Magnetic resonance system and transmitting device, transmitting method, pre-scan method

Abstract

The embodiment of the application provides a magnetic resonance system and a transmitting device and a transmitting method, and a pre-scanning method. The device comprises: a signal output unit configured to generate and output a pulse signal; a radio frequency amplifier configured to amplify the pulse signal; a signal processing unit configured to transmit the signal amplified by the radio frequency amplifier to a transmitting coil of the magnetic resonance system, receive and adjust the phase of a feedback signal, and output the feedback signal with the adjusted phase to the signal output unit; and a determination unit configured to obtain the amplitude value of the feedback signal under different phases, and determine the forward power and / or the reverse power according to the amplitude value of the feedback signal under different phases.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a magnetic resonance system, a transmitting device, a transmitting method, and a pre-scanning method. Background Technology

[0002] Magnetic resonance (MR) imaging systems have been widely used in the field of medical diagnosis. A typical MR system consists of a main magnet, a gradient radio frequency amplifier, gradient coils, a transmitter chain module, a transmitter / receiver coil, and a receiver chain module. The transmitter chain module generates pulse signals that are transmitted to the transmitter / receiver coils. The transmitter / receiver coils generate radio frequency excitation signals to excite the scanned object to generate a magnetic resonance signal. After the excitation is completed, the transmitter / receiver coils receive the magnetic resonance signal and reconstruct medical parameter images based on the magnetic resonance signal.

[0003] In magnetic resonance transmitter chain modules, forward power, reverse power, voltage standing wave ratio (VSWR), return loss, and radio frequency energy absorption ratio (SAR) are all important reference indicators. VSWR reflects the RF load matching, return loss represents the ratio of reflected power to input signal power, also reflecting RF load matching, and SAR represents the ratio of RF signal absorbed by the scanned object. Currently, couplers are widely used in various applications such as VSWR detection, power monitoring, and SAR detection. Summary of the Invention

[0004] However, when testing the above indicators, the isolation of the coupler itself will introduce measurement error, namely directional error. In other words, the performance of the coupler itself has a great impact on the accuracy of the test results. Figure 1 This is an example diagram illustrating the relationship between the aforementioned metrics and the directionality of the coupler, such as... Figure 1 As shown, couplers with different directivity have a significant impact on the detection results of various indicators. For example, when the actual VSWR is 1.4, if a coupler with a directivity of 15dB is used, the detected VSWR will be in the range of 1 to 2.1 with a large error, while the error of the detected reverse power is more than 300%. This will lead to a large error in the SAR calculated using the reverse power, resulting in false triggering of SAR protection.

[0005] At present, the directivity of the coupler is usually required to be greater than 20 dB, but even if the directivity is 20 dB, the error of the detected reverse power is still more than 150%, and in the prior art, more efforts are usually made to design a coupler with higher directivity, i.e., to improve the performance of the coupler itself to improve the accuracy of the detection result. However, in the current design method, it is difficult to design a coupler with higher directivity than 25-30 dB, especially in the case of loose coupling in high radio frequency power applications such as MR.

[0006] To at least one of the above technical problems, the embodiments of the present application provide a magnetic resonance system and a transmitting device and a transmitting method, and a pre-scan method.

[0007] According to an aspect of the embodiments of the present application, a transmitting device of a magnetic resonance system is provided, which comprises:

[0008] a signal output unit configured to generate and output a pulse signal;

[0009] a radio frequency amplifier configured to amplify the pulse signal;

[0010] a signal processing unit configured to transmit the signal amplified by the radio frequency amplifier to a transmitting coil of the magnetic resonance system, receive and adjust the phase of a feedback signal, and output the feedback signal with the adjusted phase to the signal output unit;

[0011] a determination unit configured to obtain the amplitude value of the feedback signal at different phases, and determine the forward power and / or the reverse power according to the amplitude value of the feedback signal at different phases.

[0012] Further, the signal processing unit comprises a coupler and a phase shifter, the signal amplified by the radio frequency amplifier is transmitted to the transmitting coil of the magnetic resonance system through the coupler, and after the feedback signal is obtained, the feedback signal is input to the phase shifter to adjust the phase of the feedback signal.

[0013] Further, the phase shifter continuously adjusts the phase of the feedback signal in the range of 0°-360°.

[0014] Further, the feedback signal comprises at least one of a forward feedback signal and a reverse feedback signal.

[0015] Further, the determination unit obtains the maximum amplitude value and the minimum amplitude value of the forward feedback signal at different phases, and determines the forward power and / or the reverse power according to the maximum amplitude value and the minimum amplitude value, and the coupling factor and the isolation factor of the coupler.

[0016] Further, the amplitude value is the amplitude value of voltage.

[0017] Further, the determining unit calculates a return loss and / or a standing wave ratio and / or an energy absorption rate according to the forward power and the backward power.

[0018] According to an aspect of an embodiment of the present application, a magnetic resonance system is provided, the system comprising:

[0019] a transmit coil; and

[0020] the transmit device of the preceding aspect.

[0021] According to an aspect of an embodiment of the present application, a transmit method of a magnetic resonance system is provided, the method comprising:

[0022] generating and outputting a pulse signal by a signal output unit;

[0023] amplifying the pulse signal by a radio frequency amplifier;

[0024] delivering the signal amplified by the radio frequency amplifier to a transmit coil of the magnetic resonance system by a signal processing unit, and outputting a feedback signal with adjusted phase to the signal output unit;

[0025] adjusting the phase of the feedback signal by the signal processing unit, obtaining amplitude values of the feedback signal at different phases by a determining unit, and determining a forward power and / or a backward power according to the amplitude values of the feedback signal at different phases.

[0026] According to an aspect of an embodiment of the present application, a pre-scan method of a magnetic resonance system is provided, the method comprising:

[0027] performing a center frequency search of pre-scan;

[0028] performing the transmit method of the preceding aspect.

[0029] Further, the transmit method comprises:

[0030] obtaining a maximum amplitude value and a minimum amplitude value of the feedback signal at different phases, and determining the forward power and / or the backward power according to the maximum amplitude value and the minimum amplitude value.

[0031] Further, the pre-scan method further comprises:

[0032] recording a first phase and a second phase corresponding to the maximum amplitude value and the minimum amplitude value;

[0033] adjusting a scan parameter for formal scan according to the first phase and the second phase.

[0034] Further, the pre-scan method further comprises:

[0035] calculating a standing wave ratio according to the forward power and the backward power;

[0036] When the standing wave ratio is greater than the trip level, the pre-scan is stopped.

[0037] According to another aspect of the embodiments of the present application, a storage medium storing a computer readable program is provided, wherein the computer readable program causes a computer to execute the method as described above in a device.

[0038] One of the beneficial effects of the embodiments of the present application is that: by adjusting the phase of the feedback signal, the amplitude values of the feedback signal under different phases are obtained, the real forward power and / or reverse power is determined according to the amplitude values of the feedback signal under different phases, and then the standing wave ratio and / or energy absorption rate and other indicators are calculated, so that the forward power and / or reverse power can be accurately calculated, thereby improving the accuracy of the estimation of the return loss and / or the standing wave ratio and / or the energy absorption rate and other indicators, thereby more accurately realizing automatic matching control and avoiding the risk of SAR protection false triggering, protecting the hardware of the transmit chain module, and improving the performance of the transmit chain module. And without designing a high directional coupler, the implementation difficulty is reduced.

[0039] With reference to the following description and drawings, specific embodiments of the present application are disclosed in detail, indicating the ways in which the principles of the present application can be employed. It should be understood that the embodiments of the present application are not limited in scope in terms of the appended claims and their equivalents. The embodiments of the present application include many changes, modifications and equivalents within the spirit and scope of the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0040] The included drawings provide a further understanding of the embodiments of the present application, constitute a part of the specification, serve to illustrate the embodiments of the present application, and together with the text description, explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other embodiments can be obtained by those skilled in the art without creative labor on the basis of these drawings. In the drawings:

[0041] Figure 1 is an example diagram of the relationship between the existing transmit system indicators and the directionality of the coupler;

[0042] Figure 2 is a schematic diagram of the composition of the transmitting device according to the embodiments of the present application;

[0043] Figure 3 is a schematic diagram of the composition of the signal output unit according to the embodiments of the present application;

[0044] Figure 4 is a schematic diagram of the composition of the signal processing unit according to the embodiments of the present application;

[0045] Figure 5 is a schematic diagram of the composition of the coupler according to the embodiments of the present application;

[0046] Figure 6 is a schematic diagram of adjusting the voltage amplitude value change of the forward feedback signal under different phases in the embodiment of the application;

[0047] Figure 7 is a schematic diagram of the transmission method in the embodiment of the application;

[0048] Figure 8 is a schematic diagram of the magnetic resonance imaging system in the embodiment of the application;

[0049] Figure 9 is a schematic diagram of the pre-scan method in the embodiment of the application. DETAILED DESCRIPTION

[0050] The foregoing and other features of the present application will become apparent to those skilled in the art upon consideration of the following description of specific embodiments of the application, taken in conjunction with the accompanying drawings. In the description of embodiments of the application, specific terminology is employed for the sake of clarity. However, the application is not intended to be limited to the specific embodiments described. Rather, the application is intended to include all modifications, equivalents, and alternatives that fall within the scope of the appended claims.

[0051] In the embodiments of the present application, the terms "first", "second", and the like are used to distinguish different elements from each other, but do not indicate the spatial arrangement or time sequence of the elements, and the elements should not be limited by these terms. The term "and / or" includes any one and all combinations of the associated listed terms. The terms "comprise", "include", "have", and the like mean the presence of the stated feature, element, component, or assembly, but do not exclude the presence or addition of one or more other features, elements, components, or assemblies.

[0052] In the embodiments of the present application, the singular forms "a", "an", and "the" include the plural forms, and should be broadly understood as "one" or "one kind" rather than limited to the meaning of "one"; in addition, the term "said" should be understood as including both the singular form and the plural form, unless the context clearly indicates otherwise. In addition, the term "according to" should be understood as "at least partially according to", and the term "based on" should be understood as "at least partially based on", unless the context clearly indicates otherwise.

[0053] Features described and / or illustrated with respect to one implementation can be used in one or more other implementations in the same or similar manner, combined with or substituted for features in other implementations, or used alone. The term "comprise / comprising" when used in this document is taken to mean the presence of a stated feature, integer, step or component but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0054] The embodiments of this application are described in detail below.

[0055] First aspect of the embodiments

[0056] This application provides a transmitting device for a magnetic resonance system. Figure 2 This is a schematic diagram of the transmitting device of the magnetic resonance system according to an embodiment of this application, as shown below. Figure 2 As shown, the device 200 includes:

[0057] Signal output unit 201 is used to generate and output pulse signals;

[0058] Radio frequency amplifier 202 is used to amplify the pulse signal;

[0059] The signal processing unit 203 is used to transmit the signal amplified by the radio frequency amplifier 202 to the transmitting coil of the magnetic resonance system, receive and adjust the phase of the feedback signal, and output the phase-adjusted feedback signal to the signal output unit.

[0060] The determining unit 204 is used to obtain the amplitude value of the feedback signal under different phases, and determine the forward power and / or reverse power based on the amplitude value of the feedback signal under different phases.

[0061] In some embodiments, the signal output unit 201 may include a sequence generator 300. Figure 3 This is a schematic diagram of one embodiment of the sequence generator, as shown below. Figure 3 As shown, the sequence generator includes a digital-to-analog converter 301 and a radio frequency (RF) front-end circuit 302. The sequence generator generates the required scan sequence (including RF pulse signals) during an MRI scan according to instructions. These pulse signals can generate an RF field to excite the longitudinal magnetization vector of the scanned object to reverse, thereby generating a transverse magnetization vector. This transverse magnetization vector attenuates spirally around an external magnetic field at a fixed angular frequency to generate a free-induction attenuation signal. The MRI signal for imaging can be obtained from this attenuation signal. The sequence generator typically generates low-power RF pulse signals. The sequence generator is connected to an RF amplifier 202, and the pulse signal is input to the RF amplifier 202. The type of scan sequence can be determined as needed, and this application embodiment is not intended to limit it. Optionally, the RF front-end circuit 302 may also include a transmit attenuator (not shown) to control the degree to which the pulse signal is attenuated before being input to the RF amplifier 202. Specific implementations of the above sequence generator can refer to existing technologies, and this application is not intended to limit it.

[0062] In some embodiments, the radio frequency amplifier 202 is configured to receive the low-power radio frequency pulse signal output by the signal output unit 201 and perform amplification processing, and then output the amplified radio frequency pulse signal. The radio frequency amplifier 202 can perform a series of processing such as analog-to-digital conversion or digital-to-analog conversion, modulation amplification, filtering processing, etc. on the received radio frequency pulse signal to output a high-power radio frequency pulse signal, so as to meet the imaging requirements of the magnetic resonance imaging system. The structure and type of the radio frequency amplifier 202 can refer to the prior art, which will not be illustrated one by one here.

[0063] In some embodiments, the signal processing unit 203 transmits the signal amplified by the radio frequency amplifier 202 to the transmit coil of the magnetic resonance system, and outputs a feedback signal to the signal output unit 201. Optionally, the signal processing unit 203 can include a transmit / receive mode switching switch which is not shown in the figure, and the transmit / receive mode switching switch is controlled by a pulse signal from a sequence generator to electrically connect the radio frequency amplifier 202 to the transmit coil of the magnetic resonance system during the transmit mode. In addition, the signal processing unit 203 will also receive a part of the reflection signal generated by the scanning object.

[0064] In some embodiments, the signal processing unit 203 outputs a feedback signal to the signal output unit 201, and the feedback signal includes a forward feedback signal and / or a backward feedback signal. The forward feedback signal refers to the feedback signal directly output by the signal processing unit 203, i.e. the feedback signal in front of the transmit coil. The backward feedback signal refers to the feedback signal returned from the transmit coil after the radio frequency pulse signal is amplified and reaches the transmit coil, i.e. the feedback signal at the back end of the transmit coil.

[0065] In some embodiments, Figure 4 is a schematic diagram of the signal processing unit 203, as Figure 4 shown, the signal processing unit 203 includes a coupler 401. In the measurement of high-power radio frequency signals (radio frequency signals amplified by the amplifier), a small part of the sampling signal input from the input end can be separated to the coupling end of the coupler 401, so as to obtain the forward power, the backward power, the voltage standing wave ratio (VSWR), the return loss, the specific absorption rate (SAR) and other indicators for measuring the transmit chain module by using the separated signal. The signal amplified by the radio frequency amplifier 202 is directly transmitted to the transmit coil of the magnetic resonance system after passing through the coupler 401.

[0066] In some embodiments, the signal processing unit 203 further comprises a phase shifter 402, after the signal processing unit 203 obtains the reverse feedback signal, the reverse feedback signal is input to the phase shifter 402, the phase shifter 402 can adjust the phase of the reverse feedback signal, and the reverse feedback signal after adjusting the phase is output to the signal output unit 201 through the coupler 401. The phase shifter 402 can continuously adjust the phase of the reverse feedback signal in the range of 0°-360°. The implementation of the phase shifter 402 can refer to the prior art, and the embodiments of the present application are not limited thereto. For example, the phase shifter 402 can include a first phase shifter continuously adjustable in the range of 0°-90°, a bridge, and two four-to-one switches. The output end of the first phase shifter is connected to the input end of the bridge, and the output end of the bridge is taken as the output port of the phase shifter. The two four-to-one switches can select one of the capacitance, inductance, open circuit, and short circuit under control. Then the phase difference between the input end and the output end can be in four phase intervals: 0°-90°, 90°-180°, 180°-270°, and 270°-360°. That is, the phase difference between the input end and the output end can be in any value between 0°-360°. Therefore, the phase is continuously adjustable in the range of 0°-360°.

[0067] In some embodiments, the signal processing unit 203 can further comprise a memory 403, which can store the relevant performance parameters of the coupler 401, such as coupling factor, isolation factor, directivity, etc. The memory 403 can be a RAM memory, a flash memory, a removable medium, a hard drive, a ROM memory, an EPROM memory, an EEPROM memory, etc. The embodiments of the present application are not limited thereto.

[0068] In some embodiments, the coupler 401 can be a bidirectional directional coupler, whose coupling directions include forward and reverse. For example, the signal amplified by the radio frequency amplifier 202 is directly transmitted to the transmit coil of the magnetic resonance system after the forward directional coupling. The feedback signal after adjusting the phase is output to the signal processing unit 203 after the reverse directional coupling. However, the embodiments of the present application are not limited thereto. The coupler can also be a unidirectional directional coupler. The unidirectional directional coupler is connected with the radio frequency amplifier 202. The signal amplified by the radio frequency amplifier 202 is directly transmitted to the transmit coil of the magnetic resonance system after the unidirectional directional coupling. The feedback signal after adjusting the phase is output to the signal processing unit 203 after the unidirectional directional coupling. The implementation of the above directional couplers can refer to the prior art, and the embodiments of the present application are not limited thereto.

[0069] Figure 5 is a schematic diagram of the bidirectional directional coupler, as Figure 5As shown, the coupler is a four-port element, which is composed of two ends of a through line (main line) and a coupled line (auxiliary line), port A and port B are two ports of the through line, which are respectively a signal input end and an output end, port E and port D are two ports of the coupled line, port E is a forward coupling end, and port D is a reverse coupling end, that is, the signal output by port E is the above-mentioned forward feedback signal, and the signal output by port D is the above-mentioned reverse feedback signal, the signal F amplified by the radio frequency amplifier 202 is input by port A and output by port B in part, and the other part is coupled to port E; in an ideal case, port E is regarded as a coupling end, and port D is regarded as an isolation end, and port D should be completely isolated, but due to the design of the coupler (its own directivity index affects), in the actual case, a part of the signal will leak to port D; the reverse feedback signal R after phase adjustment is input by port B and output by port A in part, and the other part is coupled to port D; in an ideal case, port D is regarded as a coupling end, and port E is regarded as an isolation end, and port E should be completely isolated, but due to the design of the coupler (its own directivity index affects), in the actual case, a part of the signal will leak to port E.

[0070] In some embodiments, at the forward coupling port E, the output signal includes the superposition of two signals, one of which is the coupled signal E1 of signal F, and the other of which is the isolated signal E2 of signal R, and at the reverse coupling port D, the output signal includes the superposition of two signals, one of which is the coupled signal D1 of signal R, and the other of which is the isolated signal D2 of signal F, as described above, in an ideal case, the forward coupling port E should only include E1 and not include E2, and the reverse coupling port D should only include D1 and not include D2, therefore, the forward feedback signal output by the forward coupling port E and the reverse feedback signal output by the reverse coupling port D both have certain errors, and if the forward power, the reverse power, the voltage standing wave ratio (VSWR), the return loss, the specific absorption rate (SAR) and other indexes are directly determined according to the feedback signals output by the ports, errors will also be introduced.

[0071] In the embodiments of the present application, the phase of the feedback signal is adjusted to obtain the amplitude value of the feedback signal at different phases, the real forward power and / or reverse power are determined according to the amplitude value of the feedback signal at different phases, and then the standing wave ratio and / or energy absorption rate and other indexes are calculated, so that the forward power and / or reverse power can be accurately calculated, and the accuracy of the estimation of the return loss and / or the standing wave ratio and / or the energy absorption rate and other indexes is improved.

[0072] The following specifically describes how to determine the above-mentioned forward power and / or reverse power.

[0073] In some embodiments, the determining unit 204 can acquire the amplitude values ​​of the feedback signal at different phases, and determine the forward power and / or the reverse power based on the amplitude values ​​of the feedback signal at different phases. Since the phase shifter 402 can continuously adjust the phase of the reverse feedback signal within a range of 0° to 360°, the determining unit 204 can acquire the maximum and minimum amplitude values ​​of the forward feedback signal at different phases, and determine the forward power and / or the reverse power based on the maximum and minimum amplitude values, as well as the coupling factor and isolation factor of the coupler 401.

[0074] In some embodiments, since the signal output from the coupling end of coupler 401 is a radio frequency signal, the signal output from the coupling end can be detected and converted into a voltage signal, and the voltage signal can be transmitted to the analog-to-digital converter (ADC) module (not shown) in the determination unit 204 to sample the received voltage signal to obtain the signal amplitude value, which can be the voltage amplitude value. Figure 5 As shown, V1 = V f ×C, V2=V r ×I,V fwd =V1+V2, V4=V f ×I, V3=V r ×C,V rfl =V3+V4, where C represents the coupling factor of the coupler, I represents the isolation factor of the coupler, and V f V represents the actual forward power. r V represents the actual reverse power. fwd V represents the forward feedback signal voltage. rfl V1 represents the voltage of the reverse feedback signal, V2 represents the voltage of the coupled signal in the forward feedback signal, V3 represents the voltage of the coupled signal in the reverse feedback signal, and V4 represents the voltage of the isolated signal in the forward feedback signal.

[0075] Figure 6 This is a schematic diagram illustrating the voltage amplitude changes of the forward feedback signal under different phases in an embodiment of this application, as shown below. Figure 6 As shown, when V1 and V2 are in phase, V fwd The amplitude value is the largest when V1 and V2 are out of phase. fwd The amplitude value is the smallest, and the maximum and minimum amplitude values ​​can be expressed by the following formulas (1) and (2):

[0076]

[0077] V1 and V2 can be obtained according to the following formulas (3) and (4):

[0078]

[0079] In some embodiments, the determining unit 204 (which can be read by a processor described later) can read the isolation factor I and the coupling factor C of the coupler from the memory of the signal processing unit 203, and calculate the real forward power and the real reverse power using the following formulas (5) and (6):

[0080] V f = V1 / C formula (5)

[0081] V r = V2 / I formula (6)

[0082] For example, according to the pre-stored corresponding relationship between the voltage and the power, after obtaining V f and V r , V f and V r are converted into corresponding power values P f and P r , where P f = V f 2 / 2R, P r = V r 2 / 2R, R is the connected load, or V f and V r may also be taken as the relative values of the forward power and the reverse power (this is because in some cases only the relative relationship of the forward power and the reverse power is considered, and the absolute values of the forward power and the reverse power are not required), the embodiments of the present application are not limited thereto.

[0083] The above takes the determination unit 204 obtaining the maximum amplitude value and the minimum amplitude value of the forward feedback signal at different phases as an example to illustrate how to determine the forward power and / or the reverse power. The determination unit 204 can also obtain the maximum amplitude value and the minimum amplitude value of the reverse feedback signal at different phases to calculate V3 and V4, and then calculate the forward power and / or the reverse power, which is similar to the calculation method of formulas (1)-(6), and will not be repeated here.

[0084] In some embodiments, the determining unit 204 can also calculate the return loss and / or the standing wave ratio and / or the energy absorption rate according to the forward power and the reverse power. The specific calculation method can refer to any existing method, and the embodiments of the present application are not limited thereto. For example, the return loss RL can be calculated using the following formula (7), the standing wave ratio VSWR can be calculated using the following formula (8), and the energy absorption rate S AR can be calculated using the following formula (9), but the embodiments of the present application are not limited thereto.

[0085]

[0086]

[0087] wherein J std represents a molecular model (e.g., a head model or a body part model), cableLoss and coilLoss represent cable loss and coil loss, refl is a reflection coefficient, which is equal to P f / P net , P net is the power reaching the coil.

[0088] In some embodiments, the determining unit 204 can include a processor to perform the calculation functions of the above-mentioned formulas (1)-(9) in addition to the analog-to-digital conversion module. The processor can be implemented as a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any appropriate combination thereof, for performing the functions described in the present application. The embodiments of the present application are not limited in this regard.

[0089] In some embodiments, the determining unit 204 can be a separate module component, or the devices of the determining unit 204 can be placed in the signal processing unit 203 and / or the signal output unit 201, or the functions of the determining unit 204 can be integrated in the signal processing unit 203 and / or the signal output unit 201. The embodiments of the present application are not limited in this regard. For example, the functions of the processor of the determining unit 204 can be integrated into the processor of the signal processing unit 203 and / or the signal output unit 201. Here, examples are not repeated one by one.

[0090] For simplicity, Figure 6 only the connection relationship or signal path between the components or modules is exemplarily shown in the above-mentioned embodiments, but it should be clear to those skilled in the art that various related technologies such as bus connection can be used. The above-mentioned components or modules can be implemented by hardware facilities such as processors, memories, etc.; the embodiments of the present application are not limited in this regard.

[0091] It should be noted that the transmitting device can further include Figure 2 components not shown in the above-mentioned embodiments, which can be referred to related technologies, and examples are not repeated here.

[0092] The above-mentioned embodiments are only exemplarily described, but the present application is not limited in this regard, and appropriate modifications can be made on the basis of the above-mentioned embodiments. For example, the above-mentioned embodiments can be used alone, or one or more of the above-mentioned embodiments can be combined.

[0093] From the above embodiments, by adjusting the phase of the feedback signal, the amplitude values of the feedback signal under different phases are obtained, the real forward power and / or reverse power is determined according to the amplitude values of the feedback signal under different phases, and then the standing wave ratio and / or energy absorption rate and other indicators are calculated, so that the forward power and / or reverse power can be accurately calculated, thereby improving the accuracy of the estimation of other indicators such as return loss and / or standing wave ratio and / or energy absorption rate, thereby more accurately realizing automatic matching control and avoiding the risk of SAR protection false triggering, protecting the hardware of the transmit chain module, and improving the performance of the transmit chain module. Moreover, a high directional coupler does not need to be designed, and the implementation difficulty is reduced.

[0094] Embodiments of the second aspect

[0095] Embodiments of the present application provide a transmit method of a magnetic resonance system. The same content as the embodiments of the first aspect will not be repeated.

[0096] Figure 7 is a schematic diagram of a transmit method of a magnetic resonance system according to an embodiment of the present application. As shown in Figure 7 the transmit method of the magnetic resonance system comprises:

[0097] 701, a signal output unit generates and outputs a pulse signal;

[0098] 702, the pulse signal is amplified by a radio frequency amplifier;

[0099] 703, the signal processing unit transmits the signal amplified by the radio frequency amplifier to the transmit coil of the magnetic resonance system, and outputs the feedback signal after adjusting the phase to the signal output unit;

[0100] 704, the phase of the feedback signal is adjusted by the signal processing unit, the amplitude values of the feedback signal under different phases are obtained by the determination unit, and the forward power and / or reverse power is determined according to the amplitude values of the feedback signal under different phases.

[0101] In some embodiments, the implementation of 701-704 and the implementation of the signal output unit, the radio frequency amplifier, the signal processing unit, and the determination unit can refer to the embodiments of the first aspect, and the repeated parts will not be repeated.

[0102] In some embodiments, the signal processing unit can continuously adjust the phase of the feedback signal in the range of 0°-360°.

[0103] In some embodiments, the feedback signal includes forward feedback signal and / or reverse feedback signal

[0104] In some embodiments, in 704, the maximum amplitude value and the minimum amplitude value of the forward feedback signal under different phases are obtained, and the forward power and / or the reverse power is determined according to the maximum amplitude value and the minimum amplitude value, the amplitude value being a voltage amplitude value.

[0105] In some embodiments, the method can further include (not shown): calculating a standing wave ratio and / or an energy absorption rate according to the forward power and the reverse power.

[0106] It is worth noting that the above-mentioned Figure 7 The embodiments of the present application are only illustratively described, but the present application is not limited thereto. For example, the execution order between the operations can be appropriately adjusted, and in addition, some operations can be added or some operations can be reduced. Those skilled in the art can make appropriate modifications based on the above description, and the description of the above-mentioned Figure 7 is not limited thereto.

[0107] The above-mentioned embodiments are only illustratively described, but the present application is not limited thereto, and appropriate modifications can be made on the basis of the above-mentioned embodiments. For example, the above-mentioned embodiments can be used alone, or one or more of the above-mentioned embodiments can be combined.

[0108] As can be seen from the above-mentioned embodiments, by adjusting the phase of the feedback signal, the amplitude value of the feedback signal under different phases is obtained, the real forward power and / or reverse power is determined according to the amplitude value of the feedback signal under different phases, and then the standing wave ratio and / or the energy absorption rate and other indicators are calculated, so that the forward power and / or the reverse power can be accurately calculated, thereby improving the accuracy of the estimation of the return loss and / or the standing wave ratio and / or the energy absorption rate and other indicators, thereby more accurately realizing automatic matching control and avoiding the risk of SAR protection false triggering, protecting the hardware of the transmit chain module, and improving the performance of the transmit chain module. And without designing a high directivity coupler, the implementation difficulty is reduced.

[0109] Embodiments of the third aspect

[0110] The embodiments of the present application also provide a magnetic resonance imaging system.

[0111] Figure 8 is a schematic diagram of the magnetic resonance imaging system, as Figure 8 shown, the system 800 includes a transmit coil 801 and the transmit device 200 in the embodiments of the first aspect, which can be used to set the scan parameters before the MRI system performs a pre-scan or a formal scan. The same content as the embodiments of the first aspect will not be described again.

[0112] In some embodiments, the magnetic resonance imaging system can further include a main magnet assembly 802, a gradient coil assembly 803, a gradient coil driver 804, a receiving device 805, a controller 806, a scan bed 807, an image processing unit 808, etc. The specific implementation can refer to the related art, and the embodiments of the present application are not limited thereto.

[0113] In some embodiments, the main magnet assembly 802 generally includes, for example, a superconducting magnet having main magnet coils disposed circumferentially therearound, which is mounted within a toroidal vacuum container and defines a cylindrical imaging space around the object to be scanned. A constant static magnetic field, such as the static magnetic field B0, is generated along the Z direction of the imaging space. The MRI system uses the generated static magnetic field B0 to transmit a static magnetic pulse signal to the object to be scanned placed in the imaging space, so that the precession of the protons in the object to be scanned is ordered, and a longitudinal magnetization vector is generated.

[0114] In some embodiments, the transmit coil 801 is generally disposed along the inner ring of the main magnet and is used to respond to the RF excitation pulse transmitted from the transmitting device 200 to transmit a radio frequency field B1 orthogonal to the static magnetic field B0 to the object to be scanned to excite the atomic nucleus in the object to be scanned 1016, so that the longitudinal magnetization vector is converted into a transverse magnetization vector. For example, the controller 806 can generate a scan sequence by instructing the signal output unit 201, generate an RF pulse signal, and after amplification by the RF amplifier 202, transmit the signal to the RF transmit coil 801 by the signal processing unit 203.

[0115] In some embodiments, when the radio frequency excitation pulse ends, a free induction decay signal is generated in the process of gradually restoring the transverse magnetization vector of the object to be scanned to zero, that is, the magnetic resonance signal that can be collected.

[0116] In some embodiments, the RF transmit coil 801 can be switched between a transmit mode and a receive mode by a transmit / receive mode switch in the signal processing unit 203, wherein in the receive mode, the RF transmit coil 801 can be used to receive the magnetic resonance signal from the object to be scanned, which can also be collected via the RF receiving coil 809 (optional) disposed close to the object to be scanned.

[0117] In some embodiments, the controller 806 provides a gradient waveform to the gradient coil driver 804, which includes GX, GY, and GZ amplifiers, etc. Each GX, GY, and GZ gradient amplifier excites a corresponding gradient coil in the gradient coil assembly 803 to generate a magnetic field gradient for spatially encoding the MR signal during an MRI scan.

[0118] In some embodiments, the receiving device 805 is configured to receive the magnetic resonance signals collected by the receiving coil 809 or the transmitting coil 801 in the receiving mode. The receiving device 805 can include an RF preamplifier configured to amplify the received magnetic resonance signals, a phase detector configured to perform phase detection on the amplified magnetic resonance signals, and an analog / digital conversion module configured to convert the phase-detected magnetic resonance signals from analog signals to digital signals and send the digital signals to the image processing unit 808, etc. in accordance with the related art.

[0119] In some embodiments, the image processing unit 808 can perform pre-processing, reconstruction, etc. on the received digitized magnetic resonance signals to obtain the desired images or image data. The image processing unit 808 can include a processor and a storage medium on which a program of predetermined data processing to be executed by the processor is recorded. The image processing unit 808 can be connected to the controller 806 and perform data processing based on the control signals received from the controller 806. Alternatively, the image processing unit 808 can also be a separate device connected to the MRI system, or the functions of the image processing unit 808 can be integrated into the controller 806, which is not limited in the embodiments of the present application.

[0120] In some embodiments, the controller 806 can include a processor and a storage medium for storing a program executable by the processor, which can cause the components of the MRI system to perform corresponding operations to implement the scanning process of the object to be scanned when the computer executes the program. The scanning process can include pre-scanning and formal scanning after pre-scanning.

[0121] For example, the controller 806 can control the MRI system to perform pre-scanning according to a predetermined pulse sequence, which can involve but is not limited to controlling the amplitude, power, flip angle, frequency, etc. of the RF pulse signals emitted by the transmitting device 200, and controlling the power of the drive signals emitted by the gradient coil driver 804 and the density of the magnetic resonance signals collected by the receiving device 805, etc.

[0122] Although it is described in the first embodiment that the determination unit 204 can be a separate module component, the devices of the determination unit 204 can also be placed in the signal processing unit 203 and / or the signal output unit 201, and the functions of the determination unit 204 can also be integrated into the signal processing unit 203 and / or the signal output unit 201, which is not limited in the embodiments of the present application. For example, the functions of the processor of the determination unit 204 can be integrated into the processor of the signal processing unit 203 and / or the signal output unit 201. However, it can be understood that the functions of the determination unit 204 can also be implemented by the processor of the controller 806.

[0123] In some embodiments, the MRI system can further include a user input device (not shown), such as a keyboard and a mouse, through which an operator can input operation signals to the controller 806. For example, a user can send pre-set scan parameters, etc. to the controller 806 through the input device. In some embodiments, the MRI system can further include a display unit 810. The display unit can be connected to the input device to display an operation interface, or connected to the image processing unit 808 to display images. In addition, the storage medium in the controller 806 and the image processing unit 808 and the memory can include, for example, a ROM, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, or a non-volatile memory card, etc., and the embodiments of the present application are not limited thereto.

[0124] In addition, the magnetic resonance imaging system 800 can further include Figure 8 components not shown in the figure, such as a physiological acquisition controller, a scan object positioning device, etc., which can be referred to in the related art and will not be exemplified one by one here.

[0125] From the above embodiments, it can be seen that by adjusting the phase of the feedback signal, the amplitude values of the feedback signal at different phases are obtained, the real forward power and / or reverse power is determined according to the amplitude values of the feedback signal at different phases, and then the standing wave ratio and / or energy absorption rate and other indicators are calculated, so that the forward power and / or reverse power can be accurately calculated, thereby improving the accuracy of the estimation of the return loss and / or standing wave ratio and / or energy absorption rate and other indicators, thereby more accurately realizing automatic matching control and avoiding the risk of false triggering of SAR protection, protecting the hardware of the transmit chain module, and improving the performance of the transmit chain module. And without designing a high directivity coupler, the implementation difficulty is reduced.

[0126] Embodiments of the fourth aspect

[0127] The embodiments of the present application also provide a pre-scan method of a magnetic resonance system, Figure 9 is a schematic diagram of the pre-scan method, as Figure 9 shown, the method comprises:

[0128] 901, a center frequency search for pre-scan is performed;

[0129] 902, the transmit method of the second aspect embodiment is executed.

[0130] In some embodiments, with reference Figure 8 After the object to be scanned enters the scanning bore (i.e. the imaging space defined by the main magnet), the scan parameter setting is performed, for example, the scan parameters can be set through the input device based on the part to be detected. The setting of the scan parameters includes various settings of the scan parameters such as scan range, scan protocol, etc.

[0131] In 901, in the process of pre-scanning, the center frequency needs to be corrected first to determine the optimal resonance frequency, and the correction process includes: central frequency searching (CFL) to determine the center frequency which is the same as the precession frequency of the proton in the object to be scanned.

[0132] In 902, the signal output unit generates a set of pulse signals with the center frequency, and outputs the set of pulse signals to the signal processing unit after amplification by the RF amplifier, receives the feedback signal and adjusts the phase of the feedback signal, and outputs the feedback signal to the signal output unit, and obtains the amplitude value of the feedback signal at different phases, for example, the maximum amplitude value and the minimum amplitude value of the feedback signal at different phases, and determines the forward power and / or the reverse power according to the maximum amplitude value and the signal amplitude value.

[0133] In 902, the method further comprises: calculating the standing wave ratio according to the forward power and the reverse power; when the standing wave ratio is greater than the open circuit level, stopping the pre-scanning and outputting an alarm information, otherwise executing 903-905.

[0134] In some embodiments, the method can further comprise:

[0135] 903, recording the first phase and the second phase corresponding to the maximum amplitude value and the minimum amplitude value; and

[0136] 904, performing formal scanning, and adjusting the scanning parameters according to the first phase and the second phase during the formal scanning, the scanning parameters also including the phase of the phase shifter, that is, during the formal scanning, the phase of the phase shifter is not continuously changed in the range of 0°-360°, but is fixed at the first phase and the second phase;

[0137] 905, calculating the forward power and the reverse power under formal scanning, and estimating the performance indicators such as SAR, VSWR, etc., which can be referred to the prior art and will not be described here.

[0138] In some embodiments, if the next scanning object is changed to accept scanning, or different parts are scanned, the above pre-scanning method will be repeated.

[0139] The embodiments of the present application also provide a computer readable program, wherein when the program is executed in a transmitting device or an MRI system, the program causes the computer to execute the method as described in the embodiments of the second or fourth aspects in the transmitting device or the MRI system.

[0140] The embodiments of the present application further provide a storage medium storing a computer readable program, wherein the computer readable program causes a computer to execute the method according to the embodiments of the second or fourth aspect in a transmitting device or an MRI system.

[0141] The apparatus and method described above can be implemented by hardware, or by hardware in combination with software. The present application relates to a computer readable program which, when executed by a logic unit, causes the logic unit to implement the apparatus or component described above, or causes the logic unit to implement the various methods or steps described above. The present application also relates to a storage medium for storing the above program, such as a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, etc.

[0142] The method / apparatus described in combination with the embodiments of the present application can be directly embodied as hardware, a software module executed by a processor, or a combination of the two. For example, one or more of the functional blocks shown in the functional block diagram, and / or a combination of one or more of the functional blocks, can correspond to a software module of a computer program flow, or to a hardware module. The software modules can correspond to the respective steps shown in the figure. The hardware modules can be implemented by, for example, fixing the software modules by using a field programmable gate array (FPGA).

[0143] The software modules can be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a mobile disk, a CD-ROM, or any other form of storage medium known in the art. A storage medium can be coupled to the processor, so that the processor can read information from the storage medium, and write information to the storage medium; or the storage medium can be an integral part of the processor. The processor and the storage medium can be located in an ASIC. The software modules can be stored in a memory of the mobile terminal, or in a memory card which can be inserted into the mobile terminal. For example, if the device (such as a mobile terminal) uses a MEGA-SIM card or a large capacity flash memory device, the software modules can be stored in the MEGA-SIM card or the large capacity flash memory device.

[0144] One or more of the functional blocks described in the figures can be implemented as a general -purpose processor, a Digital Signal Processor (DSP), an Application-Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any appropriate combination of the foregoing, in which case the functions described with respect to the functional blocks can be implemented with either software or hardware, or a combination of the two. One or more of the functional blocks described in the figures can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0145] The application has been described in relation to particular embodiments, which are intended in all respects to be illustrative rather than restrictive. Those skilled in the art could readily devise variations and modifications not explicitly described herein that fall within the scope of the present application. Accordingly, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the application, and the scope and spirit of the application should be limited only by the claims and equivalents thereof.

Claims

1. A transmitting device for a magnetic resonance system, characterized in that, The device includes: A signal output unit, which is used to generate and output pulse signals; A radio frequency amplifier, used to amplify the pulse signal; The signal processing unit is used to transmit the signal amplified by the radio frequency amplifier to the transmitting coil of the magnetic resonance system, receive the reverse feedback signal returned from the transmitting coil, adjust the phase of the reverse feedback signal, and output the phase-adjusted reverse feedback signal and the forward feedback signal generated by the signal processing unit to the signal output unit. A unit is defined that performs at least one of the following processes: Obtain the amplitude values ​​of the forward feedback signal under different phases of the reverse feedback signal, and determine the forward power and / or reverse power based on the amplitude values ​​of the forward feedback signal under different phases of the reverse feedback signal. Obtain the amplitude values ​​of the reverse feedback signal at different phases, and determine the forward power and / or reverse power based on the amplitude values ​​of the reverse feedback signal at different phases.

2. The apparatus according to claim 1, characterized in that, The signal processing unit includes a coupler and a phase shifter. The signal amplified by the radio frequency amplifier is transmitted to the transmitting coil of the magnetic resonance system after passing through the coupler. After obtaining the reverse feedback signal, the reverse feedback signal is input to the phase shifter to adjust the phase of the reverse feedback signal.

3. The apparatus according to claim 2, characterized in that, The phase shifter continuously adjusts the phase of the reverse feedback signal within the range of 0° to 360°.

4. The apparatus according to claim 1, characterized in that, The determining unit obtains the maximum and minimum amplitude values ​​of the forward feedback signal under different phases, and determines the forward power and / or the reverse power based on the maximum and minimum amplitude values, as well as the coupling factor and isolation factor of the coupler in the signal processing unit.

5. The apparatus according to claim 1, characterized in that, The amplitude value is the amplitude value of the voltage.

6. The apparatus according to claim 1, characterized in that, The determining unit calculates the return loss and / or standing wave ratio and / or energy absorption rate based on the forward power and the reverse power.

7. A magnetic resonance system, the system comprising: Transmitting coil; as well as The launching device according to any one of claims 1 to 6.

8. A method for emission in a magnetic resonance system, the method comprising: The pulse signal is generated and output by the signal output unit; The pulse signal is amplified by a radio frequency amplifier; The signal processing unit transmits the amplified signal from the radio frequency amplifier to the transmitting coil of the magnetic resonance system, and outputs the phase-adjusted reverse feedback signal and the forward feedback signal generated by the signal processing unit to the signal output unit. The signal processing unit adjusts the phase of the reverse feedback signal returned from the transmitting coil, and the determining unit performs at least one of the following processes: obtaining the amplitude value of the forward feedback signal of the reverse feedback signal at different phases, and determining the forward power and / or reverse power based on the amplitude value of the forward feedback signal of the reverse feedback signal at different phases; Obtain the amplitude values ​​of the reverse feedback signal at different phases, and determine the forward power and / or reverse power based on the amplitude values ​​of the reverse feedback signal at different phases.

9. A pre-scanning method for a magnetic resonance system, the pre-scanning method comprising: Perform a pre-scan center frequency search; Perform the launching method as described in claim 8.

10. The method according to claim 9, characterized in that, The launch method includes: Obtain the maximum and minimum amplitude values ​​of the forward feedback signal under different phases, and determine the forward power and / or the reverse power based on the maximum and minimum amplitude values.

11. The method according to claim 10, characterized in that, The pre-scanning method further includes: Record the first phase and the second phase corresponding to the maximum and minimum amplitude values; The scanning parameters used for the actual scan are adjusted based on the first phase and the second phase.

12. The method according to claim 10, characterized in that, The pre-scanning method further includes: VSWR is calculated based on the forward power and the reverse power; When the VSWR is greater than the open circuit level, the pre-scan is stopped.

13. A storage medium storing a computer-readable program, characterized in that, The computer-readable program causes a computer to perform the method described in any one of claims 8 to 12 in the device.

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