Magnetic resonance imaging equipment

Abstract

The embodiment of the utility model provides a magnetic resonance imaging method and device. The equipment comprises a scanning bed used for bearing an imaging object; the transmitting module is used for transmitting a radio frequency signal to an imaging object; the receiving module comprises a tunnel magnetoresistance effect sensor array and is used for collecting nuclear spin magnetic field signals of an imaging object; and the processing module is used for generating a magnetic resonance image of the imaging object based on the nuclear spinning magnetic field signal.

Description

Technical Field

[0001] The present invention relates to the field of magnetic resonance imaging, and in particular to a magnetic resonance imaging method and device. Background Art

[0002] The principle of magnetic resonance imaging mainly relies on the following three points: strong magnetic field generates nuclear spin magnetic field, gradient magnetic field generates spatial encoding, and radio frequency coil generates resonance excitation and signal reception. However, existing magnetic resonance imaging equipment has the following three problems: 1) The existence of nuclear spin field leads to large magnetic resonance volume and requires liquid helium cooling; 2) gradient is stressed in strong magnetic field and generates huge noise; 3) radio frequency coil needs to wrap the imaging object, the signal-to-noise ratio is low, and the number of channels is limited.

[0003] At present, the magnetic field of magnetic resonance equipment (including static magnetic field, gradient magnetic field and radio frequency transmission field) is monitored based on the nuclear magnetic resonance effect (i.e., NMR (Spin Magnetic Resonance) effect) itself. The monitoring of the above magnetic field requires complex transmission and reception links, and the electronics and logic are complex, the cost is high, and the universality is poor. It is usually only used by manufacturers and cannot be used in daily clinical practice at customer sites (for example, hospitals).

[0004] Based on this, it is expected to propose a magnetic resonance imaging method and device to improve the efficiency and quality of magnetic resonance imaging. Utility Model Content

[0005] One or more embodiments of the present specification provide a magnetic resonance imaging device, which includes: a scanning bed for carrying an imaging object; a transmitting module for transmitting a radio frequency signal to the imaging object; a receiving module, the receiving module including a tunnel magnetoresistance effect sensor array for collecting a nuclear spin magnetic field signal of the imaging object; and a processing module for generating a magnetic resonance image of the imaging object based on the nuclear spin magnetic field signal.

[0006] In some embodiments, the receiving module is further used to monitor electrophysiological information of the imaging object.

[0007] In some embodiments, the magnetic resonance imaging device further comprises a magnetic field monitoring module, and the magnetic field monitoring module is used to monitor the spatial distribution and / or temporal distribution of the static magnetic field and / or the gradient field in real time.

[0008] In some embodiments, the static magnetic field is generated by an ultra-low field magnet assembly; the ultra-low field is a static magnetic field with a magnetic induction intensity lower than an ultra-low field threshold.

[0009] In some embodiments, the magnetic field monitoring module is disposed in the scanning hole and covers a scanning area of ​​the scanning hole.

[0010] In some embodiments, the magnetic field monitoring module includes a plurality of tunnel magnetoresistive effect sensors, and the plurality of tunnel magnetoresistive effect sensors are distributed at different positions of the scanning hole.

[0011] In some embodiments, the magnetic resonance imaging device further comprises a device monitoring module, which comprises one or more additional tunnel magnetoresistance effect sensors for monitoring device operation information and / or performing metal detection.

[0012] In some embodiments, the device monitoring module is disposed at an edge of the scanning bed.

[0013] In some embodiments, the operation information includes at least magnetic field anomaly information and / or equipment failure information; metal detection includes detecting whether there is redundant metal in the monitoring area, and the monitoring area includes at least the scanning bed.

[0014] In some embodiments, the tunnel magnetoresistive effect sensors in the tunnel magnetoresistive effect sensor array form one or more bridge circuits.

[0015] The beneficial effects of the magnetic resonance imaging device provided in one or more embodiments of the present specification include at least: by using a tunnel magnetoresistance effect sensor array to replace the traditional receiving coil to collect the nuclear spin magnetic field signal of the imaging object, the operation time of the magnet and the gradient coil is reduced, and the operation cost of the magnetic resonance imaging device is saved; in addition, when collecting the nuclear spin magnetic field signal, the static magnetic field and the gradient field are turned off, which can reduce the noise in the final imaging result and improve the imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] This specification will be further described in the form of exemplary embodiments, which will be described in detail by the accompanying drawings. These embodiments are not restrictive, and in these embodiments, the same number represents the same structure, wherein:

[0017] Figure 1 is a schematic diagram of an application scenario of a magnetic resonance imaging device according to some embodiments of this specification;

[0018] Figure 2 is a schematic diagram of a magnetic resonance imaging device according to some embodiments of the present specification;

[0019] Figure 3 is a schematic diagram of the structure of a tunnel magnetoresistance effect sensor according to some embodiments of this specification;

[0020] Figure 4 is a schematic diagram of a bridge circuit of a tunnel magnetoresistance effect sensor according to some embodiments of this specification;

[0021] Figure 5Ais a schematic diagram of a tunnel magnetoresistance effect sensor array according to some embodiments of this specification;

[0022] Figure 5B is another schematic diagram of a tunnel magnetoresistance effect sensor array according to some embodiments of this specification;

[0023] Figure 6 is a schematic diagram of a tunnel magnetoresistance effect sensor array carrier according to some embodiments of this specification;

[0024] Figure 7 is a schematic diagram of a magnetic field monitoring module according to some embodiments of this specification;

[0025] Figure 8 is a schematic diagram of a device monitoring module according to some embodiments of this specification;

[0026] Fig. 9 is an exemplary flow chart of a magnetic resonance imaging method according to some embodiments of the present specification. DETAILED DESCRIPTION

[0027] In order to more clearly illustrate the technical solutions of the embodiments of this specification, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of this specification. For ordinary technicians in this field, this specification can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0028] It should be understood that the "system", "device", "unit" and / or "module" used herein are a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions.

[0029] As shown in this specification and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0030] Flowcharts are used in this specification to illustrate the operations performed by the system according to the embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed precisely in order. Instead, the steps may be processed in reverse order or simultaneously. At the same time, other operations may also be added to these processes, or one or more operations may be removed from these processes.

[0031] As mentioned above, the current methods of measuring magnetic fields in magnetic resonance imaging are all based on the nuclear magnetic resonance effect itself, that is, measuring static magnetic fields, monitoring gradient magnetic fields, and radio frequency transmission fields based on the nuclear magnetic resonance effect. However, this method relies on complex transmission and reception links, and the electronics and logic are complex, costly, and have poor universality. It is usually only used by manufacturers and cannot be used in daily clinical practice at customer sites (for example, hospitals).

[0032] In some prior arts, in order to solve the above-mentioned problems 1-3 and other technical problems that restrict the cost and wide application of magnetic resonance, various ultra-low field (for example, 0.55T, 0.3T, 0.065T, etc.) magnetic resonance equipment have been introduced. As the magnetic field weakens, problems 1 and 2 are better solved, but the price paid is the deterioration of the quality of magnetic resonance images. At the same time, since such magnetic resonance equipment does not essentially change the way of collecting magnetic resonance signals, they still rely on receiving coils to receive magnetic resonance signals.

[0033] In recent years, tunnel magnetoresistance sensors (TMR) have made great progress based on the invention of new materials in consumer electronics and quantum mechanics. Their measurement accuracy has rapidly increased from the traditional μT level to the pT or even fT level, and their manufacturing costs have been greatly reduced, which undoubtedly provides a good entry opportunity for their wide application in the medical field. Based on this, tunnel magnetoresistance sensors can be introduced into magnetic resonance imaging equipment to solve the above-mentioned problems 1-3, the three core problems that restrict the development of magnetic resonance. In addition, tunnel magnetoresistance sensors can also be introduced into existing magnetic resonance imaging equipment to improve their performance.

[0034] The magnetic resonance imaging device provided in the embodiment of the present application uses tunnel magnetoresistance effect sensors to monitor the spatial and temporal distribution of static magnetic fields and gradient fields in real time, which can improve the efficiency and quality of magnetic resonance imaging; and uses a tunnel magnetoresistance effect sensor array to replace the original receiving coil in the ultra-low field magnetic resonance device to receive the radio frequency field of human nuclear spins.

[0035] Figure 1 is a schematic diagram of an application scenario of a magnetic resonance imaging device according to some embodiments of this specification. Figure 1As shown, an application scenario 100 of a magnetic resonance imaging device (hereinafter referred to as application scenario 100 ) may include a processing device 110 , a network 120 , a storage device 130 , a magnetic resonance imaging device 140 and a user terminal 150 .

[0036] The processing device 110 refers to a device for processing data and / or information from at least one component of the application scenario 100 or an external data source (e.g., a cloud data center). The processing device 110 can access data or information from the storage device 130, the magnetic resonance imaging device 140, and / or the user terminal 150 through the network 120. The processing device 110 can also be directly connected to the storage device 130, the magnetic resonance imaging device 140, and / or the user terminal 150 to access information and / or data. For example, the processing device 110 can obtain the nuclear spin magnetic field signal of the imaging object collected by the magnetic resonance imaging device 140 from the magnetic resonance imaging device 140. For another example, the processing device 110 can determine the K-space data based on the nuclear spin magnetic field signal.

[0037] The network 120 may connect the various components of the application scenario 100 and / or connect the application scenario 100 with external resources. In some embodiments, one or more components of the application scenario 100 (e.g., the processing device 110, the storage device 130, the magnetic resonance imaging device 140, and / or the user terminal 150) may exchange information and / or data through the network 120.

[0038] In some embodiments, the network 120 may be any one or more of a wired network or a wireless network. In some embodiments, the network 120 may include one or more network access points. For example, the network 120 may include a wired or wireless network access point (e.g., a base station and / or a network switching point), through which one or more components of the application scenario 100 may be connected to the network 120 to exchange data and / or information.

[0039] The storage device 130 refers to a device for storing data, instructions and / or any other information. In some embodiments, the storage device 130 may store data and / or information obtained from the processing device 110, the magnetic resonance imaging device 140 and / or the user terminal 150. For example, the storage device 130 may store the nuclear spin magnetic field signal of the imaging object acquired by the magnetic resonance imaging device 140. For another example, the storage device 130 may store the magnetic resonance image determined by the processing device 110. In some embodiments, the storage device 130 may include a large-capacity memory, a removable memory, or any combination thereof.

[0040] The magnetic resonance imaging device 140 refers to a device for imaging the imaging part of the imaging object based on the principle of magnetic resonance. For example, the magnetic resonance imaging device 140 can be an MRI (Magnetic Resonance Imaging) device, etc. The MRI device uses a strong magnetic field, a gradient magnetic field and radio waves to generate a magnetic resonance image of the imaging object to be scanned. In some embodiments, the MRI device may include a magnet assembly and a gradient coil assembly. The magnet assembly can generate a first magnetic field (also called a static magnetic field or a main static magnetic field) for polarizing the imaging object. The gradient coil assembly can be used to generate a second magnetic field (also called a gradient field or a gradient magnetic field).

[0041] In some embodiments, the MRI device may further include a radio frequency (RF) coil. In some embodiments, the radio frequency coil may include one or more transmitting coils and / or one or more receiving coils. The RF transmitting coil may transmit a radio frequency signal (such as an RF pulse) to the imaging object. Under the synergistic effect of the static magnetic field / gradient magnetic field and the RF pulse, a magnetic resonance signal related to the imaging object may be generated according to a pulse sequence. The RF receiving coil may acquire a magnetic resonance signal from the imaging object according to the pulse sequence. The magnetic resonance signal may also be referred to as an echo signal. A transformation operation (e.g., Fourier transform) may be used to process the magnetic resonance signal to fill the K space to acquire K space data, thereby generating a magnetic resonance image of the imaging target object.

[0042] For example, Figure 7 or Figure 8 As shown, the magnetic resonance imaging device 140 includes a magnet assembly 710 , a gradient coil assembly 720 , a radio frequency transmitting coil 730 , and a scanning hole 750 (the central axis of the scanning hole 750 is an axis 751 ).

[0043] In the embodiment of this specification, the radio frequency coil only includes one or more radio frequency transmitting coils. The magnetic resonance imaging device 140 uses a tunnel magnetoresistance effect sensor array instead of a radio frequency receiving coil to obtain nuclear spin magnetic field signals. For more information, see Figure 2 Described in.

[0044] In some embodiments, the magnetic resonance imaging device 140 may include a scanning bed 141 for carrying an imaging object. In some embodiments, the scanning bed 141 may be movable relative to the MRI device (such as a frame 142 of the MRI device). For example, the scanning bed 141 may be movable along the Z direction in the figure, where the Z direction is a direction parallel to the central axis of the scanning hole of the magnetic resonance imaging device 140. In some embodiments, the scanning bed 141 may be independent of the imaging device. For example, the magnetic resonance imaging device 140 and the scanning bed 141 are two independent devices.

[0045] The user terminal 150 refers to one or more terminals or software used by a user of the magnetic resonance imaging device 140 (e.g., a doctor, a researcher, etc. using the magnetic resonance imaging device 140) or an imaging subject. Figure 1 As shown, the user terminal 150 may include but is not limited to a smart phone 151, a tablet computer 152, a laptop computer 153, a desktop computer 154, etc. In some embodiments, the user terminal 150 may interact with other components in the application scenario 100 through the network 120. For example, the user terminal 150 may obtain the magnetic resonance image determined by the processing device 110 through the network 120 and output it to the user. For another example, the user terminal 150 may control the imaging process of the magnetic resonance imaging device 140 through the network 120 (for example, turn off the static magnetic field and / or gradient field of the magnetic resonance imaging device 140).

[0046] Figure 2 is a schematic diagram of a magnetic resonance imaging device according to some embodiments of the present specification. Figure 2 As shown, the magnetic resonance imaging device 140 may include a transmitting module 210 , a receiving module 220 and a processing module 230 .

[0047] The transmitting module 210 is used to transmit a radio frequency signal to the imaging object. The transmitting module may include a radio frequency transmitting coil, and the radio frequency signal refers to a magnetic field signal emitted by the radio frequency transmitting coil. For example, the transmitting module 210 may include a coil support and a transmitting coil, and the transmitting coil is arranged on the coil support. For example, after receiving a transmission command, the transmitting module 210 may control the radio frequency transmitting coil to transmit a radio frequency signal, such as a radio frequency pulse.

[0048] The receiving module 220 includes a tunnel magnetoresistance effect sensor array for collecting nuclear spin magnetic field signals of the imaging object.

[0049] A tunnel magnetoresistance sensor (TMR) is a sensing device that can sense magnetic field information (eg, the magnetic induction intensity of a magnetic field) and thereby change its own resistance value. Figure 3 Schematic diagram of the structure of a tunnel magnetoresistance effect sensor according to some embodiments of this specification. Figure 3 As shown, the tunnel magnetoresistance effect sensor may include a free layer 310, a non-magnetic layer 320 and a pin layer 330. The magnetization direction 311 of the free layer 310 may change based on the change of the external magnetic field, the non-magnetic layer 320 cannot be magnetized, and the magnetization direction 331 of the pin layer 330 is fixed. Based on this, the change of the equivalent resistance value of the tunnel magnetoresistance effect sensor depends on the relative angle between the magnetization directions of the pin layer 330 and the free layer 310.

[0050] After connecting the tunnel magnetoresistance effect sensor to the bridge circuit, the strength, direction and other information of the magnetic field can be detected based on the observed electrical information of the bridge circuit (such as current information or voltage information, etc.). Figure 4 is a schematic diagram of a bridge circuit of a tunnel magnetoresistance effect sensor according to some embodiments of this specification, Figure 4 The bridge circuit shown includes a total of 4 tunnel magnetoresistance effect sensors (including tunnel magnetoresistance effect sensor 410, tunnel magnetoresistance effect sensor 420, tunnel magnetoresistance effect sensor 430, and tunnel magnetoresistance effect sensor 440, and the direction of the arrow on the tunnel magnetoresistance effect sensor represents the magnetization direction of its pin layer). When the resistance value of the tunnel magnetoresistance effect sensor changes due to the change of the external magnetic field, the potential value of the output end (Output) of the bridge circuit will change accordingly. In some embodiments, the number of tunnel magnetoresistance effect sensors in the bridge circuit can also be other numbers (for example, 2, 6), and other series-parallel modes can also be used, which are not limited here.

[0051] The tunnel magnetoresistance effect sensor array refers to an array composed of multiple tunnel magnetoresistance effect sensors in a plane or a curved surface. Figure 5A and Figure 5B is a schematic diagram of a tunnel magnetoresistance effect sensor array according to some embodiments of this specification. Figure 5A or Figure 5B As shown, a plurality of tunnel magnetoresistive effect sensors 511 form a tunnel magnetoresistive effect sensor array 510 in a plane.

[0052] Multiple tunnel magnetoresistance effect sensors can be arranged uniformly or non-uniformly in the tunnel magnetoresistance effect sensor array. Uniform arrangement means that the spacing between adjacent tunnel magnetoresistance effect sensors is equal (e.g. Figure 5A or Figure 5B The non-uniform arrangement means that the spacing between adjacent tunnel magnetoresistance effect sensors is not equal. The spacing between adjacent tunnel magnetoresistance effect sensors can be preset manually, for example, the spacing between adjacent tunnel magnetoresistance effect sensors can be preset to 1 mm.

[0053] In some embodiments, the tunnel magnetoresistance effect sensor array may be disposed in a tunnel magnetoresistance effect sensor array carrier (for example, a plurality of uniformly or non-uniformly arranged tunnel magnetoresistance effect sensors may be sewn or pasted on the carrier), and the tunnel magnetoresistance effect sensor array carrier covers the imaging part of the imaging object during imaging. The imaging part refers to the part of the imaging object that needs to be imaged, for example, it may be the abdomen, legs, chest, neck, etc. of the imaging object. For example, Figure 6As shown, taking the imaging part as the abdomen of the imaging object 630 as an example, the tunnel magnetoresistance effect sensor array carrier 611 can be covered on the abdomen of the imaging object 630 (the imaging object 630 lies flat on the scanning bed 141), so that the tunnel magnetoresistance effect sensor array 510 can collect the nuclear spin magnetic field signal of the abdomen of the imaging object 630. The material of the tunnel magnetoresistance effect sensor array carrier can be hard (for example, the same material as the shell of the magnetic resonance imaging device) or soft (for example, soft plastic, fabric, etc.). Based on this, the tunnel magnetoresistance effect sensor array can be in contact with the imaging part of the imaging object (for example, when the tunnel magnetoresistance effect sensor array carrier is a soft material, it can wrap the surface of the imaging part of the imaging object by folding or the like) or not in contact (for example, when the tunnel magnetoresistance effect sensor array carrier is a hard material, the carrier can support the tunnel magnetoresistance effect sensor array on the imaging part of the imaging object). In some embodiments, the carrier may include an intermediate layer and a wrapping layer. Among them, a plurality of tunnel magnetoresistance effect sensors arranged uniformly or non-uniformly are sewn or pasted on the intermediate layer, and the wrapping layer covers the outermost layer.

[0054] In some embodiments, the tunnel magnetoresistance effect sensor array may be a planar structure or a 3D structure. For example, the tunnel magnetoresistance effect sensor array may be a planar structure similar to paper when not in use, and may be folded to cover or wrap the imaging part when in use. For another example, the tunnel magnetoresistance effect sensor array may be a 3D structure capable of covering or wrapping the neck, legs, elbows or knee joints.

[0055] Multiple tunnel magnetoresistance effect sensors in the tunnel magnetoresistance effect sensor array can be connected to the same bridge circuit, or they can be connected to multiple identical bridge circuits. For example, taking the tunnel magnetoresistance effect sensor array as an example, there are 100 tunnel magnetoresistance effect sensors, and the 100 tunnel magnetoresistance effect sensors can be connected to 25 such as 4 in a group. Figure 4 In the bridge circuit shown.

[0056] In some embodiments, the tunnel magnetoresistance effect sensor array is also used to monitor the electrophysiological information of the imaging object. Fig. 9 Described in.

[0057] The processing module 230 is configured to generate a magnetic resonance image of the imaging object based on the nuclear spin magnetic field signal.

[0058] In some embodiments, the processing module 230 may determine K-space data based on the nuclear spin magnetic field signal; and acquire a magnetic resonance image of the imaging object through image reconstruction based on the K-space data. For more information about the above embodiments, see Fig. 9 and its related description.

[0059] In some embodiments, Figure 2As shown, the magnetic resonance imaging device 140 may further include a magnetic field monitoring module 240. The magnetic field monitoring module 240 may include a plurality of tunnel magnetoresistance effect sensors (first tunnel magnetoresistance effect sensors) for real-time monitoring of the spatial distribution and / or temporal distribution of the static magnetic field and / or the gradient field.

[0060] In conjunction with the above, the static magnetic field refers to the static magnetic field generated by the magnet assembly in the magnetic resonance imaging device. The distribution of the static magnetic field in the scanning hole of the magnetic resonance imaging device is uniform (that is, the magnetic induction intensity of the magnetic field generated at any position of the scanning hole is the same). For example, the magnetic induction intensity of the static magnetic field can be 3T. In some embodiments, the magnet assembly in the magnetic resonance imaging device can be an ultra-low field magnet assembly, on this basis, the static magnetic field is generated by the ultra-low field magnet assembly, and at this time, the static magnetic field is an ultra-low field (for example, 0.55T, 0.3T, 0.065T, etc.). The ultra-low field magnet assembly refers to a magnet assembly that can generate an ultra-low field. The ultra-low field is a static magnetic field whose magnetic induction intensity is lower than the ultra-low field threshold, and the ultra-low field threshold can be preset, for example, the ultra-low field threshold can be preset to 0.6T.

[0061] In conjunction with the above, the gradient field refers to the magnetic field generated by the gradient coil assembly in the magnetic resonance imaging device. When the magnetic induction intensity of the magnetic field is observed in any observation direction of the scanning hole, the magnetic induction intensity at different positions is gradually changing (i.e., the magnetic field is linearly distributed in space). Figure 7 As shown, in some embodiments, the gradient coil assembly can generate one or more magnetic field gradient pulses for the main magnetic field in the X direction (Gx), Y direction (Gy) and Z direction (Gz) to encode the spatial information of the imaging object. In some embodiments, the X direction can be designated as the frequency encoding direction, and the Y direction can be designated as the phase encoding direction. In some embodiments, Gx can be used for frequency encoding or signal readout, which is generally referred to as a frequency encoding gradient or readout (RO) gradient. In some embodiments, Gy can be used for phase encoding, which is generally referred to as a phase encoding (PE, Phase-Encoding) gradient. In some embodiments, Gz can be used for slice selection to obtain two-dimensional K-space data, which is generally referred to as a slice selection (SS) gradient. In some embodiments, Gz can be used for phase encoding to obtain three-dimensional K-space data.

[0062] In some embodiments, the magnetic field monitoring module 240 is disposed in the scanning hole and covers the scanning area of ​​the scanning hole. For example, a plurality of tunnel magnetoresistance effect sensors of the magnetic field monitoring module 240 can be arranged linearly along the axial direction of the scanning hole to cover the scanning area of ​​the scanning hole.

[0063] In some embodiments, the magnetic field monitoring module 240 includes a plurality of tunnel magnetoresistive effect sensors distributed at different positions of the scanning hole.

[0064] Figure 7 is a schematic diagram of a magnetic field monitoring module according to some embodiments of this specification. Figure 7 As shown, the magnetic field monitoring module 240 may include six tunnel magnetoresistance effect sensors: tunnel magnetoresistance effect sensor 761, tunnel magnetoresistance effect sensor 762, tunnel magnetoresistance effect sensor 763, tunnel magnetoresistance effect sensor 764, tunnel magnetoresistance effect sensor 765, and tunnel magnetoresistance effect sensor 766, which are respectively located at the two ends and / or the area between the two ends of the inner wall of the scanning hole 750. Specifically, as Figure 7 As shown in , the tunnel magnetoresistance effect sensor 761 and the tunnel magnetoresistance effect sensor 762 are respectively located at the front end and the rear end of the inner wall of the scanning hole 750, the tunnel magnetoresistance effect sensor 764 and the tunnel magnetoresistance effect sensor 766 are located at the left side of the inner wall of the scanning hole 750, and the tunnel magnetoresistance effect sensor 763 and the tunnel magnetoresistance effect sensor 765 are respectively located at the right side of the inner wall of the scanning hole 750. Among them, the front end of the scanning hole 750 refers to the side where the entrance of the scanning hole is located, and the rear end is the side opposite to the entrance; the left side of the scanning hole 750 refers to the side corresponding to the positive direction of the X-axis, and the right side is the side corresponding to the negative direction of the X-axis.

[0065] In some embodiments, one or more of the tunnel magnetoresistance effect sensor 763, the tunnel magnetoresistance effect sensor 764, the tunnel magnetoresistance effect sensor 765, and the tunnel magnetoresistance effect sensor 766 may be arranged on a circle formed with the center point of the effective length of the axis 751 as the center, and the aforementioned circle may be formed with a point at 1 / 4, 3 / 4, 1 / 3, 2 / 3, 3 / 5, 2 / 5, or 4 / 5 of the effective length of the axis 751 as the center, and this specification does not impose any specific restrictions on this. Among them, the effective length of the axis 751 refers to the distance from the entrance to the rear end of the scanning hole 750.

[0066] In some embodiments, the magnetic field monitoring module 240 may include one or more (e.g., 2, 4, 6, etc.) tunnel magnetoresistance effect sensor groups. Each tunnel magnetoresistance effect sensor group includes at least two (e.g., 2 or 3 or 4, etc.) tunnel magnetoresistance effect sensors. The above-mentioned tunnel magnetoresistance effect sensor groups may be located at both ends of the inner wall of the scanning hole 750 and / or in the area between the two ends.

[0067] In some embodiments, Figure 2 As shown, the magnetic resonance imaging device 140 may further include a device monitoring module 250. The device monitoring module 250 includes one or more additional tunnel magnetoresistance effect sensors (second tunnel magnetoresistance effect sensors) for monitoring device operation information and / or performing metal detection.

[0068] The equipment operation information includes at least magnetic field anomaly information and / or equipment failure information.

[0069] Magnetic field anomaly information refers to information reflecting the abnormal situation of the magnetic induction intensity of the magnetic field (static magnetic field and / or gradient field). Magnetic field anomaly information may include normal / abnormal static magnetic field, and normal / abnormal gradient field. Abnormal means that the magnitude of the magnetic induction intensity of the static magnetic field is not within the normal range, or the gradient intensity of the gradient field is not within the normal range. The above normal range can be preset, for example, the normal range of the magnitude of the magnetic induction intensity of the static magnetic field can be preset to [2T, 6T], and the normal range of the gradient intensity of the gradient field can be preset to [10T / m, 80T / m]. Based on the above normal range, for example, when the magnitude of the magnetic induction intensity of the static magnetic field is 1.8T (not within the normal range), the static magnetic field can be determined to be abnormal. For another example, when the gradient intensity of the gradient field is 15T / m (within the normal range), the gradient field can be determined to be normal.

[0070] Equipment failure information refers to information reflecting whether the magnet or gradient coil is faulty. Equipment failure information may include magnet failure / no failure, and gradient coil failure / no failure. When the magnet fails, the magnet assembly cannot generate a static magnetic field (the magnetic induction intensity of the static magnetic field is 0). When the gradient coil fails, the gradient coil assembly cannot generate a gradient field (the gradient intensity of the gradient field is 0 T / m).

[0071] Figure 8 is a schematic diagram of a device monitoring module according to some embodiments of this specification. Figure 8 As shown, the equipment monitoring module 250 may include an additional tunnel magnetoresistance effect sensor 861 located on the inner wall of the scanning hole 750 to monitor the magnetic induction intensity of the static magnetic field and / or the gradient field, and then determine the magnetic field abnormality information or equipment failure information. In some embodiments, the additional tunnel magnetoresistance effect sensor 861 can be set at any position on the inner wall of the scanning hole 750. Preferably, the additional tunnel magnetoresistance effect sensor 861 can be set on a circle formed with the center point of the effective length of the axis 751 as the center.

[0072] Metal detection includes whether there is redundant metal in the monitoring area. The monitoring area at least includes the scanning bed, and at least one additional tunnel magnetoresistance effect sensor is located in the monitoring area to perform metal detection in the monitoring area. Redundant metal refers to metal objects that do not belong to the magnetic resonance imaging equipment (for example, stainless steel cups) or objects containing metal (for example, doctors' mobile phones), as well as metal objects carried by the imaging subject (for example, the patient's keys, metal jewelry worn, etc.). When there is redundant metal in the monitoring area, the metal detection result is "yes", conversely, when there is no redundant metal in the monitoring area, the metal detection result is "no".

[0073] In some embodiments, the additional tunnel magnetoresistance effect sensor in the monitoring area may be connected to an external circuit. When the additional tunnel magnetoresistance effect sensor detects the presence of a magnetic field generated by metal in the monitoring area, the resistance value of the additional tunnel magnetoresistance effect sensor changes, causing the current value in the external circuit to change. This change can be monitored by a current monitoring device (for example, an ammeter) in the external circuit to determine whether there is redundant metal in the monitoring area (if the current changes, then there is redundant metal, and if the current does not change, then there is no redundant metal).

[0074] like Figure 8 As shown, the equipment monitoring module 250 may include an additional tunnel magnetoresistance effect sensor 862 located on the scanning bed for metal detection. In some embodiments, the additional tunnel magnetoresistance effect sensor 862 may be disposed at any position of the scanning bed 141. Preferably, the additional tunnel magnetoresistance effect sensor 862 may be disposed on a side of the scanning bed away from the scanning hole 750.

[0075] In some embodiments, the device monitoring module 250 is disposed at the edge of the scanning bed. For example, the device monitoring module 250 includes an additional tunnel magnetoresistive effect sensor, which is disposed at the left side of the scanning bed (eg, Figure 8 For another example, the equipment monitoring module 250 includes three additional tunnel magnetoresistive effect sensors, which are respectively set on the left and right sides of the scanning bed (such as Figure 8 The additional tunnel magnetoresistance effect sensor 863 and the additional tunnel magnetoresistance effect sensor 864) and a bottom edge (such as Figure 8 Adding a tunnel magnetoresistance effect sensor 865).

[0076] In some embodiments, the device monitoring module 250 may be disposed in the scanning room. For example, the device monitoring module 250 may include one or more additional tunnel magnetoresistance effect sensors disposed on the ceiling, floor, or wall of the scanning room.

[0077] In some embodiments, the equipment monitoring module 250 is disposed at the edge of the scanning bed and in the scanning room. For example, the equipment monitoring module 250 may include five additional tunnel magnetoresistance effect sensors, which are disposed at the edge of the scanning bed 141 away from the frame and at the four corners of the ceiling of the scanning room.

[0078] In some embodiments, the device monitoring module 250 may also be disposed at other locations of the magnetic resonance imaging device, such as the inside or outside of a housing of the magnetic resonance imaging device.

[0079] For more information about the transmitting module 210, the receiving module 220, the processing module 230, the magnetic field monitoring module 240 and the device monitoring module 250, see Fig. 9 and its related description.

[0080] It should be noted that the above description of the magnetic resonance imaging device 140 and its modules is only for convenience of description and does not limit the present specification to the scope of the embodiments. It is understandable that, after understanding the principle of the system, those skilled in the art may arbitrarily combine the modules or form a subsystem to connect with other modules without deviating from the principle. In some embodiments, Figure 2 The transmitting module 210, receiving module 220, processing module 230, magnetic field monitoring module 240 and device monitoring module 250 disclosed in the specification can be different modules in one device, or one module can realize the functions of two or more modules mentioned above. For example, each module can share a storage module, or each module can have its own storage module. Such variations are all within the protection scope of this specification.

[0081] Fig. 9 is an exemplary flow chart of a magnetic resonance imaging method according to some embodiments of the present specification. Fig. 9 As shown, the process 900 includes the following steps: In some embodiments, the process 900 may be performed by the magnetic resonance imaging device 140 .

[0082] Step 910 : collecting the nuclear spin magnetic field signal of the imaging object based on the tunnel magnetoresistance effect sensor array. In some embodiments, step 910 may be performed by the receiving module 220 .

[0083] The imaging subject refers to a person who needs to undergo magnetic resonance imaging by a magnetic resonance imaging device (eg, the magnetic resonance imaging device 140 ). For example, the imaging subject may be a patient or an experimental subject.

[0084] The nuclear spin magnetic field signal refers to the time domain, in which multiple tunnel magnetoresistance effect sensors in the tunnel magnetoresistance effect sensor array generate a signal of hydrogen nuclei (H + ) when the bridge circuit resonates. The nuclear spin magnetic field signal can be characterized based on the relationship curve between the electrical signal output by the bridge circuit and time.

[0085] Nuclear spin refers to the Larmor precession of hydrogen nuclei. The nuclear spin magnetic field can be characterized based on the near magnetization vector of hydrogen nuclei in resonance, which includes the near magnetization vector magnitude and near magnetization vector direction.

[0086] Before applying a radio frequency pulse to the imaging object, the hydrogen nuclei in the imaging object are in the superposition field of the static magnetic field and the gradient field (i.e., the gradient magnetic field), the direction of the near magnetization vector of the hydrogen nuclei is in the same direction as the magnetic field direction of the superposition field at the location of the hydrogen nuclei, and the magnitude of the near magnetization vector is positively correlated with the magnitude of the magnetic field of the superposition field at the location of the hydrogen nuclei; when the radio frequency pulse is applied to the imaging object, the hydrogen nuclei in its body resonate under the action of the radio frequency pulse, and the magnitude and direction of the near magnetization vector of the hydrogen nuclei in its body will change under the influence of the radio frequency pulse, and each tunnel magnetoresistive effect sensor in the tunnel magnetoresistive effect sensor array can monitor the sum of the changes in the near magnetization vectors of the hydrogen nuclei in the imaging part of the imaging object when resonating, thereby causing a change in its own resistance value, causing a change in the electrical signal output by the bridge circuit, and the changed electrical signal is the nuclear spin magnetic field signal.

[0087] In some embodiments, if the tunnel magnetoresistance effect sensor array includes only one bridge circuit, the electrical signal output by the bridge circuit can be determined as a nuclear spin magnetic field signal in the time domain; if the tunnel magnetoresistance effect sensor array includes multiple bridge circuits, the average of the electrical signals output by the multiple bridge circuits can be determined as a nuclear spin magnetic field signal in the time domain.

[0088] In some embodiments, during the process of acquiring the nuclear spin magnetic field signal of the imaging object, the static magnetic field and / or the gradient field of the magnetic resonance imaging device are turned off.

[0089] In some embodiments of the present specification, the nuclear spin magnetic field signals of the imaging object are collected by using a tunnel magnetoresistance effect sensor array. Compared with the reception of magnetic resonance signals by the original receiving coil of the magnetic resonance imaging device, the dependence on the static magnetic field and the gradient field in the reception process is eliminated, the operation time of the magnet and the gradient coil is reduced, and thus the operation cost of the magnetic resonance imaging device is saved; in addition, when collecting the nuclear spin magnetic field signals, the static magnetic field and the gradient field are turned off, so as to avoid the influence of the static magnetic field and the gradient field on the nuclear spin magnetic field signals, thereby reducing the noise in the final imaging result.

[0090] In some embodiments, the tunnel magnetoresistance effect sensor array is also used to monitor electrophysiological information of the imaging subject.

[0091] Electrophysiological information refers to information reflecting the bioelectric characteristics of the imaging object. The electrophysiological information may be electrocardiographic information or electromyographic information of the imaging object. The electrocardiographic information may be characterized based on the electrocardiographic current value or the electrocardiographic potential value. The electromyographic information may be characterized based on the electromyographic current value or the electromyographic potential value.

[0092] In some embodiments, the receiving module 220 or the processing device (e.g., the processing device 110) can determine the electrophysiological information of the imaging object based on the nuclear spin magnetic field signal collected by the tunnel magnetoresistance effect sensor array. For example, a mapping relationship comparison table between the nuclear spin magnetic field signal and the electrocardiographic information can be preset, and the corresponding electrocardiographic information can be obtained by looking up the table based on the nuclear spin magnetic field signal collected by the tunnel magnetoresistance effect sensor array.

[0093] In some embodiments of the present specification, electrophysiological information of an imaging object is monitored by using a tunnel magnetoresistance effect sensor, thereby expanding the application field of the tunnel magnetoresistance effect sensor and thus expanding the functional types of a magnetic resonance imaging device equipped with a tunnel magnetoresistance effect sensor.

[0094] Step 920 , determining K-space data based on the nuclear spin magnetic field signal. In some embodiments, step 920 may be performed by the processing module 230 .

[0095] K-space data refers to data obtained after filling the nuclear spin magnetic field signal into the K-space (frequency domain space).

[0096] The filling method may be Fourier transform. Based on this, the processing module 240 or the processing device (eg, the processing device 110) may convert the nuclear spin magnetic field signal into K-space data based on Fourier transform.

[0097] Step 930 , based on the K-space data, obtain a magnetic resonance image of the imaging object through image reconstruction. In some embodiments, step 930 may be performed by the processing module 230 .

[0098] The magnetic resonance image refers to an image of an imaging site of an imaging subject acquired by a magnetic resonance imaging apparatus (eg, the magnetic resonance imaging apparatus 140 ).

[0099] The image reconstruction method may be an inverse Fourier transform algorithm, an interpolation algorithm, a phase-corrected conjugate synthesis algorithm, a convex set projection algorithm, etc. Based on this, illustratively, the processing module 240 or the processing device (e.g., the processing device 110) may transform the K-space data based on an inverse Fourier transform to obtain a magnetic resonance image.

[0100] In some embodiments, during the process of performing magnetic resonance imaging on the imaging object (such as before, during, and after the transmission of the radio frequency pulse, before, during, and after the acquisition of the nuclear spin magnetic field signal, etc.), the magnetic field monitoring module can be used to monitor the spatial distribution and / or temporal distribution of the static magnetic field and / or gradient field in real time.

[0101] Spatial distribution refers to data that reflects the distribution characteristics of the magnetic induction intensity of the static magnetic field or gradient field in space.

[0102] Since the static magnetic field is uniformly distributed and has a fixed direction (such as along Figure 7 The spatial distribution of the static magnetic field can be directly characterized based on the magnetic induction intensity value of the static magnetic field. For example, the spatial distribution of the static magnetic field can be 3T.

[0103] The spatial distribution of the gradient field can be characterized based on the gradient strength of the gradient field. For example, the spatial distribution of the gradient field can be "the gradient strength in the X direction is 20 T / m, the gradient strength in the Y direction is 20 T / m, and the gradient strength in the Z direction is 30 T / m".

[0104] In some embodiments, the spatial distribution of the gradient field may be data in the form of a vector. For example, continuing with the above example, the vector corresponding to the spatial distribution of the gradient field in the above example may be (20, 20, 30).

[0105] The time distribution refers to data reflecting the value of the magnetic induction intensity of the static magnetic field or gradient field within the imaging time. The imaging time refers to the time required for the magnetic resonance imaging device to complete the imaging process of the imaging object. The duration of the imaging time can be preset based on experience, for example, the duration of the imaging time can be 2 minutes.

[0106] The time distribution of the static magnetic field can be characterized based on the time distribution vector of the static magnetic field. For example, the time distribution of the static magnetic field characterized by the time distribution vector can be (3, 3, 3, 2.99, 3, ...), which means that when at each observation time point within the imaging time, the magnetic induction intensity of the static magnetic field is 3T, 3T, 3T, 2.99T, 3T, ... respectively. The time interval between two adjacent observation time points can be preset, for example, the above time interval can be 0.1s.

[0107] The time distribution of the gradient field can be characterized based on the time distribution matrix of the gradient field. For example, the time distribution of the gradient field characterized by the time distribution matrix can be shown in the following matrix A:

[0108] The elements of the first row in matrix A represent that the gradient strengths in the X direction are 20 T / m, 20 T / m, 19.99 T / m, 20 T / m, 20 T / m, 20.01 T / m, ... at various observation time points within the imaging time; the elements of the second row represent that the gradient strengths in the Y direction are 20 T / m, 20 T / m, 20 T / m, 20.01 T / m, 20.01 T / m, 20 T / m, ... at various observation time points within the imaging time; the elements of the third row represent that the gradient strengths in the Z direction are 30 T / m, 30 T / m, 30 T / m, 30 T / m, 29.99 T / m, 30 T / m, ... at various observation time points within the imaging time.

[0109] In some embodiments of the present specification, by real-time monitoring of the spatial distribution and / or temporal distribution of the static magnetic field and / or the gradient field, timely adjustments can be made to the static magnetic field and / or the gradient field when large fluctuations occur, so as to avoid the adverse effects of the above fluctuations on the imaging results.

[0110] In some embodiments, during magnetic resonance imaging of an imaging object (such as before, during, and after the transmission of a radio frequency pulse, before, during, and after the acquisition of a nuclear spin magnetic field signal, etc.), equipment operation information can be monitored based on one or more additional tunnel magnetoresistance effect sensors (i.e., equipment monitoring modules), and / or metal detection can be performed based on one or more additional tunnel magnetoresistance effect sensors.

[0111] In combination with the above, the equipment operation information may include magnetic field anomaly information and / or equipment failure information. The equipment monitoring module (such as the equipment monitoring module 250) can determine the magnetic field anomaly information or equipment failure information by monitoring the magnetic induction intensity of the static magnetic field and / or the gradient field. Metal detection includes whether there is redundant metal in the monitoring area. The equipment monitoring module (such as the equipment monitoring module 250) can monitor the change of current value through the current monitoring device in the connected external circuit to determine whether there is redundant metal in the monitoring area. For more details, see Figure 2 describe.

[0112] In some embodiments of the present specification, by adding tunnel magnetoresistance effect sensors to monitor equipment operation information and perform metal detection, the use of tunnel magnetoresistance effect sensors in magnetic resonance imaging systems is expanded, and the tunnel magnetoresistance effect sensors are used as detectors to monitor equipment failures and potential safety issues.

[0113] It should be noted that the above description of process 900 is only for illustration and explanation, and does not limit the scope of application of this specification. For those skilled in the art, various modifications and changes can be made to process 900 under the guidance of this specification. However, these modifications and changes are still within the scope of this specification. For example, multiple additional tunnel magnetoresistance effect sensors are used to monitor the operation information of the equipment.

[0114] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of this specification. Although not explicitly stated here, those skilled in the art may make various modifications, improvements and corrections to this specification. Such modifications, improvements and corrections are suggested in this specification, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of this specification.

[0115] At the same time, this specification uses specific words to describe the embodiments of this specification. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of this specification. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of this specification can be appropriately combined.

[0116] In addition, unless explicitly stated in the claims, the order of the processing elements and sequences described in this specification, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some invention embodiments that are currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the attached claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the essence and scope of the embodiments of this specification. For example, although the system components described above can be implemented by hardware devices, they can also be implemented only by software solutions, such as installing the described system on an existing server or mobile device.

[0117] Similarly, it should be noted that in order to simplify the description disclosed in this specification and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this specification, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the subject matter of this specification are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0118] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of this specification are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0119] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this specification are hereby incorporated by reference in their entirety. Except for application history documents that are inconsistent with or conflicting with the contents of this specification, documents that limit the broadest scope of the claims of this specification (currently or later attached to this specification) are also excluded. It should be noted that if the descriptions, definitions, and / or use of terms in the materials attached to this specification are inconsistent or conflicting with the contents described in this specification, the descriptions, definitions, and / or use of terms in this specification shall prevail.

[0120] Finally, it should be understood that the embodiments described in this specification are only used to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, as an example and not a limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly introduced and described in this specification.

Claims

1. A magnetic resonance imaging device, characterized in that: include: A scanning bed for carrying an imaging object; A transmitting module, used for transmitting a radio frequency signal to the imaging object; A receiving module, the receiving module comprising a tunnel magnetoresistance effect sensor array, for collecting a nuclear spin magnetic field signal of the imaging object; A processing module is used to generate a magnetic resonance image of the imaging object based on the nuclear spin magnetic field signal.

2. The device according to claim 1, characterized in that The receiving module is also used to monitor the electrophysiological information of the imaging object.

3. The device according to claim 1, characterized in that Also includes: The magnetic field monitoring module is used to monitor the spatial distribution and / or temporal distribution of the static magnetic field and / or the gradient field in real time.

4. The device according to claim 3, characterized in that The static magnetic field is generated by an ultra-low field magnet assembly; the ultra-low field is a static magnetic field whose magnetic induction intensity is lower than the ultra-low field threshold.

5. The device according to claim 3, characterized in that The magnetic field monitoring module is arranged in the scanning hole and covers the scanning area of ​​the scanning hole.

6. The device according to claim 5, characterized in that The magnetic field monitoring module includes a plurality of tunnel magnetoresistance effect sensors, and the plurality of tunnel magnetoresistance effect sensors are distributed at different positions of the scanning hole.

7. The device according to claim 1, characterized in that Also includes: The equipment monitoring module includes one or more additional tunnel magnetoresistance effect sensors for monitoring equipment operation information and / or performing metal detection.

8. The device according to claim 7, characterized in that The equipment monitoring module is arranged at the edge of the scanning bed.

9. The device according to claim 7, characterized in that The operation information at least includes magnetic field anomaly information and / or equipment failure information; the metal detection includes detecting whether there is redundant metal in the monitoring area, and the monitoring area at least includes the scanning bed.

10. The device according to any one of claims 1 to 9, characterized in that: The tunnel magnetoresistance effect sensors in the tunnel magnetoresistance effect sensor array form one or more bridge circuits.

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