JP2016151488A - Magnetic resonance measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to obtain information indicting the characteristic of an electric circuit for measuring magnetic resonance in a nuclear magnetic resonance device without having to give a signal to the electric circuit.SOLUTION: A detection circuit 28 detects an NMR signal generated from a nuclide to be measured and outputs the detected signal to a spectrophotometer 40. A reception unit 50 of the spectrophotometer 40 receives a thermal noise signal generated by the detection circuit 28 at a stage for making the resonance frequency of the detection circuit 28 tuned to a frequency appropriate for the nuclide to be measured, and at a stage for matching electrical impedances. In the spectrophotometer 40, the thermal noise signal is analyzed, and information indicating the characteristic of the detection circuit 28 in a reception period for detecting the NMR signal (for example, the spectrum data of the thermal noise signal, the resonance frequency of the detection circuit 28, a Q value) is thereby obtained. The tuning and matching of the detection circuit 28 is achieved utilizing the information.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic resonance measuring apparatus, and more particularly to a technique for detecting characteristics of an electric circuit for magnetic resonance measurement.

  As a magnetic resonance measuring apparatus, a nuclear magnetic resonance (NMR) measuring apparatus and an electron spin resonance (ESR) measuring apparatus are known. As an apparatus similar to the NMR measurement apparatus, a magnetic resonance imaging (MRI) apparatus is also known. Hereinafter, the NMR measurement apparatus will be described.

  NMR is a phenomenon in which nuclei placed in a static magnetic field interact with electromagnetic waves having a specific frequency. An apparatus for measuring a sample at the atomic level using this phenomenon is an NMR measuring apparatus. The NMR measurement apparatus is utilized in the analysis of organic compounds (for example, medicines and agricultural chemicals), polymer materials (for example, vinyl, polyethylene), biological substances (for example, nucleic acids, proteins), and the like. If an NMR measuring apparatus is used, for example, the molecular structure of the sample can be clarified.

  In an NMR apparatus, an NMR probe (NMR signal detection probe) is placed together with a sample in a superconducting magnet that generates a static magnetic field. The NMR probe includes a transmission coil and a reception coil. The coil has a function of applying a varying magnetic field to the sample during the irradiation time period (transmission period) and detecting the NMR signal of the sample during the observation time period (reception period). Since the resonance frequency varies depending on the nuclide to be observed, a high frequency signal having a specific frequency suitable for the nuclide to be observed is given to the coil at the time of sample measurement. In general, the detection circuit in the NMR probe includes a variable capacitor for tuning and a variable capacitor for matching in addition to the coil. That is, the detection circuit includes a tuning circuit and a matching circuit.

  Prior to sample measurement, tuning of the detection circuit (adjustment of operating conditions) is performed. That is, tuning and matching is performed. A transmission method and a reflection method are known as general tuning matching methods. In the transmission method, a transmission signal having a target frequency is supplied to a detection circuit, and the level of the signal that has passed through the detection circuit is observed. The level changes in accordance with the degree of loss of synchronization and the degree of mismatch. Therefore, by changing each setting value (capacitance) of the tuning variable capacitor and the matching variable capacitor while referring to the signal level, the resonance frequency of the detection circuit is adapted to the resonance frequency corresponding to the nuclide to be observed, The impedance of the detection circuit is matched to the impedance on the transmission side. In the reflection method, a directional coupler is provided on the signal path from the transmission side to the detection circuit, and a reflected wave returning from the detection circuit to the transmission side is observed. The level of the reflected wave changes in accordance with the degree of loss of synchronization and the degree of mismatch. Therefore, the tuning and matching of the detection circuit can be achieved by changing each setting value of the tuning variable capacitor and the matching variable capacitor while referring to the level of the reflected wave.

  As a method for detecting an NMR signal, a method using Faraday's law of electromagnetic induction is known. In this method, Johnson noise becomes the dominant noise. Johnson noise is known to be proportional to the square root of the coil temperature and the square root of the electrical resistance of the coil.

  Non-Patent Document 1 describes that a superconducting material is used as a material for a detection coil. Since the superconductive material has almost zero electric resistance under cooling, the noise can be reduced and the detection sensitivity of the NMR signal can be improved.

US Pat. No. 5,565,778

“High Temperature Superconducting Radio Frequency Coils for NMR Spectroscopy and Magnetic Resonance Imaging”, Steven M. Anlage, “Microwave Superconductivity,” ed. By H. Weinstock and M. Nisenoff, (Kluwer, Amsterdam, 2001), pp.337-352 . D.E.Oates, Nonlinear behavior of superconducting devices, “Microwave Superconductivity,” ed. By H. Weinstock and M. Nisenoff, (Kluwer, Amsterdam, 2001), pp.337-352.

  As described above, the NMR method has an irradiation time period (transmission period) in which a transmission signal is supplied to a detection circuit and an observation time period (reception period) in which the NMR signal is detected. The transmission method and reflection method described above are methods for tuning and matching the detection circuit by supplying a transmission signal to the detection circuit. Therefore, these methods can be said to be suitable methods for achieving tuning and matching of the detection circuit in the irradiation time zone. However, since the observation time zone is a time zone during which no transmission signal is supplied to the detection circuit, the tuning state and matching state of the detection circuit adjusted using the transmission method and reflection method are the operating conditions of the detection circuit during the observation time zone. However, it is not always suitable, and a problem of deviating from an ideal operating condition may occur.

  In addition, when a detection coil made of a superconductive material is used, it is known that high-frequency conduction characteristics become nonlinear, and the Q value and resonance frequency of the resonance characteristics vary according to the transmission signal (for example, Patent Document 1). Non-Patent Document 2). Therefore, even if the tuning state and the matching state of the detection circuit are adjusted using the transmission method or the reflection method, the operation conditions suitable for the observation time period are not always set. Note that the metal detection coil may have the same problem as the detection coil made of a superconductive material depending on the observation conditions.

  An object of the present invention is to enable a magnetic resonance apparatus to obtain information indicating characteristics of an electric circuit without giving a signal to the electric circuit for magnetic resonance measurement. Alternatively, information for tuning and matching of the electric circuit is obtained.

  The magnetic resonance measurement apparatus according to the present invention analyzes the characteristics of the electric circuit by analyzing an electric circuit for magnetic resonance measurement and a thermal noise signal generated in the electric circuit in an adjustment stage of operating conditions of the electric circuit. Characteristic information generating means for generating characteristic information to be shown.

  The thermal noise signal generated in the electric circuit can be evaluated using the characteristic of the electric circuit as an index. Therefore, characteristic information indicating the characteristics of the electric circuit can be generated by analyzing the thermal noise signal. According to the above configuration, the characteristic information can be obtained without giving any signal or power to the electric circuit. For example, with respect to an electric circuit whose characteristics change depending on whether or not a signal is applied to the electric circuit, characteristic information when no signal is applied can be obtained. The electric circuit is a circuit that detects a magnetic resonance signal generated in the observation target nuclide, for example. According to said structure, the characteristic information in the period (reception period) which detects a magnetic resonance signal with an electric circuit is obtained. By using the characteristic information, it is possible to appropriately adjust the operating conditions of the electric circuit during the reception period.

  Preferably, the adjusting step is a step for tuning the resonance frequency of the electric circuit to a frequency suitable for the nuclide to be observed, and a step of matching the electric impedance, and the characteristic information is the electric information. It is information indicating at least one of the resonance frequency and Q value of the circuit.

  According to the above configuration, the resonance frequency and the Q value suitable for the observation target nuclide can be obtained in the reception period. By using these pieces of information, the electric circuit can be tuned and matched during the reception period. The electric circuit includes, for example, a detection coil for detecting a magnetic resonance signal, a tuning variable capacitor, and a matching variable capacitor. The tuning and matching of the electric circuit can be achieved by changing the set values of the tuning variable capacitor and the matching variable capacitor with reference to the obtained resonance frequency and Q value. Each set value may be changed by manual work by an operator, or may be automatically changed. For example, each set value is changed so that the obtained resonance frequency matches the resonance frequency of the observation target nuclide.

  Preferably, the characteristic information generating unit generates spectral data of the thermal noise signal. For example, spectral data is generated by applying a Fourier transform to the thermal noise signal. By analyzing the spectrum data, the characteristics of the electric circuit are analyzed.

  Preferably, the apparatus further includes spectrum display means for displaying the spectrum data. Thereby, information for adjusting the tuning state and the matching state of the electric circuit is provided to an operator or the like. For example, the operator can evaluate the resonance frequency and the Q value of the electric circuit by referring to the spectrum data, and adjust the tuning state and the matching state of the electric circuit based on the evaluation result.

  Preferably, the characteristic information generating unit calculates at least one of a resonance frequency and a Q value of the electric circuit by analyzing the spectrum data. For example, the resonance frequency and the Q value can be obtained from the spectrum data by using the theoretical formula obtained from the theoretical formula indicating the thermal noise signal and the device function of the electric circuit.

  Preferably, the characteristic information generating unit calculates at least one of a resonance frequency and a Q value of the electric circuit by analyzing a periodic component included in the waveform of the thermal noise signal.

  Preferably, the characteristic information generating means extracts the periodic component by applying an autocorrelation method to the thermal noise signal, and performs waveform fitting on the periodic component, thereby At least one of the resonance frequency and the Q value is calculated.

  Preferably, the information generating means extracts the periodic component by applying an autocorrelation method to the thermal noise signal, and applies an autoregressive method to the periodic component, thereby At least one of the resonance frequency and the Q value is calculated.

  Preferably, adjustment means for adjusting a tuning state and a matching state of the electric circuit based on at least one of a resonance frequency and a Q value of the electric circuit is further included. The synchronization state and the alignment state may be adjusted manually by an operator or may be automatically adjusted.

  Preferably, in the magnetic resonance measurement stage, a transmission period for supplying a transmission signal for magnetic resonance measurement to the electric circuit, and a reception period for detecting the magnetic resonance signal generated in the observation target nuclide by the electric circuit, Control means for dynamically switching a tuning state and a matching state of the electric circuit, wherein the control means is configured to provide a signal to the electric circuit indicating the tuning state and the matching state of the electric circuit during the transmission period. In the reception period, the tuning state and the matching state of the electric circuit are set to the tuning state and the matching state adjusted by the adjusting unit.

  For example, the setting values of the tuning variable capacitor and the matching variable capacitor included in the electric circuit are dynamically switched between the transmission period and the reception period. Specifically, a resonance frequency and a Q value that match the resonance frequency of the observation target nuclide are obtained in the transmission period, and each setting value (setting value at the time of transmission) of the tuning variable capacitor and the matching variable capacitor from which these values are obtained. ) Is determined. Also, the resonance frequency and Q value that match the resonance frequency of the target nuclide are obtained during the reception period, and each setting value (setting value at the time of reception) of the tuning variable capacitor and matching variable capacitor from which these values are obtained is determined. Is done. In the measurement stage of the magnetic resonance signal, the set value at the time of transmission is set in the tuning variable capacitor and the variable capacitor for matching in the transmission period, and the set value at the time of reception is set in the tuning variable capacitor and the variable capacitor for matching in the reception period. Set to According to the above configuration, the tuning state and the matching state of the electric circuit are set to ideal states in each of the transmission period and the reception period.

  According to the present invention, information indicating the characteristics of an electrical circuit can be obtained without applying a signal to the electrical circuit for magnetic resonance measurement.

It is a block diagram which shows the NMR apparatus which concerns on embodiment of this invention. It is an expansion perspective view which shows a sample chamber and a detection coil typically. It is a circuit diagram which shows a detection circuit. It is a figure which shows an example of the sequence at the time of NMR signal measurement. 3 is a flowchart for explaining circuit characteristic information generation processing according to the first embodiment; 6 is a flowchart for explaining circuit characteristic information display processing according to the first embodiment; 12 is a flowchart for explaining circuit characteristic information generation processing according to the second embodiment; 12 is a flowchart for explaining circuit characteristic information display processing according to the second embodiment; 12 is a flowchart for explaining circuit characteristic information generation processing according to the third embodiment. 12 is a flowchart for explaining circuit characteristic information display processing according to the third embodiment; It is a figure which shows the measurement result of a thermal noise power spectrum.

  FIG. 1 shows an NMR apparatus 10 according to the present embodiment. This NMR apparatus 10 is an apparatus for measuring NMR signals generated by observation nuclei in a sample.

  The static magnetic field generator 12 is a device that generates a static magnetic field, and a bore 12A is formed as a hollow portion extending in the vertical direction at the center thereof. The NMR probe 14 is roughly divided into an insertion portion 16 and a base portion 18. The insertion portion 16 has a cylindrical shape that extends in the vertical direction as a whole, and is inserted into the bore 12 </ b> A of the static magnetic field generator 12.

  A detection circuit 28 is provided in the probe head in the insertion portion 16. The detection circuit 28 is a tuning matching circuit, and includes electronic components such as a detection coil 30 for detecting NMR signals, a coupling coil 34 for transmission and reception, a tuning variable capacitor, and a matching variable capacitor. The coupling coil 34 is also called a pickup coil or a transmission / reception coil, generates a high-frequency magnetic field in an irradiation time zone (transmission period), and receives an NMR signal detected by the detection coil 30 in an observation time zone (reception period). As shown in a specific example later in FIG. 3, the characteristics of the detection circuit 28 are optimized by changing the set values (capacitance) of the tuning variable capacitor and the matching variable capacitor. That is, tuning and matching are achieved.

  The transmission unit 42 includes a signal generator, a power amplifier, and the like, and generates and outputs a transmission signal. In the NMR measurement mode, the natural frequency of the observation target nuclide is set as the frequency of the transmission signal. The transmission signal output from the transmission unit 42 is sent to the detection circuit 28 in the NMR probe 14 via the directional coupler 44 and the duplexer 46. The directional coupler 44 is a circuit that detects a reflected wave as described below, and the duplexer 46 is a transmission / reception switch. They may be placed in the NMR probe 14.

  The NMR signal (reception signal) detected by the detection coil 30 is sent to the receiving unit 50 via the duplexer 46. The receiving unit 50 has a known circuit configuration including an orthogonal detection circuit, an A / D converter, and the like, and performs predetermined processing on the received signal. The received signal processed by the receiving unit 50 is sent to the spectrum processing unit 52. The spectrum processing unit 52 generates a spectrum by performing FFT processing on the received signal, and performs necessary analysis and the like on the spectrum. The display unit 60 displays the processing result of the spectrum processing unit 52.

  The directional coupler 44 is a circuit that functions in a mode (transmission tuning mode) in which a transmission signal is supplied to the detection circuit 28 to execute tuning, and a reflected wave reflected by the detection circuit 28 and returning to the transmission side is observed ( Circuit). The level of the reflected wave is information indicating the tuning state and matching state of the detection circuit 28. The reflected wave level detector 48 performs processing such as detection on the reflected wave observed by the directional coupler 44, determines its level, and generates information indicating the level. In adjusting the characteristic of the detection circuit 28, that is, in tuning, either manual tuning or auto tuning can be selected. In the auto tuning, the tuning control unit 56 is used, and information indicating the level of the reflected wave is sent to the tuning control unit 56. In manual tuning, the level of the reflected wave is displayed on the display unit 60. The operator adjusts the setting value (capacitance) of the tuning variable capacitor and the matching variable capacitor while referring to the level, so that the detection circuit 28 is tuned and matched.

  As will be described later, the NMR apparatus 10 has a function of executing a reception tuning mode. In the reception tuning mode, the directional coupler 44 and the reflected wave level detector 48 are not used, and the operating condition of the detection circuit 28 is adjusted without supplying the transmission signal to the detection circuit 28. In the reception tuning mode, either manual tuning or auto tuning can be selected. That is, in this embodiment, it is possible to select either the transmission tuning mode or the reception tuning mode, and it is possible to select either manual tuning or auto tuning in each tuning mode.

The noise analysis unit 54 analyzes the thermal noise signal (thermal noise signal) generated in the detection circuit 28 at the stage of adjusting the operation condition of the detection circuit 28, thereby circuit characteristic information indicating the characteristics of the detection circuit 28 in the reception period. Is generated. For example, at least one of the resonance frequency f ₀ and the Q value of the detection circuit 28 is obtained as circuit characteristic information. The processing content of the noise analysis unit 54 will be described in detail later.

The tuning control unit 56 is a unit that controls auto-tuning, and a tuning variable capacitor and a matching variable included in the detection circuit 28 so that the resonance frequency f ₀ of the detection circuit 28 matches the resonance frequency of the observation target nuclide. Each set value of the capacitor is changed mechanically or electrically. For example, in the transmission auto-tuning mode (a mode in which auto-tuning is executed in the transmission tuning mode), the tuning control unit 56 sequentially sets a set of a plurality of setting values on the tuning variable capacitor and the matching variable capacitor sequentially. Then, several reflected wave levels are observed sequentially. Then, based on the observation result, the tuning control unit 56 sets a setting value at which the resonance frequency f ₀ matches the resonance frequency of the observation target nuclide. In the reception auto-tuning mode (a mode in which auto-tuning is executed in the reception tuning mode), the tuning control unit 56 sequentially sets a set of a plurality of setting values to the tuning variable capacitor and the matching variable capacitor sequentially. Then, the plurality of resonance frequencies f ₀ obtained by the noise analysis unit 54 are sequentially observed. Then, based on the observation result, the tuning control unit 56 sets a setting value at which the resonance frequency f ₀ matches the resonance frequency of the observation target nuclide.

  The display unit 60 displays NMR measurement results, circuit characteristic information indicating the characteristics of the detection circuit 28, and the like. The input unit 62 is used for specifying a measurement target nuclide, inputting an auto tuning execution command, and the like.

  The spectrum processing unit 52 and the noise analysis unit 54 may be configured by a computer.

  The cooling system 70 includes, for example, a refrigerator, supplies helium gas cooled by the refrigerator to the NMR probe 14, and thereby cools the component to be cooled in the NMR probe 14. For example, the part to be cooled is cooled to 20K or less.

  FIG. 2 schematically shows the sample chamber and the detection coil. In the insertion portion 16, a sample chamber is provided on the inner side of the sample temperature adjustment pipe 26. The inside of the airtight chamber 22 is decompressed to a vacuum state. The sample temperature adjustment pipe 26 is a glass tube, for example, and is provided through the stage 19 and the probe cap 20. A sample tube 24 in which a sample is accommodated is arranged in the sample temperature adjusting pipe 26. The insertion portion 16 is installed in the bore 12A of the static magnetic field generator 12 so that the center of the sample and the sample tube 24 coincides with the center of the magnetic field. The inside of the sample temperature adjusting pipe 26 is an atmospheric space, and the temperature in the sample temperature adjusting pipe 26 is maintained at room temperature, for example. As a result, the sample is placed in the atmospheric space, and its temperature is maintained at room temperature.

  An airtight chamber 22 is formed between the sample temperature adjusting pipe 26 and the outer wall of the insertion portion 16. The inside of the airtight chamber 22 is decompressed to a vacuum state. A detection circuit 28 (detection coils 30A and 30B, a coupling coil 34, a tuning variable capacitor, and a matching variable capacitor) is installed in the hermetic chamber 22 under a vacuum. The detection coils 30A and 30B are arranged to face each other so as to be parallel to each other with the sample and the sample tube 24 in between. The detection coil 30A is formed on the substrate 32A, and the detection coil 30B is similarly formed on the substrate 32B, although not shown. As an example, the detection coils 30A and 30B are made of a superconductive material. Of course, a metal detection coil may be used. The detection coil 30A is formed as a coil pattern on the substrate 32A, and includes an element of inductance L and an element of capacitance C. Although not shown, the detection coil 30B similarly includes a reactance L and a capacitance C. By adopting this configuration, an LC resonance circuit is formed.

  In the above configuration, the detection circuit 28 corresponds to a component to be cooled and is cooled to an extremely low temperature. In order to improve the S / N of the signal, the variable capacitor is also cooled together with the detection coils 30A and 30B and the coupling coil. As the cooling mechanism, for example, a cooling system (cryostat cooling system) described in Japanese Patent Application Laid-Open No. 2014-41103 can be used. Specifically, the helium gas cooled from the cooling system 70 is introduced into the heat exchanger 36 connected to the stage 19, and the heat exchanger 36 is cooled to an extremely low temperature (for example, 20K or less). Thereby, the component to be cooled is cooled. As the detection coils 30A and 30B are cooled, the electrical resistance of the detection coils 30A and 30B decreases and the Q value increases. In addition, electrical thermal noise is reduced. As a result, the detection sensitivity at the time of NMR measurement can be improved. The NMR probe 14 is provided with a temperature sensor (not shown), and the temperature of the component to be cooled is detected by the temperature sensor.

  FIG. 3 shows an equivalent circuit of the detection circuit 28. The capacitor C1 and the coil L1 are formed by the detection coil 30A, and an LC resonance circuit is formed by these. Similarly, the capacitor C2 and the coil L2 are formed by the detection coil 30B, and an LC resonance circuit is formed by these. Coil L1 and coupling coil 34 (coil L3) are inductively coupled, and similarly, coil L2 and coil L3 are inductively coupled. A matching variable capacitor C4 is connected to the coil L3. The capacitance of the capacitor C1 or the capacitance of the capacitor C2 is mechanically changed by bringing a dielectric having a high dielectric constant close to the detection coil, for example. The mechanically changeable capacitor C1 or C2 is called a tuning variable capacitor. Thereby, matching and tuning of the detection circuit 28 are achieved. A preamplifier 47 is connected to the matching variable capacitor C4. The preamplifier 47 is installed in the insertion portion 16 as a part to be cooled, and is cooled to an extremely low temperature. The NMR signals (reception signals) detected by the detection coils 30A and 30B are transmitted to the coupling coil 34 by inductive coupling and are amplified by the preamplifier 47. The amplified NMR signal is sent to the receiving unit 50 via the duplexer 46.

  It can be said that the thermal noise generated in the detection circuit 28 indicates the characteristic of the detection circuit 28. Therefore, by analyzing the thermal noise generated in the detection circuit 28, information indicating the characteristics of the detection circuit 28 can be obtained. In the present embodiment, noise generated by the preamplifier 47 is also sent to the receiving unit 50. The noise generated in the preamplifier 47 is generally white and has a small frequency characteristic, so that it can be regarded as floor noise and can be distinguished from thermal noise generated in the detection circuit 28. Therefore, it is possible to analyze thermal noise generated in the detection circuit 28 by performing frequency analysis or time correlation analysis on the noise received by the receiving unit 50. The thermal noise generated in the detection circuit 28 is also amplified by the preamplifier 47, and the signal strength of the noise to be analyzed can be increased.

Next, specific generation processing of the circuit characteristic information (resonance frequency f ₀ and Q value) of the detection circuit 28 will be described.

In general, it is known that Johnson-Nyquist noise density P _n represented by the following formula (1) is generated in a matched resonance circuit.

In the above equation (1), k _B is the Boltzmann constant, and T is the temperature of the detection system.

Further, the LC resonance circuit can be regarded as a module having a device function G (f) represented by the following formula (2). As an example, the following device function G (f) is a device function in a series resonant circuit.

In the above equation (2), f ₀ is the resonance frequency, and Q is the resonance Q value.

As shown in FIG. 3, the signal that has passed through the LC resonance circuit is sent to the receiving unit 50 via the preamplifier 47. By using an LC resonance circuit having an extremely high Q value and a receiving system with low floor noise, a thermal noise signal (thermal noise signal) can be directly observed. The frequency dependence of thermal noise reflects the device function G (f) expressed by the above equation (2). Therefore, if it is possible to observe the thermal noise directly, by analyzing the noise spectrum, it is possible to determine the resonance frequency f ₀ contained in the device function G (f) and the resonance Q value. That is, circuit characteristic information indicating the characteristics of the detection circuit 28 can be obtained.

  According to the method according to the present embodiment using thermal noise, circuit characteristic information of the detection circuit 28 can be obtained without using an excitation source. In a general transmission method or reflection method, it is necessary to supply some high frequency power to the resonance circuit by an excitation source. On the other hand, in this embodiment, circuit characteristic information is obtained by using thermal noise generated in the detection circuit 28. Therefore, it is not necessary to supply any power to the detection circuit 28, and circuit characteristic information can be obtained without using an excitation source. Thereby, even when a superconducting material is used as the material of the detection coil 30, the detection circuit 28 can be appropriately tuned and matched. Since the superconducting material has a non-linear response when energized, the resonance characteristic of the detection circuit 28 using the superconducting material changes depending on the energized state. Therefore, it is generally difficult to properly tune and match the detection circuit 28. On the other hand, according to the present embodiment, since circuit characteristic information can be obtained without supplying power to the detection circuit 28, even if a superconductive material is used for the detection circuit 28, the detection circuit 28 tuning and matching can be performed appropriately.

In addition, according to the method using thermal noise, it is not necessary to observe the response with the transmission source, and it is possible to obtain a spectrum in a desired frequency range only by measuring thermal noise. In the conventional method of observing the response with the transmission source, when observing the response to each frequency, the time constant of the resonance circuit is set to Q / f ₀ and it is necessary to provide a time interval of about 10 times the time constant. On the other hand, in the method using thermal noise, as described in Example 1 (method using Fourier transform), which will be described later, spectral information of the entire desired band can be obtained in an observation time about 10 times the time constant. . In Examples 2 and 3 (methods for observing the time correlation) described later, the resonance frequency f ₀ and the Q value can be evaluated with an observation time that is several times the time constant. For example, as shown in FIG. 4, the resonance frequency f ₀ and the Q value can be measured in a short time even in a local time zone such as an observation time zone (reception period) after transmission pulse irradiation (RF pulse irradiation). .

Hereinafter, a specific calculation method (Examples 1 to 3) of the resonance frequency f ₀ and the Q value will be described. The processes according to the following first to third embodiments are executed at the stage of adjusting the tuning state and the matching state of the detection circuit 28. At this time, a transmission signal is not transmitted from the transmission unit 42 to the detection circuit 28. That is, the processes according to the first to third embodiments are executed under the same conditions as the observation time period (reception period).

Example 1
With reference to FIG. 5, the circuit characteristic information generation processing according to the first embodiment will be described. In the first embodiment, data on a frequency space is used. Specifically, spectrum data is generated by applying Fourier transform, and the resonance frequency f ₀ and the Q value are obtained based on the spectrum data.

The measurement time zone ΔT (FFT processing time window) and the number of integrations n are determined in advance. The measurement time zone ΔT is about 5 × Q / f ₀ as an example. Further, assuming that the amplification factor of the preamplifier 47 is A, the power of floor noise at the time of reception is P _floor, and the thermal noise at the time of reception is k _B TQA, the number of integrations is, for example, k _B TQA / P _floor × (n ) ^1/2 > 5.

First, the noise analysis unit 54 sets the number of executed circuit characteristic information generation processes to k, and sets the number of processes k to 0 (S01). Next, the noise analysis unit 54 adds 1 to the processing count k (S02). Then, in the observation time zone (reception period), that is, in a state where the transmission signal is not sent to the detection circuit 28, the reception unit 50 receives the noise data (y _k ) as the reception signal (S03). The spectrum processing unit 52 performs FFT processing on the noise data (y _k ) (S04). Thereby, power spectrum data | Y _k (f) | is obtained. The power spectrum data | Y _k (f) | is stored in the spectrometer 40 as k-th data (S05). When k <n (S06, No), the process returns to step S02, and the processes after step S02 are executed. When k ≧ n (S06, Yes), the noise analysis unit 54 integrates the columns of n pieces of power spectrum data | Y _k (f) | from the first to the n-th (S07). That is, the sum of n pieces of power spectrum data | Y _k (f) | is calculated. Next, the noise analysis unit 54 uses the formula (P _n × G (f)) obtained by multiplying the above formula (1) and formula (2) as a theoretical formula, and is obtained in step S07. The least square method is applied to the integration result (S08). That is, waveform fitting is executed. Specifically, the noise analysis unit 54 changes the resonance frequency f ₀ and the Q value included in the theoretical formula (P _n × G (f)) to match the theoretical formula with the integration result, thereby obtaining the value of the theoretical formula. And the resonance frequency f ₀ and the Q value (optimal resonance frequency f ₀ and Q value) that minimize the difference between the calculation result and the integration result are obtained.

It said optimum resonance frequency f ₀ and Q values obtained by the process, for example, is displayed on the display unit 60. In receiving the manual tuning mode, the operator, so that the resonance frequency f ₀ obtained conforms to the resonance frequency of the observation target species changes the set values of the tuning variable capacitor and the variable capacitor matching. In other words, obtained each time the set values of the tuning variable capacitor and a variable capacitor for matching is changed, the processing of steps S01~S08 are executed, thereby, the resonance frequency f ₀ and Q values for each set value It is done. Then, the operator sets each set value so that the obtained resonance frequency f ₀ matches the resonance frequency of the observation target nuclide. In the reception auto-tuning mode, the tuning control unit 56 sequentially changes each set value to obtain a plurality of resonance frequencies f _0, and the obtained resonance frequency f ₀ matches the resonance frequency of the observation target nuclide. Set each setting value.

Through the above processing, the resonance frequency f ₀ and the Q value that match the resonance frequency of the observation target nuclide are obtained in the observation time zone (reception period). Further, by displaying the obtained resonance frequency f ₀ and Q value in the reception manual tuning mode, it is possible to provide useful information for tuning and matching to the operator. In the reception auto-tuning mode, the detection circuit 28 is automatically tuned and matched.

Next, an example of processing in the reception manual tuning mode will be described with reference to FIG. First, the noise analysis unit 54 sets the number of executed circuit characteristic information generation processes to k, sets the number of processes k to 0, and sets flag to 0 (S10). Next, the noise analysis unit 54 adds 1 to the processing count k (S11). Then, in the observation time zone (reception period), the receiving unit 50 receives the noise data (y _k ) as a received signal (S12). The spectrum processing unit 52 performs FFT processing on the noise data (y _k ) (S13). Thereby, power spectrum data | Y _k (f) | is obtained. The power spectrum data | Y _k (f) | is stored in the spectrometer 40 as k-th data. Next, when the flag is 1 (S15, Yes), the noise analysis unit 54 calculates an average of n power spectrum data | Y _k (f) | A graph of the power spectrum data | Y _k (f) | is displayed on the display unit 60 (S16). Then, the process returns to step S11. On the other hand, when the flag is not 1 in step S15 (S15, No), the noise analysis unit 54 calculates the average of the _k power spectrum data | Y _k (f) | A graph of the averaged power spectrum data | Y _k (f) | is displayed on the display unit 60 (S17). When k is n (S18, Yes), the noise analysis unit 54 sets flag to 1 and sets the processing count k to 0 (S19). Then, the process returns to step S11. On the other hand, if k is not n (S18, No), the process returns to step S11. Similarly, the processing is repeated thereafter.

The operator refers to the graph of the power spectrum data | Y _k (f) | so that the frequency indicating the peak position of the graph matches the resonance frequency of the observation target nuclide, and the peak intensity of the graph is Each setting value of the tuning variable capacitor and the matching variable capacitor is changed so as to be maximized. That is, each time the setting values of the tuning variable capacitor and the matching variable capacitor are changed, the processing of the above steps S10 to S19 is executed, whereby the power spectrum data | Y _k (f) for each setting value. A graph of | is obtained and displayed. Then, the worker changes each set value while referring to the graph. Thereby, the tuning and matching of the detection circuit 28 in the observation time zone (reception period) is achieved by manual operation.

The resonance frequency f ₀ and the Q value are displayed on the display unit 60 together with the graph of the power spectrum data | Y _k (f) |, and the operator refers to the information and adjusts the tuning variable capacitor and the matching variable. Each set value of the capacitor may be changed.

(Example 2)
Next, circuit characteristic information generation processing according to the second embodiment will be described with reference to FIG. In the second embodiment, data on time space is used. Specifically, the periodic component included in the thermal noise waveform is extracted by the autocorrelation method, and the resonance frequency f ₀ and the Q value are obtained based on the extraction result.

Assuming that the data of thermal noise generated in the detection circuit 28 is x (t), the signal y (t) output from the preamplifier 47 subsequent to the detection circuit 28 is expressed by the following equation (3).

In the above equation (3), t is time, g (τ) is a device function of the detection circuit 28, and w _n (t) is noise added by the preamplifier 47.

The device function g (τ) of the matched series resonant circuit is expressed by the following equation (4).

The measurement time zone ΔT and the number of integrations n are determined in advance. The measurement time zone ΔT is about Q / f ₀ as an example. Further, assuming that the amplification factor of the preamplifier 47 is A, the power of floor noise at the time of reception is P _floor, and the thermal noise at the time of reception is k _B TQA, the number of integrations is, for example, k _B TQA / P _floor × (n ) ^1/2 > 5.

First, the noise analysis unit 54 sets the number of executed circuit characteristic information generation processes to k, and sets the number of processes k to 0 (S30). Next, the noise analysis unit 54 adds 1 to the processing count k (S31). Then, in the observation time zone (reception period), that is, in a state where the transmission signal is not sent to the detection circuit 28, the reception unit 50 receives the noise data (y _k ) as the reception signal (S32). The noise analysis unit 54 performs autocorrelation processing on the noise data (y _k ) (S33). Specifically, the noise analysis unit 54 calculates an autocorrelation function g _k (τ) expressed in the following equation (5). Thereby, a periodic component which is a component governed by the device function is extracted.

The calculation result g _k (τ) of the autocorrelation process is stored in the spectrometer 40 as k-th data (S34). If k <n (S35, No), the process returns to step S31, and the processes after step S31 are executed. When k ≧ n (S35, Yes), the noise analysis unit 54 integrates a column of n pieces of data | g _k (τ) | from the first to the n-th (S36). That is, the sum of n pieces of data | g _k (τ) | is calculated. Next, the noise analysis unit 54 uses the equation (Ag (τ) + B) as a theoretical equation, and applies the least square method to the integration result obtained in step S36 (S37). That is, waveform fitting is executed. Here, the coefficients A and B are unknown numbers, the coefficient A corresponds to the amplitude, and the coefficient B corresponds to the offset. The noise analysis unit 54 changes the coefficients A and B, the resonance frequency f _0, and the Q value included in the theoretical formula (Ag (τ) + B) to match the theoretical formula with the integration result, thereby integrating the value of the theoretical formula and the integration. The resonance frequency f ₀ and Q value (optimal resonance frequency f ₀ and Q value) that minimize the difference from the result are obtained.

As in the first embodiment, the optimum resonance frequency f ₀ and Q value obtained by the above processing are displayed on the display unit 60, for example. Then, the reception manual tuning mode or the reception auto tuning mode is executed. As a result, the resonance frequency f ₀ and the Q value matching the resonance frequency of the observation target nuclide are obtained in the observation time period (reception period), and the detection circuit 28 is tuned and matched.

Next, an example of processing in the reception manual tuning mode will be described with reference to FIG. First, the noise analyzing unit 54 sets the number of executed circuit characteristic information generation processes to k, sets the number of processes k to 0, and sets flag to 0 (S40). Next, the noise analysis unit 54 adds 1 to the processing count k (S41). Then, in the observation time zone (reception period), the reception unit 50 receives the noise data (y _k ) as a reception signal (S42). The noise analysis unit 54 performs autocorrelation processing on the noise data (y _k ) (S43). Specifically, the noise analysis unit 54 calculates the autocorrelation function g _k (τ) expressed in the above equation (5). The calculation result g _k (τ) of the autocorrelation process is stored in the spectrometer 40 as k-th data (S44). Next, when flag is 1 (S45, Yes), the noise analysis unit 54 calculates the average of n pieces of data | g _k (τ) | A graph of g _k (τ) | is displayed on the display unit 60 (S46). Then, the process returns to step S41. On the other hand, if the flag is not 1 in step S45 (S45, No), the noise analysis unit 54 calculates the average of _k data | g _k (τ) | The graph of the data | g _k (τ) | is displayed on the display unit 60 (S47). Further, the noise analysis unit 54 obtains the optimum resonance frequency f ₀ and Q value by executing the processing of steps S36 and S37 (application of the least square method) shown in FIG. It is displayed on the display unit 60 (S48). When k is n (S49, Yes), the noise analysis unit 54 sets flag to 1 and sets the processing count k to 0 (S50). Then, the process returns to step S41. On the other hand, if k is not n (S49, No), the process returns to step S41. Similarly, the processing is repeated thereafter.

The operator refers to the graph of the data | g _k (τ) | and the resonance frequency f _{0 so} that the frequency indicating the peak value of the graph matches the resonance frequency of the target nuclide, Each setting value of the tuning variable capacitor and the matching variable capacitor is changed so that the peak intensity becomes maximum. That is, each time the set values of the tuning variable capacitor and the matching variable capacitor are changed, the processing of the above steps S40 to S50 is executed, whereby the data | g _k (τ) | A graph is obtained and displayed. Then, the worker changes each set value while referring to the graph. Thereby, the tuning and matching of the detection circuit 28 in the observation time zone (reception period) is achieved by manual operation.

(Example 3)
Next, a circuit characteristic information generation process according to the third embodiment will be described with reference to FIG. In practical example 3, data on time space is used. Specifically, periodic components contained in the waveform of the thermal noise is extracted by the autocorrelation method, by applying an autoregressive method for the extraction result, Q value is obtained and the resonance frequency f _0.

The measurement time zone ΔT and the number of integrations n are determined in advance. The measurement time zone ΔT is about f ₀ / 2Q as an example. Further, assuming that the amplification factor of the preamplifier 47 is A, the power of floor noise at the time of reception is P _floor, and the thermal noise at the time of reception is k _B TQA, the number of integrations is, for example, k _B TQA / P _floor × (n ) ^1/2 > 5.

First, the noise analysis unit 54 sets the number of executed circuit characteristic information generation processes to k, and sets the number of processes k to 0 (S60). Next, the noise analysis unit 54 adds 1 to the processing count k (S61). In the observation time period (reception period), that is, in a state where the transmission signal is not sent to the detection circuit 28, the reception unit 50 receives the noise data (y _k ) as the reception signal. The noise analysis unit 54 performs autocorrelation processing on the noise data (y _k ) (S62). Specifically, the noise analysis unit 54 calculates the autocorrelation function g _k (τ) expressed in the above equation (5). Thereby, a periodic component which is a component governed by the device function is extracted.

The calculation result g _k (τ) of the autocorrelation process is stored in the spectrometer 40 as k-th data (S64). If k <n (S65, No), the process returns to step S61, and the processes after step S61 are executed. When k ≧ n (S65, Yes), the noise analysis unit 54 integrates a column of n pieces of data | g _k (τ) | from the first to the n-th (S66). That is, the sum of n pieces of data | g _k (τ) | is calculated. Next, the noise analysis unit 54 applies the autoregressive method to the integration result obtained in step S66 (S67). Thus, ₀ and Q values optimum resonance frequency f is determined.

Hereinafter, the autoregressive method will be described. Assuming that the sampling time is Δt and N = ΔT / (2Δt), the discrete data string of the integration result is expressed as the following equation (6).
{G _j } = {g ₁ , g ₂ ,..., G _j ,..., G _n } (6)

Here, Z ₁ and Z ₂ represented by the following formula (7) are defined.

{Gj} can be regarded as a result of adding thermal noise to the theoretical formula represented by the formula (4), and the recurrence represented by the following formula (8) by a known Z transformation. The expression is satisfied.
(G _j −w _j ) = (Z ₁ + Z ₂ ) (g _j−1 −W _j−1 ) −Z ₁ Z ₂ (g _j−2 −W _{j− 2} ) (8)

According to the recurrence formula (8), the point (g _j−2 , g _j−1 , g _j ) including noise passes through the origin (0, 0, 0) and the normal vector (Z ₁ , Z ₂ , − It can be seen that it lies on a plane with (Z ₁ + Z ₂ ), 1). That is, the time series data {g _j } as a measurement result is plotted as a point (g _j−2 , g _j−1 , g _j ) on a three-dimensional space, and the data is fitted on a plane by the least square method. For example, Z ₁ and Z ₂ are uniquely determined. Specifically, when applying the least square method, time series data is expressed by the following equation (9), and a solution x is obtained by the following equation (10).

Here, y, x, and H are defined by the following equations (11), (12), and (13).

Finally, the above equation (8) is modified and Z ₁ and Z ₂ are used, so that the resonance frequency f ₀ is expressed as shown in the following equations (14) and (15). A Q value is obtained.

That is, by applying the least square method to the time series data {g _j } using the equation (8) representing the plane as a theoretical formula, Z ₁ and Z that fit the plane most to the time series data {g _j } ₂ , that is, Z ₁ and Z ₂ that minimize the difference between the theoretical formula and the time series data {g _j }. Then, by substituting the obtained Z ₁ and Z ₂ into the above equations (14) and (15), the resonance frequency f ₀ and the Q value are obtained.

As in the first embodiment, the optimum resonance frequency f ₀ and Q value obtained by the above processing are displayed on the display unit 60, for example. Then, the reception manual tuning mode or the reception auto tuning mode is executed. As a result, the resonance frequency f ₀ and the Q value matching the resonance frequency of the observation target nuclide are obtained in the observation time period (reception period), and the detection circuit 28 is tuned and matched.

Next, an example of processing in the reception manual tuning mode will be described with reference to FIG. First, the noise analysis unit 54 sets the number of executed circuit characteristic information generation processes to k, sets the number of processes k to 0, and sets flag to 0 (S70). Next, the noise analysis unit 54 adds 1 to the processing count k (S71). Then, in the observation time zone (reception period), the reception unit 50 receives the noise data (y _k ) as a reception signal (S72). The noise analysis unit 54 performs autocorrelation processing on the noise data (y _k ) (S73). Specifically, the noise analysis unit 54 calculates the autocorrelation function g _k (τ) expressed in the above equation (5). The calculation result g _k (τ) of the autocorrelation process is stored in the spectrometer 40 as k-th data (S74). Next, when flag is 1 (S75, Yes), the noise analysis unit 54 calculates the average of n pieces of data | g _k (τ) | from the 1st to the n-th, and the averaged data | A graph of g _k (τ) | is displayed on the display unit 60 (S76). Then, the process returns to step S71. On the other hand, if the flag is not 1 in step S75 (S75, No), the noise analysis unit 54 calculates the average of the k pieces of data | g _k (τ) | The graph of the data | g _k (τ) | is displayed on the display unit 60 (S77). Further, the noise analysis unit 54 obtains the optimum resonance frequency f ₀ and Q value by executing the processing of steps S66 and S67 (application of the autoregressive method) shown in FIG. It is displayed on the display unit 60 (S78). When k is n (S79, Yes), the noise analysis unit 54 sets flag to 1 and sets the processing count k to 0 (S80). Then, the process returns to step S71. On the other hand, if k is not n (S79, No), the process returns to step S71. Similarly, the processing is repeated thereafter.

The operator refers to the graph of the data | g _k (τ) | and the resonance frequency f _{0 so} that the frequency indicating the peak value of the graph matches the resonance frequency of the target nuclide, Each setting value of the tuning variable capacitor and the matching variable capacitor is changed so that the peak intensity becomes maximum. That is, each time the setting values of the tuning variable capacitor and the matching variable capacitor are changed, the processing of the above steps S70 to S80 is executed, whereby the data | g _k (τ) | A graph is obtained and displayed. Then, the worker changes each set value while referring to the graph. Thereby, the tuning and matching of the detection circuit 28 in the observation time zone (reception period) is achieved by manual operation.

Next, an actual application example of the first embodiment will be described. FIG. 11 shows a graph actually obtained by the processing according to the first embodiment. This graph is a graph showing power spectrum data of thermal noise. In FIG. 11, the horizontal axis represents the frequency f (MHz), and the vertical axis represents the power value (dBm) of the power spectrum of thermal noise. In this experiment, a high-temperature superconducting material YBCO is used as a material for the detection coils 30A and 30B. The detection circuit 28 is cooled to 19K, and impedance matching is achieved. Thermal noise data was directly observed with a high-precision digital oscilloscope after passing through a preamplifier with an amplification factor of 18 dB (a loss due to a separate path was about 1 dB) and a buffer amplifier of 10 dB. In this graph, a clear peak is formed in the vicinity of 702.0 MHz. The solid line in the graph indicates the result of fitting the above-described theoretical formula (P _n × G (f)) to the graph of the measurement result. From this fitting, the resonance frequency f ₀ was 701.97 ± 0.02, and the Q value was 17420 ± 230. Thus, by executing the processing according to the present embodiment, the resonance frequency f ₀ and the Q value are obtained. By using these pieces of information, the detection circuit 28 can be tuned and matched.

(Modification)
Next, the process which concerns on a modification is demonstrated. In the modification, transmission tuning and reception tuning are performed. Then, in the transmission period of the NMR signal measurement stage, the transmission tuning result is used to set the operating condition of the detection circuit 28, and in the measurement stage reception period, the reception tuning result is used to detect the detection circuit 28. Operating conditions are set. Specific processing will be described below.

Transmission manual tuning or transmission auto-tuning is executed, whereby a resonance frequency f ₁ and a Q value (Q ₁ ) that match the resonance frequency of the observation target nuclide are obtained in the transmission period, and these values are obtained. Each setting value of the capacitor and the variable capacitor for matching is determined. Each set value is stored in the spectrometer 40 as a set value in the transmission period.

In addition, any one of the processes of the first to third embodiments described above is executed, whereby the resonance frequency f ₂ and the Q value (Q ₂ ) that match the resonance frequency of the observation target nuclide are obtained in the reception period. Each setting value of the tuning variable capacitor and the matching variable capacitor from which the value is obtained is determined. Each set value is stored in the spectrometer 40 as a set value in the reception period.

In the NMR signal measurement stage, the operating conditions of the detection circuit 28 are dynamically switched between the transmission period and the reception period. Specifically, the tuning control unit 56 dynamically switches the setting values of the tuning variable capacitor and the matching variable capacitor between the transmission period and the reception period. More specifically, in the transmission period, the tuning control unit 56 sets each set value corresponding to the resonance frequency f ₁ and the Q value (Q ₁ ) in the tuning variable capacitor and the matching variable capacitor, and receives the reception period. Then, setting values corresponding to the resonance frequency f ₂ and the Q value (Q ₂ ) are set in the tuning variable capacitor and the matching variable capacitor. As a result, in each of the transmission period and the reception period, set values for obtaining an ideal resonance frequency that matches the resonance frequency of the observation target nuclide are set in the tuning variable capacitor and the matching variable capacitor. That is, in each of the transmission period and the reception period, the tuning state and the matching state of the detection circuit 28 are set to ideal states.

  10 NMR apparatus, 12 static magnetic field generator, 14 NMR probe, 16 insertion section, 18 base, 28 detection circuit, 30 detection coil, 34 coupling coil, 40 spectrometer, 42 transmission section, 50 reception section, 52 spectrum processing section, 54 Noise analysis unit, 56 Tuning control unit.

Claims (10)

An electrical circuit for magnetic resonance measurement;
Characteristic information generating means for generating characteristic information indicating characteristics of the electric circuit by analyzing a thermal noise signal generated in the electric circuit in the adjustment stage of the operating condition of the electric circuit;
A magnetic resonance measuring apparatus comprising: The magnetic resonance measuring apparatus according to claim 1.
The adjusting step is a step for tuning the resonance frequency of the electric circuit to a frequency suitable for the nuclide to be observed, and a step of matching the electric impedance,
The characteristic information is information indicating at least one of a resonance frequency and a Q value of the electric circuit.
A magnetic resonance measuring apparatus. In the magnetic resonance measuring apparatus according to claim 1 or 2,
The characteristic information generating means generates spectral data of the thermal noise signal;
A magnetic resonance measuring apparatus. The magnetic resonance measuring apparatus according to claim 3.
Further comprising spectrum display means for displaying the spectrum data.
A magnetic resonance measuring apparatus. In the magnetic resonance measuring apparatus according to claim 3 or 4,
The characteristic information generating means calculates at least one of a resonance frequency and a Q value of the electric circuit by analyzing the spectrum data.
A magnetic resonance measuring apparatus. In the magnetic resonance measuring apparatus according to claim 1 or 2,
The characteristic information generating means calculates at least one of a resonance frequency and a Q value of the electric circuit by analyzing a periodic component included in the waveform of the thermal noise signal.
A magnetic resonance measuring apparatus. The magnetic resonance measuring apparatus according to claim 6.
The characteristic information generating means extracts the periodic component by applying an autocorrelation method to the thermal noise signal, and performs waveform fitting on the periodic component to thereby obtain a resonance frequency of the electric circuit and Calculating at least one of the Q values;
A magnetic resonance measuring apparatus. The magnetic resonance measuring apparatus according to claim 6.
The characteristic information generating means extracts the periodic component by applying an autocorrelation method to the thermal noise signal, and applies an autoregressive method to the periodic component to thereby obtain a resonance frequency of the electric circuit. And calculating at least one of the Q value,
A magnetic resonance measuring apparatus. In the magnetic resonance measuring apparatus according to any one of claims 5 to 8,
Adjusting means for adjusting a tuning state and a matching state of the electric circuit based on at least one of a resonance frequency and a Q value of the electric circuit;
A magnetic resonance measuring apparatus. The magnetic resonance measuring apparatus according to claim 9.
In the magnetic resonance measurement step, the electric circuit includes a transmission period for supplying a transmission signal for magnetic resonance measurement to the electric circuit and a reception period for detecting the magnetic resonance signal generated in the nuclide to be observed by the electric circuit. Control means for dynamically switching the tuning state and the matching state of
The control means sets a tuning state and a matching state of the electric circuit in the transmission period to a tuning state and a matching state adjusted by a signal supplied to the electric circuit, and the electric circuit in the reception period. Setting the tuning state and the matching state to the tuning state and the matching state adjusted by the adjusting means,
A magnetic resonance measuring apparatus.