Filtering low-flip-angle multi-echo imaging method and system

Abstract

The invention relates to a filtering low-flip-angle multi-echo imaging method and system, and the method comprises the following steps: obtaining the magnetic resonance data of a target tissue collected at a low flip angle which is far smaller than the Ennst angle of a grey matter; extracting one or more echoes from the magnetic resonance data as a first group of image data; obtaining intermediate image data based on the first group of image data; and carrying out filtering processing on the intermediate image data, and realizing imaging through image reconstruction. Compared with the prior art, the method has the advantages that the authenticity of target tissue imaging is ensured, the signal-to-noise ratio of target tissue imaging is improved, and the required collection frequency is reduced.

Description

Technical Field

[0001] The present invention relates to the field of magnetic resonance imaging technology, and in particular to a filtered low flip angle multi-echo (FLAME) imaging method and system. Background Art

[0002] There are relatively few studies on magnetic resonance imaging (MRI) of white matter (WM) fiber tracts in the thalamus and brainstem. Spin echo imaging is commonly used to study cranial nerves, but not to study fiber tracts in the thalamus or brainstem.

[0003] In the past decade, “Deistung, A., et al., High-Resolution MR Imaging of the Human Brainstem In vivo at 7 Tesla. 2013.7.” and “Straub, S., et al., Mapping the human brainstem: Brain nuclei and fiber tracts at 3T and 7T. 2019. 32(9): p. e4118.” showed reasonable results of mapping fiber bundles and nuclei at 7T magnetic resonance imaging, with improved image signal-to-noise ratio. However, neither paper used or discussed low flip angles, 3D technology, or gradient echo imaging sequences.

[0004] In addition, "Mueller, SG, Mapping internal brainstem structures using T1 and T2weighted 3T images. 2023.2." used 3T T1W and T2W images to segment the internal structures of the brainstem. Studies of the thalamus and lateral geniculate nucleus also used spin density T2* weighted imaging, but the echo time was longer.

[0005] In summary, there is an urgent need for a method and system for thalamus and brainstem imaging to improve the imaging effect of the thalamus and brainstem. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a filtered low flip angle multi-echo imaging method and system to solve or partially solve the problem that the imaging method is not ideal in contrast and / or signal-to-noise ratio.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] One aspect of the present invention provides a filtered low flip angle multi-echo imaging method, comprising the following steps:

[0009] Acquiring 2D or 3D gradient echo magnetic resonance data of the target tissue acquired using a low flip angle, wherein the low flip angle is much smaller than the Ernst angle of the gray matter;

[0010] extracting one or more echoes from the magnetic resonance data as a first set of image data;

[0011] Performing averaging processing on first two or more echoes in the first group of image data;

[0012] Filter processing is performed on the first group of image data, and imaging is achieved through image reconstruction.

[0013] As a preferred technical solution, the process of filtering includes the following steps:

[0014] A low-pass filtering process is performed on the intermediate image data to enhance the signal-to-noise ratio.

[0015] As a preferred technical solution, the process of filtering includes the following steps:

[0016] High-pass filtering is performed on the intermediate image data to improve image uniformity.

[0017] As a preferred technical solution, the process of filtering includes the following steps:

[0018] Sliding window filtering is performed on the first set of image data to improve the signal-to-noise ratio within and / or across the scanning plane.

[0019] As a preferred technical solution, the magnetic resonance data is collected in a low-bandwidth manner.

[0020] As a preferred technical solution, the target tissues are the thalamus and the brainstem.

[0021] Another aspect of the present invention provides another filtered low flip angle multi-echo imaging method, comprising the following steps:

[0022] Acquiring 2D or 3D gradient echo magnetic resonance data of the target tissue acquired using a low flip angle, wherein the low flip angle is much smaller than the Ernst angle of the gray matter;

[0023] extracting one or more echoes from the magnetic resonance data as a first set of image data;

[0024] acquiring new 2D or 3D gradient echo magnetic resonance data of the target tissue acquired using a high flip angle, wherein the high flip angle is greater than the Ernst angle of the gray matter;

[0025] extracting one or more echoes from the new magnetic resonance data as a second set of image data;

[0026] Dividing the first set of image data by the second set of image data to obtain intermediate image data;

[0027] Performing averaging processing on first two or more echoes in the intermediate image data;

[0028] Filter processing is performed on the intermediate image data, and imaging is achieved through image reconstruction.

[0029] As a preferred technical solution, the following steps are also included:

[0030] The magnetic resonance data of the target tissue are collected multiple times, and the images reconstructed from the magnetic resonance data each time are averaged to obtain the final reconstructed image.

[0031] As a preferred technical solution, the process of filtering includes the following steps:

[0032] A low-pass filtering process is performed on the intermediate image data to enhance the signal-to-noise ratio.

[0033] As a preferred technical solution, the process of filtering includes the following steps:

[0034] High-pass filtering is performed on the intermediate image data to improve image uniformity.

[0035] As a preferred technical solution, the process of filtering includes the following steps:

[0036] Sliding window filtering is performed on the first set of image data to improve the signal-to-noise ratio within and / or across the scanning plane.

[0037] As a preferred technical solution, the target tissues are the thalamus and the brainstem.

[0038] Another aspect of the present invention provides another filtered low flip angle multi-echo imaging method, comprising the following steps:

[0039] Acquiring magnetic resonance susceptibility transfer data of a target tissue acquired using a low flip angle, wherein the low flip angle is much smaller than an Ernst angle of gray matter;

[0040] extracting one or more echoes from the magnetic resonance data as a first set of image data;

[0041] Based on the first set of image data, obtaining intermediate image data;

[0042] Performing averaging processing on first two or more echoes in the first group of image data;

[0043] Filter processing is performed on the first group of image data, and imaging is achieved through image reconstruction.

[0044] As a preferred technical solution, the following steps are also included:

[0045] The magnetic resonance data of the target tissue are collected multiple times, and the images reconstructed from the magnetic resonance data each time are averaged to obtain the final reconstructed image.

[0046] The filtering process includes the following steps:

[0047] A low-pass filtering process is performed on the intermediate image data to enhance the signal-to-noise ratio.

[0048] As a preferred technical solution, the process of filtering includes the following steps:

[0049] High-pass filtering is performed on the intermediate image data to improve image uniformity.

[0050] As a preferred technical solution, the process of filtering includes the following steps:

[0051] Sliding window filtering is performed on the first set of image data to improve the signal-to-noise ratio within and / or across the scanning plane.

[0052] As a preferred technical solution, the image resolution is 1mm×1mm×2mm.

[0053] As a preferred technical solution, the image resolution is 0.67mm×0.67mm×1.34mm.

[0054] As a preferred technical solution, the target tissues are the thalamus and the brainstem.

[0055] Another aspect of the present invention provides another filtered low flip angle multi-echo imaging method, comprising the following steps:

[0056] Acquiring 2D or 3D gradient echo magnetic resonance data of the target tissue acquired using a low flip angle, wherein the low flip angle is much smaller than the Ernst angle of the gray matter;

[0057] extracting one or more echoes from the magnetic resonance data as a first set of image data;

[0058] acquiring new 2D or 3D gradient echo magnetic resonance data of the target tissue acquired using a high flip angle, wherein the high flip angle is greater than the Ernst angle of the gray matter;

[0059] Based on the multiple echoes in the magnetic resonance data, a spin density map and a T2* map are extracted and used as a third set of image data and a fourth set of image data respectively;

[0060] multiplying the third set of image data and the fourth set of image data to obtain the intermediate image data;

[0061] Performing averaging processing on first two or more echoes in the intermediate image data;

[0062] Filter processing is performed on the intermediate image data, and imaging is achieved through image reconstruction.

[0063] As a preferred technical solution, the following steps are also included:

[0064] The magnetic resonance data of the target tissue are collected multiple times, and the images reconstructed from the magnetic resonance data each time are averaged to obtain the final reconstructed image.

[0065] The filtering process includes the following steps:

[0066] A low-pass filtering process is performed on the intermediate image data to enhance the signal-to-noise ratio.

[0067] As a preferred technical solution, the process of filtering includes the following steps:

[0068] High-pass filtering is performed on the intermediate image data to improve image uniformity.

[0069] As a preferred technical solution, the process of filtering includes the following steps:

[0070] Sliding window filtering is performed on the first set of image data to improve the signal-to-noise ratio within and / or across the scanning plane.

[0071] As a preferred technical solution, the target tissues are the thalamus and the brainstem.

[0072] Another aspect of the present invention provides a nuclear magnetic resonance imaging system, characterized in that it includes:

[0073] at least one processor;

[0074] A memory stores computer code instructions, which are executed by the at least one processor to execute the instructions of the aforementioned filtered low flip angle multi-echo imaging method.

[0075] Another aspect of the present invention provides a computer-readable storage medium, characterized in that it includes one or more programs for execution by one or more processors of an electronic device, and the one or more programs include instructions for executing the aforementioned filtered low flip angle multi-echo imaging method.

[0076] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0077] (1) Ensuring the authenticity of target tissue imaging: The present invention ensures true spin density weighted imaging of gray matter and white matter by using an Ernst angle whose flip angle is much smaller than that of gray matter (GM) for imaging.

[0078] (2) Improving the signal-to-noise ratio of the target tissue: The present invention acquires the magnetic resonance data in a low-bandwidth manner, uses a small bandwidth for echo to obtain the best signal-to-noise ratio, and uses a short echo time to obtain the best image quality. In addition, the signal-to-noise ratio can be further improved by acquiring data multiple times and averaging each data.

[0079] (3) Reducing the number of acquisitions required: For short repetition time imaging and sufficiently short echo time, the present invention improves the signal-to-noise ratio by averaging the first two or more echoes, thereby reducing the number of acquisitions required.

[0080] (4) Improving the contrast between gray matter and white matter in the image: The contrast can be further improved by multiplying the T2* and proton density images, or calculating the ratio of the small flip angle to the scored rotation angle.

[0081] (5) Elimination of B1 receptive field bias effects: By calculating the ratio of the small flip angle to the scoring angle for imaging, all B1 receptive field bias effects are eliminated and the contrast between white matter and gray matter is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 A comparison diagram of the imaging effect of the first image in the embodiment;

[0083] Figure 2 for Figure 1 A schematic diagram after partial enlargement;

[0084] Figure 3 A comparison diagram of the imaging effect of the second image in the embodiment;

[0085] Figure 4 It is a comparison diagram of the imaging effect of the third image in the embodiment. DETAILED DESCRIPTION

[0086] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0087] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0088] Example 1

[0089] In view of the problems existing in the aforementioned prior art, the present embodiment provides a filtered low flip angle multi-echo imaging method, which aims to improve and optimize the contrast of gray matter and white matter in thalamus and brainstem imaging by using filtered small flip angle multi-echo (FLAME) 3D gradient echo imaging. The data source can be T1 weighted optimized image, T1 quantitative image or magnetization transfer contrast (MTC).

[0090] The steps involved in this method mainly include:

[0091] (1) Use low flip angle imaging, preferably, use an Ernst angle with a flip angle much smaller than that of gray matter (GM), to ensure true spin density weighted imaging of gray matter and white matter. For 3D GRE sequences, the Ernst equation gives the signal as a function of the flip angle FA (θ), as follows:

[0092]

[0093] Where E1 = e -TR / T1 , When the flip angle is much smaller than the Ernst angle, θE=cos-1(θ), or the Ernst angle can be approximated as θE=sqrt(2TR / T1). A small flip angle means that the square of the flip angle is much smaller than the square of the Ernst angle, or in this embodiment: θ 2 <<θE 2 .

[0094] (2) Use short echo times for acquisition to obtain the best image quality. For example, a short echo time at 3T is equivalent to approximately 3 milliseconds or less to avoid air / tissue interface issues. When pituitary imaging is not involved, longer echo times (e.g., 5 milliseconds) and flow compensation are acceptable.

[0095] (3) For short repetition time imaging and sufficiently short echo times, the signal-to-noise ratio can be improved by averaging the first two or more echo signals, thereby reducing the number of acquisitions required.

[0096] Preferably, longer repetition times and multiple echoes are used to generate quantitative T2* and proton density images with good white matter to gray matter contrast. The contrast can be further improved by multiplying the T2* map by the spin density map. However, although a longer scan time is required, since the signal-to-noise ratio in the T2* map increases linearly with the time between the first and last echo, it is actually more efficient than acquiring two short echoes with a short repetition time.

[0097] In this case, the average is calculated by adding the signal s(TE1) from TE1 and the signal s(TE2) from TE2 and dividing by 2: S avg (TE1, TE2)=(s(TE1)+s(TE2)) / 2.

[0098] (4) All echoes are collected using a small bandwidth to obtain the best signal-to-noise ratio.

[0099] Bandwidth is related to sampling time. The lower the bandwidth, the longer the sampling time required. A bandwidth of 125 Hz / pixel is commonly used, for example, which requires a sampling time of 8 milliseconds. Therefore, the shortest first two echoes are approximately 5 milliseconds and 13 milliseconds.

[0100] (5) Preferably, a sliding window filtering process is used to further enhance the signal-to-noise ratio within a layer or between layers, or the intra-layer and inter-layer signals are filtered simultaneously.

[0101] Sliding window filtering takes a set of consecutive pixels, say s(i), and successively averages them to produce a new image s swf2 (i) = (s(i) + s(i + 1)) / 2, where 1 <= i <= N. For s(N), the average value is not used because there is no information on s(N).

[0102] (6) Preferably, data is collected multiple times and the individual data are averaged to improve the signal-to-noise ratio.

[0103] If the data is collected N times, then the mean is the sum of all images collected divided by N.

[0104] (7) Eliminating the field deviation by filtering the data. It should be noted that any other method can be used to eliminate the B1 receiving field deviation and / or the B1 sending field deviation without conflict.

[0105] Apply (1)-(7) to Figure 1 , Figure 2 and Figure 3 The image in .

[0106] See also Figure 1, where a) the original 3° flip angle data; b) the average of two dual echo data; c) the average of two adjacent sections; d) the result after high pass filtering in image c. Note the improvement in signal to noise ratio from a to b to c and the uniformity in image d. It can be seen that given the very low signal to noise ratio in image a, this data cannot be used to map brainstem fibers or nuclei. Although the signal in images b and c is not uniform, both provide better quality data. The signal in image d is now uniform.

[0107] See also Figure 2 for Figure 1 Zoomed in images, where a) the original 3° flip angle data; b) the average of two dual echo data; c) the average of two adjacent sections; d) the result after high pass filtering of c. Note the improvement in SNR from a to b to c and the uniformity in image d, which is very obvious in this set of zoomed images. The white arrow represents the pyramidal corticospinal tract and the black arrow represents the inferior cerebral peduncle.

[0108] See also Figure 3 , where a) the original 3° flip angle with very low signal-to-noise ratio in the middle of the brain image; b) the average of three data sets and two echoes; c) the reformatted sagittal image showing the thalamic tract (white arrow). d) the same as in c after high pass filtering the data. It can be seen that averaging can make a major difference in image quality, while filtering makes the image uniform and easy to adjust to view the entire brain with a single window / level setting.

[0109] In addition to (1)-(7), it also includes:

[0110] (8) By performing multiple scans, i.e., large flip angle scans, the contrast can be enhanced.

[0111] (9) The ratio of the small flip angle to the large flip angle data, called SPORT (SPin density OVerR T1W, proton density weighted divided by T1 weighted), has proton density-dominated contrast. This eliminates all B1 receptive field bias effects and enhances the contrast between white matter and gray matter.

[0112] (10) The SPORT image is used to replace the average small flip angle data itself, followed by high-pass filtering.

[0113] In general, whenever any addition, subtraction, multiplication, or division is performed on images with equal SNR, a sqrt(2) is lost in the final image. This is because the error square or variance is the orthogonal addition of each variance (var):

[0114] var avg (S1, S2)=var(S1 / 2)+var(S2 / 2)

[0115] var avg (S1, S2)=1 / 4(var(S1)+var(S2))

[0116] If the two variances are the same and equal to σ 2 ,but:

[0117] Var(s1,s2)=σ 2 / 2

[0118] Therefore, the noise or error in the mean is reduced to σ / sqrt(2) or a factor of sqrt(2) less than the original noise σ.

[0119] See also Figure 4 (1)-(10) are implemented in , where a) original 3° low flip angle data averaging two echoes; b) motion image and c) same as in b after high pass filtering the data; d) MTC 8°.

[0120] It can be seen that although the contrast from b to d seems to be slightly improved, the contrast can be further increased by using MTC. Although it requires longer acquisition time, the use of MTC method has greater advantages under the premise that the improvement is greater than sqrt(2).

[0121] Data visualization is achieved by performing minimum intensity projections (mIPs) on two or more slices to observe fiber bundle connections. This can be done in the original transverse plane or in the reconstructed sagittal plane, as shown in Figure 2. Figure 2 and 3 Preferably, data is collected by cutting the fibers (ie, using cross sections) at high image resolution to achieve the best results for vertical fiber display.

[0122] Specifically, the method comprises the following steps:

[0123] S1, receiving 2D or 3D gradient echo magnetic resonance (MR) data acquired using a flip angle much smaller than the gray matter Ernst angle;

[0124] S2, extracting a first set of image data corresponding to one or more echoes from the acquired MR data;

[0125] S3, averaging data of first two or more echoes in the first set of image data;

[0126] S4, filtering one or all images to reconstruct a more uniform image.

[0127] Preferably, the filtering process in step S4 includes low-pass filtering, and the image data is processed by low-pass filtering to enhance the signal-to-noise ratio.

[0128] Preferably, the filtering process in step S4 includes high-pass filtering, and the image data is subjected to high-pass filtering to obtain a more uniform image on all images.

[0129] Preferably, the filtering process in step S4 comprises sliding window filtering, and the filtering improves the signal-to-noise ratio (SNR) within the scan plane, across the scan plane, or both.

[0130] It should be noted that, under the premise of no conflict, any other noise reduction technology may be used to improve the SNR within the scanning plane, across the scanning plane, or in both.

[0131] Preferably, the magnetic resonance data is collected with as low a bandwidth as possible.

[0132] Example 2

[0133] Based on the above-mentioned embodiment, this embodiment provides another filtered low flip angle multi-echo imaging method, comprising the following steps:

[0134] S1, receiving thalamus and brainstem magnetic resonance (MR) data acquired using a flip angle much smaller than the Ernst angle;

[0135] S2, extracting a first set of image data corresponding to one or more echoes from the small flip angle data from the acquired MR data set;

[0136] S3, receiving thalamus and brainstem magnetic resonance (MR) data acquired using a flip angle higher than the Ernst angle;

[0137] S4, extracting a second set of image data corresponding to one or more echoes from the large flip angle data from the acquired MR data set;

[0138] S5, dividing the small flip angle data by the large flip angle data to obtain intermediate image data;

[0139] S6, averaging data of one or more echoes in the intermediate image data;

[0140] S7, filtering one or all images to reconstruct a more uniform image.

[0141] Preferably, the magnetic resonance data of the thalamus and the brainstem are collected multiple times, and the images reconstructed from the magnetic resonance data each time are averaged to serve as the final reconstructed image.

[0142] Preferably, the filtering process in step S7 includes low-pass filtering, and the image data is processed by low-pass filtering to enhance the signal-to-noise ratio.

[0143] Preferably, the filtering process in step S7 includes high-pass filtering, and the image data is subjected to high-pass filtering to obtain a more uniform image on all images.

[0144] Preferably, the filtering process in step S7 comprises sliding window filtering, and the filtering improves the signal-to-noise ratio (SNR) within the scan plane, across the scan plane, or both.

[0145] Compared with Example 1, this embodiment realizes imaging through the ratio of small flip angle data to large flip angle data, eliminates all B1 receptive field deviation effects and enhances the contrast between white matter and gray matter.

[0146] Example 3

[0147] Based on the above-mentioned embodiment, this embodiment provides another filtered low flip angle multi-echo imaging method, comprising the following steps:

[0148] S1, receiving magnetic resonance (MR) magnetic susceptibility transfer (MTC) data acquired using a flip angle much smaller than the Ernst angle;

[0149] S2, extracting a first set of image data corresponding to one or more echoes from the low flip angle data from the acquired MR data set;

[0150] S3, averaging the data of one or more echoes;

[0151] S4, filtering one or all images to reconstruct a more uniform image.

[0152] Preferably, the magnetic resonance data of the thalamus and the brainstem are collected multiple times, and the images reconstructed from the magnetic resonance data each time are averaged to serve as the final reconstructed image.

[0153] Preferably, the filtering process in step S4 includes low-pass filtering, and the image data is processed by low-pass filtering to enhance the signal-to-noise ratio.

[0154] Preferably, the filtering process in step S4 includes high-pass filtering, and the image data is subjected to high-pass filtering to obtain a more uniform image on all images.

[0155] Preferably, the filtering process in step S4 comprises sliding window filtering, and the filtering improves the signal-to-noise ratio (SNR) in the scanning plane, across the scanning plane, or both.

[0156] Compared with Example 1, this embodiment has a greater advantage in using the MTC method under the premise that the improvement is greater than sqrt(2).

[0157] Example 4

[0158] Based on the above-mentioned embodiment, this embodiment provides another filtered low flip angle multi-echo imaging method, comprising the following steps:

[0159] S1, receiving magnetic resonance (MR) data acquired using a flip angle much smaller than the Ernst angle;

[0160] S2, extracting a first set of image data corresponding to one or more echoes from the small flip angle data from the acquired MR data set;

[0161] S3, extracting a third set of image data and a fourth set of image data from the proton density quantitative map and the T2* quantitative map from the acquired MR data set, using at least two of the plurality of echoes, preferably all of the echoes; and then multiplying the proton density quantitative map by the T2* quantitative map;

[0162] S4, filtering one or all images to reconstruct a more uniform image.

[0163] Preferably, the magnetic resonance data of the thalamus and the brainstem are collected multiple times, and the images reconstructed from the magnetic resonance data each time are averaged to serve as the final reconstructed image.

[0164] Preferably, the filtering process in step S4 includes low-pass filtering, and the image data is processed by low-pass filtering to enhance the signal-to-noise ratio.

[0165] Preferably, the filtering process in step S4 includes high-pass filtering, and the image data is subjected to high-pass filtering to obtain a more uniform image on all images.

[0166] Preferably, the filtering process in step S4 comprises sliding window filtering, and the signal-to-noise ratio (SNR) in the scanning plane, in the through-plane or in both is improved by filtering.

[0167] Compared with Example 3, this embodiment will not be affected by the MTC high-frequency pulse, takes less time, and has a higher contrast.

[0168] If MTC is used to increase the contrast by a factor of √2, the same contrast-to-noise ratio can be achieved by averaging the original FLAME images acquired three times. In addition, the scheme of averaging the original FLAME images is not affected by the high RF power pulses associated with MTC, thus reducing noise interference.

[0169] Since the Ernst angle is approximately √(2TR / T1), if TR is increased by p times, the small flip angle can be increased by √p times. According to predictions, if MTC suppresses white matter to 0.4 times the original value and gray matter to 0.5 times the original value, the total improvement in contrast is only 1.2 times. In order to prove that MTC is better than the method of this embodiment, it must produce at least a 0.2-fold change, that is, white matter must be suppressed to 0.3 times and gray matter must be suppressed to 0.5 times. In addition, if time remains consistent, the susceptibility transfer sequence can only collect half the range of data obtained by the short repetition time non-susceptibility transfer gradient echo sequence, because the repetition time of the susceptibility transfer sequence is twice the repetition time of the short repetition time non-susceptibility transfer gradient echo sequence.

[0170] It should be noted that the above echo imaging method can be applied to other body tissues except the thalamus and brainstem, provided there is no conflict.

[0171] Example 5

[0172] This embodiment provides a nuclear magnetic resonance imaging system, comprising: at least one processor; a memory on which computer code instructions are stored. The computer code instructions are executed by the at least one processor, and the processor executes instructions of the filtered low flip angle multi-echo imaging method described in any of the aforementioned embodiments.

[0173] Example 6

[0174] This embodiment provides a computer-readable storage medium, including one or more programs for execution by one or more processors of an electronic device, wherein the one or more programs include instructions for executing any of the filtered low flip angle multi-echo imaging methods described in the aforementioned embodiments.

[0175] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction device.

[0176] These computer program instructions may also be loaded onto a computer or other programmable data processing device, so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process.

[0177] In a typical configuration, an electronic device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0178] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0179] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0180] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A filtered low flip angle multi-echo imaging method, characterized in that: The steps include: Acquiring magnetic resonance data of a target tissue acquired using a low flip angle, wherein the low flip angle is much smaller than an Ernst angle of gray matter; extracting one or more echoes from the magnetic resonance data as a first set of image data; Based on the first set of image data, obtaining intermediate image data; Filter processing is performed on the intermediate image data, and imaging is achieved through image reconstruction.

2. A filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The filtering process includes the following steps: A low-pass filtering process is performed on the intermediate image data to enhance the signal-to-noise ratio.

3. A filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The filtering process includes the following steps: High-pass filtering is performed on the intermediate image data to improve image uniformity.

4. A filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The filtering process includes the following steps: Sliding window filtering is performed on the first set of image data to improve the signal-to-noise ratio within and / or across the scanning plane.

5. The filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The magnetic resonance data are acquired in a low bandwidth manner.

6. A filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The magnetic resonance data is 2D or 3D gradient echo magnetic resonance data.

7. A filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: After obtaining the intermediate image data, the following steps are also included: An averaging process is performed on the first two or more echoes in the intermediate image data.

8. A filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The process of acquiring the intermediate image data comprises the following steps: acquiring new 2D or 3D gradient echo magnetic resonance data of the target tissue acquired using a high flip angle, wherein the high flip angle is greater than the Ernst angle of the gray matter; extracting one or more echoes from the new magnetic resonance data as a second set of image data; The first set of image data is divided by the second set of image data to obtain the intermediate image data.

9. A filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The magnetic resonance data is magnetic resonance susceptibility transfer data.

10. The filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The image resolution is 1mm×1mm×2mm.

11. A filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The image resolution is 0.67mm×0.67mm×1.34mm.

12. A filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The process of acquiring the intermediate image data comprises the following steps: Based on the multiple echoes in the magnetic resonance data, a spin density map and a T2* map are extracted and used as a third set of image data and a fourth set of image data respectively; The third set of image data and the fourth set of image data are multiplied to obtain the intermediate image data.

13. A filtered low flip angle multi-echo imaging method according to claim 1, characterized in that: The following steps are also included: The magnetic resonance data of the target tissue are collected multiple times, and the images reconstructed from the magnetic resonance data each time are averaged to obtain the final reconstructed image.

14. A nuclear magnetic resonance imaging system, characterized in that: include: at least one processor; A memory having computer code instructions stored thereon, wherein the computer code instructions are executed by the at least one processor, and the processor executes instructions of the filtered low flip angle multi-echo imaging method according to any one of claims 1-13.

15. A computer-readable storage medium, characterized in that: It comprises one or more programs for execution by one or more processors of an electronic device, wherein the one or more programs comprise instructions for executing the filtered low flip angle multi-echo imaging method according to any one of claims 1 to 13.

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