A method to calibrate a nuclear magnetic resonance tool is disclosed having steps of starting a nuclear magnetic resonance sequence from the nuclear magnetic resonance tool, disabling an active damping circuit in the nuclear magnetic resonance tool, collecting auxiliary calibration data for the nuclear magnetic resonance tool, estimating a natural Q value for the nuclear magnetic resonance tool, determining an optimal active damping setting for the tool, deploying the optimal active damping setting for the tool, collecting nuclear magnetic resonance response data generated from the nuclear magnetic resonance sequence and calibrating the nuclear magnetic resonance data.

A method for measuring one or more properties of a formation includes applying a magnetic field to a subterranean formation using a downhole tool. A radiofrequency signal is transmitted into the subterranean formation that is exposed to the magnetic field. The radiofrequency signal induces a transverse magnetization in the subterranean formation, and the transverse magnetization induces an initial voltage signal in the downhole tool. The initial voltage signal is amplified using a first amplifier in the downhole tool such that the first amplifier outputs a first amplified voltage signal. The first amplified voltage signal is introduced to an input of the first amplifier, such that the first amplifier amplifies the first amplified voltage signal and outputs a second amplified voltage signal

In a magnetic resonance (MR) apparatus and an operating method therefor, the MR apparatus has multiple reception coils each having an associated reception channel, a reference dataset is obtained from an examination volume of a subject, wherein the reference dataset completely fills a region of k-space. In a computer, a subregion of the examination volume is determined that has a lower homogeneity than other subregions of the examination volume, and the computer also determines at least one of the reception channels in which raw data signals are received that have a higher intensity in the determined subregion than others of the reception channels. The computer calculates a weighting matrix, in which signals, the determined reception channel are given a lower weighting than signals from the other channels. The weighting matrix is then applied to diagnostic data acquired with parallel imaging using the multiple reception coils and channels.

The present invention relates to a method for supplying current to a gradient coil (107,207) of a magnetic resonance imaging system (100) by a gradient amplifier (222), the method comprising: supplying, by an electrical power supply (241), a voltage at first level to the gradient amplifier output to generate a gradient current in the gradient coil (107,207) to produce a magnetic gradient field at an slew rate, wherein the slew rate is set to a first value, resetting the slew rate to a second value, comparing the second value to the first value, and adjusting the voltage to a second level if the second value is different from the first value.

In a method to optimize a magnetic resonance sequence of a magnetic resonance apparatus and a magnetic resonance apparatus operated according to such a method, optimization of the timing of the magnetic resonance sequence is implemented by adopting a magnetic resonance sequence as a starting sequence includes a first time interval set of one or more first time intervals and a second time interval set of one or more second time intervals, wherein the first time intervals of the first time interval set are to be left unmodified with regard to an optimization of the duration. The magnetic resonance sequence is automatically analyzed to identify the first time intervals of the first time interval set and the second time intervals of the second time interval set in the magnetic resonance sequence. The duration of at least one second time interval of the second time interval set is then automatically optimized.

An electron spin resonance device includes a microwave oscillator, a magnet, a modulation coil, and a cavity resonator having an opening. A microwave generated in the microwave oscillator resonates in the cavity resonator and is emitted from the opening toward a measurement target located outside the opening. The magnet applies a magnetic field toward an irradiation surface of the measurement target, the irradiation surface being irradiated with the microwave. The modulation coil modulates an intensity of the magnetic field or a frequency of the microwave applied toward the irradiation surface of the measurement target irradiated with the microwave.

A radiofrequency antenna has a plurality of channels. A Q-value calculating unit computes reflected signals of the plurality of channels of the radiofrequency antenna, respectively, in a case where transmission signals as electrical signals are simultaneously supplied to the plurality of channels of the radiofrequency antenna, also including a signal obtained when the transmission signal supplied to one channel of the plurality of channels is reflected from another channel, and computes a Q value of the radiofrequency antenna using the reflected signal. An SAR calculating unit calculates a specific absorption rate (SAR) using the Q value.

Circuits including a low noise amplifier (LNA) configured to receive a radio-frequency (RF) that include an input transistor to receive a waveform control signal at a gate terminal are provided. The circuits include a control transistor configured to receive a gate signal from a source terminal in the input transistor when the waveform control signal is high and to discharge the gate signal into a current sink coupled to ground when the waveform control signal is low at a controlled rate based on a resistor-capacitor (RC) network and a changing gain of the control transistor. The circuits include a buffer and a dump transistor to connect the critical resistor for optimal damping to the input of LNA when the dump transistor is on and disconnect when the dump transistor if off. Systems and methods for use in an NMR sensor including a circuit as above are also provided.

A magnetic resonance imaging (MRI) apparatus and a method of detecting an error of the MRI apparatus are provided. The MRI apparatus includes a radio frequency (RF) coil configured to transmit and receive an RF signal, a bias circuit configured to tune and detune the RF coil, and a monitoring circuit configured to monitor a parameter among a bias voltage and a bias current of the bias circuit, based on a monitoring pattern. The MRI apparatus further includes a controller configured to determine whether the bias circuit is in an abnormal state, based on a determination criteria and the monitored parameter, and either one or both of the monitoring pattern and the determination criteria vary based on a status of the bias circuit.

Circuits including a low noise amplifier (LNA) configured to receive a radio-frequency (RF) that include an input transistor to receive a waveform control signal at a gate terminal are provided. The circuits include a control transistor configured to receive a gate signal from a source terminal in the input transistor when the waveform control signal is high and to discharge the gate signal into a current sink coupled to ground when the waveform control signal is low at a controlled rate based on a resistor-capacitor (RC) network and a changing gain of the control transistor. The circuits include a buffer and a dump transistor to connect the critical resistor for optimal damping to the input of LNA when the dump transistor is on and disconnect when the dump transistor if off. Systems and methods for use in an NMR sensor including a circuit as above are also provided.