CN110988764B - Tissue parameter monitoring method, device, imaging system and medium - Google Patents

Tissue parameter monitoring method, device, imaging system and medium Download PDF

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CN110988764B
CN110988764B CN201911265477.1A CN201911265477A CN110988764B CN 110988764 B CN110988764 B CN 110988764B CN 201911265477 A CN201911265477 A CN 201911265477A CN 110988764 B CN110988764 B CN 110988764B
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magnetic resonance
displacement
sequence
target tissue
resonance image
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CN110988764A (en
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郑海荣
刘新
乔阳紫
邹超
孟德
程传力
帖长军
文剑洪
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Shenzhen Institute of Advanced Technology of CAS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/543—Control of the operation of the MR system, e.g. setting of acquisition parameters prior to or during MR data acquisition, dynamic shimming, use of one or more scout images for scan plane prescription
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0033—Features or image-related aspects of imaging apparatus classified in A61B5/00, e.g. for MRI, optical tomography or impedance tomography apparatus; arrangements of imaging apparatus in a room
    • A61B5/0035—Features or image-related aspects of imaging apparatus classified in A61B5/00, e.g. for MRI, optical tomography or impedance tomography apparatus; arrangements of imaging apparatus in a room adapted for acquisition of images from more than one imaging mode, e.g. combining MRI and optical tomography
    • A—HUMAN NECESSITIES
    • 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
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings
    • A61B8/0833—Detecting organic movements or changes, e.g. tumours, cysts, swellings involving detecting or locating foreign bodies or organic structures
    • A61B8/085—Detecting organic movements or changes, e.g. tumours, cysts, swellings involving detecting or locating foreign bodies or organic structures for locating body or organic structures, e.g. tumours, calculi, blood vessels, nodules
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/52—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/5215—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving processing of medical diagnostic data
    • A61B8/5238—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving processing of medical diagnostic data for combining image data of patient, e.g. merging several images from different acquisition modes into one image
    • A61B8/5261—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving processing of medical diagnostic data for combining image data of patient, e.g. merging several images from different acquisition modes into one image combining images from different diagnostic modalities, e.g. ultrasound and X-ray

Abstract

The embodiment of the invention discloses a method and a device for monitoring tissue parameters, an imaging system and a medium, wherein the method comprises the following steps: acquiring magnetic resonance data of a target tissue implementing the encoding pulse signals corresponding to the encoding time sequence to obtain a reference magnetic resonance image; acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the displacement preparation sequence is implemented so as to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before an imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissues, which is generated by the high-intensity focusing pulses, onto longitudinal magnetization vectors; and determining the displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field. The problem of ultrasonic energy deposit too much in the cranium when present magnetic resonance acoustic radiation force imaging technique is through cranium tight-focusing is solved.

Description

Tissue parameter monitoring method, device, imaging system and medium
Technical Field
The embodiment of the invention relates to the field of medical imaging, in particular to a method and a device for monitoring tissue parameters, an imaging system and a medium.
Background
The ultrasonic nerve regulation and control technology can non-invasively focus ultrasonic energy on a brain target area, and achieve the excitation or inhibition effect on the activity of cells of a special functional nerve nucleus group. "noninvasive transcranial" is a key advantage of ultrasound neuromodulation and is a great challenge. The accuracy of locating the actual site of action of ultrasound is critical to ensure the safety and effectiveness of ultrasound neuromodulation.
Magnetic resonance acoustic radiation force imaging (MR-ARFI) is an ultrasound monitoring technique. The magnetic resonance acoustic radiation force imaging of the prior art can encode local tissue displacement caused by the action of ultrasonic pulses in the millisecond range (5-20ms) as image phase contrast. The method specifically comprises the following steps: by adding a pair of displacement encoding gradients before reading out the gradients and controlling the relative duration of the ultrasonic working time and one of the displacement encoding gradients, the displacement information caused by the ultrasonic radiation force is encoded into a magnetic resonance phase diagram to monitor the ultrasonic focus. The method is sensitive to ultrasonic mechanical action, short in action time of single ultrasonic pulse, low in duty ratio and free of obvious temperature rise. However, MR-ARFI based on spin echo or gradient echo require multiple repeated ultrasound pulse excitations, which may cause local heating of tissue, and in ultrasound neuromodulation may cause biological effects. Although MR-ARFI based on single-shot planar echo imaging can image displacement caused by ultrasonic radiation force only by one-time ultrasonic pulse excitation, planar echo imaging generally has high requirements on magnetic resonance imaging system hardware and a large number of imaging artifacts, and may cause error of focal displacement estimation in ultrasonic nerve regulation and control focal positioning, thereby causing potential safety hazards.
In conclusion, the existing magnetic resonance acoustic radiation force imaging technology has the safety problem of excessive ultrasonic energy deposition in focus displacement monitoring.
Disclosure of Invention
The embodiment of the invention provides a method, a device, an imaging system and a medium for monitoring tissue parameters, which solve the safety problem of excessive ultrasonic energy deposition in focus displacement monitoring in the existing magnetic resonance acoustic radiation force imaging technology.
In a first aspect, an embodiment of the present invention provides a method for monitoring a tissue parameter, including:
acquiring magnetic resonance data of a target tissue of a coding pulse signal corresponding to a coding time sequence after implementation to obtain a reference magnetic resonance image;
acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the displacement preparation sequence is implemented so as to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before an imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissues, which is generated by the high-intensity focusing pulses, onto longitudinal magnetization vectors;
and determining the displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field.
In a second aspect, an embodiment of the present invention further provides a tissue parameter monitoring apparatus, including:
a reference image acquisition module for acquiring magnetic resonance data of a target tissue of an encoding pulse signal corresponding to an encoding time sequence after implementation of encoding to obtain a reference magnetic resonance image;
the quantitative image acquisition module is used for acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the implementation of the displacement preparation sequence so as to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before the imaging sequence and comprises an ultrasonic time sequence used for generating high-intensity focusing pulses and an encoding time sequence used for encoding displacement information of the target tissues generated by the high-intensity focusing pulses onto longitudinal magnetization vectors;
and the displacement quantification module is used for determining a displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantification magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field.
In a third aspect, an embodiment of the present invention further provides an imaging system, including:
the ultrasonic device is used for outputting ultrahigh-strength focusing pulses to target tissues under the control of an ultrasonic time sequence;
the magnetic resonance device is used for outputting encoding pulses to the target tissue under the control of the encoding time sequence so as to realize the encoding of the displacement information of the target tissue and outputting imaging pulses to the target tissue under the control of the imaging sequence so as to obtain magnetic resonance data;
a processor for controlling the magnetic resonance apparatus to acquire magnetic resonance data of the target tissue subjected to the encoding pulse through an imaging sequence to obtain a reference magnetic resonance image; the magnetic resonance imaging device is used for controlling the magnetic resonance device to acquire magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the displacement preparation sequence is implemented so as to obtain a quantitative magnetic resonance image; and determining a displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantification magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field, wherein the displacement preparation sequence is applied before the imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissue generated by the high-intensity focusing pulses onto the longitudinal magnetization vector.
In a fourth aspect, embodiments of the present invention further provide a storage medium containing computer-executable instructions, which when executed by a computer processor, are configured to perform the tissue parameter monitoring method according to any of the embodiments.
According to the technical scheme of the tissue parameter monitoring method provided by the embodiment of the invention, magnetic resonance data of a target tissue of a coding pulse signal corresponding to a coding time sequence is obtained to obtain a reference magnetic resonance image; acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the displacement preparation sequence is implemented so as to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before an imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissues, which is generated by the high-intensity focusing pulses, onto longitudinal magnetization vectors; and determining the displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field. The displacement information of the target tissue generated by the high-intensity focusing pulse is encoded on the longitudinal magnetization vector, so that the displacement change of the target tissue is determined through the amplitude information change of the magnetic resonance image, the phase change corresponding to the displacement change is realized, the phase change caused by the displacement and the phase change caused by the temperature do not need to be separated, the displacement quantitative result of the target tissue can be directly obtained, only single ultrasonic excitation is needed, the imaging speed is determined by an imaging sequence and is not limited by a displacement preparation sequence, the artifact of the obtained image is small, the displacement quantification is simple, and the accuracy is high.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a flow chart of a tissue parameter monitoring method according to an embodiment of the present invention;
FIG. 2A is a schematic diagram of a coding sequence according to an embodiment of the present invention;
FIG. 2B is a diagram of a fast imaging sequence provided by an embodiment of the present invention;
FIG. 2C is a diagram of a shift preparation sequence according to an embodiment of the present invention;
FIG. 3 is a flowchart of a tissue parameter monitoring method according to a second embodiment of the present invention;
FIG. 4 is a flowchart of a tissue parameter monitoring method according to a third embodiment of the present invention;
FIG. 5A is a diagram of a displacement preparation sequence provided in accordance with a third embodiment of the present invention;
FIG. 5B is a diagram of a contrast shift preparation sequence provided in the third embodiment of the present invention;
fig. 6 is a block diagram of a tissue monitoring apparatus according to a fourth embodiment of the present invention;
fig. 7 is a block diagram of a further tissue monitoring device according to a fourth embodiment of the present invention;
fig. 8 is a block diagram of an acoustic radiation force magnetic resonance imaging system according to a fifth embodiment of the present invention;
fig. 9 is a block diagram of a structure of another acoustic radiation force magnetic resonance imaging system according to a fifth embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described through embodiments with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example one
Fig. 1 is a flowchart of a tissue parameter monitoring method according to an embodiment of the present invention. The technical solution of the present embodiment is suitable for monitoring tissue parameters by an acoustic radiation force magnetic resonance imaging system. The method can be executed by a tissue parameter monitoring device provided by the embodiment of the invention, and the device can be realized in a software and/or hardware manner and is configured to be applied in a processor of an acoustic radiation force magnetic resonance imaging system. The method specifically comprises the following steps:
s101, acquiring magnetic resonance data of a target tissue of the encoding pulse signal corresponding to the encoding time sequence to obtain a reference magnetic resonance image.
It will be appreciated that the displacement of the target tissue is relative to its reference state, and that in determining the current displacement result of the target tissue, it is necessary to acquire a magnetic resonance image of the target tissue in the reference state, i.e. a reference magnetic resonance image.
When acquiring a reference magnetic resonance image of a target tissue, an encoding pulse corresponding to an encoding time sequence is applied to the target tissue. After the encoding pulse is applied, the imaging pulse corresponding to the imaging sequence is applied to the target tissue to obtain magnetic resonance data of the target tissue, and then the magnetic resonance data is subjected to image reconstruction to obtain a reference magnetic resonance image of the target tissue.
Wherein the encoding timing is located prior to the imaging sequence. As shown in fig. 2A, the encoding timing includes timing information of the rf pulse, the displacement encoding gradient, and the spoiled gradient. The radio frequency pulse comprises two 90-degree inversion pulses and a 180-degree radio frequency pulse positioned between the two 90-degree inversion pulses, the longitudinal magnetization vector of the target tissue is inverted to a transverse plane through the first 90-degree inversion pulse, the magnetization vector currently positioned in the transverse plane is subjected to mirror inversion through the 180-degree radio frequency pulse, and finally the magnetization vector positioned in the transverse plane is inverted to the longitudinal direction again through the second 90-degree inversion pulse. The displacement encoding gradient may be a unipolar displacement encoding gradient, a repeating bipolar displacement encoding gradient, or an inverted bipolar displacement encoding gradient.
With radio-frequency pulses including
Figure GDA0003154403020000061
Figure GDA0003154403020000062
And
Figure GDA0003154403020000063
the displacement encoding gradient is a unipolar displacement encoding gradient, for example, the displacement encoding gradient is located at
Figure GDA0003154403020000064
Before and after the RF pulse
Figure GDA0003154403020000065
The residual magnetization vector of the transverse plane is then broken up by the destruction gradient to facilitate subsequent rapid imaging sequence use. It can be understood that if the target tissue is in a static state, the accumulated phase of the target tissue after the displacement encoding gradient is 0, and the corresponding longitudinal magnetization vector can be expressed as:
Figure GDA0003154403020000066
wherein M is0Is the total magnetization vector in the thermal equilibrium state,
Figure GDA0003154403020000067
phase due to B0 field inhomogeneity, susceptibility, etc., exp (-bD) signal attenuation due to diffusion, TpMEGTo encode the temporal duration of action, T2 is the transverse relaxation time.
It will be appreciated that if the second 90 degree inversion pulse is
Figure GDA0003154403020000068
Then after the corresponding encoding pulse is applied, the corresponding longitudinal magnetization vector of the target tissue can be expressed as:
Figure GDA0003154403020000069
it can be understood that, for the target tissue to which the encoding pulse signal corresponding to the encoding sequence has been applied, the phase information of the corresponding reference magnetic resonance image does not change due to the effect of the encoding pulse, so the phase information of the reference magnetic resonance image corresponds to the reference state of the target tissue.
In this embodiment, the SPGRE is taken as an example (see fig. 2B), and the imaging sequence may be selected according to specific situations in actual use.
S102, acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the implementation of the displacement preparation sequence to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before the imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissues generated by the high-intensity focusing pulses onto longitudinal magnetization vectors.
Wherein the displacement preparation sequence precedes the imaging sequence, which comprises the ultrasound timing sequence and the aforementioned encoding timing sequence. The ultrasonic time sequence is used for controlling the high-intensity focused ultrasonic system to transmit the corresponding high-intensity focused ultrasonic pulse.
For the displacement preparation sequence, see fig. 2C, it is used to invert the longitudinal magnetization vector of the target tissue to the transverse plane by the first 90-degree inversion pulse, mirror-invert the magnetization vector currently in the transverse plane by the 180-degree radio frequency pulse, apply the displacement encoding gradient before and after the 180-degree radio frequency pulse, and simultaneously apply the high-intensity focusing pulse on the first displacement encoding gradient, so that the target tissue is displaced after the high-intensity focusing pulse, and after the displacement encoding gradient encoding, the displacement is proportional to the corresponding phase change, then invert the magnetization vector in the transverse plane to the longitudinal direction by the second 90-degree inversion pulse, and finally break up the residual magnetization vector in the transverse plane by the spoiling gradient for use by the subsequent rapid imaging sequence. And finally the included angle between the magnetization vector turned to the longitudinal direction and the y axis is
Figure GDA0003154403020000071
To be received
Figure GDA0003154403020000072
And diffusion tensor modulation.
The longitudinal magnetization vector of the target tissue after being acted on by each pulse corresponding to the displacement preparation sequence can be expressed as:
Figure GDA0003154403020000073
therefore, the displacement information of the target tissue generated by the high-intensity focusing pulse can be encoded on the longitudinal magnetization vector by controlling each pulse corresponding to the displacement preparation sequence to act on the target tissue, the imaging pulse corresponding to the imaging sequence is applied to the target tissue at the moment to obtain corresponding magnetic resonance data, and then the magnetic resonance data is subjected to image reconstruction to obtain a quantitative magnetic resonance image of the target tissue. It will be appreciated that the quantitative magnetic resonance image carries information about the displacement of the target tissue due to the high intensity focused pulses.
In order to improve the accuracy of monitoring the displacement of the target tissue, the imaging sequence of the embodiment preferably adopts a fast imaging sequence, and when acquiring magnetic resonance data, the K-space middle line is acquired first, and then other non-central lines are acquired, so as to ensure the timeliness of key data acquisition.
It should be noted that, the magnetic resonance image reconstruction method in the prior art is only required to perform image reconstruction on the magnetic resonance data acquired in the present embodiment, and the present embodiment is not limited herein.
S103, determining a displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantification magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field.
Wherein main magnetic field inhomogeneity causes a phase change as described above
Figure GDA0003154403020000081
In some embodiments, prior art acquisition may be employed.
After the reference magnetic resonance image and the quantitative magnetic resonance image are obtained, a displacement quantitative result of the target tissue can be determined according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field. The method specifically comprises the following steps:
taking the imaging sequence as an spGRE sequence as an example, the amplitude of the signal model can be expressed as:
S＝M0 cos(α)exp(-TE/T2) (4)
wherein alpha is the included angle between the magnetization variable and the y axis, and TE is the echo time.
If the second 90-degree flip pulse corresponding to the coding time sequence is-90-xThen the amplitude expression of the reference magnetic resonance image is:
Sp_refx＝Mp_refx cos(α)exp(-TE/T2) (5)
the amplitude expression of the quantitative magnetic resonance image is:
Sp＝Mp cos(α)exp(-TE/T2) (6)
when main magnetic field inhomogeneity causes a phase change to be known
Figure GDA0003154403020000082
The amount of phase change due to the movement of the target tissue can be expressed as:
Figure GDA0003154403020000091
accordingly, the amount of change in displacement of the target tissue can be expressed as:
Figure GDA0003154403020000092
wherein gamma is the magnetic rotation ratio, Geτ is the moment of the displacement encoding gradient.
It can be understood that the signal models of different fast imaging sequences are different, and the correction of the signal should be performed according to the specific models in the practical application process.
In some embodiments, the phase change caused by main magnetic field inhomogeneity
Figure GDA0003154403020000093
Can be obtained from two reference magnetic resonance images. Illustratively, after acquiring the reference magnetic resonance image, another set of encoding pulses is applied to the target tissue, and the second 90-degree flip pulse of the set of encoding pulses is
Figure GDA0003154403020000094
The amplitude expression for the reference magnetic resonance image is then:
Sp_refy＝Mp_refy cos(α)exp(-TE/T2) (9)
from equations (4) and (8), the expression for the phase change due to main magnetic field inhomogeneity can be found as:
Figure GDA0003154403020000095
of course, the phase change caused by main magnetic field inhomogeneity can also be determined according to other methods, and this embodiment only gives an exemplary illustration.
According to the technical scheme of the tissue parameter monitoring method provided by the embodiment of the invention, magnetic resonance data of a target tissue of a coding pulse signal corresponding to a coding time sequence is obtained to obtain a reference magnetic resonance image; acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the displacement preparation sequence is implemented so as to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before an imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissues, which is generated by the high-intensity focusing pulses, onto longitudinal magnetization vectors; and determining the displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field. The displacement information of the target tissue generated by the high-intensity focusing pulse is coded on the longitudinal magnetization vector, so that the displacement change of the target tissue is reflected through the amplitude information change of the magnetic resonance image, the phase change caused by the displacement and the phase change caused by the temperature are not required to be separated, the displacement quantitative result of the target tissue can be directly obtained, only single ultrasonic excitation is required, the imaging speed is determined by an imaging sequence and is not limited by a displacement preparation sequence, the obtained image has small artifacts, the clinical diagnosis of doctors is facilitated, and the displacement quantification is simple and high in accuracy.
Example two
Fig. 3 is a flowchart of a tissue parameter monitoring method according to a second embodiment of the present invention. The embodiment of the invention is added with a step of carrying out temperature quantification on the target tissue on the basis of the embodiment.
Correspondingly, the method of the embodiment comprises the following steps:
s201, acquiring magnetic resonance data of the target tissue of the encoding pulse signal corresponding to the encoding time sequence to obtain a reference magnetic resonance image.
S202, acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the implementation of the displacement preparation sequence to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before the imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissues generated by the high-intensity focusing pulses onto longitudinal magnetization vectors.
The magnetic resonance data in this embodiment is obtained based on a temperature sensitive sequence for fast imaging, and the temperature sensitive sequence carries displacement information, and the corresponding K space acquisition mode is that a K space center line is acquired first, and then a K space non-center line is acquired.
S203, determining a displacement quantification result of the target tissue according to the amplitude information of the main magnetic field reference magnetic resonance image, the amplitude information of the quantification magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field.
And S204, subtracting the phase change caused by the main magnetic field inhomogeneity and the phase angle change amount caused by the target tissue displacement change from the phase of the current quantitative magnetic resonance image, and taking the subtraction result as the phase angle change amount caused by the temperature change of the target tissue.
Since the phase information of the magnetic resonance image changes with the temperature of the measured tissue, and the phase information of the magnetic resonance image includes the phase change caused by the inhomogeneity of the main magnetic field, the phase angle change caused by the displacement change of the tissue, and the phase angle change caused by the temperature change, equation (7) has determined the phase change caused by the displacement of the target tissue according to the amplitude information of the quantitative magnetic resonance image. Therefore, the phase angle variation of the target tissue caused by the temperature variation is: the phase of the current quantitative magnetic resonance image is subtracted by the difference between the phase change due to main magnetic field inhomogeneity and the amount of phase angle change of the target tissue due to displacement change.
S205, determining a temperature quantification result of the target tissue according to a preset temperature quantification method of the temperature sensitive sequence and a phase angle variation of the target tissue caused by temperature variation.
After the phase angle variation of the target tissue caused by the temperature variation is obtained, determining a temperature quantification result of the target tissue according to a preset temperature quantification method corresponding to the temperature sensitive sequence and the phase angle variation of the target tissue caused by the temperature variation, wherein the phase angle variation comprises the following steps:
Figure GDA0003154403020000111
wherein the content of the first and second substances,
Figure GDA0003154403020000112
to quantify the amount of phase change in a magnetic resonance image due to tissue displacement changes.
The preset temperature quantification method may be an existing temperature quantification method, and this embodiment is not specifically limited herein.
Compared with the prior art, the phase variation caused by the displacement variation of the target tissue is determined by utilizing the amplitude information variation of the quantitative magnetic resonance image, so that the phase variation caused by the temperature variation in the center of the quantitative magnetic resonance image is obtained, when the imaging sequence is a temperature sensitive sequence, the temperature variation of the target tissue can be determined according to the phase variation caused by the temperature variation in the quantitative magnetic resonance image, the phase variation caused by the displacement and the phase variation caused by the temperature are not required to be separated, the displacement and the temperature of the target tissue can be synchronously quantified, the method is convenient and rapid, and the real-time performance of monitoring the parameters of the target tissue is improved.
EXAMPLE III
Fig. 4 is a flowchart of a tissue parameter monitoring method according to a third embodiment of the present invention. The embodiment of the invention adds a T2 synchronous quantitative step on the basis of any embodiment.
Correspondingly, the method of the embodiment comprises the following steps:
s301, magnetic resonance data of the target tissue of the encoding pulse signal corresponding to the encoding time sequence is acquired to obtain a reference magnetic resonance image.
S302, acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the implementation of the displacement preparation sequence to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before the imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissues, which is generated by the high-intensity focusing pulses, onto longitudinal magnetization vectors.
And S303, determining a displacement quantitative result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field.
S304, acquiring magnetic resonance data of the target tissue of each pulse signal corresponding to the contrast displacement preparation sequence to obtain a contrast quantitative magnetic resonance image, wherein the action duration of the contrast displacement preparation sequence is different from that of the displacement preparation sequence.
As shown in fig. 5A and 5B, the shift preparation sequence and the contrast shift preparation sequence have different durations of action, so that the 180-degree rf pulse has different action time and both have T2 weighting properties. Before or after the quantitative magnetic resonance image is acquired, magnetic resonance data of the target tissue of each pulse signal corresponding to the contrast displacement preparation sequence is acquired so as to obtain a contrast quantitative magnetic resonance image.
S305, obtaining a T2 weighted image and a quantitative T2 value according to the amplitude information of the quantitative magnetic resonance data and the amplitude information of the contrast quantitative magnetic resonance data.
Due to the fact that the displacement preparation module has the T2 weighting property, the action time of the control displacement preparation sequence is different from that of the contrast displacement preparation sequence, and then the action time of the 180-degree radio frequency pulse is different. By changing the action time of the 180-degree radio frequency pulse and the action duration of the whole sequence, the longitudinal magnetization vector M of the target tissue influenced by T2 under the action of each pulse corresponding to the displacement preparation sequence can be obtainedp1And the longitudinal magnetization of the target tissue affected by T2 under the action of the pulses corresponding to the contrast shift preparation sequenceVector MP2Are respectively:
Figure GDA0003154403020000131
Figure GDA0003154403020000132
wherein, TpMG1Duration of action of preparing the sequence for displacement, TpMG2The duration of the action of the sequence was prepared for the comparison of the shifts.
Correspondingly, the amplitude expression of the quantitative magnetic resonance image and the amplitude expression of the comparative quantitative magnetic resonance image are respectively as follows:
Figure GDA0003154403020000133
Figure GDA0003154403020000134
the T2 value of the T2 weighted image can be obtained from equation (14) and equation (15) as follows:
Figure GDA0003154403020000135
compared with the prior art, the embodiment directly obtains the T2 weighted image while realizing target tissue displacement monitoring or target tissue displacement monitoring and temperature monitoring, improves the real-time performance of target tissue parameter monitoring and the imaging quality of the magnetic resonance image, and is beneficial to clinical diagnosis of doctors.
Example four
Fig. 6 is a block diagram of a tissue parameter monitoring apparatus according to an embodiment of the present invention. The device is used for executing the tissue parameter monitoring method provided by any of the above embodiments, and the device can be implemented by software or hardware. The device includes:
a reference image acquisition module 11, configured to acquire magnetic resonance data of a target tissue in which an encoding pulse signal corresponding to an encoding time sequence is implemented, so as to obtain a reference magnetic resonance image;
a quantitative image obtaining module 12, configured to obtain magnetic resonance data of a target tissue of each pulse signal corresponding to a displacement preparation sequence, so as to obtain a quantitative magnetic resonance image, where the displacement preparation sequence is applied before an imaging sequence and includes an ultrasound time sequence for generating a high-intensity focusing pulse and an encoding time sequence for encoding displacement information of the target tissue generated by the high-intensity focusing pulse onto a longitudinal magnetization vector;
and the displacement quantification module 13 is configured to determine a displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantification magnetic resonance image, and a phase change caused by inhomogeneity of the main magnetic field.
Optionally, the quantitative image obtaining module 12 may be specifically configured to apply each pulse signal corresponding to the displacement preparation sequence to the target tissue; and acquiring magnetic resonance data of the target tissue of each pulse signal corresponding to the execution of the displacement preparation sequence to obtain a quantitative magnetic resonance image.
Optionally, the reference image obtaining module 11 may be specifically configured to obtain magnetic resonance data of a target tissue in which different encoding pulse signals corresponding to different encoding time sequences are implemented, so as to obtain two sets of reference magnetic resonance images; correspondingly, the displacement quantification module 13 is further configured to determine a phase change caused by inhomogeneity of the main magnetic field according to the amplitude information of the two sets of reference magnetic resonance images; and determining the displacement quantification result of the target tissue according to the determined amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field. The different coding sequences are different in that: the application directions of the corresponding 90-degree inversion pulses for flipping the transverse magnetization vector into the longitudinal magnetization vector are different.
As shown in fig. 7, a temperature quantification module 14 is further included for subtracting the phase change caused by the inhomogeneity of the main magnetic field and the phase angle variation caused by the displacement variation of the target tissue from the phase of the current quantitative magnetic resonance image, and taking the subtraction result as the phase angle variation caused by the temperature variation of the target tissue; and determining a temperature quantification result of the target tissue according to a preset temperature quantification method corresponding to the temperature sensitive sequence and the phase angle variation of the target tissue caused by the temperature variation.
As shown in fig. 7, the apparatus further includes a T2 quantitative module 15, configured to acquire magnetic resonance data of the target tissue in which each pulse signal corresponding to the contrast displacement preparation sequence is implemented, so as to obtain a contrast quantitative magnetic resonance image; obtaining a T2 weighted image and a quantitative T2 value according to the amplitude information of the quantitative magnetic resonance data and the amplitude information of the contrast quantitative magnetic resonance data, wherein the action duration of the contrast displacement preparation sequence is different from the action duration of the displacement preparation sequence
Compared with the prior art, the embodiment of the invention realizes that the displacement change of the target tissue is determined by the amplitude information change of the magnetic resonance image and the phase change corresponding to the displacement change by encoding the displacement information of the target tissue generated by the high-intensity focusing pulse onto the longitudinal magnetization vector, and the phase change caused by the displacement and the phase change caused by the temperature do not need to be separated, so that the displacement quantitative result of the target tissue can be directly obtained.
The tissue parameter monitoring device provided by the embodiment of the invention can execute the tissue parameter monitoring method provided by any embodiment of the invention, and has corresponding functional modules and beneficial effects of the execution method.
EXAMPLE five
Fig. 8 is a schematic structural diagram of an imaging system according to a fifth embodiment of the present invention, which includes an ultrasound apparatus 21, a magnetic resonance apparatus 22, and a processor 23, where the ultrasound apparatus 21 is configured to output an ultra-high strength focused pulse to a target tissue under control of an ultrasound timing sequence; the magnetic resonance device 22 is used for outputting encoding pulses to the target tissue under the control of the encoding time sequence to realize the encoding of the displacement information of the target tissue and outputting imaging pulses to the target tissue under the control of the imaging sequence to obtain magnetic resonance data; the processor 23 is used for controlling the magnetic resonance device to acquire magnetic resonance data of the target tissue subjected to the encoding pulse through an imaging sequence so as to obtain a reference magnetic resonance image; the magnetic resonance imaging device is used for controlling the magnetic resonance device to acquire magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the displacement preparation sequence is implemented so as to obtain a quantitative magnetic resonance image; and determining a displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantification magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field, wherein a displacement preparation sequence is applied before the imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissue generated by the high-intensity focusing pulses onto the longitudinal magnetization vector.
It can be understood that the processor 23 controls the magnetic resonance apparatus to output the encoding pulse to the target tissue through the encoding time sequence, and then controls the magnetic resonance apparatus to acquire the magnetic resonance data of the target tissue to which the encoding pulse is applied through the imaging sequence, so as to obtain the reference magnetic resonance image; then, the magnetic resonance device is controlled by the coding time sequence in the displacement preparation sequence to output coding pulses to the target tissue so as to code the displacement information of the target tissue generated by the high-intensity focusing pulses to a longitudinal magnetization vector, and then the magnetic resonance device is controlled by the imaging sequence to acquire the magnetic resonance data of the target tissue of each pulse signal corresponding to the displacement preparation sequence so as to obtain a quantitative magnetic resonance image.
When acquiring a reference magnetic resonance image of a target tissue, a processor firstly applies encoding pulses corresponding to an encoding time sequence to the target tissue. After the encoding pulse is applied, the processor applies the imaging pulse corresponding to the imaging sequence to the target tissue to obtain the magnetic resonance data of the target tissue, and then performs image reconstruction on the magnetic resonance data to obtain a reference magnetic resonance image of the target tissue.
Wherein the encoding timing is located prior to the imaging sequence. As shown in fig. 2A, the encoding timing includes timing information of the rf pulse, the displacement encoding gradient, and the spoiled gradient. The radio frequency pulse comprises two 90-degree inversion pulses and a 180-degree radio frequency pulse positioned between the two 90-degree inversion pulses, the longitudinal magnetization vector of the target tissue is inverted to a transverse plane through the first 90-degree inversion pulse, the magnetization vector currently positioned in the transverse plane is subjected to mirror inversion through the 180-degree radio frequency pulse, and finally the magnetization vector positioned in the transverse plane is inverted to the longitudinal direction again through the second 90-degree inversion pulse. The displacement encoding gradient may be a unipolar displacement encoding gradient, a repeating bipolar displacement encoding gradient, or an inverted bipolar displacement encoding gradient.
With radio-frequency pulses including
Figure GDA0003154403020000161
And
Figure GDA0003154403020000162
the displacement encoding gradient is a unipolar displacement encoding gradient, for example, the displacement encoding gradient is located at
Figure GDA0003154403020000171
Before and after the RF pulse
Figure GDA0003154403020000172
The residual magnetization vector of the transverse plane is then broken up by the destruction gradient to facilitate subsequent rapid imaging sequence use. It can be understood that if the target tissue is in a static state, the accumulated phase of the target tissue after the displacement encoding gradient is 0, and the corresponding longitudinal magnetization vector can be expressed as:
Figure GDA0003154403020000173
wherein M is0Is (total magnetization vector in thermal equilibrium),
Figure GDA0003154403020000174
phase due to B0 field inhomogeneity, susceptibility, etc., exp (-bD) signal attenuation due to diffusion, TpMEGTo encode the temporal duration of action, T2 is the transverse relaxation time.
It will be appreciated that if the second 90 degree inversion pulse is
Figure GDA0003154403020000175
Then after the corresponding encoding pulse is applied, the corresponding longitudinal magnetization vector of the target tissue can be expressed as:
Figure GDA0003154403020000176
it can be understood that, for the target tissue to which the encoding pulse signal corresponding to the encoding sequence has been applied, the phase information of the corresponding reference magnetic resonance image does not change due to the effect of the encoding pulse, so the phase information of the reference magnetic resonance image corresponds to the reference state of the target tissue.
In this embodiment, the SPGRE is taken as an example (see fig. 2B), and the imaging sequence may be selected according to specific situations in actual use.
Wherein the displacement preparation sequence precedes the imaging sequence, which comprises the ultrasound timing sequence and the aforementioned encoding timing sequence. The ultrasonic time sequence is used for controlling the high-intensity focused ultrasonic system to transmit the corresponding high-intensity focused ultrasonic pulse.
For the displacement preparation sequence, see fig. 2C, it is used to invert the longitudinal magnetization vector of the target tissue to the transverse plane by the first 90-degree inversion pulse, mirror-invert the magnetization vector currently in the transverse plane by the 180-degree rf pulse, apply the displacement encoding gradient before and after the 180-degree rf pulse, and simultaneously apply the high-intensity focusing pulse at the first displacement encoding gradient, so that the target tissue is displaced after the high-intensity focusing pulse, and after being encoded by the displacement encoding gradient, the displacement and the corresponding phase change to be positiveThen the magnetization vector in the transverse plane is inverted again to the longitudinal direction by a second 90-degree inversion pulse, and finally the remanent magnetization vector in the transverse plane is scattered by the spoiling gradient to be used by the subsequent fast imaging sequence. And finally the included angle between the magnetization vector turned to the longitudinal direction and the y axis is
Figure GDA0003154403020000181
Is subjected to T2,
Figure GDA0003154403020000182
And diffusion tensor modulation.
The longitudinal magnetization vector of the target tissue after being acted on by each pulse corresponding to the displacement preparation sequence can be expressed as:
Figure GDA0003154403020000183
therefore, the processor controls each pulse corresponding to the displacement preparation sequence to act on the target tissue, can encode displacement information of the target tissue generated by the high-intensity focusing pulse onto the longitudinal magnetization vector, then apply the imaging pulse corresponding to the imaging sequence to the target tissue to obtain corresponding magnetic resonance data, and then perform image reconstruction on the magnetic resonance data to obtain a quantitative magnetic resonance image of the target tissue. It will be appreciated that the quantitative magnetic resonance image carries information about the displacement of the target tissue due to the high intensity focused pulses.
In order to improve the accuracy of monitoring the displacement of the target tissue, the imaging sequence of the embodiment preferably adopts a fast imaging sequence, and when acquiring magnetic resonance data, the K-space middle line is acquired first, and then other non-central lines are acquired, so as to ensure the timeliness of key data acquisition.
It should be noted that, the magnetic resonance image reconstruction method in the prior art is only required to perform image reconstruction on the magnetic resonance data acquired in the present embodiment, and the present embodiment is not limited herein.
Wherein the phase change caused by inhomogeneity of the main magnetic field is as described above
Figure GDA0003154403020000184
In some embodiments, prior art acquisition may be employed.
After the reference magnetic resonance image and the quantitative magnetic resonance image are obtained, a displacement quantitative result of the target tissue can be determined according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field. The method specifically comprises the following steps:
taking the imaging sequence as an spGRE sequence as an example, the amplitude of the signal model can be expressed as:
S＝M0 cos(α)exp(-TE/T2) (4)
wherein alpha is the included angle between the magnetization variable and the y axis, and TE is the echo time.
If the second 90-degree flip pulse corresponding to the coding time sequence is-90-xThen the amplitude expression of the reference magnetic resonance image is:
Sp_refx＝Mp_refx cos(α)exp(-TE/T2) (5)
the amplitude expression of the quantitative magnetic resonance image is:
Sp＝Mp cos(α)exp(-TE/T2) (6)
when the phase change caused by main magnetic field inhomogeneity is known
Figure GDA0003154403020000191
The phase change amount due to the movement of the target tissue is:
Figure GDA0003154403020000192
the amount of change in displacement of the target tissue can therefore be expressed as:
Figure GDA0003154403020000193
wherein gamma is the magnetic rotation ratio, Geτ is the moment of the displacement encoding gradient.
It can be understood that the signal models of different fast imaging sequences are different, and the correction of the signal should be performed according to the specific models in the practical application process.
In some embodiments, the phase change caused by main magnetic field inhomogeneity
Figure GDA0003154403020000194
Can be obtained from two reference magnetic resonance images. Illustratively, after acquiring the reference magnetic resonance image, another set of encoding pulses is applied to the target tissue, and the second 90-degree flip pulse of the set of encoding pulses is
Figure GDA0003154403020000195
The amplitude expression for the reference magnetic resonance image is then:
Sp_refy＝Mp_refy cos(α)exp(-TE/T2) (9)
from equations (4) and (8), the resulting expression for the phase change due to main magnetic field inhomogeneity is:
Figure GDA0003154403020000201
of course, the phase change caused by main magnetic field inhomogeneity can also be determined according to other methods, and this embodiment only gives an exemplary illustration.
In order to monitor the target tissue displacement information and the temperature information of the target tissue at the same time, in some embodiments, the processor subtracts the phase of the current quantitative magnetic resonance image from the phase change caused by the inhomogeneity of the main magnetic field and the phase angle change amount caused by the target tissue displacement change, and takes the subtraction result as the phase angle change amount caused by the temperature change of the target tissue; and then determining the temperature quantification result of the target tissue according to a preset temperature quantification method of the temperature sensitive sequence and the phase angle variation of the target tissue caused by the temperature variation.
Since the phase information of the magnetic resonance image changes with the temperature of the measured tissue, and the phase information of the magnetic resonance image includes the phase change caused by the inhomogeneity of the main magnetic field, the phase angle change caused by the displacement change of the tissue, and the phase angle change caused by the temperature change, equation (7) has determined the phase change caused by the displacement of the target tissue according to the amplitude information of the quantitative magnetic resonance image. Therefore, the phase angle variation of the target tissue caused by the temperature variation is: the phase of the current quantitative magnetic resonance image is subtracted by the difference between the phase change due to main magnetic field inhomogeneity and the amount of phase angle change of the target tissue due to displacement change.
After the phase angle variation of the target tissue caused by the temperature variation is obtained, the processor determines the temperature quantification result of the target tissue according to a preset temperature quantification method corresponding to the temperature sensitive sequence and the phase angle variation of the target tissue caused by the temperature variation, and the method comprises the following steps:
Figure GDA0003154403020000202
wherein the content of the first and second substances,
Figure GDA0003154403020000211
to quantify the amount of phase change in a magnetic resonance image due to tissue displacement changes.
The preset temperature quantification method may be an existing temperature quantification method, and the present embodiment is not limited in particular.
In order to monitor the displacement information of the target tissue or monitor the displacement information and the temperature information of the target tissue and obtain a high-quality magnetic resonance image, in some embodiments, the processor further obtains magnetic resonance data of the target tissue of each pulse signal corresponding to the contrast displacement preparation sequence to obtain a contrast quantitative magnetic resonance image; and then determining a T2 value of a T2 weighted image according to the amplitude information of the quantitative magnetic resonance data and the amplitude information of the contrast quantitative magnetic resonance data to obtain a T2 weighted image, wherein the action duration of the contrast displacement preparation sequence is different from the action duration of the displacement preparation sequence.
As shown in fig. 5A and 5B, the shift preparation sequence and the contrast shift preparation sequence have different durations of action, so that the 180-degree rf pulse has different action time and both have T2 weighting properties. Before or after the quantitative magnetic resonance image is acquired, the processor also acquires the magnetic resonance data of the target tissue of each pulse signal corresponding to the contrast displacement preparation sequence so as to obtain a contrast quantitative magnetic resonance image.
Since the shift preparation module has the T2 weighting property, as shown in fig. 5A and 5B, the action time of the rf pulse of 180 degrees is different when the control shift preparation sequence is applied and the control shift preparation sequence is applied for a different time length than the control shift preparation sequence. By changing the action time of the 180-degree radio frequency pulse and the action duration of the whole sequence, the longitudinal magnetization vector M of the target tissue influenced by T2 under the action of each pulse corresponding to the displacement preparation sequence can be obtainedp1And the longitudinal magnetization vector M of the target tissue under the influence of T2 under the action of the pulses corresponding to the contrast shift preparation sequenceP2Are respectively:
Figure GDA0003154403020000212
Figure GDA0003154403020000213
wherein, TpMG1Duration of action of preparing the sequence for displacement, TpMG2The duration of the action of the sequence was prepared for the comparison of the shifts.
Correspondingly, the amplitude expression of the quantitative magnetic resonance image and the amplitude expression of the comparative quantitative magnetic resonance image are respectively as follows:
Figure GDA0003154403020000221
Figure GDA0003154403020000222
the T2 value of the T2 weighted image can be obtained from equation 14 and equation 15 as follows:
Figure GDA0003154403020000223
compared with the prior art, the technical scheme of the acoustic radiation force magnetic resonance imaging system provided by this embodiment implements reflection of the displacement change of the target tissue through the amplitude information change of the magnetic resonance image by encoding the displacement information of the target tissue generated by the high-intensity focusing pulse onto the longitudinal magnetization vector, does not need to separate the phase change caused by the displacement from the phase change caused by the temperature, can directly obtain the displacement quantification result of the target tissue, only needs a single ultrasonic excitation, has an imaging speed determined by the imaging sequence, is not limited by the displacement preparation sequence, has small artifacts in the obtained image, is beneficial to clinical diagnosis of a doctor, is simple in displacement quantification and high in accuracy, and can simultaneously implement monitoring of the temperature and/or obtain a high-quality T2 weighted image while implementing monitoring of the displacement of the target tissue
As shown in fig. 9, the system further includes a memory 24, an input device 25, and an output device 26; the number of the processors 23 may be one or more, and fig. 9 exemplifies one processor 23; the processor 23, the memory 24, the input device 25 and the output device 26 may be connected by a bus or other means, and the bus connection is exemplified in fig. 9.
The memory 24 is a computer-readable storage medium, and can be used for storing software programs, computer-executable programs, and modules, such as program instructions/modules (e.g., the reference image acquisition module 11, the quantitative image acquisition module 12, and the displacement quantitative module 3) corresponding to the tissue parameter monitoring method in the embodiment of the present invention. The processor 23 executes various functional applications of the device and data processing by executing software programs, instructions and modules stored in the memory 24, namely, implements the above-mentioned tissue parameter monitoring method.
The memory 24 may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created according to the use of the terminal, and the like. Further, the memory 24 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some examples, the memory 24 may further include memory located remotely from the processor 23, which may be connected to the device over a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The input device 25 may be used to receive input numeric or character information and to generate key signal inputs relating to user settings and function controls of the apparatus.
The output device 26 may include a display device such as a display screen, for example, of a user terminal.
EXAMPLE five
An embodiment of the present invention further provides a storage medium containing computer-executable instructions, which when executed by a computer processor, are configured to perform a method for monitoring tissue parameters, the method including:
acquiring magnetic resonance data of a target tissue of a coding pulse signal corresponding to a coding time sequence after implementation to obtain a reference magnetic resonance image;
acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the displacement preparation sequence is implemented so as to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before an imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissues, which is generated by the high-intensity focusing pulses, onto longitudinal magnetization vectors;
and determining the displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field.
Of course, the storage medium provided by the embodiment of the present invention contains computer-executable instructions, and the computer-executable instructions are not limited to the operations of the method described above, and may also perform related operations in the tissue parameter monitoring method provided by any embodiment of the present invention.
From the above description of the embodiments, it is obvious for those skilled in the art that the present invention can be implemented by software and necessary general hardware, and certainly, can also be implemented by hardware, but the former is a better embodiment in many cases. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which may be stored in a computer-readable storage medium, such as a floppy disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a FLASH Memory (FLASH), a hard disk or an optical disk of a computer, and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device) to execute the organization parameter monitoring method according to the embodiments of the present invention.
It should be noted that, in the embodiment of the organization parameter monitoring apparatus, the included units and modules are only divided according to functional logic, but are not limited to the above division as long as the corresponding functions can be implemented; in addition, specific names of the functional units are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present invention.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (10)

1. A method of monitoring tissue parameters, comprising:
acquiring magnetic resonance data of a target tissue of a coding pulse signal corresponding to a coding time sequence and an imaging pulse corresponding to an imaging sequence which are implemented in sequence to obtain a reference magnetic resonance image;
acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the displacement preparation sequence is implemented so as to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before an imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissues, which is generated by the high-intensity focusing pulses, onto longitudinal magnetization vectors;
and determining a displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantification magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field.
2. The method of claim 1, wherein acquiring magnetic resonance data of the target tissue for each pulse signal corresponding to the displacement preparation sequence to obtain a quantitative magnetic resonance image comprises:
applying each pulse signal corresponding to the displacement preparation sequence to the target tissue;
magnetic resonance data of the target tissue of each pulse signal corresponding to the execution of the displacement preparation sequence is acquired to obtain a quantitative magnetic resonance image.
3. The method according to claim 1, wherein the acquiring magnetic resonance data of the target tissue implementing the encoding time-series corresponding encoding pulse signals to obtain the reference magnetic resonance image comprises:
acquiring magnetic resonance data of a target tissue implementing different encoding pulse signals corresponding to different encoding time sequences to obtain two groups of reference magnetic resonance images, wherein the different encoding time sequences are as follows: the application directions of the 90-degree inversion pulses for flipping the transverse magnetization vector into the longitudinal magnetization vector are different;
correspondingly, the determining the quantitative result of the displacement of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field comprises:
determining phase changes caused by main magnetic field inhomogeneity according to the amplitude information of the two groups of reference magnetic resonance images;
and determining the quantitative result of the displacement of the target tissue according to the phase change caused by the determined main magnetic field inhomogeneity, the amplitude information of one group of reference magnetic resonance images and the amplitude information of the quantitative magnetic resonance images.
4. The method of claim 1, wherein the imaging sequence is a temperature sensitive sequence carrying displacement information.
5. The method of claim 4, wherein the imaging sequence is acquired in K-space by first acquiring a K-space centerline and then acquiring a K-space non-centerline.
6. The method of any one of claims 1-5, wherein the displacement quantification defining a correspondence between a displacement of the target tissue and an amount of change in phase angle of the quantitative magnetic resonance image due to the change in the displacement of the target tissue, and wherein determining the displacement quantification of the target tissue based on the amplitude information of the reference magnetic resonance image, the amplitude information of the quantitative magnetic resonance image, and a change in phase due to inhomogeneity of the main magnetic field further comprises:
subtracting the phase change caused by the inhomogeneity of the main magnetic field and the phase angle variation caused by the displacement change of the target tissue from the phase of the current quantitative magnetic resonance image, and taking the subtraction result as the phase angle variation caused by the temperature change of the target tissue;
and determining a temperature quantification result of the target tissue according to a preset temperature quantification method corresponding to the temperature sensitive sequence and the phase angle variation of the target tissue caused by the temperature variation.
7. The method of claim 1, wherein the rf pulses corresponding to the encoding timings comprise two 90-degree flip pulses and a 180-degree rf pulse located in the middle of the two 90-degree flip pulses, the method further comprising:
acquiring magnetic resonance data of a target tissue of each pulse signal corresponding to the contrast displacement preparation sequence to obtain a contrast quantitative magnetic resonance image;
and obtaining a T2 weighted image and a quantitative T2 value according to the amplitude information of the quantitative magnetic resonance data and the amplitude information of the contrast quantitative magnetic resonance data.
8. A tissue parameter monitoring device, comprising:
the reference image acquisition module is used for acquiring magnetic resonance data of a target tissue of an encoding pulse signal corresponding to an encoding time sequence and an imaging pulse corresponding to an imaging sequence which are implemented in sequence so as to obtain a reference magnetic resonance image;
the quantitative image acquisition module is used for acquiring magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the implementation of the displacement preparation sequence so as to obtain a quantitative magnetic resonance image, wherein the displacement preparation sequence is applied before the imaging sequence and comprises an ultrasonic time sequence used for generating high-intensity focusing pulses and an encoding time sequence used for encoding displacement information of the target tissues generated by the high-intensity focusing pulses onto longitudinal magnetization vectors;
and the displacement quantification module is used for determining a displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantification magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field.
9. An imaging system, comprising:
the ultrasonic device is used for outputting ultrahigh-strength focusing pulses to target tissues under the control of an ultrasonic time sequence;
the magnetic resonance device is used for outputting coding pulses to the target tissue under the control of a coding time sequence in sequence so as to realize the coding of the displacement information of the target tissue and outputting imaging pulses to the target tissue under the control of an imaging sequence so as to obtain magnetic resonance data;
a processor for controlling the magnetic resonance apparatus to acquire magnetic resonance data of the target tissue subjected to the encoding pulse through an imaging sequence to obtain a reference magnetic resonance image; the magnetic resonance imaging device is used for controlling the magnetic resonance device to acquire magnetic resonance data of target tissues of each pulse signal corresponding to the displacement preparation sequence after the displacement preparation sequence is implemented so as to obtain a quantitative magnetic resonance image; and determining a displacement quantification result of the target tissue according to the amplitude information of the reference magnetic resonance image, the amplitude information of the quantification magnetic resonance image and the phase change caused by the inhomogeneity of the main magnetic field, wherein the displacement preparation sequence is applied before the imaging sequence and comprises an ultrasonic time sequence for generating high-intensity focusing pulses and an encoding time sequence for encoding displacement information of the target tissue generated by the high-intensity focusing pulses onto the longitudinal magnetization vector.
10. A storage medium containing computer-executable instructions for performing the tissue parameter monitoring method of any one of claims 1-7 when executed by a computer processor.
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