Target Vessel Imaging Method for Magnetic Resonance Non-Contrast Agents

Abstract

The present invention relates to a method for target vessel imaging using a magnetic resonance non-contrast agent. The nuclear magnetic resonance transmission channels are at least two parallel transmission channels. A marked area is determined according to the spatial area of the target vessel; the optimal transmission channel parameters required for the marked area during parallel transmission are obtained as the first parameter combination of the nuclear magnetic resonance transmission channels; the optimal transmission channel parameters required for the imaging area during parallel transmission are obtained as the second parameter combination of the nuclear magnetic resonance transmission channels; according to the preset marking parameters and the first parameter combination, the longitudinal magnetization vector within the marked area is inverted; after waiting for the preset recovery duration, according to the second parameter combination, an imaging sequence of the magnetic resonance sequence is executed and signals are collected; the signals collected by the imaging sequence are reconstructed. It can make the uniformity of the radiofrequency transmission field reach the best, so as to achieve the optimal display of the target vessels in the imaging area or the optimal suppression of non-target vessels.

Description

Technical Field

[0001] The present invention relates to a vascular imaging technique, and particularly to a method for target vascular imaging using magnetic resonance without contrast agent. Background Art

[0002] Magnetic resonance enhanced angiography is a non-invasive and non-intubated vascular imaging method. As an alternative to DSA (Digital Subtraction Angiography), it has been widely used in clinical diagnosis. Its principle is to inject a certain amount of contrast agent into the patient. Usually, such contrast agents have a short T1 (the time required for longitudinal magnetization to recover from zero to 63% of the original value). When the contrast agent flows into the position to be collected with the blood, a corresponding three-dimensional sequence is used to collect images, and then the images before and after injecting the contrast agent are subtracted to display the structural image of the blood vessels. It has been reported in the literature that enhanced magnetic resonance angiography can achieve the same sensitivity and specificity as DSA. However, magnetic resonance enhanced angiography is not applicable to all patients because it requires injecting contrast agents into the patient, and some patients cannot inject contrast agents. For example, such contrast agents are absolutely contraindicated in pregnant women and relatively contraindicated in patients with severe renal impairment. Therefore, magnetic resonance non-contrast vascular imaging techniques have received extensive attention and research.

[0003] Among the publicly available materials on magnetic resonance non-contrast vascular imaging techniques, Prior Art 1 ("Considerations of Magnetic Resonace Angiography by Selective Inversion Recovery, D.G. Nishimura et al., Magnetic Resonance in Medicine, Vol. 7, 472-484, 1988") discloses a method for magnetic resonance non-contrast vascular imaging. The technical solution is as follows: By applying an inversion recovery (IR) pulse, the longitudinal magnetization vector in a certain region is inverted and labeled, and then an MR image is collected after a certain time. Although the images obtained by this method can display the blood vessel images of interest, since there are parts where blood flows into the blood vessels to be examined from multiple directions, and the blood flow velocity into the imaging area varies according to the blood vessels passed through, if the said parts are included in the imaging area, this method has the defect that it is very difficult or even impossible to label the blood vessels to be diagnosed.

[0004] To this end, a common solution is to mark multiple spatial positions. For example, in one of the existing vascular imaging methods, multiple positions are marked separately first, and then the blood vessels of interest are imaged. Although this technical solution solves the problem that the prior art cannot mark multiple spatial positions for the diagnostic object, it has the following defects:

[0005] 1. For the display of some blood vessels, since many regions need to be marked, the parameters of each marked region need to be set separately; moreover, as Figure 1 shown, multiple inversion recovery (IR) pulses may be required for marking, and the parameters of IR need to be set separately. Therefore, the operation is cumbersome.

[0006] 2. In ultra-high field magnetic resonance, due to the need for multiple IR pulses, the SAR (Specific Absorption Rate) will also increase.

[0007] 3. Using the same B1 (radiofrequency magnetic field generated by the radiofrequency coil) emission field parameters of the magnetic resonance device for all regions may result in uneven spin flipping within the marked region, and further lead to uneven display of the blood vessels of interest in the imaging region or uneven suppression of the non-target blood vessel region. Summary of the Invention

[0008] Aiming at the problems existing in non-contrast magnetic resonance angiography, a method for imaging target blood vessels without contrast agent in magnetic resonance is proposed, so as to reduce the number of inversion recovery pulses, lower the SAR (specific absorption rate) value during scanning, and make the setting of the marked region more convenient and fast. Optimally obtain the uniformity of the radiofrequency emission field in the marked region, and achieve the optimal display of the target blood vessels in the imaging region or the suppression image of the non-target blood vessel region.

[0009] The technical solution of the present invention is: a method for imaging target blood vessels without contrast agent in magnetic resonance, and the nuclear magnetic resonance emission channels are at least 2 parallel emission channels.

[0010] Determine a marked region according to the spatial region of the target blood vessel.

[0011] According to the marked region, obtain the optimal emission channel parameters required for the marked region during parallel emission as the first parameter combination of the nuclear magnetic resonance emission channels.

[0012] According to the imaging region, obtain the optimal emission channel parameters required for the imaging region during parallel emission as the second parameter combination of the nuclear magnetic resonance emission channels.

[0013] Invert the longitudinal magnetization vector within the labeled region according to the preset labeling parameters and the first parameter combination; wherein, the preset labeling parameters include the preset recovery duration of the longitudinal magnetic vector within the labeled region; wait for the preset recovery duration, and according to the second parameter combination, execute the imaging sequence of the magnetic resonance sequence and acquire signals;

[0014] Reconstruct the signals acquired by the imaging sequence to obtain an enhanced display of the target blood vessels or a non-target blood vessel suppression image within the imaging region.

[0015] Furthermore, the labeled region is the target blood vessel region or the target blood vessel blood flow source region within the imaging region, and the shape of the labeled region is any unrestricted shape.

[0016] Furthermore, all of the labeled region is located inside the imaging region, or a part of the labeled region is located inside the imaging region.

[0017] Furthermore, the method for determining the labeled region includes: determining the labeled region according to the spatial region of the target blood vessels by means of a combination of machine learning, deep learning and manual adjustment, and manual setting.

[0018] Furthermore, the optimal transmit channel parameters required for the labeled region during parallel transmission satisfy the following conditions:

[0019] The radiofrequency transmit field for parallel transmission of the nuclear magnetic resonance transmit channels is within the first preset region threshold range matching the labeled region, and the uniformity of the radiofrequency transmit field meets the first uniformity threshold for the imaging image quality requirements of the labeled region.

[0020] Furthermore, the optimal transmit channel parameters required for the imaging region during parallel transmission satisfy the following conditions: the radiofrequency transmit field for parallel transmission of the nuclear magnetic resonance transmit channels is within the second preset region threshold range matching the imaging region, and the uniformity of the radiofrequency transmit field meets the second uniformity threshold for the imaging image quality requirements of the imaging region.

[0021] Furthermore, the preset labeling parameters further include the angle of the inversion recovery pulse and the control of the fat offset direction.

[0022] Furthermore, when the labeled region is the target blood vessel blood flow source region, before inverting the longitudinal magnetization vector within the labeled region according to the preset labeling parameters and the first parameter combination, apply a non-selective layer inversion recovery pulse according to the preset labeling parameters to invert all the spins.

[0023] Further, after the marked area is determined, obtain the union area of the marked area and the imaging area, and according to the union area, obtain the optimal transmission channel parameters required for the union area during parallel transmission, as the first parameter combination of the nuclear magnetic resonance transmission channel.

[0024] The beneficial effect of the present invention is that the method for target vessel imaging of magnetic resonance without contrast agent of the present invention can optimize the uniformity of the radio frequency transmission field, so as to achieve the optimal display of the target vessels in the imaging area or the optimal suppression of non-target vessels. Description of the Drawings

[0025] Figure 1 Schematic diagram of magnetic resonance imaging that requires N IR pulses in the prior art;

[0026] Figure 2 Schematic diagram of the process of the method for target vessel imaging of magnetic resonance without contrast agent of the present invention;

[0027] Figure 3 Schematic diagram of the application scenario of the first embodiment of the method of the present invention;

[0028] Figure 4 Schematic diagram of the application scenario of the second embodiment of the method of the present invention. Detailed Embodiments

[0029] The present invention will be described in detail below with reference to the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives the detailed implementation manners and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0030] The present invention provides a method for target vessel imaging of magnetic resonance without contrast agent, which can be applied to high-field and ultra-high-field magnetic resonance systems with field strengths of 3 Tesla (T), 5T, 7T, and higher, such as Figure 2 Schematic diagram of the blood vessel imaging method provided in this embodiment. As can be seen from Figure 2 The blood vessel imaging method provided in this embodiment includes the following steps:

[0031] S1: Determine a marked area according to the spatial area of the target vessel.

[0032] Specifically, the marked area includes the target vessel area or the target vessel blood flow source area within the imaging area, and the shape of the marked area drawn is arbitrary. Refer to Figure 3 and Figure 4 , where Figure 3 is one of the schematic diagrams of the marked area for the imaging of the hepatic portal vein applied in the present invention, Figure 4This is another schematic diagram of the marked area for the application of the present invention to hepatic portal vein imaging. Specifically, as shown in the markings in Figure 3 and Figure 4 , the area enclosed by the solid line in the figure is the imaging area, and the area enclosed by the dashed line is the marked area: As can be seen from Figure 3 and Figure 4 , the marked area enclosed by the dashed line in the figure is an irregular area. In other embodiments, the marked area may also be a pre-set specific shape, such as a regular shape like a circle or a square, or other custom shapes. That is, the present invention does not make any setting on the shape of the marked area, which can be a regular shape or an irregular shape.

[0033] Furthermore, the method for determining the marked area according to the target blood vessel includes: determining the marked area of this target blood vessel by using one or more of machine learning, deep learning, and / or manual setting / adjustment according to the spatial area of the target blood vessel. For example, first determine an initial marked area by machine learning or deep learning, and then adjust the initial marked area manually according to the deviation between the spatial area of the target blood vessel and the initial marked area to obtain the marked area, so that the marked area matches the spatial area of the target blood vessel to the greatest extent.

[0034] All of the marked area of the target blood vessel can be located inside the imaging area, or part of the marked area of the target blood vessel can be located inside the imaging area. The marked area is determined according to the spatial area of the target blood vessel. When selecting, it can be selected based on experience on the basis of the imaging area, or can be automatically identified independently of the imaging area by using existing identification means according to various identification means. In one embodiment, the marked area of the target blood vessel is obtained by artificial intelligence.

[0035] First, obtain a trained neural network model. Specifically, the method for obtaining the trained neural network model includes: pre-collecting a large number of sample blood vessel localization images as the input images of the initial neural network; then, manually mark the area to be marked in the sample blood vessel localization images to obtain the sample blood vessel localization images with marked areas, and use the sample blood vessel localization images with marked areas as the gold standard images; use the input images and the gold standard images to train the initial neural network to adjust the network parameters in the initial neural network to obtain the trained neural network model. Among them, the trained neural network model can represent the positional relationship between the spatial area of the target blood vessel and the corresponding marked area.

[0036] Then, obtain the pre-scanned image to be processed, and this pre-scanned image contains the target blood vessel but does not contain the corresponding marked area.

[0037] Finally, the pre-scanned image is input into the trained neural network model to determine a marked region. In this embodiment, the marked region output by the trained neural network model will be displayed on the pre-scanned image / vessel localization image.

[0038] Configured in this way, the vascular imaging method provided by the present invention can best fit the target blood vessel (the blood vessel to be examined), overcoming the defect that it is difficult to mark the parts where blood flows into the blood vessel to be examined from multiple directions. Further, in the vascular imaging method provided by the present invention, the marked region can be marked by machine learning, deep learning, and / or manual setting / adjustment, and there is no limitation on the marking method of the marked region, so the application range is wide.

[0039] S2: According to the marked region, determine a first parameter combination of the nuclear magnetic resonance emission channels. The nuclear magnetic resonance emission channels are at least 2 parallel emission channels. Preferably, in determining the first parameter combination of the emission channels according to the marked region, it includes that the first parameter combination of the emission channels satisfies the following conditions:

[0040] The radio frequency transmission field (B1 field) of the magnetic resonance device is within the first preset regional threshold range of the marked region, and the uniformity of the radio frequency transmission field of the magnetic resonance device meets the first uniformity threshold. Wherein, the first preset regional threshold range includes: according to the actual working conditions, the radio frequency transmission field of the magnetic resonance device should match the marked region (the radio frequency transmission field is close to or located within the marked region); the first uniformity threshold includes: the uniformity that can meet the imaging image quality requirements.

[0041] In one embodiment, in order to ensure the uniformity of the radio frequency transmission field in the marked region, the radio frequency pulse B1 of each emission channel i (t) can be obtained by the following solving equation to determine the first parameter combination:

[0042]

[0043] Wherein, M xy (r) is the transverse magnetization vector at the position r in the marked region; j is the imaginary part; γ is the gyromagnetic ratio; M0 is the equilibrium magnetization vector; i represents the number of the emission channel, and i is a positive integer; N is the number of emission channels used; S i (r) is the sensitivity at the spatial position r of the i-th emission channel; B1 i (t) is the radio frequency pulse waveform of the i-th emission coil; r is the spatial position; k(t) is the k-space filling trajectory with time t as the variable.

[0044] With such a configuration, the optimal parameters required for the marked area during parallel transmission can be obtained, thereby ensuring that the radio frequency transmission field conforms to or is closest to the marked area, and the uniformity of the radio frequency transmission field in the marked area can be ensured.

[0045] S3: Determine the second parameter combination of the nuclear magnetic resonance transmission channels according to the imaging area. Preferably, in determining the second parameter combination of the transmission channels according to the imaging area, it includes: the second parameter combination of the transmission channels satisfies the following conditions:

[0046] The radio frequency transmission field of the magnetic resonance device is within the second preset area threshold range of the imaging area, and the uniformity of the radio frequency transmission field of the magnetic resonance device conforms to the second uniformity threshold. Among them, the second preset threshold range includes: according to the actual working conditions, the radio frequency transmission field of the magnetic resonance device should match the imaging area (the radio frequency transmission field is close to or located within the imaging area); the second uniformity threshold includes: the uniformity that can meet the requirements of the imaging image quality.

[0047] Optionally, the specific calculation method of the second parameter combination can refer to the calculation method of the foregoing first parameter combination. The difference is only in the different ranges of the target area and the imaging area. Of course, in other alternative embodiments, different optimization algorithms can also be used for the marked area and the imaging area, for example, setting different constraint conditions; using different optimization algorithms; setting different numbers of transmission channels; different positions of the driven transmission channels, etc.

[0048] With such a configuration, the optimal parameters required for the imaging area during parallel transmission can be obtained, thereby ensuring that the radio frequency transmission field conforms to or is closest to the imaging area, and the uniformity of the radio frequency transmission field in the imaging area can be ensured.

[0049] Those skilled in the art can understand that the above is only a description of the preferred implementation manner. The present invention does not limit the execution order of steps S2 and S3 above. In some embodiments, step S2 can be executed first and then step S3. In other embodiments, step S3 can be executed first and then step S2. Even in some other embodiments, steps S2 and S3 can be executed in parallel. Further, the present invention does not impose any restrictions on the specific values of the first parameter combination and the second parameter combination, the first preset area threshold range and the second area threshold range, the first uniformity threshold and the second uniformity threshold, and whether the corresponding parameters must be the same or must be different. In specific applications, they should be reasonably selected according to the actual working conditions. The specific application scenarios are very different. For example, the requirements for head and neck vascular imaging, spinal vascular imaging, abdominal solid organs (such as hepatic portal vein imaging) are completely different, and will not be exemplified one by one, but all are within the protection scope of the present invention.

[0050] It can be seen that the vascular imaging method provided by the present invention respectively sets the parameters of the transmission channel of the magnetic resonance device according to the marked area and the imaging area. With such a configuration, the vascular imaging method provided by the present invention overcomes the defect that the same radio frequency transmission field parameters of the magnetic resonance device are used in all areas (such as the imaging area and the marked area) in the prior art, resulting in uneven spin flipping in the marked area and poor vascular imaging quality. The vascular imaging method provided by the present invention can make the uniformity of the radio frequency transmission field reach the best, so as to achieve the optimal display of the target blood vessels in the imaging area or the suppression of non-target blood vessels.

[0051] S4: Invert the longitudinal magnetization vector in the marked area according to the preset marking parameters and the first parameter combination; wherein, the preset marking parameters include the preset recovery duration of the longitudinal magnetic vector in the marked area. The preset marking parameters further include: the angle of the inversion recovery pulse and the control of the fat offset direction.

[0052] Those skilled in the art can understand that the preset marking parameters include, but are not limited to, the preset recovery duration of the longitudinal magnetic vector in the marked area, the angle of the inversion recovery pulse, and the control of the fat offset direction. The preset marking parameters are conventional parameter items in the art and will not be listed one by one here. They should be reasonably set according to actual imaging needs (including but not limited to scanning time, image quality, sensitivity to lesion display, etc.). Further, it is obvious that the present invention does not limit the timing of setting the preset marking parameters either. It can be at any time before step S4. The preset marking parameters can also use the default setting values, or can be adjusted in real time according to the actual working conditions after being set, which will not be elaborated.

[0053] S5: Wait for the preset recovery duration, and execute the imaging sequence of the magnetic resonance sequence according to the second parameter combination, and collect signals. That is: after waiting for the preset recovery duration (a certain recovery time), the magnetic resonance sequence imaging sequence is collected using the parallel radio frequency transmission parameters for imaging in the imaging area. The static tissue signals in the marked area are displayed as low signals, while the inflowing blood is not affected by the inversion pulse and is displayed as high signals, thereby obtaining a vascular image.

[0054] Preferably, in the imaging sequence for acquiring the magnetic resonance sequence according to the second parameter combination, the imaging sequence includes, but is not limited to, a GRE sequence or an SE sequence. As general common knowledge in the art, among them, the SE (Spin Echo) sequence is the most commonly used spin echo sequence in clinical practice, a sequence that generates echoes using a 134° radiofrequency pulse. By changing two parameters, TR (radiofrequency repetition time) and TE (echo time), in the sequence, weighted images of proton density β, T1, and T2 can be obtained respectively. The weighted images with three different imaging parameters each represent three different magnetic resonance characteristics of tissues, thereby distinguishing normal tissues and identifying lesions. The GRE (Gradient Recalled Echo) is a gradient echo sequence, a sequence that generates echoes by switching the readout (frequency encoding) gradient.

[0055] S6: Reconstruct the signals acquired by the imaging sequence to obtain an enhanced display of the target blood vessels or a non-target blood vessel suppression image in the imaging region.

[0056] Preferably, as an alternative, combine the steps of obtaining the first parameter combination and the second parameter combination in steps 2 and 3, and solve the combination of the optimal parameters of each transmission channel as the third parameter combination, where the third parameter combination satisfies the expectation of the radiofrequency transmission field in the union region of the imaging region and the marked region.

[0057] Specifically as follows: After determining a marked region according to the spatial region of the target blood vessels in step S1, the following steps are further included:

[0058] Obtain the union region of the marked region and the imaging region according to the marked region and the imaging region;

[0059] Determine the third parameter combination of the transmission channel according to the union region;

[0060] Among them, in step S2, the method for determining the first parameter combination of the transmission channel according to the marked region includes: using the third parameter combination as the first parameter combination;

[0061] In step S3, the method for determining the second parameter combination of the transmission channel according to the imaging region includes: using the third parameter combination as the second parameter combination.

[0062] Furthermore, the third parameter combination satisfies the following conditions: The radiofrequency transmission field of the magnetic resonance device is within the third preset region threshold range in the union region, and the uniformity of the B1 transmission field of the magnetic resonance device meets the third uniformity threshold.

[0063] Configured in this way, the alternative of the above parameter settings provided by the vascular imaging method of the present invention can combine the marked area and the imaging area to set the parameters of the transmission channel, achieving a certain balance between the complexity of parameter settings and the control accuracy, and is a practical alternative.

[0064] Preferably, in one preferred embodiment, before reversing the longitudinal magnetization vector in the marked area according to the preset marking parameters and the first parameter combination in step S4, the following steps are further included:

[0065] According to the preset marking parameters, apply an inversion recovery pulse for non-selected slices to reverse all spins.

[0066] Specifically, referring to Figure 3 and Figure 4 , it can be seen that Figure 3 and Figure 4 the marked areas are not the same (can be understood as complementary), Figure 4 the marked area of Figure 4 is the target vascular blood flow source area. Before step 4, an inversion recovery pulse for non-selected slices was applied to reverse all spins in the entire imaging area. For Figure 3 before performing in the marked area, an IR for non-selected slices is accompanied to reverse all spins, and the image with the best display of the target blood vessel and the best suppression of non-target blood vessels in the imaging area of the hepatic portal vein can also be obtained.

[0067] It can be seen from this that the vascular imaging method provided by the present invention overcomes the defects in the prior art that the operation of separately setting IR parameters for multiple inversion recovery pulses is cumbersome and leads to an increase in SAR; in the vascular imaging method provided by the present invention, there is only one marked area, reducing the number of inversion recovery pulses, with simple operation and easy implementation; and it can significantly reduce the SAR value during scanning. Further, the vascular imaging method provided by the present invention respectively sets the parameters of the transmission channel of the magnetic resonance device according to the marked area and the imaging area, overcoming the defect in the prior art that the same radiofrequency transmission field parameters of the magnetic resonance device are used in all areas, resulting in uneven spin flipping in the marked area and poor vascular imaging quality. The vascular imaging method provided by the present invention can make the uniformity of the radiofrequency transmission field reach the best, so as to achieve the purpose of the best display of the target blood vessel or the best suppression of non-target blood vessels in the imaging area. Further, the magnetic resonance device provided by the present invention does not require any additional hardware costs, is low in cost, and is easy to implement.

[0068] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for target vessel imaging of magnetic resonance non-contrast agent, characterized in that, The nuclear magnetic resonance emission channels are at least two parallel emission channels. According to the spatial region of the target blood vessel, a marked region is determined; the method for determining the marked region includes: According to the spatial region of the target blood vessel, one or more of machine learning, deep learning, and / or manual setting / adjustment are used to determine the marked region. According to the marked region, the optimal emission channel parameters required for the marked region during parallel emission are obtained as the first parameter combination of the nuclear magnetic resonance emission channels. According to the imaging region, the optimal emission channel parameters required for the imaging region during parallel emission are obtained as the second parameter combination of the nuclear magnetic resonance emission channels. According to the preset marking parameters and the first parameter combination, the longitudinal magnetization vector within the marked region is inverted; wherein, the preset marking parameters include the preset recovery duration of the longitudinal magnetic vector within the marked region. After waiting for the preset recovery duration, according to the second parameter combination, an imaging sequence of the magnetic resonance sequence is executed and signals are collected. The signals collected by the imaging sequence are reconstructed to obtain an enhanced display of the target blood vessel or a non-target blood vessel suppression image within the imaging region.

2. The target vessel imaging method for magnetic resonance non-contrast agent according to claim 1, characterized in that, The marked region is the target blood vessel region or the target blood vessel blood flow source region within the imaging region, and the shape of the marked region is any unrestricted shape.

3. The target vessel imaging method for magnetic resonance non-contrast agent according to claim 1, characterized in that, All of the marked region is located inside the imaging region, or part of the marked region is located inside the imaging region.

4. The target vessel imaging method for magnetic resonance non-contrast agent according to claim 1, wherein The optimal emission channel parameters required for the marked region during parallel emission satisfy the following conditions: The radiofrequency emission field emitted in parallel by the nuclear magnetic resonance emission channels is within the first preset region threshold range that matches the marked region, and the uniformity of the radiofrequency emission field meets the first uniformity threshold for the imaging image quality requirements of the marked region.

5. The method for target vessel imaging for magnetic resonance non-contrast agent according to claim 1, characterized in that, The optimal emission channel parameters required for the imaging region during parallel emission satisfy the following conditions: The radiofrequency emission field emitted in parallel by the nuclear magnetic resonance emission channels is within the second preset region threshold range that matches the imaging region, and the uniformity of the radiofrequency emission field meets the second uniformity threshold for the imaging image quality requirements of the imaging region.

6. The target vessel imaging method for magnetic resonance non-contrast agent according to claim 1, wherein The preset marking parameters further include the angle of the inversion recovery pulse and the control of the fat offset direction.

7. The target vessel imaging method for magnetic resonance non-contrast agent according to claim 2 or 3, characterized in that, When the marked region is the target blood vessel blood flow source region, before inverting the longitudinal magnetization vector within the marked region according to the preset marking parameters and the first parameter combination, a non-selective layer inversion recovery pulse is applied according to the preset marking parameters to invert all spins.

8. The target vessel imaging method for magnetic resonance non-contrast agent according to claim 1, characterized in that After the marked region is determined, the union region of the marked region and the imaging region is obtained, and according to the union region, the optimal emission channel parameters required for the union region during parallel emission are obtained as the first parameter combination of the nuclear magnetic resonance emission channels.

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