Free breathing heart fat fraction and multi-relaxation parameter simultaneous quantitative magnetic resonance imaging method and device, terminal and medium

Abstract

The invention provides a free breathing heart fat fraction and multi-relaxation parameter simultaneous quantitative magnetic resonance imaging method, a free breathing heart fat fraction and multi-relaxation parameter simultaneous quantitative magnetic resonance imaging device, a terminal and a medium. The method comprises the following steps: scanning a plurality of imaging layers on heart tissues of a detected object in a free breathing state to obtain a double-echo image of each cardiac cycle corresponding to each imaging layer and an electrocardio trigger signal; simulating an evolution process of a magnetization vector based on a Bloch equation and an electrocardio trigger signal, and establishing a dictionary; on the basis of the double-echo image after image processing, water-fat separation operation based on mixed multi-echo is executed, and a water signal image and a fat fraction graph are obtained; and obtaining a relaxation parameter group diagram of the detected object in a mode of matching the water signal image with the dictionary. Collection is carried out when the detected object freely breathes, the burden of the detected object is relieved, and the fat fraction quantification precision and the water-fat separation accuracy are guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic resonance imaging, and particularly to a method, device, terminal and medium for simultaneously quantitatively magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters. Background Art

[0002] Cardiac magnetic resonance quantitative imaging is a non-invasive technique that can evaluate myocardial tissue characteristics and has important application value in the diagnosis, risk assessment and treatment effect monitoring of cardiovascular diseases. Different relaxation parameters have different sensitivities to pathological changes such as myocardial fibrosis, inflammation and edema. Therefore, by comprehensively analyzing T1, T2 and T1ρ relaxation parameters, more comprehensive myocardial tissue information can be provided. Especially in the diagnosis of complex or difficult cardiomyopathies, this comprehensive analysis method can improve the accuracy of diagnosis and effectively reduce the risk of missed diagnosis. However, existing clinical cardiac magnetic resonance quantitative imaging techniques usually require multiple independent two-dimensional scans, resulting in low imaging efficiency. Moreover, existing imaging techniques usually require patients to hold their breath during scanning to reduce motion artifacts, which not only increases the burden on patients, but also may affect the comparison between parameters and the comprehensive evaluation of diseased tissues due to registration errors, thus reducing the reliability of diagnosis. More importantly, existing methods usually rely on simplified exponential relaxation models to estimate parameter values and do not fully consider non-ideal factors in the magnetic resonance imaging system, such as signal noise, field inhomogeneity, etc., which may lead to deviations in measurement results.

[0003] At the same time, fat quantification is also of great significance in the evaluation of cardiovascular diseases. For example, fat infiltration after myocardial infarction is usually closely related to the progression of the disease, impaired cardiac function and deterioration of the patient's prognosis. In addition, the partial volume effect of water and fat will affect the accuracy of parametric imaging. Therefore, it is necessary to separate water and fat, such as a technique that combines myocardial T1 quantification and water-fat separation, but this method is only applicable to in-phase and opposed-phase two-echo acquisitions and is difficult to provide an accurate fat fraction map. Accurate fat fraction quantification usually requires the acquisition of three or more echoes, but this will significantly extend the repetition time (TR), resulting in an overly long acquisition window. A water-fat separation cardiac magnetic resonance fingerprinting technique (DIXON-cMRF) based on three-echo acquisition can also be used to simultaneously obtain myocardial T1, T2 and fat fraction maps. However, due to the acquisition window and breath-holding time limitations, this technique requires a high undersampling factor and relies on a complex reconstruction process, and there is still room for improvement in imaging efficiency and stability. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present application is to provide a method, device, terminal and medium for simultaneously quantitatively magnetic resonance imaging of free-breathing cardiac fat fraction and multi-relaxation parameters, so as to solve the problems of low fat quantification accuracy and poor stability of water-fat separation magnetic resonance imaging in the prior art.

[0005] To achieve the above object and other related objects, the first aspect of the present application provides a method for simultaneously quantitatively magnetic resonance imaging of free-breathing cardiac fat fraction and multi-relaxation parameters, including: establishing a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multi-relaxation parameters; scanning the cardiac tissue of the subject in a free-breathing state through the magnetic resonance sequence at multiple imaging planes to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane; simulating the evolution process of the magnetization vector based on the Bloch equation and the electrocardiogram trigger signal, and establishing a dictionary; performing image processing on the dual-echo images of each cardiac cycle, and based on the processed dual-echo images, performing water-fat separation operation based on hybrid multi-echo to obtain a water signal image and a fat fraction map; obtaining a relaxation parameter group map of the subject by matching the water signal image with the dictionary.

[0006] In some embodiments of the first aspect of the present application, establishing a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multi-relaxation parameters includes: determining an optimized combination of the best preparation pulse sequences and the best readout radiofrequency pulse flip angle combinations for each cardiac cycle; obtaining a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multi-relaxation parameters based on the best preparation pulse sequence combination and the best readout radiofrequency pulse flip angle combination; wherein, the magnetic resonance sequence includes: pulse data corresponding to each cardiac cycle.

[0007] In some embodiments of the first aspect of the present application, scanning the cardiac tissue of the subject in a free-breathing state through the magnetic resonance sequence at multiple imaging planes to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane includes: based on the magnetic resonance sequence, performing magnetic resonance scanning operations on each imaging plane in sequence according to the electrocardiogram images of each imaging plane collected in real time to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane; wherein, the magnetic resonance scanning operation includes: based on the pulse application rule, applying corresponding pulses in each cardiac cycle according to the magnetic resonance sequence and the electrocardiogram trigger signal in the electrocardiogram images of each cardiac cycle corresponding to the imaging plane collected in real time to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to the imaging plane.

[0008] In some embodiments of the first aspect of the present application, the pulse application rules include: an inversion pulse application rule, including: when an electrocardiogram trigger signal corresponding to an inversion pulse cardiac cycle is detected in an electrocardiogram image, an inversion recovery pulse is applied according to a magnetic resonance sequence in the corresponding inversion pulse cardiac cycle to obtain a dual-echo image of the corresponding inversion pulse cardiac cycle; a T2 preparation pulse application rule, including: when an electrocardiogram trigger signal corresponding to a T2 preparation pulse cardiac cycle is detected in an electrocardiogram image, a T2 preparation pulse is applied according to a magnetic resonance sequence in the corresponding T2 preparation pulse cardiac cycle to obtain a dual-echo image of the corresponding T2 preparation pulse cardiac cycle; a T1ρ preparation pulse application rule, including: when an electrocardiogram trigger signal corresponding to a T1ρ preparation pulse cardiac cycle is detected in an electrocardiogram image, a T1ρ preparation pulse is applied according to a magnetic resonance sequence in the corresponding T1ρ preparation pulse cardiac cycle to obtain a dual-echo image of the corresponding T1ρ preparation pulse cardiac cycle; a diaphragmatic navigation pulse application rule, including: when an electrocardiogram trigger signal corresponding to an inversion pulse cardiac cycle is detected in an electrocardiogram image, according to a magnetic resonance sequence, a diaphragmatic navigation pulse is applied after applying an inversion recovery pulse in the corresponding inversion pulse cardiac cycle and a position correction operation of the imaging plane is performed; when an electrocardiogram trigger signal corresponding to a T2 preparation pulse cardiac cycle is detected in an electrocardiogram image, according to a magnetic resonance sequence, a diaphragmatic navigation pulse is applied before applying a T2 preparation pulse in the corresponding T2 preparation pulse cardiac cycle and a position correction operation of the imaging plane is performed; when an electrocardiogram trigger signal corresponding to a T1ρ preparation pulse cardiac cycle is detected in an electrocardiogram image, according to a magnetic resonance sequence, a diaphragmatic navigation pulse is applied before applying a T1ρ preparation pulse in the corresponding T1ρ preparation pulse cardiac cycle and a position correction operation of the imaging plane is performed.

[0009] In some embodiments of the first aspect of the present application, the pulse application rules further include: a dual-echo read pulse sequence application rule, including: according to a magnetic resonance sequence, a first dual-echo read pulse sequence and a second dual-echo read pulse sequence are applied in the first and second cardiac cycles respectively, and the first dual-echo read pulse sequence is applied to each cardiac cycle after the second cardiac cycle; wherein, both the first dual-echo read pulse sequence and the second dual-echo read pulse sequence are used to acquire dual-echo images; the first echo time of the second dual-echo read pulse sequence is located between the two echo times of the first dual-echo read pulse sequence, and the second echo time of the second dual-echo read pulse sequence is greater than the second echo time of the first dual-echo read pulse sequence; the diaphragmatic navigation pulse application rule further includes: when an electrocardiogram trigger signal corresponding to a cardiac cycle without a preparation pulse is detected in an electrocardiogram image, according to a magnetic resonance sequence, a diaphragmatic navigation pulse is applied before applying a dual-echo read pulse sequence in the corresponding cardiac cycle without a preparation pulse and a position correction operation of the imaging plane is performed.

[0010] In some embodiments of the first aspect of the present application, based on each dual-echo image, a water-fat separation operation based on hybrid multi-echo is performed to obtain a water signal image and a fat fraction map, including: using the GraphCut algorithm, based on the dual-echo images of the first and second cardiac cycles, obtaining a reference B0 image and a fat fraction map; using the GraphCut algorithm, based on the reference B0 image, performing water-fat separation on the dual-echo images of all cardiac cycles to obtain a water signal image.

[0011] In some embodiments of the first aspect of the present application, by matching the water signal image with the dictionary, a relaxation parameter group map of the subject is obtained, including: matching the transverse component intensity curve of the magnetization vector obtained based on each pixel point in the water signal image with the dictionary to obtain the parameter value corresponding to each pixel point; based on the parameter values corresponding to each pixel point, obtaining the relaxation parameter group map of the subject.

[0012] To achieve the above object and other related objects, the second aspect of the present application provides a free-breathing cardiac fat fraction and multi-relaxation parameter simultaneous quantitative magnetic resonance imaging device, including: a sequence establishment module for establishing a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multi-relaxation parameters; a scanning module for scanning the cardiac tissue of the subject in a free-breathing state through the magnetic resonance sequence at multiple imaging planes to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane; a dictionary establishment module for simulating the evolution process of the magnetization vector based on the Bloch equation and the electrocardiogram trigger signal and establishing a dictionary; a water-fat separation module for performing image processing on the dual-echo images of each cardiac cycle and, based on the processed dual-echo images, performing a water-fat separation operation based on hybrid multi-echo to obtain a water signal image and a fat fraction map; a group map generation module for obtaining the relaxation parameter group map of the subject by matching the water signal image with the dictionary.

[0013] To achieve the above object and other related objects, the third aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the free-breathing cardiac fat fraction and multi-relaxation parameter simultaneous quantitative magnetic resonance imaging method is implemented.

[0014] To achieve the above object and other related objects, the fourth aspect of the present application provides an electronic terminal, including a memory, a processor, and a computer program stored on the memory; the processor executes the computer program to implement the free-breathing cardiac fat fraction and multi-relaxation parameter simultaneous quantitative magnetic resonance imaging method.

[0015] As described above, the method, apparatus, terminal, and medium for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multi-relaxation parameters of the present application have the following beneficial effects:

[0016] In the present application, data is collected while the subject is breathing freely, which reduces the burden on the subject and ensures the accuracy of fat fraction quantification and the accuracy of water-fat separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It shows a schematic flowchart of the method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multi-relaxation parameters in an embodiment of the present application.

[0018] Figure 2 It shows a schematic diagram of a magnetic resonance sequence in a specific embodiment of the present application.

[0019] Figure 3 It shows a schematic diagram of a relaxation parameter group map in a specific embodiment of the present application.

[0020] Figure 4 It shows a scatter plot of the quantitative result and the reference result in a specific embodiment of the present application.

[0021] Figure 5 It shows a histogram of the average value and standard deviation of the quantitative result and the quantitative result of the traditional clinical sequence in a specific embodiment of the present application.

[0022] Figure 6 It shows a schematic block diagram of the apparatus for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multi-relaxation parameters in an embodiment of the present application.

[0023] Figure 7 It shows a schematic structural diagram of an electronic terminal in an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following specific examples illustrate the implementation manners of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0025] In the embodiments of the present application, terms such as "first" and "second" are used to distinguish the same items or similar items with basically the same functions and effects. Those skilled in the art can understand that the terms "first" and "second" do not limit the quantity and execution order, and the terms "first" and "second" do not necessarily mean different.

[0026] It should be noted that in the embodiments of the present application, words such as "exemplary" or "for example" represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0027] In the embodiments of the present application, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after. "At least one (item)" or its similar expression refers to any combination of these items, including any combination of single item (item) or plural items (items). For example, at least one (item) of a, b, or c can represent: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, c can be single or multiple.

[0028] To facilitate the understanding of the embodiments of the present application, first, in combination with Figure 1 detailed description is given. Figure 1 The flowchart of a method for simultaneous quantitative magnetic resonance imaging of free - breathing cardiac fat fraction and multi - relaxation parameters in an embodiment of the present invention is shown. The method for simultaneous quantitative magnetic resonance imaging of free - breathing cardiac fat fraction and multi - relaxation parameters in this embodiment mainly includes the following steps:

[0029] Step S11: Establish a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multi - relaxation parameters.

[0030] In one embodiment, establishing a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multi - relaxation parameters includes: determining an optimized combination of optimal preparation pulse sequences and an optimal flip - angle combination of readout radio - frequency pulses for each cardiac cycle; based on the optimal preparation pulse sequence combination and the optimal flip - angle combination of readout radio - frequency pulses, obtaining a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multi - relaxation parameters; wherein, the magnetic resonance sequence includes: pulse data corresponding to each cardiac cycle.

[0031] Specifically, the optimal preparation pulse sequence combination includes: the number of cardiac cycles for pulse application, the types of preparation pulses applied corresponding to each cardiac cycle, the number of pulses corresponding to each type of preparation pulse, and the pulse parameters of each preparation pulse. Through digital simulation experiments, phantom experiments, and in-vivo experiments, the optimal preparation pulse sequence is optimized to determine the preparation pulse sequence combination with the minimum error. Among them, the preparation pulse sequence combination with the minimum error is the optimal preparation pulse sequence combination.

[0032] It should be noted that the pulse sequence combination with the minimum error is the pulse sequence combination with the minimum quantitative error for cardiac fat fraction and multiple relaxation parameters.

[0033] Furthermore, through digital simulation experiments, phantom experiments, and in-vivo experiments, each pulse flip angle in the readout radiofrequency pulse flip angle combination is optimized to determine the readout radiofrequency pulse flip angle combination with the minimum error. Among them, the readout radiofrequency pulse flip angle combination includes: the readout radiofrequency pulse flip angles corresponding to each cardiac cycle group; the cardiac cycles for pulse application are divided into multiple groups, and each group is a cardiac cycle group. The readout radiofrequency pulse flip angle combination with the minimum error is the readout radiofrequency pulse flip angle combination with the minimum simultaneous quantitative error for cardiac fat fraction and multiple relaxation parameters, and the readout radiofrequency pulse flip angle combination with the minimum error is the optimal readout radiofrequency pulse flip angle combination. For example, assume that the number of cardiac cycles for scanning is 14, the cardiac cycles are divided into 5 groups, the pulse flip angles of each group are different, and the optimization range of the flip angle is from 2° to 16°, with a step size of 2°.

[0034] Furthermore, according to the determined optimal preparation pulse sequence combination and the optimal readout radiofrequency pulse flip angle combination, the pulse data corresponding to each cardiac cycle is determined, and then a magnetic resonance sequence for simultaneous quantitative analysis of the corresponding cardiac fat fraction and multiple relaxation parameters is obtained;

[0035] Among them, the pulse data corresponding to each cardiac cycle includes: the number of cardiac cycles for pulse application, the types of pulses applied corresponding to each cardiac cycle, the number of pulses corresponding to each type of pulse, and the pulse parameters of each pulse; among them, the pulse parameters of each pulse include: the pulse flip angle in the optimal readout radiofrequency pulse flip angle combination.

[0036] Step S12: Scan the cardiac tissue of the subject in the free breathing state through the magnetic resonance sequence to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane.

[0037] In one embodiment, the magnetic resonance sequence is used to scan the cardiac tissue of the subject under free breathing state for multiple imaging planes, and dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane are obtained, including: based on the magnetic resonance sequence, magnetic resonance scanning operations are sequentially performed on each imaging plane according to the electrocardiogram images of each imaging plane collected in real time, and dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane are obtained; wherein, the magnetic resonance scanning operation includes: based on the pulse application rule, corresponding pulses are applied in each cardiac cycle according to the magnetic resonance sequence and the electrocardiogram trigger signals in the electrocardiogram images of each cardiac cycle corresponding to the imaging plane collected in real time, so as to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to the imaging plane.

[0038] The scanning process will be explained below:

[0039] The cardiac tissue of the subject under free breathing state is divided into multiple imaging planes, and scans of multiple imaging planes are sequentially performed. For example, the short-axis plane of the cardiac tissue can be divided into three layers, namely the apical layer, the middle layer and the basal layer. The scan of each imaging plane includes: scans in multiple cardiac cycles, and one or a group of dual-echo images are obtained corresponding to each cardiac cycle. The electrocardiogram image collected in real time is the electrocardiogram (ECG) of the subject collected in real time. Among them, the electrocardiogram (ECG) is a graph of various forms of potential changes led out from the body surface by an electrocardiograph during each cardiac cycle of the heart, accompanied by the change of bioelectricity of the electrocardiogram; the electrocardiogram includes: P wave, Q wave, R wave, S wave and T wave. The electrocardiogram trigger signal is generated by the R wave. The corresponding electrocardiogram trigger signal is collected in each cardiac cycle.

[0040] Taking one imaging plane as an example, when the electrocardiogram trigger signal corresponding to a cardiac cycle is collected, corresponding pulses are applied to this cardiac cycle based on the magnetic resonance sequence, so as to obtain the dual-echo image corresponding to this cardiac cycle. After corresponding pulses are sequentially applied to the cardiac cycles corresponding to this imaging plane based on the magnetic resonance sequence, dual-echo images for all cardiac cycles corresponding to this imaging plane are obtained.

[0041] It should be noted that the cardiac cycle refers to the start of one heartbeat to the start of the next heartbeat, that is, the time required for the heart to complete one contraction and relaxation. In the present invention, the electrocardiogram trigger signal represents the start of a cardiac cycle, and the time from the current electrocardiogram trigger signal to the next trigger signal represents a cardiac cycle.

[0042] In one embodiment, the pulse application rule includes:

[0043] Inversion pulse application rules, including: when an electrocardiogram trigger signal corresponding to the inversion pulse cardiac cycle is detected in the electrocardiogram image, an inversion recovery pulse is applied according to the magnetic resonance sequence in the corresponding inversion pulse cardiac cycle to obtain a dual-echo image of the corresponding inversion pulse cardiac cycle; the inversion recovery pulse is used to introduce T1 contrast in the dual-echo image;

[0044] T2 preparation pulse application rules, including: when an electrocardiogram trigger signal corresponding to the T2 preparation pulse cardiac cycle is detected in the electrocardiogram image, a T2 preparation pulse is applied according to the magnetic resonance sequence in the corresponding T2 preparation pulse cardiac cycle to obtain a dual-echo image of the corresponding T2 preparation pulse cardiac cycle; the T2 preparation pulse is used to introduce T2 contrast in the dual-echo image;

[0045] T1ρ preparation pulse application rules, including: when an electrocardiogram trigger signal corresponding to the T1ρ preparation pulse cardiac cycle is detected in the electrocardiogram image, a T1ρ preparation pulse is applied according to the magnetic resonance sequence in the corresponding T1ρ preparation pulse cardiac cycle to obtain a dual-echo image of the corresponding T1ρ preparation pulse cardiac cycle; the T1ρ preparation pulse is used to introduce T1ρ contrast in the dual-echo image;

[0046] Dual-echo read pulse sequence application rules, including: according to the magnetic resonance sequence, a first type of dual-echo read pulse sequence and a second type of dual-echo read pulse sequence are applied in the first and second cardiac cycles respectively, and the first type of dual-echo read pulse sequence is applied to each cardiac cycle after the second cardiac cycle;

[0047] Among them, both the first type of dual-echo read pulse sequence and the second type of dual-echo read pulse sequence are used to acquire dual-echo images; the first echo time of the second type of dual-echo read pulse sequence is located between the two echo times of the first type of dual-echo read pulse sequence, and the second echo time of the second type of dual-echo read pulse sequence is greater than the second echo time of the first type of dual-echo read pulse sequence. It should be noted that in the above embodiment, the optimized pulse flip angle is the flip angle of the dual-echo read pulse sequence;

[0048] Diaphragm navigation pulse application rules, including: when an electrocardiogram trigger signal corresponding to the inversion pulse cardiac cycle is detected in the electrocardiogram image, according to the magnetic resonance sequence, a diaphragm navigation pulse is applied after the inversion recovery pulse is applied in the corresponding inversion pulse cardiac cycle and a position correction operation of the imaging plane is performed;

[0049] When an electrocardiogram trigger signal corresponding to the T2 preparation pulse cardiac cycle is detected in the electrocardiogram image, according to the magnetic resonance sequence, a diaphragm navigation pulse is applied before the T2 preparation pulse is applied in the corresponding T2 preparation pulse cardiac cycle and a position correction operation of the imaging plane is performed;

[0050] When an electrocardiogram trigger signal corresponding to the cardiac cycle of the T1ρ preparation pulse is detected in the electrocardiogram image, according to the magnetic resonance sequence, a diaphragmatic navigation pulse is applied before applying the T1ρ preparation pulse in the cardiac cycle corresponding to the T1ρ preparation pulse, and a position correction operation of the imaging plane is performed;

[0051] When an electrocardiogram trigger signal of a cardiac cycle without a preparation pulse is detected in the electrocardiogram image, according to the magnetic resonance sequence, a diaphragmatic navigation pulse is applied before applying the dual-echo read pulse sequence in the corresponding cardiac cycle without a preparation pulse, and a position correction operation of the imaging plane is performed.

[0052] It should be noted that in the existing readout methods, the four echo times are set to increase sequentially. For example, the four echo times are set to 1.42 ms, 2.68 ms, 3.94 ms, and 5.2 ms respectively. This continuously increasing design will significantly extend the maximum echo time and the repetition time (TR), resulting in an overly long acquisition window, exceeding the optimal acquisition window (about 230 ms) at the end of diastole. However, the hybrid dual echo composed of the first dual-echo read pulse sequence and the second dual-echo pulse sequence of the present invention effectively avoids the problem of overly long maximum echo time and repetition time (TR) by adjusting the distribution of the echo times, thereby controlling the acquisition window during the relatively static period of cardiac diastole. And, according to the attenuation law of the magnetic resonance echo signal, using a shorter echo time can reduce signal loss, thereby improving the signal-to-noise ratio of the image.

[0053] In a specific embodiment, the dual-echo read pulse sequence is a dual-echo spoiled gradient echo pulse sequence using Cartesian sampling, which is used to obtain a dual-echo image. It should be understood that Cartesian sampling is a sampling method based on uniform distribution and is suitable for sampling in multi-dimensional space. Its basic idea is to perform sampling independently on each dimension to form a Cartesian product. The dual-echo spoiled gradient echo pulse sequence is an MRI imaging sequence that combines dual-echo technology and spoiling technology, mainly used to improve imaging efficiency and image quality.

[0054] In a specific embodiment, a diaphragmatic navigation bar of the diaphragmatic navigation module is placed at the highest position of the liver of the subject to be examined; the diaphragmatic navigation bar applies a diaphragmatic navigation pulse (columnar excitation pulse or cross excitation pulse); after the diaphragmatic navigation module obtains the one-dimensional image monitored by the diaphragmatic navigation bar and calculates the diaphragm displacement, it adjusts the position of the imaging plane in real time to keep the imaging plane relatively static with respect to the heart of the subject to be examined, effectively eliminating the through-plane motion of the heart caused by respiratory motion, thereby improving the stability and accuracy of the quantitative results.

[0055] Specifically, before scanning, the diaphragmatic motion pattern of the subject is learned and analyzed based on the set diaphragmatic navigation repetition time (TR) to determine the position of the diaphragm at the end of respiration. According to experience, the displacement of the heart in the cephalocaudal direction is 60% of the displacement of the diaphragm. Based on the above experience, the position of the imaging plane can be corrected by the displacement of the diaphragm. Correcting the position of the imaging plane can significantly eliminate the through-plane motion of the heart caused by the respiration of the subject, so as to keep the relative stillness between the imaging plane and the heart.

[0056] It should be noted that the diaphragm is a muscle-fiber structure located between the thoracic cavity and the abdominal cavity and is an important respiratory muscle of the body. The diaphragmatic navigation repetition time is the same as the average heart beat interval of the subject; among them, the time between one heart beat and the next is the heart beat interval.

[0057] Optionally, the position of the diaphragm is detected by a cross-excited navigator bar. The position of the top of the liver is found on the transverse image, and the cross part of the diaphragmatic navigation bar is set at the position of the top of the liver; the highest position of the liver is found on the coronal image, and the center of the cross-excited navigator bar is placed at the junction of the liver and the lung.

[0058] It should be noted that in magnetic resonance imaging, the transverse (axial) position refers to the cross-sectional imaging plane perpendicular to the long axis of the human body, which is used to display the left-right and front-back distributions of anatomical structures; the coronal position refers to the coronal imaging plane parallel to the long axis of the human body and perpendicular to the sagittal plane, which is used to display the left-right and up-down distributions of anatomical structures. Both are orthogonal standard imaging orientations, which can respectively provide tomographic information of tissue organs in the horizontal and vertical directions.

[0059] In one embodiment, in the inversion pulse cardiac cycle, the T2 preparation pulse cardiac cycle, and the T1ρ preparation pulse cardiac cycle, the application order of the first dual-echo read pulse sequence is the last; when no preparation pulse cardiac cycle is applied, only the diaphragmatic navigation pulse and the dual-echo read pulse sequence are applied, and the application order of the dual-echo read pulse sequence is the last.

[0060] To better illustrate the magnetic resonance sequence for simultaneous quantification of the corresponding cardiac fat fraction and multi-relaxation parameters, a specific embodiment is provided as follows:

[0061] Embodiment 1: A magnetic resonance sequence for simultaneous quantification of the corresponding cardiac fat fraction and multi-relaxation parameters.

[0062] In the short-axis direction of the heart, the heart tissue is divided into three imaging planes, namely the apical layer, the middle layer, and the basal layer. The number of cardiac cycles corresponding to the scans is 14 (in the order from left to right in Figure 2 ).

[0063] The established magnetic resonance sequence is asFigure 2 As shown, it includes: an inversion recovery pulse (IR), a T2 preparation pulse (T2-Prep), a T1ρ preparation pulse (T1ρ-Prep), and a dual-echo read pulse sequence ( Figure 2 denoted as #1 to #14 in the figure). The inversion recovery pulse is applied to the 3rd and 9th cardiac cycles, and the inversion time is 100 s. The T2 preparation pulse is applied to the 6th to 8th cardiac cycles, and the corresponding preparation times are 35 ms, 45 ms, and 55 ms respectively. The T1ρ preparation pulse is applied to the 12th to 14th cardiac cycles, the spin-lock frequency is 350 Hz, and the corresponding spin-lock times are 16 ms, 30 ms, and 50 ms respectively. A dual-echo read pulse sequence is applied to each cardiac cycle. Among them, the first dual-echo read pulse sequence is applied to the 1st cardiac cycle, the 3rd to 14th cardiac cycles respectively, and the second dual-echo read pulse sequence is applied to the 2nd cardiac cycle. In the 3rd, 6th, 7th, 8th, 9th, 12th, 13th, and 14th cardiac cycles, the application order of the first dual-echo read pulse sequence is the last. The flip angle of the dual-echo read pulse sequence applied to the first five cardiac cycles is 8°, and the flip angle of the dual-echo read pulse sequence applied to the remaining cardiac cycles is 14°. In the 3rd or 9th cardiac cycle, after applying the inversion recovery pulse and before applying the dual-echo read pulse sequence, a diaphragmatic navigator pulse is applied and a position correction operation of the imaging plane is performed; in the 6th, 7th, or 8th cardiac cycle, before applying the T2 preparation pulse, a diaphragmatic navigator pulse is applied and a position correction operation of the imaging plane is performed; in the 12th, 13th, and 14th cardiac cycles, before applying the T1ρ preparation pulse, a diaphragmatic navigator pulse is applied and a position correction operation of the imaging plane is performed; in the 1st, 2nd, 4th, 5th, 10th, or 11th cardiac cycles (these 6 cardiac cycles are all cardiac cycles without applying preparation pulses), before applying the dual-echo read pulse sequence, a diaphragmatic navigator pulse is applied and a position correction operation of the imaging plane is performed.

[0064] To better illustrate the dual-echo read pulse sequence, a specific embodiment is provided as follows:

[0065] Embodiment 2: A first dual-echo read pulse and a second dual-echo read pulse.

[0066] The echo time of the first dual-echo read pulse is [1.42, 2.68] ms, the echo time of the second dual-echo read pulse is [2.05, 3.31] ms. The first echo time (2.05 ms) of the second dual-echo read pulse is located between the two echo times (1.42 ms and 2.68 ms) of the first dual-echo read pulse, and the second echo time (3.31 ms) of the second dual-echo read pulse is greater than the second echo time 2.68 ms of the first dual-echo read pulse.

[0067] Step S13: Simulate the evolution process of the magnetization vector based on the Bloch equation and the electrocardiogram trigger signal, and establish a dictionary.

[0068] Optionally, the simulation of the evolution process of the magnetization vector based on the Bloch equation and the electrocardiogram trigger signal, and the establishment of a dictionary, as Figure 3 shown, includes:

[0069] The first step: Obtain a plurality of parameter combinations based on the numerical change range and discretization step size of the set quantitative parameters; wherein, the quantitative parameters include: T1 (longitudinal relaxation time), T2 (transverse relaxation time), T1ρ (longitudinal relaxation time under spin-lock pulse), and B1 parameter; the parameter combinations include: discrete T1, T2, T1ρ, and B1 parameters.

[0070] It should be noted that the B1 parameter is obtained based on the flip angle of the dual-echo read pulse sequence applied to each cardiac cycle. Specifically, the flip angle determined when establishing the magnetic resonance sequence for simultaneous quantification of cardiac fat fraction and multiple relaxation parameters in step S11 is the designed flip angle, while during the actual scanning process, due to actual conditions, the actual flip angle of the dual-echo read pulse sequence applied to each cardiac cycle is different from the designed flip angle. The B1 parameter is the ratio of the actual flip angle to the designed flip angle of the dual-echo read pulse sequence applied to each cardiac cycle.

[0071] It should also be noted that the numerical change range and discretization step size of the quantitative parameters are set based on the results of traditional clinical quantification. The above quantitative parameters can be used for comprehensive evaluation of cardiac tissue. For example, in the case of edema, inflammation, and fibrosis, the increase in free water or fibrous tissue in cardiac tissue will cause the T1 value to increase; in the case of iron deposition or increased fat content (such as glycosphingolipid accumulation in Fabry disease), the T1 value will decrease. An increase in the T2 value reflects an increase in the free water content in the tissue and can be used to diagnose myocardial edema and inflammation; acute or chronic myocardial infarction and other non-ischemic myocardial diseases, such as dilated cardiomyopathy and hypertrophic cardiomyopathy, will cause an increase in the T1ρ value. The T1ρ value can detect focal and diffuse myocardial fibrosis without injecting a contrast agent.

[0072] The second step: Simulate the evolution process of the magnetization vector under each parameter combination based on the Bloch equation and the electrocardiogram trigger signal to obtain the intensity of the transverse component of the magnetization vector corresponding to the center line of the K-space; specifically, taking the simulation process of one parameter combination as an example: Simulate the evolution process of the magnetization vector under this parameter combination based on the Bloch equation and the electrocardiogram trigger signal to obtain the intensity of the transverse component of the magnetization vector corresponding to the center line of the K-space for each cardiac cycle.

[0073] It should be noted that the Bloch equations are a set of differential equations that describe the dynamic behavior of the macroscopic magnetization vector in nuclear magnetic resonance (MRI). By setting the B1 parameter for simulation, the influence of the inhomogeneity of the B1 field can be corrected. The inhomogeneity of the B1 field caused by the limitations of magnetic resonance hardware will affect the quantitative accuracy of T1, T2, and T1ρ parameters.

[0074] Step 3: Obtain the corresponding transverse component intensity curve of the magnetization vector based on the intensity of the transverse component of the magnetization vector corresponding to the central line of the K-space; specifically, taking a parameter combination as an example, when the intensity of the transverse component of the magnetization vector corresponding to the central line of the K-space for each cardiac cycle of the parameter combination is obtained, the intensity of the transverse component of the magnetization vector corresponding to the central line of the K-space for all cardiac cycles of the parameter combination constitutes the corresponding transverse component intensity curve of the magnetization vector.

[0075] It should be noted that the K-space is the Fourier space of the rectangular coordinate space, that is, the frequency space of the Fourier transform, also known as the Fourier space. The projection curve of the MR signal in the K-space is called the K-trajectory, also called the Fourier line. The magnetization vector is used to describe the intensity of magnetism.

[0076] Step 4: The parameter combination and the transverse component intensity curve of the magnetization vector form a dictionary.

[0077] Step S14: Perform image processing on each dual-echo image, and based on the processed dual-echo image, perform water-fat separation operation based on the hybrid multi-echo to obtain a water signal image and a fat fraction map.

[0078] In one embodiment, the image processing includes image registration and noise reduction. It should be noted that the image processing is used to eliminate the residual in-plane motion and improve the image quality. Those skilled in the art can select a suitable method for image registration and image noise reduction according to actual needs, and the present invention does not limit this.

[0079] In one embodiment, based on each dual-echo image, performing a water-fat separation operation based on the hybrid multi-echo to obtain a water signal image and a fat fraction map includes: using the GraphCut algorithm, based on the dual-echo images of the first and second cardiac cycles, obtaining a reference B0 image and a fat fraction map; using the GraphCut algorithm, based on the reference B0 image, performing water-fat separation on the dual-echo images of all cardiac cycles to obtain a water signal image.

[0080] Specifically, such as Figure 2As shown, the GraphCut algorithm, that is, the graph cut algorithm, is an image segmentation algorithm based on graph theory. In the present invention, through the hybrid multi-echo reading of the first two cardiac cycles, a four-echo group image (Echo1, Echo2, Echo3, and Echo4) composed of double-echo images of the first cardiac cycle and the second cardiac cycle is obtained.

[0081] Further, the four-echo group image is input into the GraphCut algorithm to obtain a high-precision fat fraction map (FatFraction) and a B0 map (B0 map). It should be noted that the GraphCut algorithm generally requires multiple echoes (>2) to generate an accurate water-fat separation result because multiple echoes can provide sufficient phase information to accurately estimate the B0 map, thereby providing necessary correction parameters for water-fat separation. The B0 image is an image used to quantify the spatial inhomogeneity of the main static magnetic field (B0) in magnetic resonance imaging, which characterizes local magnetic field distortion caused by magnet defects, sample magnetic susceptibility differences, or external interference through the magnetic field offset (unit: Hz or ppm). This distribution map can correct image geometric distortion, optimize shimming parameters, and provide key magnetic field inhomogeneity data for susceptibility-weighted imaging and quantitative analysis, thereby improving imaging accuracy and reliability. The fat fraction map is used to quantitatively evaluate the fat content in cardiac tissue.

[0082] Further, the B0 map, as a correction parameter, is input into the improved GraphCut algorithm together with the double-echo images of all cardiac cycles to obtain a water signal image (Water) and a fat image (Fat). It should be noted that taking the B0 map as an input condition can overcome the problem of insufficient double-echo information and achieve the same accuracy of water-fat separation result as multi-echo acquisition.

[0083] Step S15: Obtain the relaxation parameter group map of the subject by matching the water signal image with the dictionary.

[0084] In one embodiment, as Figure 3 shown, the relaxation parameter group map includes a water-phase T1 parameter map (water-only T1map), a water-phase T2 parameter map (water-only T2 map), and a water-phase T1ρ parameter map (water-onlyT1ρmap).

[0085] In one embodiment, obtaining the relaxation parameter group map of the subject by matching the water signal image with the dictionary includes: matching the transverse component intensity curve of the magnetization vector obtained based on each pixel point in the water signal image with the dictionary to obtain the parameter value corresponding to each pixel point; and obtaining the relaxation parameter group map of the subject based on the parameter values corresponding to each pixel point.

[0086] Specifically, the transverse component intensity curve of the magnetization vector obtained from each pixel in the water signal image is matched with the transverse component intensity curves of the magnetization vectors in the dictionary to determine the best-matching curve, and thus the parameter value corresponding to the best-matching curve is obtained according to the best-matching curve. The parameter value corresponding to the best-matching curve is the parameter value corresponding to each pixel; based on the parameter values corresponding to the respective pixels, a relaxation parameter group map of the heart tissue of the subject is obtained.

[0087] In a specific embodiment, as Figure 4 shown, it can be seen from the scatter plot of the quantitative results in the phantom experiment that there is a significant linear correlation between the measurement results and the reference values (correlation coefficient R 2 is greater than 0.98 in both cases), indicating the accuracy of the method of the present invention.

[0088] In a specific embodiment, Figure 5 the histogram of Figure 5 shows the parameter distributions of T1, T2, T1ρ, and fat fraction (FF) of 5 healthy subjects. It can be seen from

[0089] Figure 6 FIG. is a schematic block diagram of a free-breathing cardiac fat fraction and multi-relaxation parameter simultaneous quantitative magnetic resonance imaging device provided by an embodiment of the present application. As Figure 6 shown, the free-breathing cardiac fat fraction and multi-relaxation parameter simultaneous quantitative magnetic resonance imaging device 6 includes:

[0090] A sequence establishment module 61, configured to establish a magnetic resonance sequence corresponding to the simultaneous quantification of the cardiac fat fraction and multi-relaxation parameters;

[0091] A scanning module 62, connected to the sequence establishment module 61, configured to scan the cardiac tissue of the subject in a free-breathing state through the magnetic resonance sequence for multiple imaging planes, and obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane;

[0092] A dictionary establishment module 63, connected to the scanning module 62, configured to simulate the evolution process of the magnetization vector based on the Bloch equation and the electrocardiogram trigger signal, and establish a dictionary;

[0093] A water-fat separation module 64, connected to the scanning module 62, configured to perform image processing on the dual-echo images of each cardiac cycle, and perform water-fat separation operation based on the processed dual-echo images to obtain a water signal image and a fat fraction map;

[0094] The group image generation module 65 is respectively connected to the dictionary establishment module 63 and the water-fat separation module 64, and is configured to obtain the relaxation parameter group image of the subject by matching the water signal image with the dictionary.

[0095] It should be understood that the specific processes of the above respective modules performing the above corresponding steps have been described in detail in the above method embodiments. For the sake of brevity, they will not be repeated here.

[0096] It should also be understood that the division of the modules in the embodiments of the present application is illustrative, and is only a logical function division. In actual implementation, there may be other division methods. In addition, in each embodiment of the present application, the various functional modules may be integrated in one processor, or may exist separately physically, or two or more modules may be integrated in one module. The above integrated modules may be implemented in the form of hardware or in the form of software function modules.

[0097] In one embodiment, a magnetic resonance sequence for simultaneously quantifying the cardiac fat fraction and multiple relaxation parameters is established, including: determining an optimized combination of the best preparation pulse sequences and the best readout radiofrequency pulse flip angle combinations for each cardiac cycle; based on the best preparation pulse sequence combination and the best readout radiofrequency pulse flip angle combination, obtaining a magnetic resonance sequence for simultaneously quantifying the cardiac fat fraction and multiple relaxation parameters; wherein, the magnetic resonance sequence includes: pulse data corresponding to each cardiac cycle.

[0098] In one embodiment, the cardiac tissue of the subject in the free breathing state is scanned at multiple imaging planes through the magnetic resonance sequence to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane, including: based on the magnetic resonance sequence, performing magnetic resonance scanning operations on each imaging plane in sequence according to the electrocardiogram images of each imaging plane collected in real time to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane; wherein, the magnetic resonance scanning operation includes: based on the pulse application rule, applying corresponding pulses in each cardiac cycle according to the magnetic resonance sequence and the electrocardiogram trigger signals in the electrocardiogram images of each cardiac cycle corresponding to the imaging plane collected in real time to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to the imaging plane.

[0099] In one embodiment, the pulse application rules include: an inversion pulse application rule, including: when an electrocardiogram trigger signal corresponding to an inversion pulse cardiac cycle is detected in an electrocardiogram image, an inversion recovery pulse is applied according to a magnetic resonance sequence in the corresponding inversion pulse cardiac cycle to obtain a dual-echo image of the corresponding inversion pulse cardiac cycle; a T2 preparation pulse application rule, including: when an electrocardiogram trigger signal corresponding to a T2 preparation pulse cardiac cycle is detected in an electrocardiogram image, a T2 preparation pulse is applied according to a magnetic resonance sequence in the corresponding T2 preparation pulse cardiac cycle to obtain a dual-echo image of the corresponding T2 preparation pulse cardiac cycle; a T1ρ preparation pulse application rule, including: when an electrocardiogram trigger signal corresponding to a T1ρ preparation pulse cardiac cycle is detected in an electrocardiogram image, a T1ρ preparation pulse is applied according to a magnetic resonance sequence in the corresponding T1ρ preparation pulse cardiac cycle to obtain a dual-echo image of the corresponding T1ρ preparation pulse cardiac cycle; a diaphragmatic navigation pulse application rule, including: when an electrocardiogram trigger signal corresponding to an inversion pulse cardiac cycle is detected in an electrocardiogram image, according to the magnetic resonance sequence, a diaphragmatic navigation pulse is applied after the inversion recovery pulse is applied in the corresponding inversion pulse cardiac cycle and a position correction operation of the imaging plane is performed; when an electrocardiogram trigger signal corresponding to a T2 preparation pulse cardiac cycle is detected in an electrocardiogram image, according to the magnetic resonance sequence, a diaphragmatic navigation pulse is applied before the T2 preparation pulse is applied in the corresponding T2 preparation pulse cardiac cycle and a position correction operation of the imaging plane is performed; when an electrocardiogram trigger signal corresponding to a T1ρ preparation pulse cardiac cycle is detected in an electrocardiogram image, according to the magnetic resonance sequence, a diaphragmatic navigation pulse is applied before the T1ρ preparation pulse is applied in the corresponding T1ρ preparation pulse cardiac cycle and a position correction operation of the imaging plane is performed.

[0100] In one embodiment, the pulse application rules further include: a dual-echo read pulse sequence application rule, including: according to the magnetic resonance sequence, a first dual-echo read pulse sequence and a second dual-echo read pulse sequence are applied in the first and second cardiac cycles respectively, and the first dual-echo read pulse sequence is applied to each cardiac cycle after the second cardiac cycle; wherein, both the first dual-echo read pulse sequence and the second dual-echo read pulse sequence are used to acquire dual-echo images; the first echo time of the second dual-echo read pulse sequence is located between the two echo times of the first dual-echo read pulse sequence, and the second echo time of the second dual-echo read pulse sequence is greater than the second echo time of the first dual-echo read pulse sequence; the diaphragmatic navigation pulse application rule further includes: when an electrocardiogram trigger signal corresponding to a cardiac cycle without a preparation pulse is detected in an electrocardiogram image, according to the magnetic resonance sequence, a diaphragmatic navigation pulse is applied before the dual-echo read pulse sequence is applied in the corresponding cardiac cycle without a preparation pulse and a position correction operation of the imaging plane is performed.

[0101] In one embodiment, based on each dual-echo image, a water-fat separation operation based on hybrid multi-echo is performed to obtain a water signal image and a fat fraction map, including: using the GraphCut algorithm, based on the dual-echo images of the first and second cardiac cycles, obtaining a reference B0 image and a fat fraction map; using the GraphCut algorithm, based on the reference B0 image, performing water-fat separation on the dual-echo images of all cardiac cycles to obtain a water signal image.

[0102] In one embodiment, by matching the water signal image with the dictionary, a relaxation parameter group map of the subject is obtained, including: matching the transverse component intensity curve of the magnetization vector obtained based on each pixel point in the water signal image with the dictionary to obtain the parameter value corresponding to each pixel point; based on the parameter values corresponding to each pixel point, obtaining the relaxation parameter group map of the subject.

[0103] Figure 7 It is a schematic block diagram of an electronic terminal provided by an embodiment of the present application. As Figure 7 shown, the electronic terminal includes: at least one processor 701, a memory 702, at least one network interface 703, and a user interface 705. Each component in the device is coupled together through a bus system 704. It can be understood that the bus system 704 is used to realize the connection and communication between these components. In addition to the data bus, the bus system 704 also includes a power bus, a control bus, and a status signal bus. However, for the sake of clear illustration, in Figure 7 all kinds of buses are labeled as the bus system.

[0104] Among them, the user interface 705 may include a display, a keyboard, a mouse, a trackball, a click gun, a button, a button, a touchpad, or a touch screen, etc.

[0105] It can be understood that the memory 702 may be a volatile memory or a non-volatile memory, and may also include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM, Read Only Memory), a programmable read-only memory (PROM, Programmable Read-Only Memory), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM, Static Random Access Memory), synchronous static random access memory (SSRAM, Synchronous Static Random Access Memory). The memory described in the embodiments of the present invention is intended to include but not be limited to these and any other suitable categories of memories.

[0106] The memory 702 in the embodiments of the present invention is used to store various types of data to support the operation of the electronic terminal 700. Examples of such data include: any executable programs for operating on the electronic terminal 700, such as the operating system 7021 and application programs 7022; the operating system 7021 includes various system programs, such as a framework layer, a core library layer, a driver layer, etc., for implementing various basic services and processing hardware-based tasks. The application programs 7022 may include various application programs, such as a Media Player, a Browser, etc., for implementing various application services. The method for simultaneously quantitatively magnetic resonance imaging of free-breathing cardiac fat fraction and multi-relaxation parameters provided by the embodiments of the present invention may be included in the application programs 7022.

[0107] The method disclosed in the above embodiments of the present invention can be applied to the processor 701 or implemented by the processor 701. The processor 701 may be an integrated circuit chip with signal processing capabilities. During implementation, the steps of the above method can be completed by the integrated logic circuit in the hardware of the processor 701 or instructions in software form. The above-mentioned processor 701 may be a general-purpose processor, a digital signal processor (DSP), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor 701 can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. The general-purpose processor 701 may be a microprocessor or any conventional processor, etc. Combining the steps of the accessory optimization method provided by the embodiments of the present invention can be directly embodied as being executed and completed by a hardware decoding processor, or executed and completed by a combination of hardware and software modules in the decoding processor. The software module may be located in a storage medium, and this storage medium is located in the memory. The processor reads the information in the memory and combines its hardware to complete the steps of the foregoing method.

[0108] In an exemplary embodiment, the electronic terminal 700 may be one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs) for executing the foregoing method.

[0109] According to the method provided by the embodiments of the present application, the present application also provides a computer program product, which includes: computer program code, when the computer program code runs on a computer, causing the computer to execute Figure 1Free-breathing cardiac fat fraction and multi-relaxation parameter simultaneous quantitative magnetic resonance imaging method in the illustrated embodiment.

[0110] According to the method provided by the embodiments of the present application, the present application also provides a computer-readable storage medium storing program code that, when run on a computer, causes the computer to execute Figure 1 Free-breathing cardiac fat fraction and multi-relaxation parameter simultaneous quantitative magnetic resonance imaging method in the illustrated embodiment.

[0111] As used in this specification, the terms "component", "module", "system", etc. are used to refer to computer-related entities, hardware, firmware, combinations of hardware and software, software, or software in execution. For example, a component can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program, and / or a computer. By way of illustration, both an application running on a computing device and the computing device can be components. One or more components can reside in a process and / or an execution thread, and a component can be located on one computer and / or distributed between 2 or more computers. In addition, these components can execute from various computer-readable media storing various data structures. A component can communicate, for example, through a signal with other systems (e.g., via the Internet interacting with another component) through local and / or remote processes according to one or more data packets (e.g., data from two components interacting with a local system, a distributed system, and / or a network).

[0112] Those of ordinary skill in the art can realize that the various illustrative logical blocks and steps described in connection with the embodiments disclosed herein can be implemented in electronic hardware, or in a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the present application.

[0113] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments and will not be repeated here.

[0114] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of devices or units can be in electrical, mechanical, or other forms.

[0115] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0116] In addition, in each embodiment of the present application, the functional units can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit.

[0117] In the above embodiments, the functions of the functional units can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions (programs). When the computer program instructions (programs) are loaded and executed on a computer, the processes or functions according to the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from a website, computer, server, or data center to another website, computer, server, or data center in a wired manner (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that the computer can access or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a high-definition digital video disc (DVD)), or a semiconductor medium (for example, a solid-state disk (SSD), etc.).

[0118] When a function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods of various embodiments of this application. The aforementioned storage medium includes: various media such as USB flash drives, external hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0119] As described above, the above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed by this application can easily think of changes or substitutions, which should all be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

[0120] In summary, this application provides a method, device, terminal, and medium for simultaneously quantitatively magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters, including: scanning the cardiac tissue of a subject in a free-breathing state at multiple imaging planes through a magnetic resonance sequence established for simultaneously quantitatively cardiac fat fraction and multiple relaxation parameters, obtaining dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging plane; simulating the evolution process of the magnetization vector based on the Bloch equation and the electrocardiogram trigger signal, and establishing a dictionary; performing water-fat separation operation based on the mixed multi-echo on the processed dual-echo images to obtain a water signal image and a fat fraction map; obtaining a relaxation parameter group map of the subject by matching the water signal image with the dictionary. This application is collected when the subject is breathing freely, which reduces the burden on the subject and ensures the accuracy of fat fraction quantification and the accuracy of water-fat separation. Therefore, this application effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0121] The above embodiments are only illustrative of the principles and effects of this application, and are not used to limit this application. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by this application should still be covered by the claims of this application.

Claims

1. A method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters, characterized in that: include: Establish a magnetic resonance imaging sequence that corresponds to the simultaneous quantification of cardiac fat fraction and multiple relaxation parameters; Scanning the cardiac tissue of the subject in a free breathing state at multiple imaging levels through the magnetic resonance sequence to obtain double echo images and electrocardiographic triggering signals corresponding to each cardiac cycle at each imaging level; The evolution of magnetization vector is simulated based on Bloch equation and ECG trigger signal, and a dictionary is established; Performing image processing on the double echo images of each cardiac cycle, and performing a water-fat separation operation based on a hybrid multi-echo based on the processed double echo images to obtain a water signal image and a fat fraction map; The relaxation parameter group map of the subject is obtained by matching the water signal image with the dictionary.

2. The method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters according to claim 1, characterized in that: Establish a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multiple relaxation parameters, including: Determining an optimized best preparation pulse sequence combination and a best readout radio frequency pulse flip angle combination involving each cardiac cycle; Based on the optimal preparation pulse sequence combination and the optimal readout radio frequency pulse flip angle combination, a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multiple relaxation parameters is obtained; wherein the magnetic resonance sequence includes: pulse data corresponding to each cardiac cycle.

3. The method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters according to claim 2, characterized in that: Scanning the cardiac tissue of the subject in a free breathing state at multiple imaging levels by means of the magnetic resonance sequence to obtain double echo images and electrocardiographic trigger signals corresponding to each cardiac cycle at each imaging level, including: Based on the magnetic resonance sequence, magnetic resonance scanning operations are performed in sequence at each imaging level according to the electrocardiogram images of each imaging level acquired in real time, so as to obtain double echo images and electrocardiogram trigger signals corresponding to each cardiac cycle of each imaging level; Wherein, the magnetic resonance scanning operation includes: Based on the pulse application rule, corresponding pulses are applied in each cardiac cycle according to the magnetic resonance sequence and the ECG trigger signal in the ECG image of each cardiac cycle of the corresponding imaging level acquired in real time to obtain the double echo image and ECG trigger signal of each cardiac cycle of the corresponding imaging level.

4. The method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters according to claim 3, characterized in that: The pulse application rules include: The inversion pulse application rule includes: when an ECG trigger signal corresponding to an inversion pulse cardiac cycle is detected in the ECG image, applying an inversion recovery pulse in the corresponding inversion pulse cardiac cycle according to a magnetic resonance sequence to obtain a double echo image corresponding to the inversion pulse cardiac cycle; The T2 preparation pulse application rule includes: when an electrocardiographic trigger signal corresponding to a T2 preparation pulse cardiac cycle is detected in the electrocardiographic image, applying a T2 preparation pulse in the corresponding T2 preparation pulse cardiac cycle according to a magnetic resonance sequence to obtain a double echo image corresponding to the T2 preparation pulse cardiac cycle; The T1ρ preparation pulse application rule comprises: when an electrocardiographic trigger signal corresponding to a T1ρ preparation pulse cardiac cycle is detected in an electrocardiographic image, applying a T1ρ preparation pulse in a cardiac cycle corresponding to the T1ρ preparation pulse according to a magnetic resonance sequence to obtain a double echo image corresponding to the T1ρ preparation pulse cardiac cycle; The diaphragm navigation pulse application rule includes: when an ECG trigger signal corresponding to an inversion pulse cardiac cycle is detected in an ECG image, after applying an inversion recovery pulse corresponding to the inversion pulse cardiac cycle according to a magnetic resonance sequence, applying a diaphragm navigation pulse and performing a position correction operation on the imaging plane; When an ECG trigger signal corresponding to a T2 preparation pulse cardiac cycle is detected in the ECG image, a diaphragm navigation pulse is applied and a position correction operation of the imaging plane is performed before applying a T2 preparation pulse corresponding to the T2 preparation pulse cardiac cycle according to a magnetic resonance sequence; When an ECG trigger signal corresponding to a T1ρ preparation pulse cardiac cycle is detected in the ECG image, a diaphragm navigation pulse is applied and a position correction operation of the imaging plane is performed before applying the T1ρ preparation pulse corresponding to the T1ρ preparation pulse cardiac cycle according to the magnetic resonance sequence.

5. The method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters according to claim 4, characterized in that: The pulse application rule also includes: The dual echo readout pulse sequence application rule includes: applying a first dual echo readout pulse sequence and a second dual echo readout pulse sequence in the first and second cardiac cycles respectively according to the magnetic resonance sequence, and applying the first dual echo readout pulse sequence in each cardiac cycle after the second cardiac cycle respectively; Wherein, the first dual echo readout pulse sequence and the second dual echo readout pulse sequence are both used for acquiring dual echo images; the first echo time of the second dual echo readout pulse sequence is between the two echo times of the first dual echo readout pulse sequence, and the second echo time of the second dual echo readout pulse sequence is greater than the second echo time of the first dual echo readout pulse sequence; The diaphragm navigation pulse application rules also include: when an ECG trigger signal is detected in the ECG image for a cardiac cycle in which a preparation pulse is not applied, according to the magnetic resonance sequence, a diaphragm navigation pulse is applied and a position correction operation of the imaging layer is performed before a double echo readout pulse sequence is applied to the corresponding cardiac cycle in which a preparation pulse is not applied.

6. The method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters according to claim 5, characterized in that: Based on each dual echo image, a water-fat separation operation based on hybrid multi-echo is performed to obtain a water signal image and a fat fraction map, including: Using the GraphCut algorithm, the reference B0 image and fat fraction map were obtained based on the dual echo images of the first and second cardiac cycles; The GraphCut algorithm is used to perform water-fat separation on the double echo images of all cardiac cycles based on the reference B0 image to obtain a water signal image.

7. The method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters according to claim 1, characterized in that: Obtaining a relaxation parameter group map of the subject by matching the water signal image with the dictionary, including: Matching a magnetization vector transverse component intensity curve obtained based on each pixel point in the water signal image with the dictionary to obtain a parameter value corresponding to each pixel point; Based on the parameter values ​​corresponding to the pixel points, a relaxation parameter group map of the subject is obtained.

8. A magnetic resonance imaging device for simultaneous quantitative measurement of free-breathing cardiac fat fraction and multiple relaxation parameters, characterized in that: include: A sequence establishment module is used to establish a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multiple relaxation parameters; A scanning module, used to scan the cardiac tissue of the subject in a free breathing state at multiple imaging levels through the magnetic resonance sequence, and obtain a double echo image and an electrocardiogram trigger signal corresponding to each cardiac cycle of each imaging level; A dictionary building module is used to simulate the evolution process of the magnetization vector based on the Bloch equation and the ECG trigger signal, and to build a dictionary; A water-fat separation module is used to process the double echo images of each cardiac cycle, and based on the processed double echo images, perform a water-fat separation operation based on mixed multi-echo to obtain a water signal image and a fat fraction map; The group map generation module is used to obtain the relaxation parameter group map of the subject by matching the water signal image with the dictionary.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

10. An electronic terminal comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the method according to any one of claims 1 to 7.

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