CN116990736B - Nuclear magnetic resonance imaging method, device, equipment and storage medium - Google Patents
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Abstract
The application discloses a nuclear magnetic resonance imaging method, a device, equipment and a storage medium, which relate to the technical field of nuclear magnetic resonance imaging and comprise the following steps: acquiring a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scanning position based on a mode selection instruction, and recording a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image; determining a ratio of target image signals based on the spin-lattice relaxation time weighted image, the proton density weighted image, a first linear receive gain, and a second linear receive gain; determining a target inverse recovery coefficient based on a correlation between a ratio of the target image signal and a ratio of the inverse recovery coefficient to the image signal; and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameter, the target inversion recovery coefficient and the proton density weighted image. Thus, a fat-suppressed nuclear magnetic resonance image can be obtained.
Description
Technical Field
The present invention relates to the field of magnetic resonance imaging technologies, and in particular, to a magnetic resonance imaging method, apparatus, device, and storage medium.
Background
Fat suppression is of great importance in MRI (magnetic resonance imaging, (nuclear) magnetic resonance imaging) sequences, and can reduce artifacts caused by fat signals and interference with diagnosis. In small bore MRI systems, the shim volume is small. At the edges of the imaging volume, the inhomogeneity of the main magnetic field increases dramatically, while some irregularly shaped parts, such as the ankle, interact with the main magnetic field to form some higher-order magnetic field inhomogeneity terms that are difficult to eliminate. Fat saturation methods utilize a difference between the resonance frequencies of fat and water in a magnetic field of about 3.5ppm, require a very uniform magnetic field, and fail fat suppression in areas of non-uniform magnetic field, affecting diagnosis. Fat in MRI has the following characteristics: the resonance frequency was 3.5ppm chemical shift compared to water, and was about 440Hz at 3T. With typical spin-lattice relaxation times (T 1 ) About 320ms at 3T.
In the prior art, as shown in fig. 1, fat saturation method excites fat by applying a narrow bandwidth radio frequency pulse of fat resonance frequency before imaging, and the longitudinal magnetization vector of fat approaches 0 and the signal is weakened during imaging. Since the resonance frequency is proportional to the magnetic induction intensity, the non-uniformity of the magnetic field can cause deviation of the resonance frequency, and the fat saturation pulse can not be covered, so that fat suppression fails. Therefore, how to successfully acquire the fat suppression nuclear magnetic resonance image is needed to be solved.
Disclosure of Invention
Accordingly, the present application is directed to a method, apparatus, device and storage medium for nuclear magnetic resonance imaging, which can obtain a nuclear magnetic resonance image with successful fat suppression. The specific scheme is as follows:
in a first aspect, the application discloses a magnetic resonance imaging method, comprising:
acquiring a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scanning position based on a mode selection instruction, and recording a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image; wherein the echo time of the spin-lattice relaxation time weighted image and the proton density weighted image are generated to be the same and the repetition time is different;
determining a pixel ratio between each pixel layer between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receive gain, and the second linear receive gain to obtain a ratio of target image signals;
acquiring an association relation between the inversion recovery coefficient and the ratio of the image signals, and determining a target inversion recovery coefficient based on the ratio of the target image signals and the association relation;
And acquiring nuclear magnetic resonance operation parameters, and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameters, the target inversion recovery coefficient and the proton density weighted image.
Optionally, after determining the pixel ratio between each pixel layer between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receiving gain, and the second linear receiving gain to obtain the ratio of the target image signals, the method further includes:
a numerical range of ratios of the target image signals is determined based on a first repetition time used to generate the spin-lattice relaxation time weighted image and a second repetition time used to generate the proton density weighted image to determine whether noise is present in the target image signal based on the numerical range.
Optionally, the acquiring the spin-lattice relaxation time weighted image and the proton density weighted image corresponding to the target scanning location based on the mode selection instruction, and recording the first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and the second linear receiving gain corresponding to the proton density weighted image includes:
Acquiring a mode selection instruction, controlling a spectrometer to scan a rapid spin echo pulse sequence based on the mode selection instruction, setting echo time and repetition time, and scanning a target scanning part to obtain a first scanning sequence and a second scanning sequence;
processing the spatial data of the first scanning sequence and the second scanning sequence based on a preset digital change method respectively to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scanning position;
and recording a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image during scanning.
Optionally, the acquiring the spin-lattice relaxation time weighted image and the proton density weighted image corresponding to the target scanning location based on the mode selection instruction, and recording the first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and the second linear receiving gain corresponding to the proton density weighted image includes:
acquiring a first historical scanning sequence and a second historical scanning sequence corresponding to a target scanning position based on a mode selection instruction;
Judging whether the first historical scanning sequence and the second historical scanning sequence meet preset processing requirements or not according to the image metadata; the preset processing requirements are that echo time for generating the first historical scanning sequence and echo time for generating the second historical scanning sequence are the same, and repetition time is different;
if yes, processing the image vision and the resolution of the first history scanning sequence and the second history scanning sequence to obtain spin-lattice relaxation time weighted images and proton density weighted images corresponding to the target scanning position;
and acquiring a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image based on the image metadata.
Optionally, the processing the image fields and resolutions of the first historical scan sequence and the second historical scan sequence to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scan region includes:
judging whether the image fields of the first historical scanning sequence and the second historical scanning sequence are consistent;
if the images are inconsistent, determining a first processed scanning sequence and a second processed scanning sequence based on the same areas of the images of the first historical scanning sequence and the second historical scanning sequence;
Judging whether the resolutions of the first processed scanning sequence and the second processed scanning sequence are the same or not;
and if the spin-lattice relaxation time weighted image and the proton density weighted image are different, performing image adjustment on the first processed scanning sequence and the second processed scanning sequence based on a preset image scaling algorithm to obtain the spin-lattice relaxation time weighted image and the proton density weighted image corresponding to the target scanning position.
Optionally, before the acquiring the association relation between the inverse recovery coefficient and the ratio of the image signal, the method further includes:
acquiring the ratio of a plurality of image signals in a preset time range based on a ratio generation model of the preset signals;
acquiring a plurality of inversion recovery coefficients within a preset time range based on a preset inversion recovery coefficient determination model;
and determining an association relationship of the inversion recovery coefficient and the ratio of the image signals based on the corresponding ratio of the image signals and the inversion recovery coefficient at the same time.
Optionally, the determining the association relationship between the inversion recovery coefficient and the ratio of the image signals based on the ratio of the corresponding image signals and the inversion recovery coefficient at the same time includes:
determining an initial association relationship of the inverse recovery coefficient and the ratio of the image signals based on the corresponding ratio of the image signals and the inverse recovery coefficient at the same time;
And processing the initial association relation by using an interpolation processing method to determine the association relation of the ratio of the inversion recovery coefficient to the image signal.
In a second aspect, the present application discloses a magnetic resonance imaging apparatus comprising:
the image generation module is used for acquiring a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scanning position based on a mode selection instruction, and recording a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image; wherein the echo time of the spin-lattice relaxation time weighted image and the proton density weighted image are generated to be the same and the repetition time is different;
a signal ratio determining module, configured to determine a pixel ratio between each pixel layer between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receiving gain, and the second linear receiving gain, so as to obtain a target image signal ratio;
the coefficient determining module is used for obtaining the association relation between the inversion recovery coefficient and the ratio of the image signals and determining a target inversion recovery coefficient based on the ratio of the target image signals and the association relation;
And the target image acquisition module is used for acquiring nuclear magnetic resonance operation parameters and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameters, the target inversion recovery coefficient and the proton density weighted image.
In a third aspect, the present application discloses an electronic device, comprising:
a memory for storing a computer program;
and a processor for executing the computer program to implement the aforementioned nuclear magnetic resonance imaging method.
In a fourth aspect, the present application discloses a computer readable storage medium storing a computer program which, when executed by a processor, implements the aforementioned magnetic resonance imaging method.
In the application, firstly, a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scanning position are obtained based on a mode selection instruction, and a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image are recorded; wherein the echo time of the spin-lattice relaxation time weighted image and the proton density weighted image are generated to be the same and the repetition time is different; determining a pixel ratio between each pixel layer between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receive gain, and the second linear receive gain to obtain a ratio of target image signals; acquiring an association relation between the inversion recovery coefficient and the ratio of the image signals, and determining a target inversion recovery coefficient based on the ratio of the target image signals and the association relation; and acquiring nuclear magnetic resonance operation parameters, and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameters, the target inversion recovery coefficient and the proton density weighted image. The method comprises the steps of obtaining a target image signal ratio corresponding to a target scanning position, bringing the target image ratio into an association relation between an obtained inversion recovery coefficient and the image signal ratio, determining a target inversion recovery coefficient corresponding to fat in the target scanning position, and finally determining a final fat-suppressed target nuclear magnetic resonance image corresponding to the target scanning position based on the target inversion recovery coefficient and a proton density weighted image. In this way, the relaxation time characteristic of fat rather than the chemical shift characteristic is utilized to determine the final target nuclear magnetic resonance image of fat suppression corresponding to the target scanning position, so that the influence of non-uniformity of a magnetic field in the imaging process is avoided, and the fat suppression is uniform; further, the generation of fat-suppressed nuclear magnetic resonance images by proton density weighted images can reduce the nuclear magnetic resonance scanning time.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present application, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a nuclear magnetic resonance imaging method according to the present disclosure;
FIG. 2 is a flow chart of a method of MRI disclosed in the present application;
FIG. 3 is a graph showing a functional relationship of a nuclear magnetic resonance imaging method according to the present application;
FIG. 4 is a graph showing a functional relationship of another MRI method according to the present application;
FIG. 5 is a schematic diagram of a specific MRI method of the present disclosure;
FIG. 6 is a flow chart of a specific MRI method of the present disclosure;
FIG. 7 is a flow chart of another embodiment of a MRI method of the present disclosure;
FIG. 8 is a schematic diagram of a nuclear magnetic resonance imaging apparatus according to the present disclosure;
fig. 9 is a block diagram of an electronic device according to the present disclosure.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the prior art, there are four methods for obtaining fat-suppressed scanned images, respectively: designing a larger imaging range, namely, having a relatively uniform magnetic field in limb joint scanning, and improving fat suppression; using high-order dynamic shimming, namely scanning a B0 field diagram before scanning, fitting each high-order shimming item, and passing corresponding current in each shimming coil; fat suppression using a STIR (short time inversion recovery, short time inversion recovery sequence) sequence, i.e., using the spin-lattice relaxation time difference of fat and water, applying inversion pulses, imaging begins when the fat spin-lattice relaxation time relaxes to a longitudinal magnetization vector of 0; the fat-free imaging is performed using the DIXON (a fat-suppression method named by the inventor) method, i.e. by acquiring signals with different phase differences under different TEs and processing the signals to obtain a fat-free image. These methods have corresponding drawbacks. Designing a larger imaging range increases the magnet length, making the way of positioning the scanned region into the magnet impractical. The achievable gradient field strength will also be smaller, thereby increasing the scan time or reducing the scan resolution. The use of higher order dynamic shimming extends the pre-scan time. Shimming effects are limited by the distribution of the shim coils, which increase the gradient coil volume. When fat suppression is performed using the STIR sequence, other tissues are not imaged with sufficient longitudinal relaxation, and the signal amount is low, resulting in low signal-to-noise ratio. The scan requires waiting for inversion Time (TI), resulting in an extended scan time. The DIXON method is used for water-fat separation imaging, and the signals with different phase differences under different TE are collected for processing. At least two times of scanning are needed, so that the scanning time is long, the algorithm stability causes mismatch of water and fat, and streak artifacts appear at the part with uneven magnetic field. The three-point DIXON technique can correct for magnetic field inhomogeneities, but the scan time is further extended. The application will therefore be particularly directed to a method for obtaining fat-suppressed images that is free from magnetic field inhomogeneities and that is fat-suppressed homogeneously.
Example 1
Referring to fig. 1, an embodiment of the present application discloses a magnetic resonance imaging method, including:
step S11: and acquiring a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scanning position based on a mode selection instruction, and recording a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image.
Due to the spin echo (SE, i.e., spin Echo) and Fast Spin Echo (FSE, i.e., fast Spin Echo) sequences, echo Time (TE, i.e., echo Time) and Repetition Time (TR, i.e., repetition Time) are the main parameters controlling image contrast, typically。/>Is proton density, T 1 For spin-lattice relaxation time, T 2 Is the spin-spin relaxation time. Short TE and short TR available T 1 The weighted image, short TE, long TR, can yield a Proton Density (PD, proton Density) weighted image. If the images of the same TE and different TR are acquired, the tissue corresponding to the pixels at the same position is +.>Mainly determining the ratio of the position signals. Therefore, in this embodiment, a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scan site are acquired based on a mode selection instruction, and a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image are recorded. Wherein the echo time of the spin-lattice relaxation time weighted image and the echo time of the proton density weighted image are the same and the repetition time is different. In the practical application, the T-shaped part can be set firstly 1 Weighted image, set +.>For PD weighted image, set up. To obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scan site. The two images are guaranteed to have the same layer direction, layer position, field of view, and pixel row number and column number. Then, a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image are recorded.
Step S12: determining a pixel ratio between pixel layers between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receive gain, and the second linear receive gain to obtain a ratio of target image signals.
In this embodiment, the pixel ratio between each pixel layer between the spin-lattice relaxation time weighted image and the proton density weighted image is determined based on the image signal ratio formula, the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receiving gain, and the second linear receiving gain, so as to obtain the target image signal ratio. The ratio formula of the image signals is as follows:
；
Wherein R is the ratio of image signals, S 1 Weighting images, S, for spin-lattice relaxation times 2 Weighting image, A, for proton density 1 For a first linear receiving gain, A 2 For a second linear receive gain.
In this embodiment, after determining the pixel ratio between the pixel layers between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receiving gain, and the second linear receiving gain to obtain the ratio of the target image signal, the method further includes: a numerical range of ratios of the target image signals is determined based on a first repetition time used to generate the spin-lattice relaxation time weighted image and a second repetition time used to generate the proton density weighted image to determine whether noise is present in the target image signal based on the numerical range. Wherein the numerical range isTo 1. For a true signal, R should be within this range, but the value of R will exceed if noise is presentOut of this range. If the ratio R of the resulting signals is not within the stated range, R is adjusted to the nearest end of the range, i.e., an adjustment of greater than 1 to 1 and an adjustment of less than TR1/TR2 to TR1/TR2. When the signal-to-noise ratio of a general image is high in actual operation, the noise does not greatly influence the R value. But the interpolation in the subsequent steps can be enabled to use interpolation only by adjustment, so that the numerical stability is ensured.
Step S13: and acquiring an association relation between the inversion recovery coefficient and the ratio of the image signals, and determining a target inversion recovery coefficient based on the ratio of the target image signals and the association relation.
In this embodiment, before the obtaining of the association relationship between the inverse recovery coefficient and the ratio of the image signal, the method further includes: acquiring the ratio of a plurality of image signals in a preset time range based on a ratio generation model of the preset signals; acquiring a plurality of inversion recovery coefficients within a preset time range based on a preset inversion recovery coefficient determination model; and determining an association relationship of the inversion recovery coefficient and the ratio of the image signals based on the corresponding ratio of the image signals and the inversion recovery coefficient at the same time. The determining the association relationship of the inversion recovery coefficient and the ratio of the image signals based on the ratio of the corresponding image signals and the inversion recovery coefficient at the same time includes: determining an initial association relationship of the inverse recovery coefficient and the ratio of the image signals based on the corresponding ratio of the image signals and the inverse recovery coefficient at the same time; and processing the initial association relation by using an interpolation processing method to determine the association relation of the ratio of the inversion recovery coefficient to the image signal. Wherein the ratio generation model of the preset signals is as follows:
；
Wherein, R is the ratio of image signals; t (T) 1 Is spin-lattice relaxation time; TR (TR) 1 Weighting the image repetition time for spin-lattice relaxation time; TR (TR) 2 The image repetition time is weighted for proton density.
The preset reverse recovery coefficient determination model is as follows:
；
wherein the E 1 In order to invert the recovery coefficient, TI is the waiting inversion time at the time of scanning. As shown in FIG. 3, in the range of 0 to 5000 ms (this range covers the T of most tissues 1 ) For a plurality of T 1 Respectively calculating to obtain E 1 Curves with R. Then, as shown in FIG. 4, E is obtained 1 Correlation with R, wherein in FIG. 4, TR is shown 1 =500ms,TR 2 For example, =2500 ms. Determination by interpolationAbout->Functional relation->. Supplement in->At the border +.>The value to be taken is a series of interpolation control points. />，/>. The interpolation processing method includes, but is not limited to, a lagrangian interpolation method, an interpolation remainder method, and the like.
Step S14: and acquiring nuclear magnetic resonance operation parameters, and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameters, the target inversion recovery coefficient and the proton density weighted image.
In this embodiment, the nuclear magnetic resonance operating parameters are obtained, And generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameter, the target inversion recovery coefficient and the proton density weighted image. Wherein the fat-suppressed image S isAlpha is an operator adjustable parameter that interpolates between complete inhibition and the original image for adjusting the degree of fat inhibition. The image obtained in the whole process is shown in fig. 5. Wherein the image (a) is T 1 The weighted image, (b) is a PD weighted image, (a) and (b) have their signal amounts corrected by gain in the figure, (c) is a fat-suppressed image reconstructed from (a) and (b), and (d) is a fat-suppressed image obtained by STIR scanning.
In this embodiment, a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scanning position are obtained based on a mode selection instruction, and a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image are recorded; wherein the echo time of the spin-lattice relaxation time weighted image and the proton density weighted image are generated to be the same and the repetition time is different; determining a pixel ratio between each pixel layer between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receive gain, and the second linear receive gain to obtain a ratio of target image signals; acquiring an association relation between the inversion recovery coefficient and the ratio of the image signals, and determining a target inversion recovery coefficient based on the ratio of the target image signals and the association relation; and acquiring nuclear magnetic resonance operation parameters, and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameters, the target inversion recovery coefficient and the proton density weighted image. The method comprises the steps of obtaining a target image signal ratio corresponding to a target scanning position, bringing the target image ratio into an association relation between an obtained inversion recovery coefficient and the image signal ratio, determining a target inversion recovery coefficient corresponding to fat in the target scanning position, and finally determining a final fat-suppressed target nuclear magnetic resonance image corresponding to the target scanning position based on the target inversion recovery coefficient and a proton density weighted image. In this way, the relaxation time characteristic of fat rather than the chemical shift characteristic is utilized to determine the final target nuclear magnetic resonance image of fat suppression corresponding to the target scanning position, so that the influence of non-uniformity of a magnetic field in the imaging process is avoided, and the fat suppression is uniform; further, the generation of fat-suppressed nuclear magnetic resonance images by proton density weighted images can reduce the nuclear magnetic resonance scanning time.
Example two
Referring to fig. 6, an embodiment of the present application discloses a specific mri method, including:
step S21: and acquiring a mode selection instruction, controlling the spectrometer to scan the fast spin echo pulse sequence based on the mode selection instruction, setting echo time and repetition time, and scanning the target scanning part to obtain a first scanning sequence and a second scanning sequence.
In this embodiment, a mode selection instruction is acquired, and based on the mode selection instruction, the spectrometer is controlled to scan a fast spin echo pulse sequence, and an echo time and a repetition time are set to scan a target scan position to obtain a first scan sequence and a second scan sequence. That is, prior to an MRI scan, the operator chooses whether to use this technique. If used, the computer-controlled spectrometer scans the FSE sequence, sets the echo spacing to be the shortest, the center echo position to be the 1 st so that TE is as short as possible, and sets for the T1 weighted imageFor PD weighted image, set +.>. The two sequences are guaranteed to have the same layer direction, layer position, field of view, and pixel row number and column number.
Step S22: and processing the spatial data of the first scanning sequence and the second scanning sequence based on a preset digital change method respectively to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scanning position, and recording a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image during scanning.
In this embodiment, spatial data of the first scan sequence and the second scan sequence are respectively processed based on a preset digital variation method to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scan position, and a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image during scanning are recorded. Performing two-dimensional discrete Fourier transform on each layer of K space data and taking absolute value to obtain an image S 1 And S is 2 A is the linear receiving gain during recording scanning 1 And A 2 。
Step S23: determining a pixel ratio between pixel layers between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receive gain, and the second linear receive gain to obtain a ratio of target image signals.
Step S24: and acquiring an association relation between the inversion recovery coefficient and the ratio of the image signals, and determining a target inversion recovery coefficient based on the ratio of the target image signals and the association relation.
Step S25: and acquiring nuclear magnetic resonance operation parameters, and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameters, the target inversion recovery coefficient and the proton density weighted image.
The specific process of steps S23 to S25 may refer to the corresponding content disclosed in the foregoing embodiment, and will not be described herein.
In this way, by utilizing the relaxation time characteristics of fat rather than the chemical shift characteristics, the influence of non-uniformity of a magnetic field is avoided, and fat suppression is uniform; further, the generation of fat-suppressed nuclear magnetic resonance images by proton density weighted images can reduce the nuclear magnetic resonance scanning time. The signal-to-noise ratio of an MRI image is proportional to the square root of the time taken to reconstruct one pixel of the information used, in this embodiment using two scans of information, and thus the signal-to-noise ratio is improved.
Example III
Referring to fig. 7, an embodiment of the present application discloses a specific mri method, including:
step S31: and acquiring a first historical scanning sequence and a second historical scanning sequence corresponding to the target scanning position based on the mode selection instruction.
In this embodiment, a first history scan sequence and a second history scan sequence corresponding to a target scan region are acquired based on a mode selection instruction. That is, two sequences of the same examination that have been scanned are selected to obtain a first historical scan sequence and a second historical scan sequence.
Step S32: judging whether the first historical scanning sequence and the second historical scanning sequence meet preset processing requirements according to the image metadata.
In this embodiment, the preset processing requirement is that echo time for generating the first historical scan sequence and echo time for generating the second historical scan sequence are the same, and repetition time is different; that is, whether the two sequences meet the preset processing requirement is checked according to the image metadata, whether the two sequences have the same layer direction and position, the same TE, different TR, and TR1< TR2 is judged.
Step S33: and if so, processing the image visual fields and the resolutions of the first historical scanning sequence and the second historical scanning sequence to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scanning position, and acquiring a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image based on the image metadata.
In this embodiment, if two sequences have the same bedding orientation and position, the same TE, different TR, andand TR1<TR2. The processing the image field and resolution of the first historical scan sequence and the second historical scan sequence to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scan region includes: judging whether the image fields of the first historical scanning sequence and the second historical scanning sequence are consistent; if the images are inconsistent, determining a first processed scanning sequence and a second processed scanning sequence based on the same areas of the images of the first historical scanning sequence and the second historical scanning sequence; judging whether the resolutions of the first processed scanning sequence and the second processed scanning sequence are the same or not; and if the spin-lattice relaxation time weighted image and the proton density weighted image are different, performing image adjustment on the first processed scanning sequence and the second processed scanning sequence based on a preset image scaling algorithm to obtain the spin-lattice relaxation time weighted image and the proton density weighted image corresponding to the target scanning position. If the image views are different, the public view part is taken and the operator is prompted to confirm whether the information is lost, and if the resolutions are different, a preset image scaling algorithm is performed and the operator is prompted that the image quality may be reduced. Obtaining an image S with the same number of pixel rows and columns 1 And S is 2 A is the linear receiving gain when scanning according to the metadata 1 And A 2 。
Step S34: and acquiring an association relation between the inversion recovery coefficient and the ratio of the image signals, and determining a target inversion recovery coefficient based on the ratio of the target image signals and the association relation.
Step S35: and acquiring nuclear magnetic resonance operation parameters, and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameters, the target inversion recovery coefficient and the proton density weighted image.
The specific process of steps S34 to S35 may refer to the corresponding content disclosed in the foregoing embodiment, and will not be described herein.
In this way, by utilizing the relaxation time characteristics of fat rather than the chemical shift characteristics, the influence of non-uniformity of a magnetic field is avoided, and fat suppression is uniform; further, the generation of fat-suppressed nuclear magnetic resonance images by proton density weighted images can reduce the nuclear magnetic resonance scanning time.
As described with reference to fig. 8, the embodiment of the present application further correspondingly discloses a magnetic resonance imaging apparatus, including:
an image generating module 11, configured to acquire a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scanning location based on a mode selection instruction, and record a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image; wherein the echo time of the spin-lattice relaxation time weighted image and the proton density weighted image are generated to be the same and the repetition time is different;
A signal ratio determining module 12 for determining a pixel ratio between each pixel layer between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receiving gain, and the second linear receiving gain to obtain a ratio of target image signals;
a coefficient determination module 13 that acquires a correlation of a reverse recovery coefficient to a ratio of image signals, and determines a target reverse recovery coefficient based on the ratio of the target image signals and the correlation;
the target image acquisition module 14 is configured to acquire a nuclear magnetic resonance operation parameter, and generate a target nuclear magnetic resonance image corresponding to the target scanning location based on the nuclear magnetic resonance operation parameter, the target inversion recovery coefficient, and the proton density weighted image.
In this embodiment, a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scanning position are obtained based on a mode selection instruction, and a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image are recorded; wherein the echo time of the spin-lattice relaxation time weighted image and the proton density weighted image are generated to be the same and the repetition time is different; determining a pixel ratio between each pixel layer between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receive gain, and the second linear receive gain to obtain a ratio of target image signals; acquiring an association relation between the inversion recovery coefficient and the ratio of the image signals, and determining a target inversion recovery coefficient based on the ratio of the target image signals and the association relation; and acquiring nuclear magnetic resonance operation parameters, and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameters, the target inversion recovery coefficient and the proton density weighted image. The method comprises the steps of obtaining a target image signal ratio corresponding to a target scanning position, bringing the target image ratio into an association relation between an obtained inversion recovery coefficient and the image signal ratio, determining a target inversion recovery coefficient corresponding to fat in the target scanning position, and finally determining a final fat-suppressed target nuclear magnetic resonance image corresponding to the target scanning position based on the target inversion recovery coefficient and a proton density weighted image. In this way, the relaxation time characteristic of fat rather than the chemical shift characteristic is utilized to determine the final target nuclear magnetic resonance image of fat suppression corresponding to the target scanning position, so that the influence of non-uniformity of a magnetic field in the imaging process is avoided, and the fat suppression is uniform; further, the generation of fat-suppressed nuclear magnetic resonance images by proton density weighted images can reduce the nuclear magnetic resonance scanning time.
In some specific embodiments, the mri apparatus may further include:
a numerical range determination module for determining a numerical range of a ratio of the target image signal based on a first repetition time used to generate the spin-lattice relaxation time weighted image and a second repetition time used to generate the proton density weighted image to determine whether noise is present in the target image signal based on the numerical range.
In some specific embodiments, the image generating module 11 may specifically include:
the sequence acquisition unit is used for acquiring a mode selection instruction, controlling the spectrometer to scan a rapid spin echo pulse sequence based on the mode selection instruction, setting echo time and repetition time, and scanning a target scanning position to obtain a first scanning sequence and a second scanning sequence;
the weighted image acquisition unit is used for respectively processing the spatial data of the first scanning sequence and the second scanning sequence based on a preset digital change method to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scanning position;
and the scanning receiving gain acquisition unit is used for recording a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image during scanning.
In some specific embodiments, the image generating module 11 may specifically include:
a history sequence determining unit, configured to obtain a first history scanning sequence and a second history scanning sequence corresponding to the target scanning position based on the mode selection instruction;
the sequence judging unit is used for judging whether the first historical scanning sequence and the second historical scanning sequence meet preset processing requirements according to the image metadata; the preset processing requirements are that echo time for generating the first historical scanning sequence and echo time for generating the second historical scanning sequence are the same, and repetition time is different;
the image adjustment sub-module is used for processing the image vision and the resolution of the first historical scanning sequence and the second historical scanning sequence if the image vision and the resolution of the first historical scanning sequence and the second historical scanning sequence are met so as to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scanning part;
and the historical image receiving gain acquisition unit is used for acquiring a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image based on the image metadata.
In some specific embodiments, the image adjustment sub-module may specifically include:
A visual field judging unit for judging whether the image visual fields of the first history scanning sequence and the second history scanning sequence are consistent;
a region determining unit configured to determine a first post-processing scan sequence and a second post-processing scan sequence based on an image same region of the first history scan sequence and the second history scan sequence if they are inconsistent;
a resolution judging unit configured to judge whether resolutions of the first processed scanning sequence and the second processed scanning sequence are the same;
and the weighted image generating unit is used for carrying out image adjustment on the first processed scanning sequence and the second processed scanning sequence based on a preset image scaling algorithm if the first processed scanning sequence and the second processed scanning sequence are different so as to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scanning position.
In some specific embodiments, the mri apparatus may further include:
the signal ratio generation module is used for acquiring the ratio of a plurality of image signals in a preset time range based on a preset signal ratio generation model;
and an inversion recovery coefficient generation module. The method comprises the steps of determining a model based on a preset reverse recovery coefficient to obtain a plurality of reverse recovery coefficients within a preset time range;
And the association relation determining module is used for determining the association relation between the inversion recovery coefficient and the ratio of the image signals based on the corresponding ratio of the image signals and the inversion recovery coefficient at the same time.
In some specific embodiments, the association determining module may specifically include:
an initial association relation determining unit configured to determine an initial association relation of the inverse recovery coefficient and the ratio of the image signals based on the corresponding ratio of the image signals and the inverse recovery coefficient at the same time;
and the data interpolation unit is used for processing the initial association relation by utilizing an interpolation processing method to determine the association relation of the ratio of the inversion recovery coefficient to the image signal.
Further, the embodiment of the present application further discloses an electronic device, and fig. 9 is a block diagram of an electronic device 20 according to an exemplary embodiment, where the content of the figure is not to be considered as any limitation on the scope of use of the present application.
Fig. 9 is a schematic structural diagram of an electronic device 20 according to an embodiment of the present application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input output interface 25, and a communication bus 26. Wherein the memory 22 is configured to store a computer program that is loaded and executed by the processor 21 to implement the relevant steps in the mri method disclosed in any of the foregoing embodiments. In addition, the electronic device 20 in the present embodiment may be specifically an electronic computer.
In this embodiment, the power supply 23 is configured to provide an operating voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and an external device, and the communication protocol to be followed is any communication protocol applicable to the technical solution of the present application, which is not specifically limited herein; the input/output interface 25 is used for acquiring external input data or outputting external output data, and the specific interface type thereof may be selected according to the specific application requirement, which is not limited herein.
The memory 22 may be a carrier for storing resources, such as a read-only memory, a random access memory, a magnetic disk, or an optical disk, and the resources stored thereon may include an operating system 221, a computer program 222, and the like, and the storage may be temporary storage or permanent storage.
The operating system 221 is used for managing and controlling various hardware devices on the electronic device 20 and computer programs 222, which may be Windows Server, netware, unix, linux, etc. The computer program 222 may further comprise a computer program capable of performing other specific tasks in addition to the computer program capable of performing the magnetic resonance imaging method performed by the electronic device 20 as disclosed in any of the previous embodiments.
Further, the application also discloses a computer readable storage medium for storing a computer program; wherein the computer program when executed by a processor implements the previously disclosed magnetic resonance imaging method. For specific steps of the method, reference may be made to the corresponding contents disclosed in the foregoing embodiments, and no further description is given here.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative elements and steps are described above generally in terms of functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software modules may be disposed in Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing has outlined rather broadly the more detailed description of the application in order that the detailed description of the application that follows may be better understood, and in order that the present principles and embodiments may be better understood; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.
Claims (8)
1. A method of nuclear magnetic resonance imaging comprising:
acquiring a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scanning position based on a mode selection instruction, and recording a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image; wherein the echo time of the spin-lattice relaxation time weighted image and the proton density weighted image are generated to be the same and the repetition time is different;
determining a pixel ratio between each pixel layer between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receive gain, and the second linear receive gain to obtain a ratio of target image signals;
Acquiring an association relation between the inversion recovery coefficient and the ratio of the image signals, and determining a target inversion recovery coefficient based on the ratio of the target image signals and the association relation; before the association relation of the inversion recovery coefficient and the image signal ratio is obtained, the method further comprises the following steps: acquiring the ratio of a plurality of image signals in a preset time range based on a ratio generation model of the preset signals; acquiring a plurality of inversion recovery coefficients within a preset time range based on a preset inversion recovery coefficient determination model; determining an association relationship of the inversion recovery coefficient and the ratio of the image signals based on the corresponding ratio of the image signals and the inversion recovery coefficient at the same time; wherein the determining of the association relationship of the inverse recovery coefficient and the ratio of the image signals based on the ratio of the corresponding image signals and the inverse recovery coefficient at the same time includes: determining an initial association relationship of the inverse recovery coefficient and the ratio of the image signals based on the corresponding ratio of the image signals and the inverse recovery coefficient at the same time; processing the initial association relation by using an interpolation processing method to determine the association relation of the ratio of the inversion recovery coefficient to the image signal;
And acquiring nuclear magnetic resonance operation parameters, and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameters, the target inversion recovery coefficient and the proton density weighted image.
2. The method of claim 1, wherein after determining the pixel ratio between the pixel layers between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receive gain, and the second linear receive gain to obtain the ratio of target image signals, further comprising:
a numerical range of ratios of the target image signals is determined based on a first repetition time used to generate the spin-lattice relaxation time weighted image and a second repetition time used to generate the proton density weighted image to determine whether noise is present in the target image signal based on the numerical range.
3. The method of claim 1, wherein the acquiring a spin-lattice relaxation time weighted image and a proton density weighted image for a target scan site based on a mode selection instruction and recording a first linear receiving gain for the spin-lattice relaxation time weighted image and a second linear receiving gain for the proton density weighted image comprises:
Acquiring a mode selection instruction, controlling a spectrometer to scan a rapid spin echo pulse sequence based on the mode selection instruction, setting echo time and repetition time, and scanning a target scanning part to obtain a first scanning sequence and a second scanning sequence;
processing the spatial data of the first scanning sequence and the second scanning sequence based on a preset digital change method respectively to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scanning position;
and recording a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image during scanning.
4. The method of claim 1, wherein the acquiring a spin-lattice relaxation time weighted image and a proton density weighted image for a target scan site based on a mode selection instruction and recording a first linear receiving gain for the spin-lattice relaxation time weighted image and a second linear receiving gain for the proton density weighted image comprises:
acquiring a first historical scanning sequence and a second historical scanning sequence corresponding to a target scanning position based on a mode selection instruction;
Judging whether the first historical scanning sequence and the second historical scanning sequence meet preset processing requirements or not according to the image metadata; the preset processing requirements are that echo time for generating the first historical scanning sequence and echo time for generating the second historical scanning sequence are the same, and repetition time is different;
if yes, processing the image vision and the resolution of the first history scanning sequence and the second history scanning sequence to obtain spin-lattice relaxation time weighted images and proton density weighted images corresponding to the target scanning position;
and acquiring a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image based on the image metadata.
5. The method of claim 4, wherein processing the image field and resolution of the first and second historic scan sequences to obtain a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to the target scan site comprises:
judging whether the image fields of the first historical scanning sequence and the second historical scanning sequence are consistent;
If the images are inconsistent, determining a first processed scanning sequence and a second processed scanning sequence based on the same areas of the images of the first historical scanning sequence and the second historical scanning sequence;
judging whether the resolutions of the first processed scanning sequence and the second processed scanning sequence are the same or not;
and if the spin-lattice relaxation time weighted image and the proton density weighted image are different, performing image adjustment on the first processed scanning sequence and the second processed scanning sequence based on a preset image scaling algorithm to obtain the spin-lattice relaxation time weighted image and the proton density weighted image corresponding to the target scanning position.
6. A nuclear magnetic resonance imaging apparatus, comprising:
the image generation module is used for acquiring a spin-lattice relaxation time weighted image and a proton density weighted image corresponding to a target scanning position based on a mode selection instruction, and recording a first linear receiving gain corresponding to the spin-lattice relaxation time weighted image and a second linear receiving gain corresponding to the proton density weighted image; wherein the echo time of the spin-lattice relaxation time weighted image and the proton density weighted image are generated to be the same and the repetition time is different;
a signal ratio determining module, configured to determine a pixel ratio between each pixel layer between the spin-lattice relaxation time weighted image and the proton density weighted image based on the spin-lattice relaxation time weighted image, the proton density weighted image, the first linear receiving gain, and the second linear receiving gain, so as to obtain a target image signal ratio;
The coefficient determining module is used for acquiring the association relation between the inversion recovery coefficient and the ratio of the image signals and determining a target inversion recovery coefficient based on the ratio of the target image signals and the association relation; wherein, nuclear magnetic resonance imaging device still specifically is used for: acquiring the ratio of a plurality of image signals in a preset time range based on a ratio generation model of the preset signals; acquiring a plurality of inversion recovery coefficients within a preset time range based on a preset inversion recovery coefficient determination model; determining an association relationship of the inversion recovery coefficient and the ratio of the image signals based on the corresponding ratio of the image signals and the inversion recovery coefficient at the same time; wherein the process of determining the association relationship of the inversion recovery coefficient and the ratio of the image signals based on the ratio of the corresponding image signals and the inversion recovery coefficient at the same time in the nuclear magnetic resonance imaging apparatus includes: determining an initial association relationship of the inverse recovery coefficient and the ratio of the image signals based on the corresponding ratio of the image signals and the inverse recovery coefficient at the same time; processing the initial association relation by using an interpolation processing method to determine the association relation of the ratio of the inversion recovery coefficient to the image signal;
And the target image acquisition module is used for acquiring nuclear magnetic resonance operation parameters and generating a target nuclear magnetic resonance image corresponding to the target scanning position based on the nuclear magnetic resonance operation parameters, the target inversion recovery coefficient and the proton density weighted image.
7. An electronic device, comprising:
a memory for storing a computer program;
a processor for executing the computer program to implement the magnetic resonance imaging method as claimed in any one of claims 1 to 5.
8. A computer readable storage medium for storing a computer program which, when executed by a processor, implements a magnetic resonance imaging method according to any one of claims 1 to 5.
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