CN109620228B - Fat zero offset correction method in magnetic resonance imaging and magnetic resonance imaging method - Google Patents
Fat zero offset correction method in magnetic resonance imaging and magnetic resonance imaging method Download PDFInfo
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- CN109620228B CN109620228B CN201811563710.XA CN201811563710A CN109620228B CN 109620228 B CN109620228 B CN 109620228B CN 201811563710 A CN201811563710 A CN 201811563710A CN 109620228 B CN109620228 B CN 109620228B
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- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
Abstract
The application relates to a fat zero offset correction method in magnetic resonance imaging and a magnetic resonance imaging method. The method comprises the following steps: obtaining the theoretical fat zero position under the condition that the transverse magnetic vector is completely dephased; adopting an expanded phase diagram to simulate to obtain a simulated fat zero position under the actual condition; acquiring the deviation between the theoretical fat zero point position and the simulated fat zero point position, and acquiring a deviation amount lookup table; and correcting the theoretical fat zero point positions of different body parts based on the deviation lookup table. According to the fat zero point deviation correction method, the magnetic resonance imaging method and the computer equipment in the magnetic resonance imaging, when fat pressing is carried out on different body parts, doctors can find the corresponding deviation value to correct the theoretical fat zero point positions of the different body parts, so that the fat zero point position is closer to the actual condition, and a better fat pressing effect is achieved.
Description
Technical Field
The application relates to the technical field of medical magnetic resonance imaging, in particular to a fat zero offset correction method in magnetic resonance imaging and a magnetic resonance imaging method.
Background
Fat suppression technology in magnetic resonance clinical imaging, namely fat suppression, is to separately excite fat signals by using narrow-frequency pulses, scatter the excited fat signals by using a gradient magnetic field, and then execute a conventional imaging sequence.
When the fat is pressed, the position of the zero point of the fat needs to be mastered, and the acquisition sequence of the K space is adjusted, so that the zero point of the fat is filled in the central position of the K space, and the best fat pressing effect can be achieved. However, at present, the fat zero point position is calculated and deduced based on the condition that the transverse magnetic vector is completely dephased, however, the fat zero point position calculated in the deduction mode is deviated from the actual condition, and the fat pressing effect is poor.
Disclosure of Invention
Based on this, it is necessary to derive the fat zero point position based on the situation that the transverse magnetic vector is completely dephased, however, the fat zero point position calculated by the derivation method has deviation from the actual situation, resulting in the technical problem of poor fat pressing effect, and a fat zero point deviation correction method and a magnetic resonance imaging method in magnetic resonance imaging are provided.
A fat zero offset correction method in magnetic resonance imaging comprises the following steps:
obtaining the theoretical fat zero position under the condition that the transverse magnetic vector is completely dephased;
adopting extended phase diagram simulation to obtain a simulated fat zero position under the actual condition;
acquiring the deviation between a theoretical fat zero position and a simulated fat zero position, and acquiring a deviation value lookup table, wherein the deviation value lookup table records the deviation values of different body parts;
and correcting the theoretical fat zero point positions of different body parts based on the deviation lookup table.
In one embodiment, obtaining the theoretical fat zero point position in the case of completely dephasing the transverse magnetic vector comprises:
calculating a steady state value of fat before the stimulation of the fat pressing pulse;
calculating a signal value of the fat before excitation of the imaging pulse based on the steady state value;
the fat zero point position in the case of a completely dephasing of the transverse magnetic vector is calculated on the basis of the signal values.
In one embodiment, calculating the steady state value of fat prior to stimulation by the pressure pulse comprises:
and calculating the steady state value of the fat before the excitation of the fat pressing pulse based on the initial magnetization vector, the imaging pulse turning angle, the fat pressing pulse turning angle and the number of imaging pulses between adjacent fat pressing pulses.
In one embodiment, calculating the signal value of the fat before excitation of the imaging pulse based on the steady state value comprises:
and calculating a signal value of fat before the excitation of the imaging pulse based on the steady state value, the initial magnetization vector and the turnover angle of the fat pressing pulse.
In one embodiment, calculating the fat zero position in the case where the transverse magnetic vector is completely dephased based on the signal values includes:
and calculating the fat zero point position under the condition that the transverse magnetic vector is completely dephased based on the signal value, the steady state value, the initial magnetization vector and the grease pressing pulse overturning angle.
In one embodiment, the correcting the theoretical fat zero point positions of the different body parts based on the deviation amount lookup table comprises:
calculating the zero position of the target fat under the condition that the transverse magnetic vector is completely dephased;
searching a corresponding target deviation amount in a deviation amount lookup table according to the fat-pressing body part;
the target fat zero point position is corrected based on the target deviation amount.
In one embodiment, after correcting the theoretical fat zero point positions of different body parts based on the deviation amount lookup table, the method further includes:
and adjusting the acquisition sequence of the K space by a cyclic movement method to enable the corrected fat zero point to be filled in the central position of the K space.
A magnetic resonance imaging method, the method comprising:
determining scanning parameters corresponding to a part to be scanned;
respectively applying a pressurized fat pulse and an imaging pulse to a scanning part according to the scanning parameters, and acquiring a magnetic resonance signal of the part to be scanned;
acquiring a corrected fat zero position, and filling a magnetic resonance signal into a K space according to the corrected fat zero position to acquire K space data;
reconstructing K space data, and acquiring a fat pressing image of a part to be scanned;
acquiring the corrected fat zero point position includes:
obtaining a theoretical fat zero position under the condition that the transverse magnetic vector is completely dephased;
adopting an expanded phase diagram to simulate to obtain a simulated fat zero position under the actual condition;
acquiring deviation between a theoretical fat zero point position and a simulated fat zero point position, and acquiring a deviation amount lookup table, wherein the deviation amount lookup table records deviation amounts of different body parts;
and correcting theoretical fat zero positions of different body parts based on the deviation amount lookup table to obtain corrected fat zero positions.
In one embodiment, filling the K-space with magnetic resonance signals based on fat null positions, acquiring K-space data comprises:
and adjusting the filling sequence of the magnetic resonance signals according to the corrected fat zero point position, so that the fat zero point position corresponds to the center of the K space.
A computer device comprising a memory and a processor, the memory storing a computer program, the processor when executing the computer program implementing the steps of:
obtaining the theoretical fat zero position under the condition that the transverse magnetic vector is completely dephased;
adopting extended phase diagram simulation to obtain a simulated fat zero position under the actual condition;
acquiring the deviation between a theoretical fat zero position and a simulated fat zero position, and acquiring a deviation value lookup table, wherein the deviation value lookup table records the deviation values of different body parts;
and correcting the theoretical fat zero point positions of different body parts based on the deviation value lookup table.
According to the fat zero point deviation correction method, the magnetic resonance imaging method and the computer equipment in the magnetic resonance imaging, the deviation between the theoretical fat zero point position and the simulated fat zero point position is obtained, the deviation amount lookup tables of different body parts are obtained through recording, and then the fat zero point positions of different body parts are corrected based on the deviation amount lookup tables, so that a doctor can find corresponding deviation values to correct the theoretical fat zero point positions of different body parts when fat pressing is performed on different body parts, the fat zero point positions are closer to actual conditions, and a better fat pressing effect is achieved.
Drawings
Fig. 1 is a flowchart illustrating a fat null shift correction method in mri according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the change of a theoretical steady state value and a simulated steady state value of fat before the stimulation of a fat pressing pulse along with the radio frequency deflection angle;
FIG. 3 is a schematic diagram of the theoretical fat zero position and simulated fat zero position as a function of RF pulses under a long echo chain;
FIG. 4 is a schematic diagram of the theoretical fat zero position and simulated fat zero position under a short echo chain varying with radio frequency pulses;
FIG. 5 is a flow chart of a magnetic resonance imaging method according to an embodiment of the present invention;
fig. 6 is a block diagram of a fat null shift correction apparatus in mri according to an embodiment of the present invention;
FIG. 7 is a block diagram of an MRI apparatus according to an embodiment of the present invention;
fig. 8 is an internal structural diagram of a computer device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Referring to fig. 1, fig. 1 is a flowchart illustrating a fat null shift correction method in magnetic resonance imaging according to an embodiment of the present invention.
In this embodiment, the fat null point deviation correction method in magnetic resonance imaging includes:
and step 100, acquiring the theoretical fat zero point position under the condition that the transverse magnetic vector is completely dephased.
In this embodiment, obtaining the theoretical fat zero point position under the condition of complete dephasing of the transverse magnetic vector includes calculating a steady state value of fat before stimulation of a fat pressing pulse; calculating a signal value of the fat before excitation of the imaging pulse based on the steady state value; the fat zero point position in the case where the transverse magnetic vector is completely dephased is calculated based on the signal value.
Illustratively, calculating the steady state value of fat prior to excitation of the fat compression pulses comprises calculating the steady state value of fat prior to excitation of the fat compression pulses based on the initial magnetization vector, the imaging pulse flip angle, the fat compression pulse flip angle, and the number of imaging pulses between adjacent fat compression pulses. Specifically, the formula for calculating the steady state value of fat before the stimulation of the pressure pulse is as follows:
wherein Mze is the steady state value of fat before stimulation of fat pressing pulse, and M is 0 As initial magnetization vector, let T fs1 For the duration from the start of the fat pressing pulse to the center of the fat pressing pulse, let T fs2 Let alpha be the imaging pulse flip angle, let beta be the imaging pulse flip angle, let n be the number of imaging pulses between adjacent pressure fat pulses,
t1 is the longitudinal relaxation time, T2 is the transverse relaxation time, and TR is the repetition time.
Illustratively, calculating the signal value of fat prior to excitation of the imaging pulse based on the steady state value includes calculating the signal value of fat prior to excitation of the imaging pulse based on the steady state value, the initial magnetization vector, and the fat compression pulse flip angle. Specifically, the formula for calculating the signal value of fat before the excitation of the imaging pulse based on the steady state value is:
wherein Mz (ntR) - ) The signal value of fat before the excitation of the imaging pulse, mze the steady state value of fat before the excitation of the pressure pulse, M 0 Is an initial magnetization vector, beta is a fat pressing pulse turning angle, theta is an imaging turning angle, n is the number of imaging pulses between adjacent fat pressing pulses,
t1 is the longitudinal relaxation time, T2 is the transverse relaxation time, and TR is the repetition time.
Illustratively, calculating the fat zero point position in the case where the transverse magnetic vector is completely dephased based on the signal value includes calculating the fat zero point position in the case where the transverse magnetic vector is completely dephased based on the signal value, the steady state value, the initial magnetization vector, and the liposuction pulse flip angle. Specifically, let the signal value Mz (nTR) of fat before excitation of imaging pulse - ) Is 0, and the formula of the fat zero point position can be obtained according to the signal value calculation formula at this time as follows:
wherein Mze is the steady state value of fat before stimulation of pressure pulse, M 0 Is an initial magnetization vector, beta is a fat pressing pulse turning angle, theta is an imaging turning angle, n is the number of imaging pulses between adjacent fat pressing pulses,
t1 is the longitudinal relaxation time, T2 is the transverse relaxation time, and TR is the repetition time.
And 110, obtaining the simulated fat zero point position under the actual condition by adopting the extended phase diagram simulation.
It is understood that the theoretical fat zero point position in step 100 is calculated based on the situation that the transverse magnetic vector is completely dephased, but the actual situation is more complicated, for example:
(1) The signal is the result of the continuous evolution of the spin echo, the stimulus echo and the gradient echo;
(2) The signal is also the result of the combined action of water and fat, the fat has 7 peaks, and different frequency differences exist between the fat peaks and the water;
(3) The steady state values of the radio frequency phase-perturbed angle signals are different for different GRE (Gradient Recalled Echo) pressure-fat sequences. When the radio frequency phase perturbation angle is equal to 117 deg., its signal steady state value is substantially equal to the ideal model based steady state value (assuming that the transverse magnetic vector is completely out of phase).
Therefore, the fat zero point position in the actual case is different from the theoretical fat zero point position.
Illustratively, the simulated fat zero point position in the actual situation is obtained by using EPG (Extended Phase Graph) simulation.
Referring to fig. 2-4, fig. 2 is a schematic diagram of the theoretical steady state value and the simulated steady state value of fat before the stimulation of the fat pressing pulse, which vary with the radio frequency deflection angle, wherein: the horizontal axis represents the radio frequency deflection angle; the vertical axis represents the corresponding steady state value. Fig. 3 is a schematic diagram of the variation of the theoretical fat zero position and the simulated fat zero position with the radio frequency pulse under the long echo chain, wherein the horizontal axis represents the radio frequency pulse, and the vertical axis represents the fat zero position. Fig. 4 is a schematic diagram of the change of the theoretical fat zero position and the simulated fat zero position under the short echo chain along with the radio frequency pulse, wherein the horizontal axis represents the radio frequency pulse, and the vertical axis represents the fat zero position. It can be seen from the figure that due to the complexity of the actual situation, there is a certain degree of deviation between the value obtained by theoretical calculation and the value obtained by simulation, and if the filling sequence of the K space center is determined only according to the fat zero point obtained by theoretical simulation calculation, there will be a deviation between the filling sequence and the actual value, so that the fat zero point offset generates artifacts.
And 120, acquiring the deviation between the theoretical fat zero point position and the simulated fat zero point position, and acquiring a deviation value lookup table, wherein the deviation value lookup table records the deviation values of different body parts.
Illustratively, based on the theoretical fat zero point positions and the simulated fat zero point positions of the different body parts obtained in steps 100 and 110, the deviations between the theoretical fat zero point positions and the simulated fat zero point positions of the different body parts are obtained, and a deviation amount lookup table is obtained, wherein the deviation amount lookup table comprises the corresponding relations between the body parts and the deviation amounts, and each body part corresponds to different deviation amounts.
And step 130, correcting the theoretical fat zero point positions of different body parts based on the deviation amount lookup table.
Illustratively, correcting the theoretical fat zero positions of the different body parts based on the deviation amount lookup table includes calculating a target fat zero position in a case where the transverse magnetic vector is completely dephased; searching a corresponding target deviation amount in a deviation amount lookup table according to the fat-pressing body part; the target fat zero point position is corrected based on the target deviation amount. Illustratively, the theoretical fat zero point position calculated for the upper abdomen is moved positively by 2 to 3 units and the theoretical fat zero point position calculated for the mammary gland part is moved negatively by 2 to 4 units for optimal fat compression effect.
Specifically, after the theoretical fat zero point positions of different body parts are corrected based on the deviation lookup table, the acquisition sequence of the K space is adjusted by a circular movement method, so that the corrected fat zero point is filled in the central position of the K space, and the optimal fat pressing effect is obtained.
Referring to fig. 5, fig. 5 is a flow chart illustrating a magnetic resonance imaging method according to an embodiment of the invention.
In the present embodiment, a magnetic resonance imaging method includes:
Illustratively, the scan parameters include magnetic resonance scan parameters such as magnetic field strength, sequence type, scan location, and the like.
And step 510, respectively applying a pressure fat pulse and an imaging pulse to the scanning part according to the scanning parameters, and acquiring a magnetic resonance signal of the part to be scanned.
Illustratively, the compressive grease pulse may be a rapid compressive grease GRE (Gradient Recalled Echo) 3D pulse sequence. It is understood that in other embodiments, the grease pressing pulse may be other types of pulse sequences, and only needs to have a better grease pressing effect.
And step 520, acquiring the corrected fat zero point position, filling the magnetic resonance signal into a K space according to the corrected fat zero point position, and acquiring K space data.
Illustratively, acquiring corrected fat zero point positions, filling magnetic resonance signals into a K space according to the corrected fat zero point positions, and acquiring K space data includes adjusting an acquisition order of the K space between echo trains by a cyclic shift method to adjust a filling order of the magnetic resonance signals, filling the magnetic resonance signals into the K space, and filling the corrected fat zero point at a central position of the K space to acquire the K space data.
And step 530, reconstructing K space data and acquiring a fat pressing image of the part to be scanned.
Illustratively, reconstructing the K-space data and acquiring the liposuction image of the part to be scanned includes reconstructing the K-space data by using an inverse fourier transform method to acquire the liposuction image of the part to be scanned.
It is understood that, in the present embodiment, the above-mentioned fat zero point deviation correction method in magnetic resonance imaging is adopted to obtain the corrected fat zero point position. Specifically, acquiring the corrected fat zero point position includes acquiring a theoretical fat zero point position under the condition that the transverse magnetic vector is completely dephased; adopting extended phase diagram simulation to obtain a simulated fat zero position under the actual condition; acquiring deviation between a theoretical fat zero point position and a simulated fat zero point position, and acquiring a deviation amount lookup table, wherein the deviation amount lookup table records deviation amounts of different body parts; and correcting the zero position of the fat by a method for correcting the theoretical zero positions of the fat of different body parts based on the deviation amount lookup table to obtain the corrected zero position of the fat.
It should be understood that, although the steps in the flowcharts of fig. 1 and 5 are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in fig. 1 and 5 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performing the sub-steps or stages is not necessarily sequential, but may be performed alternately or alternately with other steps or at least some of the sub-steps or stages of other steps.
In one embodiment, as shown in fig. 6, there is provided a fat null shift correction apparatus in magnetic resonance imaging, including: theoretical calculation module 600, simulation module 610, lookup table establishment module 620 and correction module 630, wherein:
and the theoretical calculation module 600 is configured to obtain a theoretical fat zero point position under the condition that the transverse magnetic vectors are completely dephased.
calculating a steady state value of fat before the stimulation of the fat pressing pulse;
calculating a signal value of fat before excitation of the imaging pulse based on the steady state value;
the fat zero point position in the case where the transverse magnetic vector is completely dephased is calculated based on the signal value.
The theoretical calculation module 600 is further configured to calculate a steady state value of fat before excitation of the fat compression pulse based on the initial magnetization vector, the imaging pulse flip angle, the fat compression pulse flip angle, and the number of imaging pulses between adjacent fat compression pulses.
The theoretical calculation module 600 is further configured to calculate a signal value of fat before excitation of the imaging pulse based on the steady-state value, the initial magnetization vector, and the flip angle of the fat compression pulse.
The theoretical calculation module 600 is further configured to calculate a fat zero point position under the condition that the transverse magnetic vector is completely dephased based on the signal value, the steady state value, the initial magnetization vector and the grease pressing pulse flip angle.
And the simulation module 610 is used for obtaining the simulated fat zero point position under the actual condition by adopting the extended phase diagram simulation.
And the lookup table establishing module 620 is configured to obtain a deviation between the theoretical fat zero point position and the simulated fat zero point position, and obtain a deviation amount lookup table, where the deviation amount lookup table records deviation amounts of different body parts.
And a correcting module 630, configured to correct the fat zero point positions of different body parts based on the deviation amount lookup table.
A correction module 630, further configured to: calculating the zero position of the target fat under the condition that the transverse magnetic vector is completely dephased;
searching a corresponding target deviation amount in a deviation amount lookup table according to the fat-pressing body part;
the target fat zero point position is corrected based on the target deviation amount.
In one embodiment, as shown in fig. 7, there is provided a magnetic resonance imaging apparatus including: a scan parameter determination module 700, a magnetic resonance signal acquisition module 710, a K-space data acquisition module 720, and an image reconstruction module 730, wherein:
a scanning parameter determining module 700, configured to determine a scanning parameter corresponding to a portion to be scanned.
And a magnetic resonance signal acquisition module 710, configured to apply the pressurized lipid pulse and the imaging pulse to the scanning portion according to the scanning parameters, and acquire a magnetic resonance signal of the portion to be scanned.
The K-space data obtaining module 720 obtains the corrected zero point position of the fat, and fills the magnetic resonance signal into the K-space according to the corrected zero point position of the fat to obtain K-space data.
And the image reconstruction module 730 is used for reconstructing K space data and acquiring a fat pressing image of the part to be scanned.
For specific limitations of the fat zero offset correction apparatus and the magnetic resonance imaging apparatus in magnetic resonance imaging, reference may be made to the above limitations of the fat zero offset correction method and the magnetic resonance imaging method in magnetic resonance imaging, which are not described herein again. The fat zero offset correction device in magnetic resonance imaging and each module in the magnetic resonance imaging device can be wholly or partially realized by software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent of a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as shown in fig. 8. The computer device includes a processor, a memory, a network interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to realize a fat null offset correction method in magnetic resonance imaging and a magnetic resonance imaging method. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on the shell of the computer equipment, an external keyboard, a touch pad or a mouse and the like.
Those skilled in the art will appreciate that the architecture shown in fig. 8 is merely a block diagram of some of the structures associated with the disclosed aspects and is not intended to limit the computing devices to which the disclosed aspects apply, as particular computing devices may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.
In one embodiment, a computer device is provided, comprising a memory and a processor, the memory having a computer program stored therein, the processor implementing the following steps when executing the computer program:
obtaining the theoretical fat zero position under the condition that the transverse magnetic vector is completely dephased;
adopting extended phase diagram simulation to obtain a simulated fat zero position under the actual condition;
acquiring the deviation between a theoretical fat zero position and a simulated fat zero position, and acquiring a deviation value lookup table, wherein the deviation value lookup table records the deviation values of different body parts;
and correcting the theoretical fat zero point positions of different body parts based on the deviation lookup table.
In one embodiment, the processor when executing the computer program further performs the steps of:
calculating a steady state value of fat before the stimulation of the fat pressing pulse;
calculating a signal value of the fat before excitation of the imaging pulse based on the steady state value;
the fat zero point position in the case where the transverse magnetic vector is completely dephased is calculated based on the signal value.
In one embodiment, the processor, when executing the computer program, further performs the steps of:
and calculating the steady state value of the fat before the excitation of the fat pressing pulse based on the initial magnetization vector, the imaging pulse turning angle, the fat pressing pulse turning angle and the number of imaging pulses between adjacent fat pressing pulses.
In one embodiment, the processor when executing the computer program further performs the steps of:
and calculating a signal value of fat before the excitation of the imaging pulse based on the steady state value, the initial magnetization vector and the turnover angle of the fat pressing pulse.
In one embodiment, the processor, when executing the computer program, further performs the steps of:
and calculating the fat zero point position under the condition that the transverse magnetic vector is completely dephased based on the signal value, the steady state value, the initial magnetization vector and the grease pressing pulse overturning angle.
In one embodiment, the processor, when executing the computer program, further performs the steps of:
calculating the zero position of the target fat under the condition that the transverse magnetic vector is completely dephased;
searching a corresponding target deviation amount in a deviation amount lookup table according to the fat-pressing body part;
the target fat zero point position is corrected based on the target deviation amount.
In one embodiment, the processor when executing the computer program further performs the steps of:
and adjusting the acquisition sequence of the K space by a cyclic movement method to enable the corrected fat zero point to be filled in the central position of the K space.
In one embodiment, the processor, when executing the computer program, further performs the steps of:
determining scanning parameters corresponding to a part to be scanned;
respectively applying a pressurized lipid pulse and an imaging pulse to a scanning part according to the scanning parameters, and acquiring a magnetic resonance signal of the part to be scanned;
acquiring a corrected fat zero position, and filling a magnetic resonance signal into a K space according to the corrected fat zero position to acquire K space data;
reconstructing K space data, and acquiring a fat pressing image of a part to be scanned;
acquiring the corrected fat zero point position includes:
obtaining the theoretical fat zero position under the condition that the transverse magnetic vector is completely dephased;
adopting extended phase diagram simulation to obtain a simulated fat zero position under the actual condition;
acquiring the deviation between a theoretical fat zero position and a simulated fat zero position, and acquiring a deviation value lookup table, wherein the deviation value lookup table records the deviation values of different body parts;
and correcting theoretical fat zero positions of different body parts based on the deviation amount lookup table to obtain the corrected fat zero positions. In one embodiment, the processor, when executing the computer program, further performs the steps of:
and adjusting the filling sequence of the magnetic resonance signals according to the fat zero point position, so that the fat zero point position corresponds to the center of the K space.
In one embodiment, a computer-readable storage medium is provided, having a computer program stored thereon, which when executed by a processor, performs the steps of:
obtaining the theoretical fat zero position under the condition that the transverse magnetic vector is completely dephased;
adopting extended phase diagram simulation to obtain a simulated fat zero position under the actual condition;
acquiring the deviation between a theoretical fat zero position and a simulated fat zero position, and acquiring a deviation value lookup table, wherein the deviation value lookup table records the deviation values of different body parts;
and correcting the theoretical fat zero point positions of different body parts based on the deviation lookup table.
In one embodiment, the computer program when executed by the processor further performs the steps of:
calculating a steady state value of fat before the stimulation of the fat pressing pulse;
calculating a signal value of the fat before excitation of the imaging pulse based on the steady state value;
the fat zero point position in the case of a completely dephasing of the transverse magnetic vector is calculated on the basis of the signal values.
In one embodiment, the computer program when executed by the processor further performs the steps of:
and calculating the steady state value of the fat before the excitation of the fat pressing pulse based on the initial magnetization vector, the imaging pulse turning angle, the fat pressing pulse turning angle and the number of imaging pulses between adjacent fat pressing pulses.
In one embodiment, the computer program when executed by the processor further performs the steps of:
and calculating a signal value of fat before the excitation of the imaging pulse based on the steady state value, the initial magnetization vector and the turnover angle of the fat pressing pulse.
In one embodiment, the computer program when executed by the processor further performs the steps of:
and calculating the fat zero point position under the condition that the transverse magnetic vector is completely dephased based on the signal value, the steady state value, the initial magnetization vector and the grease pressing pulse overturning angle.
In one embodiment, the computer program when executed by the processor further performs the steps of:
calculating the zero position of the target fat under the condition that the transverse magnetic vector is completely dephased;
searching a corresponding target deviation amount in a deviation amount lookup table according to the fat-pressing body part;
the target fat zero point position is corrected based on the target deviation amount.
In one embodiment, the computer program when executed by the processor further performs the steps of:
and adjusting the acquisition sequence of the K space by a cyclic movement method to enable the corrected fat zero point to be filled in the central position of the K space.
In one embodiment, the computer program when executed by the processor further performs the steps of:
determining scanning parameters corresponding to a part to be scanned;
respectively applying a pressurized fat pulse and an imaging pulse to a scanning part according to the scanning parameters, and acquiring a magnetic resonance signal of the part to be scanned;
acquiring a corrected fat zero position, filling a magnetic resonance signal into a K space according to the corrected fat zero position, and acquiring K space data;
reconstructing K space data, and acquiring a fat pressing image of a part to be scanned;
acquiring the corrected fat zero point position includes:
obtaining a theoretical fat zero position under the condition that the transverse magnetic vector is completely dephased;
adopting extended phase diagram simulation to obtain a simulated fat zero position under the actual condition;
acquiring deviation between a theoretical fat zero point position and a simulated fat zero point position, and acquiring a deviation amount lookup table, wherein the deviation amount lookup table records deviation amounts of different body parts;
and correcting theoretical fat zero positions of different body parts based on the deviation amount lookup table to obtain corrected fat zero positions.
In one embodiment, the computer program when executed by the processor further performs the steps of:
and adjusting the filling sequence of the magnetic resonance signals according to the fat zero point position, so that the fat zero point position corresponds to the center of the K space.
According to the method for correcting the zero point deviation of the fat in the magnetic resonance imaging, the magnetic resonance imaging method and the computer equipment, the deviation between the theoretical zero point position of the fat and the simulated zero point position of the fat is obtained, the deviation amount lookup tables of different body parts are obtained through recording, and then the zero point positions of the fat of different body parts are corrected based on the deviation amount lookup tables, so that a doctor can find corresponding deviation values to correct the theoretical zero point positions of the fat of different body parts when pressing the fat of different body parts, the zero point position of the fat is closer to the actual condition, and a better fat pressing effect is achieved.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above may be implemented by hardware that is instructed by a computer program, and the computer program may be stored in a non-volatile computer-readable storage medium, and when executed, may include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), rambus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
All possible combinations of the technical features in the above embodiments may not be described for the sake of brevity, but should be considered as being within the scope of the present disclosure as long as there is no contradiction between the combinations of the technical features.
The above examples only express several embodiments of the present application, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent application shall be subject to the appended claims.
Claims (9)
1. A fat zero offset correction method in magnetic resonance imaging is used for correcting fat zero positions in a rapid fat pressing GRE3D pulse sequence, and is characterized by comprising the following steps:
calculating a steady state value of fat before the stimulation of the fat pressing pulse;
calculating a signal value of fat before excitation of an imaging pulse based on the steady state value;
calculating and obtaining a theoretical fat zero position under the condition of completely dephasing transverse magnetic vectors based on the signal value;
adopting an expanded phase diagram to simulate to obtain a simulated fat zero position under the actual condition;
acquiring the deviation between a theoretical fat zero position and a simulated fat zero position, and acquiring a deviation value lookup table, wherein the deviation value lookup table records the deviation values of different body parts;
and correcting the theoretical fat zero point positions of different body parts based on the deviation amount lookup table.
2. The method of claim 1, wherein calculating the steady state value of fat prior to stimulation by the pressure pulse comprises:
and calculating the steady state value of the fat before the excitation of the fat pressing pulse based on the initial magnetization vector, the imaging pulse turning angle, the fat pressing pulse turning angle and the number of imaging pulses between adjacent fat pressing pulses.
3. The method of claim 1, wherein the calculating the signal value of fat before excitation of the imaging pulse based on the steady state value comprises:
and calculating a signal value of fat before the excitation of the imaging pulse based on the steady state value, the initial magnetization vector and the turnover angle of the fat pressing pulse.
4. The method of claim 1, wherein the calculating the fat null position with fully dephasing of the transverse magnetic vector based on the signal values comprises:
and calculating the fat zero point position under the condition that the transverse magnetic vector is completely dephased based on the signal value, the steady state value, the initial magnetization vector and the grease pressing pulse overturning angle.
5. The method of claim 1, wherein the correcting theoretical fat null positions for different body parts based on the offset look-up table comprises:
calculating the zero position of the target fat under the condition that the transverse magnetic vector is completely dephased;
searching a corresponding target deviation amount in the deviation amount lookup table according to the fat-pressed body part;
correcting the target fat zero point position based on the target deviation amount.
6. The method of claim 1, wherein after correcting the theoretical fat zero location for different body parts based on the offset look-up table, further comprising:
and adjusting the acquisition sequence of the K space by a cyclic movement method to enable the corrected fat zero point to be filled in the central position of the K space.
7. A magnetic resonance imaging method, comprising:
determining scanning parameters corresponding to a part to be scanned;
respectively applying a pressure fat pulse and an imaging pulse to the scanning part according to the scanning parameters, and acquiring a magnetic resonance signal of the part to be scanned, wherein the pressure fat pulse is a rapid pressure fat GRE3D pulse sequence;
acquiring a corrected fat zero position, and filling the magnetic resonance signal into a K space according to the corrected fat zero position to acquire K space data;
reconstructing the K space data to obtain a fat pressing image of a part to be scanned;
the acquiring the corrected fat zero point position includes:
calculating a steady state value of fat before the stimulation of the fat pressing pulse;
calculating a signal value of fat before excitation of an imaging pulse based on the steady state value; calculating and obtaining a theoretical fat zero point position under the condition that the transverse magnetic vector is completely dephased based on the signal value;
adopting an expanded phase diagram to simulate to obtain a simulated fat zero position under the actual condition;
obtaining the deviation between the theoretical fat zero point position and the simulated fat zero point position, and obtaining a deviation amount lookup table, wherein,
the deviation amount lookup table records deviation amounts of different body parts;
and correcting theoretical fat zero positions of different body parts based on the deviation amount lookup table to obtain corrected fat zero positions.
8. The method of claim 7, wherein the filling of the K-space with the magnetic resonance signals according to fat null positions, the acquiring of K-space data comprises:
and adjusting the filling sequence of the magnetic resonance signals according to the corrected fat zero point position, so that the fat zero point position corresponds to the K space center.
9. A computer device comprising a memory and a processor, the memory storing a computer program, wherein the processor implements the steps of the method of any one of claims 1 to 8 when executing the computer program.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5270652A (en) * | 1992-05-20 | 1993-12-14 | North American Philips Corporation | MR method and apparatus employing magnetization transfer contrast inducing fat-selective RF pulse |
| CN103654779A (en) * | 2012-09-26 | 2014-03-26 | 西门子(深圳)磁共振有限公司 | Magnetic resonance imaging method and device |
| CN105929350A (en) * | 2016-05-05 | 2016-09-07 | 大连锐谱科技有限责任公司 | Single-excitation fat-water separation imaging error correction system and method |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7099499B2 (en) * | 2002-08-15 | 2006-08-29 | General Electric Company | Fat/water separation and fat minimization magnetic resonance imaging systems and methods |
| US8010179B2 (en) * | 2003-09-25 | 2011-08-30 | General Electric Company | Method and apparatus of gradient echo imaging with on-the-fly optimization of tissue suppression |
| US7706855B1 (en) * | 2004-07-20 | 2010-04-27 | General Electric Company | System and method for MR data acquisition with uniform fat suppression |
| US20080081986A1 (en) * | 2006-09-29 | 2008-04-03 | General Electric Company | Method and apparatus for generating a magnetic resonance image |
| JP5366484B2 (en) * | 2007-09-28 | 2013-12-11 | 株式会社東芝 | Magnetic resonance imaging apparatus and analysis method of fat suppression effect in the magnetic resonance imaging apparatus |
| JP5508697B2 (en) * | 2007-10-04 | 2014-06-04 | 株式会社東芝 | MRI equipment |
| DE102008057294B4 (en) * | 2008-11-14 | 2010-10-07 | Siemens Aktiengesellschaft | Separation of fat and water images according to the two-point Dixon method, taking into account the T * 2 decay |
| JP5355240B2 (en) * | 2009-06-17 | 2013-11-27 | 株式会社東芝 | Image processing apparatus, magnetic resonance imaging apparatus, and image management system |
| CN102772206B (en) * | 2011-05-12 | 2014-11-19 | 上海联影医疗科技有限公司 | Magnetic resonance imaging method |
| JP6045793B2 (en) * | 2012-01-13 | 2016-12-14 | 東芝メディカルシステムズ株式会社 | Magnetic resonance imaging device |
| DE102012218422B3 (en) * | 2012-10-10 | 2014-02-27 | Siemens Aktiengesellschaft | Method for recording image of patient with magnetic resonance device using e.g. point wise encoding time reduction with radial acquisition sequence, involves providing part of measuring points of region of k-space close to center of K-space |
| JP6391920B2 (en) * | 2013-07-09 | 2018-09-19 | キヤノンメディカルシステムズ株式会社 | Magnetic resonance imaging system |
| CN106466182B (en) * | 2015-08-18 | 2020-03-31 | 上海联影医疗科技有限公司 | Magnetic resonance imaging method and system |
| US10557906B2 (en) * | 2016-04-29 | 2020-02-11 | The Chinese University Of Hong Kong | Quantitative magnetic resonance imaging relaxometry with suppression of blood signal |
| CN108363026A (en) * | 2018-03-05 | 2018-08-03 | 奥泰医疗系统有限责任公司 | A kind of black blood MR imaging method of fat compacting |
-
2018
- 2018-12-20 CN CN201811563710.XA patent/CN109620228B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5270652A (en) * | 1992-05-20 | 1993-12-14 | North American Philips Corporation | MR method and apparatus employing magnetization transfer contrast inducing fat-selective RF pulse |
| CN103654779A (en) * | 2012-09-26 | 2014-03-26 | 西门子(深圳)磁共振有限公司 | Magnetic resonance imaging method and device |
| CN105929350A (en) * | 2016-05-05 | 2016-09-07 | 大连锐谱科技有限责任公司 | Single-excitation fat-water separation imaging error correction system and method |
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