram showing an MRI apparatus according to a first embodiment of the present invention. In the MRI apparatus 100, the magnet assembly 1 has a space (bore) for inserting a subject therein, and a static magnetic field for applying a constant static magnetic field to the subject so as to surround the space. Coil 1p and gradient magnetic field of X axis, Y axis, Z axis (X axis,
A gradient magnetic field coil 1g for generating a slice gradient axis, a read gradient axis, and a phase encoding gradient axis by a combination of the Y axis and the Z axis), and an RF pulse for exciting spins of nuclei in the subject. Transmit coil 1 that gives
t and a receiving coil 1 for detecting an NMR signal from the subject
r are arranged. The static magnetic field coil 1p, the gradient magnetic field coil 1g, the transmission coil 1t, and the reception coil 1r
Are the static magnetic field power supply 2, the gradient magnetic field drive circuit 3, and the RF
It is connected to a power amplifier 4 and a preamplifier 5.

The sequence storage circuit 6 operates the gradient magnetic field drive circuit 3 based on the stored pulse sequence in accordance with a command from the computer 7 to generate a gradient magnetic field from the gradient magnetic field coil 1g of the magnet assembly 1 and , The gate modulation circuit 8 is operated to modulate the carrier output signal of the RF oscillation circuit 9 into a pulse signal having a predetermined timing and a predetermined envelope shape, which is added to the RF power amplifier 4 as an RF pulse. After power amplification,
This is applied to the transmission coil 1t of the magnet assembly 1 to selectively excite a desired imaging surface.

The preamplifier 5 includes a magnet assembly 1
, And amplifies the NMR signal from the subject received by the receiving coil 1r and inputs the amplified signal to the phase detector 10. Phase detector 10
Uses the carrier output signal of the RF oscillation circuit 9 as a reference signal,
The NMR signal from the preamplifier 5 is phase-detected and supplied to the AD converter 11. The AD converter 11 converts the analog signal after the phase detection into digital data and inputs the digital data to the computer 7.

The computer 7 performs overall control such as receiving information input from the operation console 12.
The computer 7 reads the digital data from the AD converter 11 and performs an image reconstruction operation to generate an MR image. The display device 13 displays the MR image.

FIG. 2 is a conceptual diagram of a k-space and an MR data acquisition trajectory. The k space is a two-dimensional space in the lead axis direction and the phase encode axis direction. Here, it is assumed that there are views # 1 to # 16 in the phase encode axis direction. The k space includes a first area of views # 1 to # 4, a second area of views # 5 to # 8, a third area of views # 9 to # 12, and a first area of views # 13 to # 16. It is assumed that the area is divided into four areas. Note that the view number and the area number can be freely assigned.

FIG. 3 shows an example of a pulse sequence called FIESTA. In the FIESTA sequence, an RF pulse is repeatedly hit with a TR shorter than T2 to be measured, and MR data is collected from an FID signal and an echo signal (spin echo signal or stimulated echo signal) that appear in the SSFP state.
A gradient magnetic field waveform in which the time integration value of the gradient magnetic field in 1TR becomes “0” is adopted. Further, the phase encoding axis gradient can be sequentially changed to a size corresponding to each view.

FIG. 4 is an example of a pulse sequence for collecting navigation data. In this navigation sequence, the gradient magnetic field other than the slice axis is omitted from the FIESTA sequence.

FIG. 5 is an illustration of the data collection order according to the first embodiment. First, the FIESTA sequence is repeated without collecting MR data, and the state is changed to the SSFP state. This is called empty. Once in SSFP state, F
Views # 1 to # 1 of the first area by the IESTA sequence
Four MR data are continuously collected. Subsequently, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal (there is no static magnetic field fluctuation) or abnormal (there is a static magnetic field fluctuation). If an uncollected area remains, the MR of the next-order MR data uncollected area
Proceed to data collection. Here, the process proceeds to MR data acquisition in the second area.

In the MR data collection of the second area, first, the area is set to the SSFP state in the empty space. Once in the SSFP state, the view # of the second area is
5 to # 8 MR data are continuously collected. Subsequently, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal. If the navigation data is normal and a next-order MR data non-collection area remains, the next-order MR data has not been collected. Proceed to collecting MR data for the region. Here, the process proceeds to the MR data acquisition in the third area.

In the MR data collection of the third area, first, the area is set to the SSFP state in the empty space. Once in the SSFP state, the view # of the third area is
9 to # 12 MR data are continuously collected. continue,
Navigation data is collected according to the navigation sequence, and whether the navigation data is normal or abnormal is determined. If the navigation data is abnormal, the area where the latest MR data is collected is regarded as the next MR data uncollected area, and the next Proceed to collecting MR data in the MR data uncollected area. Here, the process proceeds to the MR data acquisition of the third region again.

In the MR data collection of the third area again, first, an abnormality adjustment process is executed according to the navigation data. For example, the current amount of the static magnetic field coil 1p is adjusted, the transmission frequency is adjusted, the transmission frequency and the reception frequency are adjusted, and the transmission phase and the reception phase are adjusted. Next, the state is changed to the SSFP state in the empty state. SSFP
When the state is reached, the MR data of the views # 9 to # 12 in the third area are continuously re-collected by the FIESTA sequence. Subsequently, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal. If the navigation data is normal and the next MR data uncollected area remains, the next M
Proceed to collecting MR data in the R data uncollected area. Here, the process proceeds to the MR data acquisition in the fourth area.

In the MR data acquisition of the fourth area, first, the area is set to the SSFP state in the empty space. Once in the SSFP state, the view # of the fourth area is
13 to # 16 MR data are continuously collected. Subsequently, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal.
The region in which the R data has been collected is regarded as the next MR data non-collection region, and the process proceeds to the acquisition of the MR data in the next MR data non-collection region. Here, the process proceeds to the acquisition of the MR data in the fourth area again.

In the acquisition of the MR data in the fourth area again, first, an abnormality adjustment process is executed according to the navigation data. Next, the state is changed to the SSFP state in the empty space. SSF
Once in the P state, the fourth
The MR data of the region views # 13 to # 16 are continuously re-collected. Subsequently, navigation data is collected by the navigation sequence, and it is determined whether the navigation data is normal or abnormal. If the navigation data is normal and there is no next MR data uncollected area, the data collection ends.

According to the above-described first embodiment, not only the MR data at the time of detecting the frequency fluctuation is re-collected, but also the MR data of one entire region is re-collected.
Improper MR data after the SFP state has been broken will not remain, and proper MR data can be reliably collected. Also, the order as originally planned (# 1,
The k-space can be filled with MR data in the order of # 2, # 3,..., # 16).

Second Embodiment A block diagram of an MRI apparatus according to a second embodiment of the present invention is the same as FIG.

FIG. 6 is a view showing an example of a data collection order according to the second embodiment. First, the SSFP state is set in the empty space. Once in the SSFP state, the MR data of the views # 1 to # 4 in the first area are continuously collected by the FIESTA sequence. Subsequently, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal. If the navigation data is normal and a next-order MR data non-collection area remains, the next-order MR data has not been collected. Proceed to collecting MR data for the region. Here, the process proceeds to MR data acquisition in the second area.

In the MR data collection of the second area, first, the apparatus is set to the SSFP state in the empty space. Once in the SSFP state, the view # of the second area is
5 to # 8 MR data are continuously collected. Subsequently, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal. If the navigation data is normal and a next-order MR data non-collection area remains, the next-order MR data has not been collected. Proceed to collecting MR data for the region. Here, the process proceeds to the MR data acquisition in the third area.

In the MR data collection of the third area, first, the area is set to the SSFP state in the empty space. Once in the SSFP state, the view # of the third area is
9 to # 12 MR data are continuously collected. continue,
Navigation data is collected by the navigation sequence, and whether the navigation data is normal or abnormal is determined. If the navigation data is abnormal, the region where the latest MR data is collected is added in the order after the last MR data uncollected region, and the next The process proceeds to the acquisition of MR data in the MR data uncollected area in order. Here, the third region is added after the fourth region, and the process proceeds to the MR data acquisition of the fourth region.

In the MR data collection of the fourth area, first, an abnormality adjustment process is executed according to the navigation data.
Next, the state is changed to the SSFP state in the empty space. Once in the SSFP state, the MR data of the views # 13 to # 16 in the fourth area are continuously collected by the FIESTA sequence. Subsequently, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal. If the navigation data is normal and the next MR data uncollected area remains, the next MR
Proceed to collecting MR data in the data uncollected area. Here, the process proceeds to the MR data acquisition in the third area.

In the MR data collection of the third area again, first, the state is set to the SSFP state in the empty space. Once in the SSFP state, the MR data of the views # 9 to # 12 in the third area are continuously re-collected by the FIESTA sequence.
Subsequently, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal. In addition, the M of the next MR data uncollected area
Proceed to collecting R data. In this case, since there is no MR data uncollected area in the next order, the third area is set in the next order, and the process proceeds to MR data acquisition in the third area.

In the MR data acquisition of the third region again,
First, an abnormality adjustment process is performed according to the navigation data. Next, the state is changed to the SSFP state in the empty space. SS
When the FP state is entered, the MR data of the views # 9 to # 12 in the third area are continuously and again collected by the FIESTA sequence. Subsequently, navigation data is collected according to the navigation sequence, and it is determined whether the navigation data is normal or abnormal. If the navigation data is normal and there is no next MR data uncollected area, the MR data collection ends.

According to the above-described second embodiment, MR data for one entire region is re-collected instead of re-collecting only the MR data when the frequency fluctuation is detected.
Improper MR data after the SFP state has been broken will not remain, and proper MR data can be reliably collected. Further, the timing at which the MR data of the region where the navigation data is normal (the first region, the second region, and the third region in the example of FIG. 6) fills the k space is as originally planned.

Third Embodiment A block diagram of an MRI apparatus according to a third embodiment of the present invention is the same as FIG.

FIG. 7 is an illustration of the order of data collection according to the third embodiment. First, the SSFP state is set in the empty space. When the SSFP state is entered, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal. If the navigation data is normal, the process proceeds to collecting MR data in the next uncollected MR data area. Here, the process proceeds to the first region MR data acquisition.

In the MR data acquisition of the first area, first, the area is set to the SSFP state in the empty space. Once in the SSFP state, the view # of the first area is
The MR data of 1 to # 4 is continuously collected. Subsequently, navigation data is collected according to a navigation sequence, and it is determined whether the navigation data is normal or abnormal. If the navigation data is normal, the process proceeds to collecting MR data in the next uncollected MR data area. Here, the second
Proceed to MR data acquisition for the area.

In the MR data collection of the second area, first, the state is set to the SSFP state in the empty space. Once in the SSFP state, the view # of the second area is
5 to # 8 MR data are continuously collected. Subsequently, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal. If the navigation data is normal and a next-order MR data non-collection area remains, the next-order MR data has not been collected. Proceed to collecting MR data for the region. Here, the process proceeds to the MR data acquisition in the third area.

In the MR data collection of the third area, first, the state is changed to the SSFP state in the empty space. Once in the SSFP state, the view # of the third area is
9 to # 12 MR data are continuously collected. continue,
Navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal.

If the navigation data is abnormal, an abnormality adjusting process is executed according to the navigation data.
Next, the state is changed to the SSFP state in the empty space. When the SSFP state is reached, navigation data is collected by a navigation sequence, and it is determined whether the navigation data is normal or abnormal. This is repeated until the navigation data becomes normal.

When the navigation data becomes normal,
The process proceeds to the acquisition of MR data in the next-order MR data uncollected area. Here, the process proceeds to the MR data acquisition in the fourth area.

In the MR data acquisition of the fourth area, first, the area is set to the SSFP state in the empty space. Once in the SSFP state, the view # of the fourth area is
13 to # 16 MR data are continuously collected. If there is no next MR data uncollected area,
The MR data collection ends.

According to the third embodiment described above, the acquisition of MR data is stopped when frequency fluctuation is detected, and the collection of MR data in the SSFP state is resumed when frequency fluctuation is no longer detected. MR data can be reliably collected.

[0054]

The MR data acquisition method and MR of the present invention
According to the I apparatus, continuous acquisition of MR data in the SSFP state can be suitably performed even when a frequency fluctuation occurs due to a moving metal or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram of an MRI apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a k-space and a view.

FIG. 3 is a pulse sequence diagram illustrating an example of a FIESTA sequence.

FIG. 4 is a pulse sequence diagram illustrating an example of a navigation sequence.

FIG. 5 is an exemplary diagram of a data collection order according to the first embodiment.

FIG. 6 is an exemplary diagram of a data collection order according to the second embodiment.

FIG. 7 is a diagram illustrating an example of a data collection order according to a third embodiment.

[Explanation of symbols]

 Reference Signs List 100 MRI apparatus 1 Magnet assembly 1g Gradient magnetic field coil 1p Static magnetic field coil 1r Receiving coil 1t Transmitting coil 6 Sequence storage circuit 7 Computer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Aki Yamazaki 127, 4-7 Asahigaoka, Hino-shi, Tokyo F-term (reference) 4G096 AB11 AD06 AD08 AD10 BA03 BA04 BA24 BA50 CA03 CA29 CA49 CC31 CC40

Claims (14)

[Claims] 1. A method of dividing k-space into first to M-th (≧ 2) regions and continuously acquiring MR data of a plurality of views included in an m-th region in an SSFP state, m = 1 From 1 to m = M.
Following collection of MR data of a certain area, navigation data for detecting a frequency fluctuation is collected, and no frequency fluctuation is detected in the navigation data and the next MR
If a data uncollected area remains, the process proceeds to collecting MR data in the next MR data uncollected area. If a frequency fluctuation is detected in the navigation data, the area in which the latest MR data has been collected is regarded as an MR data uncollected area. Then, reacquisition of MR data is performed again at an appropriate timing thereafter, and if no frequency fluctuation is detected in the navigation data and if no next MR data unacquired area remains, acquisition of MR data is terminated. MR data acquisition method. 2. The MR data acquisition method according to claim 1, wherein when a frequency fluctuation is detected in the navigation data, the region in which the latest MR data is acquired is set in the next M order.
An MR data acquisition method, wherein an R data unacquired area is set, and the order of the original MR data unacquired area is reduced. 3. The MR data collection method according to claim 1, wherein when a frequency fluctuation is detected in the navigation data, a region in which the latest MR data is collected is set to the last M.
A method for acquiring MR data, wherein the MR data is added in the order after the R data uncollected area. 4. The MR data acquisition method according to claim 1, wherein when a frequency fluctuation is detected in the navigation data, an adjustment process is performed before the next data acquisition. MR data acquisition method. 5. The MR data acquisition method according to claim 4, wherein the adjustment processing includes adjusting a current amount of a static magnetic field coil, adjusting a transmission frequency, adjusting a reception frequency, and adjusting a transmission phase. An MR data acquisition method, which is any one of a process of adjusting and a process of adjusting a reception phase or a combination of two or more thereof. 6. The MR data acquisition method according to claim 1, wherein said pulse sequence simultaneously acquires an FID signal and an echo signal when a time integration value of a gradient magnetic field in 1TR is 0. A MR data acquisition method, wherein 7. While continuously collecting MR data of a plurality of views in an SSFP state, collecting navigation data for detecting a frequency fluctuation between the views, and detecting a frequency fluctuation in the navigation data, the MR data is acquired. An MR data acquisition method, comprising: stopping acquisition, repeating acquisition of navigation data, and restarting acquisition of MR data in an SSFP state after detecting no frequency variation in the navigation data. 8. A driving coil for transmitting an RF pulse, a gradient coil for applying a gradient magnetic field, a receiving coil for receiving an NMR signal, and driving the transmitting coil, the gradient coil, and the receiving coil Then, dividing the k-space into first to M-th (≧ 2) regions and continuously collecting MR data of a plurality of views included in the m-th region in the SSFP state, m = 1 to m = M, an MR data collection unit that repeats the sequence up to M, a navigation data collection unit that collects navigation data for detecting a frequency change following the collection of MR data in a certain area, and whether a frequency change is detected in the navigation data. Determination means for determining whether or not frequency fluctuation is not detected and the next-order MR data non-collection area remains if the next-order MR data non-collection area remains When the frequency fluctuation is detected, the region where the latest MR data is collected is regarded as the MR data non-collection region, and the MR data is re-collected again at an appropriate timing thereafter. MR
An MRI apparatus comprising: data acquisition control means for terminating the acquisition of MR data if no data unacquired area remains. 9. The MRI apparatus according to claim 8, wherein
The MRI apparatus according to claim 1, wherein the data acquisition control means, when detecting a frequency variation, sets an area in which the latest MR data is acquired as a next MR data non-acquisition area and moves down the original MR data non-acquisition area. apparatus. 10. The MRI apparatus according to claim 8, wherein the data acquisition control unit adds, in a case where a frequency variation is detected, an area in which the latest MR data is acquired in the order after the last MR data unacquired area. MR characterized by the following:
I device. 11. The MRI apparatus according to claim 8, further comprising an adjustment processing means for executing an adjustment process before a next data collection when a frequency fluctuation is detected. MRI apparatus. 12. The MRI apparatus according to claim 11, wherein the adjustment processing means adjusts a current amount of a static magnetic field coil, adjusts a transmission frequency, adjusts a reception frequency, and adjusts a transmission phase. An MRI apparatus, which executes any one of a process for adjusting a reception phase and a process for adjusting a reception phase. 13. The MRI apparatus according to claim 8, wherein the pulse sequence comprises:
An MRI apparatus characterized in that the time integration value of the gradient magnetic field in 1TR is 0 and the sequence is to collect FID signals and echo signals simultaneously. 14. A transmission coil for transmitting an RF pulse; a gradient coil for applying a gradient magnetic field;
A receiving coil for receiving a signal, an MR data collecting means for driving the transmitting coil, the gradient coil, and the receiving coil to continuously collect MR data of a plurality of views in an SSFP state; Navigation data collecting means for collecting navigation data for detecting a change; determining means for determining whether or not a frequency change is detected in the navigation data; An MRI apparatus comprising: data acquisition control means for repeating acquisition of data, and restarting acquisition of MR data in the SSFP state after frequency fluctuations are no longer detected.