CN107510458B

CN107510458B - Magnetic resonance imaging method and equipment

Info

Publication number: CN107510458B
Application number: CN201710686293.7A
Authority: CN
Inventors: 徐健
Original assignee: Shanghai United Imaging Healthcare Co Ltd
Current assignee: Shanghai United Imaging Healthcare Co Ltd
Priority date: 2017-08-11
Filing date: 2017-08-11
Publication date: 2020-09-11
Anticipated expiration: 2037-08-11
Also published as: CN107510458A

Abstract

The embodiment of the invention discloses a magnetic resonance imaging method and equipment, wherein the method comprises the following steps: moving a target part to be scanned to a scanning cavity of a magnetic resonance imaging device, wherein the target part comprises a first block and a second block which extend along the long axis direction of the scanning cavity; simultaneously applying a layer selection gradient along the left and right directions; simultaneously exciting a plurality of slice layers of the first block and the second block by using a plurality of radio frequency pulses to acquire magnetic resonance signals corresponding to the slice layers; respectively applying phase coding along the front-back direction and frequency coding along the long axis direction to the magnetic resonance signals to obtain coded data corresponding to the magnetic resonance signals; filling coded data into two independent K spaces respectively; and reconstructing the two K spaces to acquire magnetic resonance images of the first block and the second block. The embodiment of the invention realizes the block acquisition of the target part, effectively shortens the acquisition time and improves the acquisition efficiency.

Description

Magnetic resonance imaging method and equipment

Technical Field

The embodiment of the invention relates to the technical field of magnetic resonance scanning, in particular to a method and equipment for magnetic resonance imaging.

Background

In MRI (Magnetic Resonance Imaging), an MRI apparatus applies a Radio Frequency Pulse (Radio Frequency Pulse) to a human body placed in a Magnetic field, so that nuclei in the human body generate spins to form an MR Signal, and an MRI image is reconstructed according to the MR Signal. The MRI apparatus includes a cylindrical magnet for forming a magnetic field, a cylindrical coil coaxially disposed inside the cylindrical magnet, a gradient magnetic field coil, an RF coil, a control device, and a flat plate for carrying a human body. In the MRI apparatus, the z direction of the spatial coordinate system is set to the axial direction of the cylindrical magnet or the cylindrical coil, the body length direction of the human body is usually aligned with the z direction to perform imaging, the horizontal plane is set to an xz plane, the x direction is perpendicular to the z direction, the y direction is a vertical direction, and the x and z directions are perpendicular to each other.

Currently, the techniques for performing contrast imaging of peripheral lower limb blood vessels using magnetic resonance techniques include: contrast enhancement techniques and non-contrast enhancement techniques, which in turn include 3D imaging techniques.

In 3D imaging, as shown in fig. 1a, a coronal plane, i.e. a plane viewed from top to bottom in a downward-looking manner when a human body lies down for detection, is often scanned to obtain a maximum FOV (field of View). In order to obtain a coronal plane image, a layer selection is performed first in the scanning process, and the layer selection coding direction is performed from the front side to the back side of the human body. As shown in fig. 1b, the human body side section is also called sagittal plane, and the slice selection coding direction is from left to right of the human body. The scanning direction in which the pulse sequence is to be applied is called the phase encoding direction, and is generally performed from the left side to the right side of the human body; the direction of detecting the excited magnetic field signal and filling the read magnetic field signal data into the K space is called the reading direction, and is generally performed from the head to the footsteps of the human body, as shown in fig. 1 a.

Because the lower limb scanning is characterized in that the two legs are parallel and independent, when the encoding direction is selected by adopting the layer surface from front to back of the coronal plane, the coronal plane images of the two legs are simultaneously acquired, the phase encoding number is larger than the coronal plane width of the two legs, the acquisition time is long, the imaging efficiency is low, and the comfort level of a patient is reduced.

Disclosure of Invention

The embodiment of the invention provides a magnetic resonance imaging scanning method, magnetic resonance scanning equipment and a medium, and solves the problems of long acquisition time, low imaging efficiency and poor patient comfort degree of the existing magnetic resonance imaging.

In a first aspect, an embodiment of the present invention provides a magnetic resonance imaging scanning method, including:

moving a target part to be scanned to a scanning cavity of a magnetic resonance imaging device, wherein the target part comprises a first block and a second block which extend along the long axis direction of the scanning cavity;

simultaneously applying a layer selection gradient along the left-right direction to the first block and the second block, and dividing the first block and the second block into a plurality of sheet layers along the left-right direction;

simultaneously exciting a plurality of slice layers of the first block and the second block by using a plurality of radio frequency pulses to acquire magnetic resonance signals corresponding to the slice layers of the first block and the second block;

respectively applying phase encoding along the front-back direction and frequency encoding along the long axis direction to the magnetic resonance signals to acquire encoded data corresponding to the magnetic resonance signals;

filling the encoded data into two K spaces;

and respectively carrying out reconstruction processing on the two K spaces to obtain magnetic resonance images of the first block and the second block.

Optionally, the target portion to be scanned includes two lower limbs or two upper limbs, the left upper limb or the left lower limb corresponds to the first segment, and the right upper limb or the right lower limb corresponds to the second segment.

Optionally, the first and second patches are 3D patches, and each rf pulse simultaneously excites multiple slices of the first patch or multiple slices of the second patch.

Optionally, the method further comprises:

and splicing the magnetic resonance image of the first block and the magnetic resonance image of the second block together according to the structure position of the human body to generate the magnetic resonance image of the target part.

Optionally, the simultaneously exciting the multiple slices of the first block and the second block with multiple radio frequency pulses to acquire magnetic resonance signals corresponding to the multiple slices of the first block and the second block includes:

and respectively carrying out multi-layer magnetic resonance detection on the first sub-block and the second sub-block by using a parallel simultaneous multi-layer excitation method.

Optionally, the plurality of radio frequency pulses comprises a traffic insensitive sequence, the method further comprising:

detecting the first block and the second block by using the flow insensitive sequence to obtain a first type of magnetic resonance signal;

and acquiring a first type magnetic resonance image corresponding to the target part according to the first type magnetic resonance signal.

Optionally, the plurality of radio frequency pulses further comprises a flow sensitive sequence, the method comprising:

detecting the first block and the second block by using the flow sensitive sequence to acquire a second type of magnetic resonance signal;

acquiring a second type magnetic resonance image corresponding to the target part according to the second type magnetic resonance signal;

registering the first and second type of magnetic resonance images;

subtracting the registered second type magnetic resonance image from the registered first type magnetic resonance image to obtain a subtraction image;

and displaying the angiogram corresponding to the subtraction image in the form of the MIP vessel tree.

Optionally, the target site comprises a blood vessel, the method further comprising:

applying a flow-sensitive dephasing gradient magnetic field during the vasoconstriction period, the flow-sensitive dephasing gradient magnetic field being followed by a gradient magnetic field that cancels residual magnetic moments;

collecting a blood flow magnetic resonance image in a vasoconstriction period;

acquiring a blood flow magnetic resonance image in a vasodilation period;

and carrying out weighted or unweighted subtraction on the blood flow magnetic resonance image in the systolic period and the blood flow magnetic resonance image in the diastolic period to obtain a blood flow image.

According to a second aspect of the application, a magnetic resonance scanning apparatus is proposed, comprising:

the scanning bed is used for moving a target part to be scanned to a scanning cavity of the magnetic resonance imaging equipment, and the part to be scanned comprises a first block and a second block which extend along the long axis direction of the scanning cavity;

the radio frequency coil is used for providing a radio frequency pulse which can simultaneously excite a plurality of slice layers of the first block and the second block and acquire magnetic resonance signals corresponding to the slice layers of the first block and the second block;

gradient coils for providing gradient fields for generating gradient fields for slice selection encoding, phase encoding and frequency encoding to acquire encoded data corresponding to the magnetic resonance signals;

one or more processors;

a storage device for storing one or more programs,

the processor executes a program for stuffing the encoded data into two K spaces;

and reconstructing the K space to acquire magnetic resonance images of the first block and the second block.

Optionally, the gradient field corresponding to the slice selection encoding is along the left-right direction, the gradient field corresponding to the phase encoding is along the front-back direction, and the gradient field corresponding to the frequency encoding is along the long axis direction.

According to the embodiment of the invention, the target part to be scanned is divided into the first block and the second block, and the first block and the second block are simultaneously excited by utilizing the radio frequency pulse, so that the block acquisition of the target part is realized, the acquisition time is shortened, and the acquisition efficiency is improved.

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. 1a is a schematic view of a coronal plane scan provided by the background of the present invention;

FIG. 1b is a schematic view of a sagittal scan provided by the background of the present invention;

fig. 2 is a flowchart of a magnetic resonance imaging scanning method according to an embodiment of the present invention;

fig. 3a is a schematic view of a layer selection encoding direction of a left lower limb according to an embodiment of the present invention;

FIG. 3b is a schematic diagram of a layer selection encoding direction of a right lower limb according to an embodiment of the present invention;

fig. 3c is a schematic view of a phase encoding direction of a lower limb according to an embodiment of the present invention;

fig. 4 is a magnetic resonance imaging method according to a second embodiment of the present invention;

FIG. 5a is a first type of magnetic resonance image obtained using a flow insensitive SSFP sequence according to an embodiment of the present application;

FIG. 5b is a second type of magnetic resonance image obtained using a flow sensitive SSFP sequence according to an embodiment of the present application;

figure 5c is a subtraction image obtained using the first type of magnetic resonance image of figure 5a and the second type of magnetic resonance image of figure 5 b;

FIG. 5d is a two lower limb angiogram obtained by maximum intensity projection of FIG. 5 c;

fig. 6 is a schematic structural diagram of a magnetic resonance scanning apparatus according to a third 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.

The application provides a magnetic resonance imaging method, which comprises the following steps: moving a target part to be scanned to a scanning cavity of a magnetic resonance imaging device, wherein the target part comprises a first block and a second block which extend along the long axis direction of the scanning cavity, and each block is a 3D (three-dimensional) volume or volume; simultaneously applying a layer selection gradient along the left-right direction to the first block and the second block, and dividing the first block and the second block into a plurality of sheet layers along the left-right direction; simultaneously exciting a plurality of slice layers of the first block and the second block by using a plurality of radio frequency pulses to acquire magnetic resonance signals corresponding to the slice layers of the first block and the second block; respectively applying phase coding along the front-back direction and frequency coding along the long axis direction to the magnetic resonance signals to obtain coded data corresponding to the magnetic resonance signals; filling the coded data into two K spaces; and reconstructing the two K spaces to acquire magnetic resonance images of the first block and the second block. Optionally, the magnetic resonance images of the first and second blocks are combined to obtain a magnetic resonance image of the target region. Optionally, the magnetic resonance images of the first segment and the second segment at different times or under different imaging conditions are respectively acquired, and blood vessel imaging or lesion detection can be performed on the part to be scanned. It should be noted that the magnetic resonance signal in the present application may include an intrinsic induced decay signal, a spin echo signal, a gradient echo signal, and the like.

Example one

Fig. 2 is a flowchart of a magnetic resonance imaging method according to an embodiment of the present invention. The technical solution of the present embodiment can be applied to the case of performing a magnetic resonance scan. The method specifically comprises the following operations:

s110, moving a target part to be scanned to a scanning cavity or a scanning area of a magnetic resonance imaging device, and dividing the target part into at least two three-dimensional blocks, wherein each three-dimensional block comprises a plurality of (2D) slice layers. In one embodiment, the three-dimensional blocks correspond to the part to be scanned and comprise a first block and a second block which extend along the long axis direction of the scanning cavity (the system axis direction of the scanning cavity). Of course, the long axis direction in the present application may be replaced with the up-down direction/head-to-foot direction of the target portion of the subject.

A three-dimensional block is a portion of a target organ having a volume. The target organ to be scanned may be an organ having at least two independent structures in the human body, each independent structure corresponding to a three-dimensional segment; or at least two parts of an organ, wherein each part can be divided into at least two parts with equal volume according to the volume of the organ, or can be divided into at least two parts at equal distance according to the central axis of the cross section of the organ, and each part corresponds to a three-dimensional block. Illustratively, the head of a person is divided into three parts at equal intervals according to the central axis of the head cross section, namely, the target organ is divided into three-dimensional blocks. The target organ is divided into at least two three-dimensional blocks, so that multi-block synchronous scanning of the target organ can be realized, and the scanning time is shortened.

Wherein the target organ to be scanned may include: both lower limbs or both upper limbs. The two lower limbs or the two upper limbs have independent left and right structures, each of which may correspond to one three-dimensional block, and then moving the target organ to be scanned to the scanning area, and dividing the target organ into at least two three-dimensional blocks includes:

and moving the two lower limbs or the two upper limbs to a scanning area, and dividing the two lower limbs or the two upper limbs into two three-dimensional blocks along the left-right direction, wherein the left upper limb or the left lower limb corresponds to one three-dimensional block, and the right upper limb or the right lower limb corresponds to one three-dimensional block. Further, for both upper limbs, the left upper limb may correspond to the first segment and the right upper limb may correspond to the second segment; for a double lower limb, the left lower limb may correspond to the first segment and the right lower limb may correspond to the second segment.

And S120, simultaneously exciting the at least two three-dimensional blocks by utilizing radio frequency pulses, and acquiring magnetic resonance signals corresponding to the three-dimensional blocks.

And simultaneously exciting each three-dimensional block by a radio frequency pulse, wherein the atomic nucleus in each three-dimensional block generates spin under the action of the radio frequency pulse, so that a magnetic resonance signal corresponding to each block is obtained. Therefore, the target organ is synchronously acquired in blocks, and the acquisition speed of the magnetic resonance signal is improved. Wherein the parameters of the radio frequency pulses exciting the at least two three-dimensional patches are the same. The parameters include amplitude intensity and frequency of the pulses. Thereby ensuring that each three-dimensional block is in the same radio frequency pulse environment.

In this embodiment, the target portion includes a first segment and a second segment extending along the long axis direction of the scanning cavity, and the first segment and the second segment are simultaneously applied with a slice selection gradient along the left-right direction, so that the first segment and the second segment can be divided into a plurality of slices along the left-right direction; and a plurality of radio frequency pulses are utilized to simultaneously excite a plurality of slice layers of the first block and the second block, so that magnetic resonance signals corresponding to the plurality of slice layers of the first block and the second block can be acquired. Further, the first and second sub-blocks may be subjected to multi-layer magnetic resonance detection by using a parallel simultaneous multi-layer excitation method or a compressive sensing method, wherein the compressive sensing method may be referred to as Cand es E J, rommberg J, Tao t. robust across real principles: Exact signal reception from high efficiency in compression information, IEEE transformations on information, 2006,52(2): 489-; the parallel simultaneous multi-layer excitation method can be referred to in Posse S, Ackley E, Mutihac R, et al, enhancement of temporal resolution and BOLD sensitivity in real-time fMRI using multi-slab echo-volume imaging [ J ]. Neuroimage,2012,61(1): 115-130.

And S130, respectively applying phase encoding along the front-back direction and frequency encoding along the long axis direction to the magnetic resonance signals to acquire encoded data corresponding to the magnetic resonance signals.

And the gradient field parameter change rules in different directions applied to each three-dimensional block are the same. The parameters include amplitude intensity and frequency of the pulses. The law of change may be, for example, a gradual decrease or increase in the intensity of the amplitude. Therefore, each three-dimensional block can be ensured to be in the same gradient field, and the situation that errors are caused by different gradient fields is avoided.

In magnetic resonance imaging, when a human body lies on the front or back on a scanning bed, a magnetic resonance signal may be phase-encoded (PE) using a gradient field in the front-back direction (i.e., y direction), slice-Selected (SPE) using a gradient field in the left-right direction (i.e., x direction), and frequency-encoded/frequency-Readout (RE) using a gradient field in the up-down direction (i.e., z direction).

In three-dimensional magnetic resonance imaging, slice selection is first required, frequency encoding and phase encoding are performed within a slice plane, and magnetic resonance signals are distributed to different pixel positions, thereby forming a magnetic resonance image. For example, slice selection encoding may be performed using a gradient field in the left-right direction (left-right direction with respect to the human body), and the phase encoding direction may be perpendicular to the slice selection encoding direction, that is, the phase encoding direction may be the front-back direction/the side direction pointing along the front of the human body. Of course, the slice selection encoding direction is also the front-back direction, and correspondingly, the phase encoding direction is the left-right direction.

Preferably, the performing phase encoding and frequency encoding on the magnetic resonance signals according to gradient fields in different directions respectively includes:

the magnetic resonance signals are subjected to phase encoding by using gradient fields in the front-back direction of the limb, and are subjected to frequency readout encoding in the direction of blood flow in the limb, so that encoded data corresponding to the magnetic resonance signals are acquired.

Exemplarily, fig. 3a is a schematic view of the encoding direction of the coronal plane of the left lower limb; FIG. 3b is a schematic view of the encoding direction of the coronal plane of the right lower limb; FIG. 3c is a schematic view of the encoding direction in the sagittal plane of the lower limb. When the target organ is a lower limb, the width of a single lower limb, such as the left or right lower limb, is half the width of both lower limbs.

In this embodiment, the lower limb of the subject is scanned using the existing method and the method of the present application, respectively. In the process of encoding magnetic resonance signals by adopting the existing method, the reading direction is along the direction of blood flow of the lower limbs (from head to foot); the phase encoding direction is the left-right direction relative to the examinee; the slice selection direction is the anterior-posterior direction relative to the subject. When the prior art is used for scanning, the 3D volume scanned by the whole lower limb comprises 72 layers of two-dimensional slices, the number of encoding bits in the layer selection direction is 72, the number of phase encoding bits in the reading direction is 256, and the number of encoding bits in the phase encoding direction is 192.

In the process of encoding magnetic resonance signals by adopting the method, the lower limb of a detected person is divided into a left three-dimensional block and a right three-dimensional block, namely a first block and a second block, and for each three-dimensional block: the readout direction is along the direction of blood flow in the lower limb (from head to foot) or the long axis direction; the phase encoding direction is the front-back direction relative to the examinee; the slice selection direction is a left-right direction with respect to the subject. When utilizing this application to scan, every three-dimensional piecemeal includes 72 layers two-dimensional slices, and the code number of selecting the direction along the aspect is 72, and the phase place code number of following the readout direction is 256, because the left and right parts of low limbs carry out three-dimensional piecemeal scanning respectively, non-target area can be got rid of to the target area, and the code number of following the phase place code direction is 80.

Compared with the method of carrying out the level selection coding on two lower limbs together by utilizing the gradient fields in the front and back directions, the method has the advantages that the coding quantity is reduced by half, and the coding speed is improved. And simultaneously carrying out phase coding on the single lower limbs which are respectively subjected to the layer selection coding to obtain the coded data corresponding to the single lower limbs.

And S140, filling the coded data into two K spaces, wherein the K spaces correspond to the first block and the second block one to one. The K space in the application is a three-dimensional K space, and each coding position in the three-dimensional K space can correspond to a plurality of pixel points in a subsequent reconstructed image.

And filling the coded data corresponding to the magnetic resonance signals of each three-dimensional block into each K space respectively. The K-space, also known as fourier space, is a filled space of encoded data with spatially localized encoded information, each MR image having its corresponding K-space data lattice. And performing Fourier transform on the data in the K space to obtain MR digital signals with different frequencies, phases and amplitudes corresponding to the encoded data, and distributing the MR digital signals to corresponding pixels to obtain an MR image.

S150, reconstructing the K space to obtain a plurality of slice images or two three-dimensional images, wherein each three-dimensional image can comprise a plurality of two-dimensional slice images.

The first block and the second block correspond to a K space respectively, and the image corresponding to each three-dimensional block is obtained by reconstructing each K space.

Further, S160, performing reconstruction processing on the multiple slice images to obtain a magnetic resonance image corresponding to the target organ/region. For example, the obtained magnetic resonance images of the first and second blocks may be arranged according to a positional relationship of the three-dimensional blocks in the target organ, so as to obtain a magnetic resonance image corresponding to the target organ.

In another preferred embodiment of the present invention, after performing the reconstruction processing on the plurality of slice images to acquire the magnetic resonance image corresponding to the target organ, the method further includes: and splicing the magnetic resonance images corresponding to each three-dimensional block together according to the structure position of the human body for displaying. Therefore, the user can conveniently obtain the complete image of the target organ, and the integral analysis based on the target organ is convenient.

According to the embodiment, the target part to be scanned is divided into the first block and the second block, and the divided three-dimensional blocks are simultaneously excited by utilizing the radio frequency pulse, so that the block acquisition of the target part is realized, the acquisition time is shortened, and the acquisition efficiency is improved.

Example two

Fig. 4 is a magnetic resonance imaging method according to a second embodiment of the present invention. On the basis of the above embodiments, the embodiment of the present invention further defines that the target region is divided into two three-dimensional blocks, and the radio frequency pulse includes a flow insensitive sequence and/or a flow sensitive sequence, where the flow insensitive sequence and/or the flow sensitive sequence may include a fast self-selection echo sequence (FSE), a fast inversion recovery sequence (FIR), a gradient echo sequence (GRE), a normal Steady State Free Precession (SSFP) sequence, a plane echo imaging (EPI) sequence, and the like

The flow insensitive sequence and the flow sensitive sequence of this embodiment are exemplified by SSFP, and the method includes:

s210, moving a target organ to be scanned to a scanning cavity of a magnetic resonance imaging device, and dividing the target organ into two three-dimensional blocks, wherein the two three-dimensional blocks comprise a first block and a second block which extend along the long axis direction of the scanning cavity.

Illustratively, the left lower limb corresponds to a first segment, the right lower limb comprises a second segment, and each three-dimensional segment comprises a plurality of slices.

S220, simultaneously applying a layer selection gradient along the left-right direction to the first block and the second block, and dividing the first block and the second block into a plurality of slice layers along the left-right direction.

And S230, simultaneously exciting the first block and the second block by utilizing a radio frequency pulse, and acquiring proton imaging signals or magnetic resonance imaging signals corresponding to the first block and the second block, wherein the radio frequency pulse comprises a steady state free precession gradient echo (SSFP) sequence which is insensitive to flow and/or a flow sensitive SSFP sequence.

S240, for each three-dimensional block in the two three-dimensional blocks, detecting the three-dimensional block by using the SSFP sequence insensitive to flow to obtain a first type magnetic resonance signal, and obtaining a first type magnetic resonance image corresponding to a target organ according to the first type magnetic resonance signal.

And S250, detecting the three-dimensional blocks by using the flow-sensitive SSFP sequence to obtain a second type magnetic resonance signal, and obtaining a second type magnetic resonance image corresponding to the target organ according to the second type magnetic resonance signal.

The following operations are respectively performed on the magnetic resonance signals corresponding to the two three-dimensional blocks: performing slice selection coding and phase coding on the first type of magnetic resonance signals to acquire coded data corresponding to the magnetic resonance signals; and carrying out slice selection coding and phase coding on the second type magnetic resonance signals to acquire coded data corresponding to the magnetic resonance signals. Filling the coded data into two K spaces, wherein one K space corresponds to an SSFP sequence with insensitive flow, and reconstructing the K space to obtain a first type magnetic resonance image corresponding to a target organ; and the other K space corresponds to the SSFP sequence sensitive to the flow, and the reconstruction of the K space can acquire a second type magnetic resonance image corresponding to the target organ.

And S260, registering the first type magnetic resonance image and the second type magnetic resonance image.

The image registration method may adopt an existing registration method, and may be, for example, a correlation method, a atlas method, a surface method, or the like. And respectively adopting an image registration method to register the first type of magnetic resonance image and register the second type of magnetic resonance image.

And S270, subtracting the registered second type magnetic resonance image from the registered first type magnetic resonance image to obtain a subtraction image.

And subtracting the pixel value of each pixel point of the second type magnetic resonance image after the registration from the pixel value of each pixel point of the first type magnetic resonance image after the registration to obtain a subtraction image.

And S280, displaying the double-lower-limb angiogram corresponding to the subtraction image in the form of an MIP (MIP maximum intensity projection) vessel tree.

In the embodiment, the three-dimensional blocks are respectively scanned by using the flow insensitive SSFP sequence and the flow sensitive SSFP sequence, the first type magnetic resonance image and the second type magnetic resonance image are respectively obtained, and the registered images are subtracted to obtain the silhouette image, so that the accurate obtaining of the angiogram is realized.

In another embodiment, the target site includes a blood vessel, a magnetic resonance imaging method, comprising:

collecting a blood flow magnetic resonance image in a vasoconstriction period, wherein the collection method can refer to the embodiment;

collecting a blood flow magnetic resonance image in a vasodilation period, wherein the collection method can refer to the embodiment;

Fig. 5a is a first type of magnetic resonance image obtained by using a flow insensitive SSFP sequence according to an embodiment of the present application, in which the pixel values of blood in a blood vessel are similar to surrounding muscles or bones, and are displayed as a high gray scale or dark signal. Fig. 5b is a second type of magnetic resonance image obtained by using a flow-sensitive SSFP sequence according to an embodiment of the present application, in which the pixel values of blood in a blood vessel are displayed as low-gray or bright signals, and the pixel values of surrounding muscles or bones are displayed as high-gray or dark signals. Fig. 5c is a subtraction image obtained using the first type of magnetic resonance image in fig. 5a and the second type of magnetic resonance image in fig. 5b, in which only an image of a blood vessel is displayed. Fig. 5d is a photograph of the double lower limb angiogram obtained by maximum intensity projection of fig. 5c, in which the blood vessels are clearly visible in sharp contrast to the surrounding tissue.

EXAMPLE III

Fig. 6 is a schematic structural diagram of a magnetic resonance scanning apparatus according to a third embodiment of the present invention, which includes a scanning bed for moving a target region to be scanned to a scanning region or a scanning chamber of a magnetic resonance imaging apparatus, where the target region is divided into two or more three-dimensional blocks, each of the three-dimensional blocks extends along a long axis direction of the scanning chamber and includes a plurality of slice layers; the radio frequency coil is used for providing radio frequency pulses, and the radio frequency pulses can simultaneously excite the at least two three-dimensional blocks to acquire magnetic resonance signals corresponding to the three-dimensional blocks; and the gradient coil is used for providing a gradient field, and the gradient field is used for performing slice selection encoding, phase encoding and frequency encoding on the magnetic resonance signals to acquire encoded data corresponding to the magnetic resonance signals. Wherein the scanning bed, gradient coils and radio frequency coils are not shown in the figure. As shown in fig. 6, the apparatus further comprises a processor 30, a memory 31, an input device 32 and an output device 33; the number of processors 30 in the device may be one or more, and fig. 6 illustrates one processor 30, which executes a program for filling the encoded data into two K spaces, where the K spaces correspond to the three-dimensional partitions one by one; reconstructing the K space to obtain two magnetic resonance images (three-dimensional); and carrying out reconstruction processing on the two magnetic resonance images to obtain a magnetic resonance image corresponding to the target organ. The gradient field is also used for carrying out frequency encoding on the magnetic resonance signals, the gradient field corresponding to the slice selection encoding is along the left-right direction relative to the limb, the gradient field corresponding to the phase encoding is along the front-back direction of the limb, and the gradient field corresponding to the frequency encoding is along the blood flow direction in the limb. The processor 30, the memory 31, the input means 32 and the output means 33 in the device may be connected by a bus or other means, as exemplified by the bus connection in fig. 6.

The memory 31 is a computer readable storage medium and can be used for storing software programs, computer executable programs, and modules, such as program instructions/modules corresponding to the magnetic resonance imaging method in the embodiment of the present invention. The processor 30 executes software programs, instructions and modules stored in the memory 31 so as to execute various functional applications of the apparatus and data processing, namely, to realize the magnetic resonance imaging scanning method.

The memory 31 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 31 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 31 may further include memory located remotely from the processor 30, 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 32 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 33 may include a display device such as a display screen.

Example four

A fourth embodiment of the present invention further provides a storage medium containing computer-executable instructions, which when executed by a computer processor, perform a method of magnetic resonance imaging, the method comprising:

filling the encoded data into two K spaces;

Of course, the storage medium containing the computer-executable instructions provided by the embodiments of the present invention is not limited to the method operations described above, and may also perform related operations in the magnetic resonance imaging method provided by any embodiments 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 instructions for enabling a magnetic resonance scanning apparatus to perform the methods according to the embodiments of the present invention.

It should be noted that, in the embodiment of the execution device with authority operation, each unit and each module included in the execution device are only divided according to functional logic, but are not limited to the above division, as long as the corresponding function can be realized; 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

1. A magnetic resonance imaging method, comprising:

filling the encoded data into two K spaces;

2. The mri method of claim 1, wherein the target region to be scanned comprises two lower limbs or two upper limbs, and wherein the left upper limb or the left lower limb corresponds to the first segment and the right upper limb or the right lower limb corresponds to the second segment.

3. A method as claimed in claim 1, wherein the first and second patches are 3D patches and each radio frequency pulse simultaneously excites multiple slices of the first patch or multiple slices of the second patch.

4. A magnetic resonance imaging method according to claim 1, characterized in that the method further comprises:

5. The magnetic resonance imaging method of claim 1, wherein the acquiring magnetic resonance signals corresponding to the slices of the first and second blocks by simultaneously exciting the slices of the first and second blocks with a plurality of radio frequency pulses comprises:

6. The magnetic resonance imaging method of any one of claims 1 to 5, wherein the plurality of radio frequency pulses comprise flow insensitive sequences, the method further comprising:

7. The magnetic resonance imaging method of claim 6, wherein the plurality of radio frequency pulses further comprises a flow sensitive sequence, the method comprising:

registering the first and second type of magnetic resonance images;

8. The magnetic resonance imaging method of claim 1, wherein the target site includes a blood vessel, the method further comprising:

applying a flow-sensitive dephasing gradient magnetic field during the vasoconstriction period, and applying a gradient magnetic field for eliminating residual magnetic moment after the flow-sensitive dephasing gradient magnetic field;

collecting a blood flow magnetic resonance image in a vasoconstriction period;

acquiring a blood flow magnetic resonance image in a vasodilation period;

9. A magnetic resonance scanning apparatus comprising:

the scanning bed is used for moving a target part to be scanned to a scanning cavity of the magnetic resonance imaging equipment, and the target part comprises a first block and a second block which extend along the long axis direction of the scanning cavity;

the gradient coil is used for providing a gradient field, the gradient field is used for generating a gradient field of slice selection encoding, phase encoding and frequency encoding so as to acquire encoded data corresponding to the magnetic resonance signal, the gradient field corresponding to the slice selection encoding is along the left-right direction, the gradient field corresponding to the phase encoding is along the front-back direction, and the gradient field corresponding to the frequency encoding is along the long axis direction;

one or more processors;

a storage device for storing one or more programs,

the processor implements, when executing the program:

filling the encoded data into two K spaces;