Simultaneous quantitative magnetic resonance imaging method, device, terminal and medium for free breathing cardiac fat fraction and multiple relaxation parameters

Abstract

This application provides a method, device, terminal, and medium for simultaneous quantitative magnetic resonance imaging (MRI) of cardiac fat fraction and multiple relaxation parameters during free breathing. The method includes: scanning the cardiac tissue of a subject under free breathing conditions using an established MRI sequence corresponding to the simultaneous quantification of cardiac fat fraction and multiple relaxation parameters, obtaining dual-echo images and ECG trigger signals for each cardiac cycle at each imaging level; simulating the evolution of the magnetization vector based on the Bloch equation and the ECG trigger signal, and establishing a dictionary; performing a water-fat separation operation based on mixed multi-echo imaging on the processed dual-echo images to obtain water signal images and fat fraction maps; and obtaining a set of relaxation parameter maps of the subject by matching the water signal images with the dictionary. This application acquires data during free breathing, reducing the burden on the subject while ensuring the accuracy of fat fraction quantification and water-fat separation.

Description

Technical Field

[0001] This application relates to the field of magnetic resonance imaging technology, and in particular to a method, device, terminal and medium for simultaneous quantitative magnetic resonance imaging of free breathing heart fat fraction and multiple relaxation parameters. Background Technology

[0002] Quantitative cardiac magnetic resonance imaging (QMRI) is a non-invasive technique capable of assessing myocardial tissue characteristics, and it holds significant value in the diagnosis, risk assessment, and treatment monitoring of cardiovascular diseases. Different relaxation parameters exhibit varying sensitivities to pathological changes such as myocardial fibrosis, inflammation, and edema. Therefore, comprehensive analysis of T1, T2, and T1ρ relaxation parameters can provide more complete information about myocardial tissue, particularly in the diagnosis of complex or difficult-to-diagnose cardiomyopathy. This comprehensive analysis method can improve diagnostic accuracy and effectively reduce the risk of missed diagnoses. However, current clinical QMRI techniques typically require multiple independent two-dimensional scans, resulting in low imaging efficiency. Furthermore, existing imaging techniques often require patients to hold their breath during scanning to reduce motion artifacts, which not only increases the patient's burden but may also affect parameter comparisons and the comprehensive assessment of diseased tissue due to registration errors, thereby reducing diagnostic reliability. More importantly, existing methods often rely on simplified exponential relaxation models to estimate parameter values, failing to adequately account for non-ideal factors in the magnetic resonance imaging system, such as signal noise and field inhomogeneity, which may lead to biased measurement results.

[0003] Meanwhile, fat quantification is also crucial in the assessment of cardiovascular diseases. For example, fat infiltration after myocardial infarction is often closely associated with disease progression, impaired cardiac function, and worsening patient prognosis. Furthermore, the partial volume effect of water and fat can affect the accuracy of parametric imaging. Therefore, water and fat separation is necessary, for example, through a combined myocardial T1 quantification and water-fat separation technique. However, this method is only applicable to in-phase and out-of-phase two-echo acquisitions, making it difficult to provide accurate fat fraction maps. Accurate fat fraction quantification typically requires acquiring three or more echoes, but this significantly prolongs the repetition time (TR), resulting in an excessively long acquisition window. A three-echo acquisition-based water-fat separation cardiac magnetic resonance fingerprinting technique (DIXON-cMRF) can also be used, capable of simultaneously acquiring myocardial T1, T2, and fat fraction maps. However, due to limitations in the acquisition window and breath-hold time, this technique requires a high undersampling factor and relies on a complex reconstruction process; its imaging efficiency and stability still have room for improvement. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a method, device, terminal and medium for simultaneous quantitative magnetic resonance imaging of free breathing cardiac fat fraction and multiple relaxation parameters, in order to solve the problems of low accuracy of fat quantification and poor stability of water-lipid separation magnetic resonance imaging in the prior art.

[0005] To achieve the above and other related objectives, a first aspect of this application provides a method for simultaneous quantitative magnetic resonance imaging (MRI) of cardiac fat fraction and multiple relaxation parameters during free breathing, comprising: establishing an MRI sequence corresponding to the simultaneous quantitative analysis of cardiac fat fraction and multiple relaxation parameters; scanning the cardiac tissue of a subject under free breathing conditions using the MRI 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 of magnetization vectors based on the Bloch equation and the electrocardiogram trigger signals, and establishing a dictionary; performing image processing on the dual-echo images of each cardiac cycle, and performing a water-fat separation operation based on mixed multi-echo images to obtain water signal images and fat fraction maps; and obtaining a relaxation parameter map of the subject by matching the water signal images with the dictionary.

[0006] In some embodiments of the first aspect of this application, establishing a magnetic resonance imaging (MRI) sequence that simultaneously quantifies cardiac fat fraction and multiple relaxation parameters includes: determining an optimized combination of preparation pulse sequences and an optimal combination of readout radiofrequency pulse flip angles for each cardiac cycle; and obtaining an MRI sequence that simultaneously quantifies cardiac fat fraction and multiple relaxation parameters based on the optimal combination of preparation pulse sequences and the optimal combination of readout radiofrequency pulse flip angles; wherein the MRI sequence includes pulse data corresponding to each cardiac cycle.

[0007] In some embodiments of the first aspect of this application, the heart tissue of the subject under free breathing is scanned at multiple imaging levels using the magnetic resonance sequence to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging level. This includes: based on the magnetic resonance sequence, performing magnetic resonance scanning operations sequentially at each imaging level according to the electrocardiogram images acquired in real time at each imaging level to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging level; wherein, the magnetic resonance scanning operation includes: based on pulse application rules, 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 acquired in real time at the corresponding imaging level to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle at the corresponding imaging level.

[0008] In some embodiments of the first aspect of this application, the pulse application rules include: a reverse pulse application rule, comprising: when an electrocardiogram trigger signal corresponding to the reverse pulse cardiac cycle is detected in the electrocardiogram, applying a reverse recovery pulse according to the magnetic resonance sequence in the corresponding reverse pulse cardiac cycle to obtain a double echo image of the corresponding reverse pulse cardiac cycle; a T2 preparation pulse application rule, comprising: when an electrocardiogram trigger signal corresponding to the T2 preparation pulse cardiac cycle is detected in the electrocardiogram, applying a T2 preparation pulse according to the magnetic resonance sequence in the corresponding T2 preparation pulse cardiac cycle to obtain a double echo image of the corresponding T2 preparation pulse cardiac cycle; and a T1ρ preparation pulse application rule, comprising: when an electrocardiogram trigger signal corresponding to the T1ρ preparation pulse cardiac cycle is detected in the electrocardiogram, applying a T1ρ preparation pulse according to the magnetic resonance sequence in the corresponding T1ρ preparation pulse cardiac cycle to obtain a double echo image of the corresponding T2 preparation pulse cardiac cycle. Obtain a dual-echo image of the cardiac cycle corresponding to the T1ρ preparation pulse; the diaphragm navigation pulse application rules include: when an ECG trigger signal corresponding to the inverted pulse cardiac cycle is detected in the ECG image, according to the magnetic resonance sequence, after applying the inverted recovery pulse of the corresponding inverted pulse cardiac cycle, apply a diaphragm navigation pulse and perform a position correction operation on the imaging plane; when an ECG trigger signal corresponding to the T2 preparation pulse cardiac cycle is detected in the ECG image, according to the magnetic resonance sequence, before applying the T2 preparation pulse of the corresponding T2 preparation pulse cardiac cycle, apply a diaphragm navigation pulse and perform a position correction operation on the imaging plane; when an ECG trigger signal corresponding to the T1ρ preparation pulse cardiac cycle is detected in the ECG image, according to the magnetic resonance sequence, before applying the T1ρ preparation pulse of the corresponding T1ρ preparation pulse cardiac cycle, apply a diaphragm navigation pulse and perform a position correction operation on the imaging plane.

[0009] In some embodiments of the first aspect of this application, the pulse application rule further includes: a dual-echo readout pulse sequence application rule, comprising: 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 to each cardiac cycle after the second cardiac cycle; wherein, both the first dual-echo readout pulse sequence and the second dual-echo readout pulse sequence are used to acquire dual-echo images; the first echo time of the second dual-echo readout pulse sequence is located 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 rule further includes: when an electrocardiogram trigger signal of a cardiac cycle in which no preparation pulse is applied is detected in the electrocardiogram, applying a diaphragm navigation pulse and performing a position correction operation on the imaging plane before applying the dual-echo readout pulse sequence in the corresponding cardiac cycle in which no preparation pulse is applied, according to the magnetic resonance sequence.

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

[0011] In some embodiments of the first aspect of this application, obtaining a relaxation parameter map of the tested object by matching the water signal image with the dictionary includes: matching the magnetization vector lateral component intensity curve obtained based on each pixel in the water signal image with the dictionary to obtain the parameter value corresponding to each pixel; and obtaining a relaxation parameter map of the tested object based on the parameter value corresponding to each pixel.

[0012] To achieve the above and other related objectives, a second aspect of this application provides a magnetic resonance imaging (MRI) device for simultaneously quantifying cardiac fat fraction and multiple relaxation parameters during free breathing, comprising: a sequence establishment module for establishing a magnetic resonance sequence corresponding to the simultaneous quantification of cardiac fat fraction and multiple relaxation parameters; a scanning module for scanning the cardiac tissue of the subject under free breathing conditions using the magnetic resonance sequence to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging layer; a dictionary establishment module for simulating the evolution of magnetization vectors based on the Bloch equation and the electrocardiogram trigger signals, and establishing a dictionary; a water-fat separation module for image processing of the dual-echo images of each cardiac cycle, and performing a water-fat separation operation based on mixed multi-echo images to obtain water signal images and fat fraction maps; and a group map generation module for obtaining relaxation parameter group maps of the subject by matching the water signal images with the dictionary.

[0013] To achieve the above and other related objectives, a third aspect of this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters.

[0014] To achieve the above and other related objectives, a fourth aspect of this application provides an electronic terminal, including a memory, a processor, and a computer program stored in the memory; the processor executes the computer program to implement the method for simultaneous quantitative magnetic resonance imaging of free breathing cardiac fat fraction and multiple relaxation parameters.

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

[0016] This application collects samples while the subject is breathing freely, reducing the burden on the subject and ensuring the accuracy of fat fraction quantification and water-lipid separation. Attached Figure Description

[0017] Figure 1 The diagram shown is a flowchart illustrating a method for simultaneously quantifying the fat fraction and multiple relaxation parameters of the heart during free breathing, according to an embodiment of this application.

[0018] Figure 2 The diagram shown is a schematic representation of a magnetic resonance sequence in a specific embodiment of this application.

[0019] Figure 3 The diagram shown is a schematic diagram of a relaxation parameter group in a specific embodiment of this application.

[0020] Figure 4 The results are shown as a scatter plot of quantitative results and reference results in a specific embodiment of this application.

[0021] Figure 5 The image shows a histogram of the average and standard deviation of the quantitative results compared to the quantitative results of a traditional clinical sequence in a specific embodiment of this application.

[0022] Figure 6 The diagram shown is a schematic block diagram of a magnetic resonance imaging device for simultaneously quantifying the fat fraction and multiple relaxation parameters of the heart during free breathing, according to one embodiment of this application.

[0023] Figure 7 The diagram shown is a structural schematic of an electronic terminal according to an embodiment of this application. Detailed Implementation

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

[0025] In the embodiments of this application, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" do not necessarily imply that they are different.

[0026] It should be noted that, in the embodiments of this application, the words "exemplary" or "for example" indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0027] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0028] To facilitate understanding of the embodiments of this application, firstly, in conjunction with Figure 1 Detailed explanation. Figure 1 This document illustrates a flowchart of a method for simultaneous quantitative magnetic resonance imaging (MRI) of cardiac fat fraction and multiple relaxation parameters during free breathing, according to an embodiment of the present invention. The method for simultaneous quantitative MRI of cardiac fat fraction and multiple relaxation parameters during free breathing in this embodiment mainly includes the following steps:

[0029] Step S11: Establish a magnetic resonance sequence that simultaneously quantifies the corresponding cardiac fat fraction and multiple relaxation parameters.

[0030] In one embodiment, establishing a magnetic resonance imaging (MRI) sequence that simultaneously quantifies cardiac fat fraction and multiple relaxation parameters includes: determining an optimized combination of preparation pulse sequences and an optimal combination of readout radiofrequency pulse flip angles for each cardiac cycle; and obtaining an MRI sequence that simultaneously quantifies cardiac fat fraction and multiple relaxation parameters based on the optimal combination of preparation pulse sequences and the optimal combination of readout radiofrequency pulse flip angles; wherein the MRI sequence includes pulse data corresponding to each cardiac cycle.

[0031] Specifically, the optimal preparation pulse sequence combination includes: the number of cardiac cycles to which pulses are applied, the type of preparation pulse applied for each cardiac cycle, the number of pulses corresponding to each type of preparation pulse, and the pulse parameters of each preparation pulse. The optimal preparation pulse sequence is optimized through digital simulation experiments, phantom experiments, and in vivo experiments to determine the preparation pulse sequence combination with the minimum error. The preparation pulse sequence combination with the minimum error is considered the optimal preparation pulse sequence combination.

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

[0033] Furthermore, the readout RF pulse flip angle combinations were optimized through digital simulation experiments, phantom experiments, and in vivo experiments to determine the readout RF pulse flip angle combination with the minimum error. The readout RF pulse flip angle combination includes: the readout RF pulse flip angles corresponding to each cardiac cycle group; the cardiac cycle to which the pulses are applied is divided into multiple groups, each group being a cardiac cycle group. The readout RF pulse flip angle combination with the minimum error is the one with the minimum simultaneous quantitative error for cardiac fat fraction and multiple relaxation parameters; this combination is considered the optimal readout RF pulse flip angle combination. For example, assuming the number of cardiac cycles scanned is 14, the cardiac cycles are divided into 5 groups, each group having a different pulse flip angle, and the optimization range of the flip angle is 2° to 16°, with a step size of 2°.

[0034] Furthermore, based on the determined optimal combination of preparation pulse sequences and optimal combination of readout radio frequency pulse flip angles, the pulse data corresponding to each cardiac cycle is determined, thereby obtaining a magnetic resonance sequence that simultaneously quantifies the corresponding cardiac fat fraction and multiple relaxation parameters.

[0035] The pulse data corresponding to each cardiac cycle includes: the number of cardiac cycles to which the pulse is applied, the type of pulse applied for each cardiac cycle, the number of pulses corresponding to each type of pulse, and the pulse parameters of each pulse; among which, the pulse parameters of each pulse include: the pulse flip angle in the optimal readout radio frequency pulse flip angle combination.

[0036] Step S12: The heart tissue of the subject under free breathing is scanned at multiple imaging levels using the magnetic resonance sequence to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging level.

[0037] In one embodiment, the magnetic resonance sequence is used to scan the heart tissue of the subject under free breathing conditions at multiple imaging levels to obtain dual-echo images and electrocardiogram (ECG) trigger signals for each cardiac cycle corresponding to each imaging level. This includes: based on the magnetic resonance sequence, performing magnetic resonance scanning operations sequentially at each imaging level according to the real-time acquired ECG images of each imaging level to obtain dual-echo images and ECG trigger signals for each cardiac cycle corresponding to each imaging level; wherein the magnetic resonance scanning operation includes: based on pulse application rules, applying corresponding pulses to each cardiac cycle according to the magnetic resonance sequence and the ECG trigger signals in the real-time acquired ECG images of each cardiac cycle at the corresponding imaging level to obtain dual-echo images and ECG trigger signals for each cardiac cycle at the corresponding imaging level.

[0038] The scanning process will be explained below:

[0039] The heart tissue of the subject under free breathing is divided into multiple imaging planes, and scans of these planes are performed sequentially. For example, the short-axis plane of the heart tissue can be divided into three layers: the apical layer, the middle layer, and the basal layer. Scanning of each imaging plane includes scanning over multiple cardiac cycles, with one or a set of dual-echo images acquired for each cardiac cycle. The real-time acquired electrocardiogram (ECG) is a graphical representation of the heart's bioelectrical changes during each cardiac cycle, caused by the successive excitation of the pacemaker, atria, and ventricles. The ECG includes P waves, Q waves, R waves, S waves, and T waves. The ECG trigger signal is generated by the R wave. A corresponding ECG trigger signal is acquired for each cardiac cycle.

[0040] Taking a single imaging layer as an example, when an electrocardiogram trigger signal corresponding to a cardiac cycle is acquired, a corresponding pulse is applied to that cardiac cycle based on a magnetic resonance imaging (MRI) sequence to obtain a dual-echo image corresponding to that cardiac cycle. After sequentially applying the corresponding pulses to the cardiac cycles corresponding to that imaging layer based on the MRI sequence, dual-echo images of all cardiac cycles corresponding to that imaging layer are obtained.

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

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

[0043] The inversion pulse application rules include: when an ECG trigger signal corresponding to the inversion pulse cardiac cycle is detected in the ECG image, an inversion recovery pulse is applied to the corresponding inversion pulse cardiac cycle according to the magnetic resonance sequence 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] The T2 preparation pulse application rules include: when an ECG trigger signal corresponding to the T2 preparation pulse cardiac cycle is detected in the ECG image, a T2 preparation pulse is applied according to the magnetic resonance sequence at 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] The T1ρ preparation pulse application rules include: 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] The rules for applying the dual-echo readout pulse sequence include: applying a first type of dual-echo readout pulse sequence and a second type of dual-echo readout pulse sequence in the first and second cardiac cycles, respectively, based on the magnetic resonance sequence, and applying the first type of dual-echo readout pulse sequence in each cardiac cycle after the second cardiac cycle.

[0047] In this embodiment, both the first and second dual-echo readout pulse sequences are used to acquire dual-echo images. The first echo time of the second dual-echo readout pulse sequence is located 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. It should be noted that the pulse flip angle optimized in the above embodiment is the flip angle of the dual-echo readout pulse sequence.

[0048] The rules for applying the diaphragm navigation pulse include: when an electrocardiogram trigger signal corresponding to the inverted pulse cardiac cycle is detected in the electrocardiogram, the diaphragm navigation pulse is applied after the inverted recovery pulse is applied in the corresponding inverted pulse cardiac cycle according to the magnetic resonance sequence, and the 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, a diaphragmatic navigation pulse is applied before the T2 preparation pulse is applied in the corresponding T2 preparation pulse cardiac cycle, and the position correction operation of the imaging plane is performed according to the magnetic resonance sequence.

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

[0051] When an ECG trigger signal for an unprepared cardiac cycle is detected in the ECG image, a diaphragmatic navigation pulse is applied and a position correction operation of the imaging plane is performed before applying a dual-echo readout pulse sequence for the corresponding unprepared cardiac cycle, according to the magnetic resonance sequence.

[0052] It should be noted that in existing readout methods, the four echo times are set to increase sequentially. For example, the four echo times are set to 1.42ms, 2.68ms, 3.94ms, and 5.2ms, respectively. This continuously increasing design significantly prolongs the maximum echo time and repetition time (TR), resulting in an excessively long acquisition window that exceeds the optimal acquisition window at the end of diastole (approximately 230ms). The hybrid dual-echo method of this invention, consisting of the first dual-echo readout pulse sequence and the second dual-echo pulse sequence, effectively avoids the problem of excessively long maximum echo time and repetition time (TR) by adjusting the distribution of echo times, thereby controlling the acquisition window within the relatively quiescent period of diastole. Furthermore, based on the attenuation law of magnetic resonance echo signals, using shorter echo times can reduce signal loss, thereby improving the signal-to-noise ratio of the image.

[0053] In one specific embodiment, the dual-echo readout pulse sequence is a dual-echo scrambled phase gradient echo pulse sequence using Cartesian sampling, used to acquire dual-echo images. It should be understood that Cartesian sampling is a sampling method based on uniform distribution, suitable for sampling in multi-dimensional space. Its basic idea is to perform sampling independently in each dimension, forming a Cartesian product. The dual-echo scrambled phase gradient echo pulse sequence is an MRI imaging sequence combining dual-echo technology and phase scrambling technology, primarily used to improve imaging efficiency and image quality.

[0054] In one specific embodiment, the diaphragm navigation strip of the diaphragm navigation module is placed at the highest position of the liver of the subject; diaphragm navigation pulses (columnar excitation pulses or cross excitation pulses) are applied to the diaphragm navigation strip; after acquiring the one-dimensional image monitored by the diaphragm navigation strip and calculating the diaphragm displacement, the diaphragm navigation module adjusts the position of the imaging plane in real time so that the imaging plane remains relatively stationary with respect to the heart of the subject, effectively eliminating the transplane motion of the heart caused by respiratory movements, thereby improving the stability and accuracy of quantitative results.

[0055] Specifically, before scanning, the diaphragm movement pattern of the subject is learned and analyzed based on the set diaphragm navigation repetition time (TR) to determine the diaphragm position at the end of respiration. Empirically, the displacement of the heart in the head-to-foot direction is 60% of the diaphragm displacement. Based on this experience, the position of the imaging plane can be corrected by adjusting the diaphragm displacement. Correcting the imaging plane position can significantly eliminate the transplane motion of the heart caused by the subject's breathing, thus maintaining 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 and abdominal cavities and is an important respiratory muscle in the body. The diaphragm navigation repetition time is the same as the average heartbeat interval of the subject being examined; the heartbeat interval is the time between one heartbeat and the next.

[0057] Optionally, the diaphragm position can be detected using cross-excited navigation bars. On a transverse image, the liver apex is located, and the cross-excited portion of the diaphragm navigation bar is positioned at this location; on a coronal image, the highest point of the liver is located, and the center of the cross-excited navigation bar is placed at the junction of the liver and lungs.

[0058] It should be noted that in magnetic resonance imaging (MRI), the transverse (axial) view refers to the imaging plane perpendicular to the long axis of the human body, used to show the left-right and front-back distribution of anatomical structures; the coronal view refers to the imaging plane parallel to the long axis of the human body and perpendicular to the sagittal plane, used to show the left-right and vertical distribution of anatomical structures. Both are orthogonal standard imaging orientations, providing horizontal and vertical tomographic information of tissues and organs, respectively.

[0059] In one embodiment, during the inverted pulse cardiac cycle, the T2 preparation pulse cardiac cycle, and the T1ρ preparation pulse cardiac cycle, the first dual-echo readout pulse sequence is applied last; when no preparation pulse cardiac cycle is applied, and only the diaphragm navigation pulse and the dual-echo readout pulse sequence are applied, the dual-echo readout pulse sequence is applied last.

[0060] To better illustrate the simultaneous quantification of cardiac fat fraction and multiple relaxation parameters using magnetic resonance imaging (MRI) sequences, a specific embodiment is provided below:

[0061] Example 1: A magnetic resonance sequence that simultaneously quantifies cardiac fat fraction and multiple relaxation parameters.

[0062] The heart tissue is divided into three imaging planes along the short axis: the apical, intermediate, and basal planes. The number of cardiac cycles scanned is 14 (in the following order). Figure 2 (From left to right in the middle).

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

[0064] To better illustrate the dual-echo readout pulse sequence, a specific embodiment is provided below:

[0065] Example 2: A first type of dual-echo readout pulse and a second type of dual-echo readout pulse.

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

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

[0068] Optionally, the evolution of the magnetization vector is simulated based on the Bloch equation and ECG trigger signal, and a dictionary is established, such as... Figure 3 As shown, it includes:

[0069] Step 1: Based on the numerical variation range of the set quantitative parameters and the discretization step size, obtain multiple parameter combinations; among them, the quantitative parameters include: T1 (longitudinal relaxation time), T2 (lateral relaxation time), T1ρ (longitudinal relaxation time under spin-locked pulse) and B1 parameter; the parameter combinations include: discrete T1, T2, T1ρ and B1 parameters.

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

[0071] It should also be noted that the numerical range of the quantitative parameters and the discretization step size are based on the results of traditional clinical quantification. These quantitative parameters can be used for comprehensive assessment of cardiac tissue. For example, in cases of edema, inflammation, and fibrosis, increased free water or fibrous tissue within the cardiac tissue leads to an elevated T1 value; conversely, increased iron deposition or fat content (such as glycosphingolipid accumulation in Fabry disease) leads to a decreased T1 value. An elevated T2 value reflects increased 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, result in an elevated T1ρ value. The T1ρ value can detect focal and diffuse myocardial fibrosis without the injection of contrast agents.

[0072] Step 2: Simulate the evolution of the magnetization vector under various parameter combinations based on the Bloch equation and ECG trigger signal to obtain the transverse component intensity of the magnetization vector corresponding to the K-space center line; specifically, take the simulation process of one parameter combination as an example: simulate the evolution of the magnetization vector under this parameter combination based on the Bloch equation and ECG trigger signal to obtain the transverse component intensity of the magnetization vector corresponding to each cardiac cycle.

[0073] It should be noted that the Bloch equations are a set of differential equations describing the dynamic behavior of macroscopic magnetization vectors in nuclear magnetic resonance (MRI). By setting the B1 parameter in simulations, the effects of B1 field inhomogeneities can be corrected. B1 field inhomogeneities caused by MRI hardware limitations can affect the quantitative accuracy of the T1, T2, and T1ρ parameters.

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

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

[0076] Step 4: The parameter combination and the intensity curve of the transverse component 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 a water-fat separation operation based on mixed multi-echo to obtain a water signal image and a fat fraction map.

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

[0079] In one embodiment, a water-lipid separation operation based on mixed multi-echo images is performed to obtain a water signal image and a fat fraction map, including: using the GraphCut algorithm to obtain a reference B0 image and a fat fraction map based on the dual-echo images of the first and second cardiac cycles; and using the GraphCut algorithm to perform water-lipid separation on the dual-echo images of all cardiac cycles based on the reference B0 image to obtain a water signal image.

[0080] Specifically, such as Figure 2As shown, the GraphCut algorithm is an image segmentation algorithm based on graph theory. This invention obtains a four-echo group (Echo1, Echo2, Echo3, and Echo4) composed of the dual-echo images of the first and second cardiac cycles by hybrid multi-echo readings of the first two cardiac cycles.

[0081] Furthermore, the four-echo image set is input into the GraphCut algorithm to obtain high-precision fat fraction maps and B0 maps. It should be noted that the GraphCut algorithm generally requires multiple echoes (>2) to generate accurate fat-water separation results, as multiple echoes provide sufficient phase information to accurately estimate the B0 map, thus providing the necessary correction parameters for fat-water separation. The B0 image is used in magnetic resonance imaging to quantify the spatial inhomogeneity of the master static magnetic field (B0). It characterizes local magnetic field distortion caused by magnet defects, differences in sample magnetic susceptibility, or external interference through 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 magnetic susceptibility-weighted imaging and quantitative analysis, thereby improving imaging accuracy and reliability. The fat fraction map is used to quantitatively assess the fat content in cardiac tissue.

[0082] Furthermore, the B0 image, used as a correction parameter, is input along with the dual-echo images from all cardiac cycles into the improved GraphCut algorithm to obtain water and fat images. It should be noted that using the B0 image as input overcomes the problem of insufficient dual-echo information, achieving water-fat separation results with the same accuracy as multi-echo acquisition.

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

[0084] In one embodiment, such as Figure 3 As shown, the relaxation parameter group map includes the water-only T1 map, the water-only T2 map, and the water-only T1ρ map.

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

[0086] Specifically, the transverse component intensity curves of the magnetization vector obtained from each pixel in the water signal image are matched with the transverse component intensity curves of the magnetization vector in the dictionary to determine the optimal matching curve. The parameter values ​​corresponding to this optimal matching curve are then obtained. The parameter values ​​corresponding to this optimal matching curve are the parameter values ​​corresponding to each pixel. Based on the parameter values ​​corresponding to each pixel, a set of relaxation parameter maps of the heart tissue of the examined object is obtained.

[0087] In one specific embodiment, such as Figure 4 As shown in the scatter plot of the quantitative results from the phantom experiment, there is a significant linear correlation between the measured results and the reference values ​​(correlation coefficient R). 2 The fact that all values ​​are greater than 0.98 indicates the accuracy of the method of the present invention.

[0088] In one specific embodiment, Figure 5 The histogram shows the distribution of T1, T2, T1ρ, and body fat fraction (FF) parameters in five healthy subjects. Figure 5 As can be seen from the results, the method of the present invention exhibits good stability and quantitative consistency in actual experiments.

[0089] Figure 6 This is a schematic block diagram of a magnetic resonance imaging (MRI) device for simultaneously quantifying the fat fraction and multiple relaxation parameters of the heart during free breathing, as provided in an embodiment of this application. Figure 6 As shown, the simultaneous quantitative magnetic resonance imaging (MRI) device 6 for free-breathing cardiac fat fraction and multiple relaxation parameters includes:

[0090] The sequence establishment module 61 is used to establish magnetic resonance sequences that simultaneously quantify the corresponding cardiac fat fraction and multiple relaxation parameters.

[0091] The scanning module 62, connected to the sequence establishment module 61, is used to scan the heart tissue of the subject under free breathing state using the magnetic resonance sequence to obtain dual-echo images of each cardiac cycle corresponding to each imaging layer and electrocardiogram trigger signals.

[0092] The dictionary building module 63, connected to the scanning module 62, is used to simulate the evolution of the magnetization vector based on the Bloch equation and ECG trigger signal, and to build a dictionary.

[0093] The water-lipid separation module 64 is connected to the scanning module 62 and is used to process the dual-echo images of each cardiac cycle. Based on the processed dual-echo images, it performs a water-lipid separation operation based on mixed multi-echo to obtain water signal images and fat fraction maps.

[0094] The image generation module 65, together with the dictionary building module 63 and the water-lipid separation module 64, is used to obtain the relaxation parameter image of the tested object by matching the water signal image with the dictionary.

[0095] It should be understood that the specific process of each module performing the above-mentioned steps has been described in detail in the above method embodiments, and will not be repeated here for the sake of brevity.

[0096] It should also be understood that the module division in the embodiments of this application is illustrative and only represents a logical functional division; in actual implementation, there may be other division methods. Furthermore, the functional modules in the various embodiments of this application can be integrated into a single processor, exist as separate physical entities, or be integrated into a single module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0097] In one embodiment, establishing a magnetic resonance imaging (MRI) sequence that simultaneously quantifies cardiac fat fraction and multiple relaxation parameters includes: determining an optimized combination of preparation pulse sequences and an optimal combination of readout radiofrequency pulse flip angles for each cardiac cycle; and obtaining an MRI sequence that simultaneously quantifies cardiac fat fraction and multiple relaxation parameters based on the optimal combination of preparation pulse sequences and the optimal combination of readout radiofrequency pulse flip angles; wherein the MRI sequence includes pulse data corresponding to each cardiac cycle.

[0098] In one embodiment, the magnetic resonance sequence is used to scan the heart tissue of the subject under free breathing conditions at multiple imaging levels to obtain dual-echo images and electrocardiogram (ECG) trigger signals for each cardiac cycle corresponding to each imaging level. This includes: based on the magnetic resonance sequence, performing magnetic resonance scanning operations sequentially at each imaging level according to the real-time acquired ECG images of each imaging level to obtain dual-echo images and ECG trigger signals for each cardiac cycle corresponding to each imaging level; wherein the magnetic resonance scanning operation includes: based on pulse application rules, applying corresponding pulses to each cardiac cycle according to the magnetic resonance sequence and the ECG trigger signals in the real-time acquired ECG images of each cardiac cycle at the corresponding imaging level to obtain dual-echo images and ECG trigger signals for each cardiac cycle at the corresponding imaging level.

[0099] In one embodiment, the pulse application rules include: a reverse pulse application rule, comprising: when an electrocardiogram trigger signal corresponding to the reverse pulse cardiac cycle is detected in the electrocardiogram, applying a reverse recovery pulse according to the magnetic resonance sequence in the corresponding reverse pulse cardiac cycle to obtain a double echo image of the corresponding reverse pulse cardiac cycle; a T2 preparation pulse application rule, comprising: when an electrocardiogram trigger signal corresponding to the T2 preparation pulse cardiac cycle is detected in the electrocardiogram, applying a T2 preparation pulse according to the magnetic resonance sequence in the corresponding T2 preparation pulse cardiac cycle to obtain a double echo image of the corresponding T2 preparation pulse cardiac cycle; and a T1ρ preparation pulse application rule, comprising: when an electrocardiogram trigger signal corresponding to the T1ρ preparation pulse cardiac cycle is detected in the electrocardiogram, applying a T1ρ preparation pulse according to the magnetic resonance sequence in the corresponding T1ρ preparation pulse cardiac cycle to obtain a double echo image of the corresponding T2 preparation pulse cardiac cycle. Dual-echo images of the T1ρ preparatory pulse cardiac cycle; diaphragmatic navigation pulse application rules, including: when an ECG trigger signal corresponding to the inverted pulse cardiac cycle is detected in the ECG image, applying a diaphragmatic navigation pulse after applying an inverted recovery pulse according to the magnetic resonance sequence and performing position correction operations on the imaging plane; when an ECG trigger signal corresponding to the T2 preparatory pulse cardiac cycle is detected in the ECG image, applying a diaphragmatic navigation pulse before applying a T2 preparatory pulse according to the magnetic resonance sequence and performing position correction operations on the imaging plane; when an ECG trigger signal corresponding to the T1ρ preparatory pulse cardiac cycle is detected in the ECG image, applying a diaphragmatic navigation pulse before applying a T1ρ preparatory pulse according to the magnetic resonance sequence and performing position correction operations on the imaging plane.

[0100] In one embodiment, the pulse application rule further includes a dual-echo readout pulse sequence application rule, comprising: 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 to each cardiac cycle after the second cardiac cycle; wherein, both the first dual-echo readout pulse sequence and the second dual-echo readout pulse sequence are used to acquire dual-echo images; the first echo time of the second dual-echo readout pulse sequence is located 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 rule further includes: when an electrocardiogram trigger signal of a cardiac cycle in which no preparation pulse is applied is detected in the electrocardiogram, applying a diaphragm navigation pulse and performing a position correction operation on the imaging plane before applying the dual-echo readout pulse sequence in the corresponding cardiac cycle in which no preparation pulse is applied, according to the magnetic resonance sequence.

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

[0102] In one embodiment, obtaining a relaxation parameter map of the tested object by matching the water signal image with the dictionary includes: matching the magnetization vector lateral component intensity curve obtained based on each pixel in the water signal image with the dictionary to obtain the parameter value corresponding to each pixel; and obtaining a relaxation parameter map of the tested object based on the parameter value corresponding to each pixel.

[0103] Figure 7 This is a schematic block diagram of the electronic terminal provided in an embodiment of this application. Figure 7 As shown, the electronic terminal includes at least one processor 701, a memory 702, at least one network interface 703, and a user interface 705. The various components in the device are coupled together via a bus system 704. It is understood that the bus system 704 is used to implement communication between these components. In addition to a data bus, the bus system 704 also includes a power bus, a control bus, and a status signal bus. However, for clarity, in... Figure 7 The general will label all buses as bus systems.

[0104] The user interface 705 may include a monitor, keyboard, mouse, trackball, clicker, button, touchpad, or touch screen.

[0105] It is understood that memory 702 can be volatile memory or non-volatile memory, or both. Non-volatile memory can be read-only memory (ROM) or programmable read-only memory (PROM), 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) and synchronous static random access memory (SSRAM). The memories described in the embodiments of this invention are intended to include, but are not limited to, these and any other suitable categories of memory.

[0106] In this embodiment of the invention, the memory 702 is used to store various types of data to support the operation of the electronic terminal 700. Examples of this data include: any executable program for operation on the electronic terminal 700, such as the operating system 7021 and application program 7022; the operating system 7021 contains various system programs, such as the framework layer, core library layer, driver layer, etc., for implementing various basic services and handling hardware-based tasks. The application program 7022 may contain various applications, such as a media player, browser, etc., for implementing various application services. The method for simultaneous quantitative magnetic resonance imaging of free breathing cardiac fat fraction and multiple relaxation parameters provided in this embodiment of the invention can be included in the application program 7022.

[0107] The methods disclosed in the above embodiments of the present invention can be applied to or implemented by processor 701. Processor 701 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the integrated logic circuit of the hardware in processor 701 or by instructions in software form. The 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. Processor 701 can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. General-purpose processor 701 may be a microprocessor or any conventional processor, etc. The steps of the accessory optimization method provided in the embodiments of the present invention can be directly reflected as being executed by a hardware decoding processor, or being executed by a combination of hardware and software modules in the decoding processor. The software module may be located in a storage medium, which is located in memory. The processor reads the information in the memory and combines it with its hardware to complete the steps of the aforementioned method.

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

[0109] According to the method provided in the embodiments of this application, this application also provides a computer program product, which includes: computer program code, which, when run on a computer, causes the computer to execute... Figure 1The illustrated embodiment presents a method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters.

[0110] According to the method provided in the embodiments of this application, this application also provides a computer-readable storage medium storing program code, which, when executed on a computer, causes the computer to perform... Figure 1 The illustrated embodiment presents a method for simultaneous quantitative magnetic resonance imaging of free-breathing cardiac fat fraction and multiple relaxation parameters.

[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. As illustrated, applications running on computing devices and computing devices can both be components. One or more components may reside in a process and / or an execution thread, and components may be located on a single computer and / or distributed among two or more computers. Furthermore, these components can be executed from various computer-readable media on which various data structures are stored. Components can communicate, for example, via local and / or remote processes based on signals having one or more data packets (e.g., data from two components interacting with another component between a local system, a distributed system, and / or a network, such as the Internet interacting with other systems via signals).

[0112] Those skilled in the art will recognize that the various illustrative logical blocks and steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

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

[0114] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

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

[0116] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0117] In the above embodiments, the functions of each functional unit can be implemented entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. A computer program product includes one or more computer instructions (programs). When the computer program instructions (programs) are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. Computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs, DVDs), or semiconductor media (e.g., solid-state disks, SSDs, etc.).

[0118] If a function is implemented as 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 the 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 to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0119] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0120] In summary, this application provides a method, apparatus, terminal, and medium for simultaneous quantitative magnetic resonance imaging of cardiac fat fraction and multiple relaxation parameters during free breathing. The method includes: scanning the cardiac tissue of a subject under free breathing conditions using a magnetic resonance sequence corresponding to the simultaneous quantitative analysis of cardiac fat fraction and multiple relaxation parameters, obtaining dual-echo images and ECG trigger signals for each cardiac cycle at each imaging level; simulating the evolution of the magnetization vector based on the Bloch equation and the ECG trigger signal, and establishing a dictionary; performing a water-fat separation operation based on mixed multi-echo imaging on the processed dual-echo images to obtain water signal images and fat fraction maps; and obtaining a set of relaxation parameter maps of the subject by matching the water signal images with the dictionary. This application acquires data during free breathing, reducing the burden on the subject while ensuring the accuracy of fat fraction quantification and water-fat separation. Therefore, this application effectively overcomes the various shortcomings of existing technologies and has high industrial applicability.

[0121] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A method for simultaneous quantitative magnetic resonance imaging of fat fraction and multiple relaxation parameters in a freely breathing heart, characterized in that, include: A magnetic resonance imaging (MRI) sequence for simultaneous quantification of cardiac fat fraction and multiple relaxation parameters is established. This process includes: determining an optimized combination of preparatory pulse sequences and an optimal combination of readout radiofrequency pulse flip angles for each cardiac cycle; obtaining the MRI sequence for simultaneous quantification of cardiac fat fraction and multiple relaxation parameters based on the optimal preparatory pulse sequence combination and the optimal readout radiofrequency pulse flip angle combination; and wherein the MRI sequence includes pulse data corresponding to each cardiac cycle. The magnetic resonance sequence was used to scan the heart tissue of the subject under free breathing conditions at multiple imaging levels to obtain dual-echo images and electrocardiogram trigger signals for each cardiac cycle corresponding to each imaging level. The evolution of the magnetization vector was simulated based on the Bloch equation and ECG trigger signals, and a dictionary was established. Image processing was performed on the dual-echo images of each cardiac cycle, and based on the processed dual-echo images, a water-lipid separation operation based on mixed multi-echo was performed to obtain water signal images and fat fraction maps. The relaxation parameter group map of the tested object is obtained by matching the water signal image with the dictionary.

2. The method for simultaneous quantitative magnetic resonance imaging of fat fraction and multiple relaxation parameters of the heart during free breathing according to claim 1, characterized in that, The magnetic resonance imaging sequence was used to scan the heart tissue of the subject under free breathing conditions at multiple imaging levels, obtaining dual-echo images and electrocardiogram trigger signals for each cardiac cycle at each imaging level, including: Based on the magnetic resonance sequence, magnetic resonance scanning operations are performed sequentially on each imaging layer according to the real-time acquired electrocardiogram images of each imaging layer to obtain the dual echo image and electrocardiogram trigger signal for each cardiac cycle corresponding to each imaging layer. The magnetic resonance scanning operation includes: Based on the pulse application rule, a corresponding pulse is applied to each cardiac cycle according to the magnetic resonance sequence and the electrocardiogram trigger signal in the electrocardiogram image of each cardiac cycle acquired in real time at the corresponding imaging level, so as to obtain the dual echo image and electrocardiogram trigger signal of each cardiac cycle at the corresponding imaging level.

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, The pulse application rules include: The inversion pulse application rule includes: when an electrocardiogram trigger signal corresponding to the inversion pulse cardiac cycle is detected in the electrocardiogram image, an inversion recovery pulse is applied to the corresponding inversion pulse cardiac cycle according to the magnetic resonance sequence to obtain a double echo image of the corresponding inversion pulse cardiac cycle; The T2 preparation pulse application rules include: when an electrocardiogram trigger signal corresponding to the T2 preparation pulse cardiac cycle is detected in the electrocardiogram, a T2 preparation pulse is applied according to the magnetic resonance sequence at the corresponding T2 preparation pulse cardiac cycle to obtain a dual echo image of the corresponding T2 preparation pulse cardiac cycle. The T1ρ preparation pulse application rules include: when an electrocardiogram trigger signal corresponding to the T1ρ preparation pulse cardiac cycle is detected in the electrocardiogram, 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 rules for applying the diaphragm navigation pulse include: when an electrocardiogram trigger signal corresponding to the inverted pulse cardiac cycle is detected in the electrocardiogram, the diaphragm navigation pulse is applied after the inverted recovery pulse is applied in the corresponding inverted pulse cardiac cycle according to the magnetic resonance sequence, and the position correction operation of the imaging plane is performed. When an electrocardiogram trigger signal corresponding to the T2 preparation pulse cardiac cycle is detected in the electrocardiogram, a diaphragmatic navigation pulse is applied before the T2 preparation pulse is applied in the corresponding T2 preparation pulse cardiac cycle, and the position correction operation of the imaging plane is performed according to the magnetic resonance sequence. When an electrocardiogram trigger signal corresponding to the T1ρ preparation pulse cardiac cycle is detected in the electrocardiogram, 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 according to the magnetic resonance sequence.

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 rule also includes: The rules for applying the dual-echo readout pulse sequence include: applying a first type of dual-echo readout pulse sequence and a second type of dual-echo readout pulse sequence in the first and second cardiac cycles, respectively, based on the magnetic resonance sequence, and applying the first type of dual-echo readout pulse sequence in each cardiac cycle after the second cardiac cycle. Both the first type of dual-echo readout pulse sequence and the second type of dual-echo readout pulse sequence are used to acquire dual-echo images; the first echo time of the second type of dual-echo readout pulse sequence is located between the two echo times of the first type of dual-echo readout pulse sequence, and the second echo time of the second type of dual-echo readout pulse sequence is greater than the second echo time of the first type of dual-echo readout pulse sequence. The rules for applying the diaphragm navigation pulse also include: when an electrocardiogram trigger signal for an unprepared pulse cardiac cycle is detected in the electrocardiogram, a diaphragm navigation pulse is applied and a position correction operation is performed on the imaging plane before applying the dual-echo readout pulse sequence for the corresponding unprepared pulse cardiac cycle, according to the magnetic resonance sequence.

5. The method for simultaneous quantitative magnetic resonance imaging of fat fraction and multiple relaxation parameters of the heart during free breathing according to claim 4, characterized in that, Based on each dual-echo image, a water-fat separation operation based on hybrid multi-echo is performed to obtain water signal images and fat fraction maps, including: Using the GraphCut algorithm, a reference B0 image and a fat fraction map were obtained based on the dual-echo images of the first and second cardiac cycles. Using the GraphCut algorithm, water and lipid separation is performed on the dual-echo images of all cardiac cycles based on the reference B0 image to obtain water signal images.

6. 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, The relaxation parameter map of the tested object is obtained by matching the water signal image with the dictionary, including: The magnetization vector lateral component intensity curve obtained from each pixel in the water signal image is matched with the dictionary to obtain the parameter value corresponding to each pixel. Based on the parameter values ​​corresponding to each pixel, a relaxation parameter group map of the inspected object is obtained.

7. A device for simultaneous quantitative magnetic resonance imaging 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 imaging (MRI) sequence for simultaneous quantitative analysis of cardiac fat fraction and multiple relaxation parameters. Establishing the MRI sequence for simultaneous quantitative analysis of cardiac fat fraction and multiple relaxation parameters includes: determining an optimized combination of preparation pulse sequences and an optimal combination of readout radiofrequency pulse flip angles for each cardiac cycle; obtaining the MRI sequence for simultaneous quantitative analysis of cardiac fat fraction and multiple relaxation parameters based on the optimal combination of preparation pulse sequences and the optimal combination of readout radiofrequency pulse flip angles; and wherein the MRI sequence includes pulse data corresponding to each cardiac cycle. The scanning module is used to scan the heart tissue of the subject under free breathing state using the magnetic resonance sequence to obtain dual-echo images of each cardiac cycle corresponding to each imaging layer and electrocardiogram trigger signals. The dictionary building module is used to simulate the evolution of the magnetization vector based on the Bloch equation and ECG trigger signals, and to build a dictionary. The water-lipid separation module is used to process the dual-echo images of each cardiac cycle, and based on the processed dual-echo images, to perform water-lipid separation based on mixed multi-echo to obtain water signal images and fat fraction maps. The image generation module is used to obtain a set of relaxation parameters of the tested object by matching the water signal image with the dictionary.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1 to 6.

9. 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 6.

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