A method for operating an MR system with a gradient power amplifier having at least one output stage that is connectable to a gradient coil, and having four switching elements connected to one another as an H-bridge includes, to operate the gradient coil, in alternation: switching the switching elements attached to a common first pole of a voltage supply to conductive and switching the switching elements attached to a common second pole of a voltage supply to blocking by inverting power drivers; and switching the switching elements attached to a common first pole of a voltage supply to blocking and switching the switching elements attached to a common second pole of a voltage supply to conductive by inverting power drivers. The switching elements attached to the first pole are switched by non-inverting power drivers, and the switching elements attached to the second pole are switched by inverting power drivers.

In some aspects, a magnetic system for use in a low-field MRI system. The magnetic system comprises at least one electromagnet configured to, when operated, generate a magnetic field to contribute to a B.sub.0 field for the low-field MRI system, and at least one permanent magnet to produce a magnetic field to contribute to the B.sub.0 field.

A dual frequency coil package system for use in transmitting and receiving at least two frequencies in an MRI system, including a frequency converter coupled to the MRI system to receive a first frequency through the local transmit coil port and convert the first frequency to a second frequency, a second frequency transmit coil to receive the second frequency from the frequency converter and to transmit the second frequency, a dual tuned receiver coil to receive and to output the at least two frequencies, and a switchable receiver to receive the at least two frequencies output from the dual tuned receiver coil and to transmit the first frequency received from the dual tuned receiver coil directly to the MRI system, and to convert the second frequency received from the dual tuned receiver coil to the first frequency before transmission to the MRI system.

The disclosure relates to techniques to acquire at least one quantitative physiological parameter using a magnetic resonance system by means of MR fingerprinting. In this process, a plurality of slices are excited simultaneously using different imaging parameters to produce MR signal evolutions in each of the plurality of slices, and the MR data from the plurality of slices is then acquired simultaneously. For the simultaneous excitation of the plurality of slices, a flip angle (FW) that is used to excite one of the plurality of slices differs from a flip angle (FW) that is used to excite another of the plurality of slices.

Methods and apparatus for reducing noise in RF signal chain circuitry for a low-field magnetic resonance imaging system are provided. A switching circuit in the RF signal chain circuitry may include at least one field effect transistor (FET) configured to operate as an RF switch at an operating frequency of less than 10 MHz. A decoupling circuit may include tuning circuitry coupled across inputs of an amplifier and active feedback circuitry coupled between an output of the amplifier and an input of the amplifier, wherein the active feedback circuitry includes a feedback capacitor configured to reduce a quality factor of an RF coil coupled to the amplifier.

A radio frequency amplifying device according to an embodiment includes amplifying circuitry, obtaining circuitry, and correcting circuitry. The amplifying circuitry is configured to output an amplified signal obtained by amplifying a signal input thereto. The obtaining circuitry is configured to obtain an envelope indicating a waveform of a radio frequency signal as digital data. The correcting circuitry is configured to correct the obtained envelope on the basis of a rising characteristic of the amplifying circuitry and to input the signal generated on the basis of the envelope resulting from the correction to the amplifying circuitry.

According to some aspects, a method of suppressing noise in an environment of a magnetic resonance imaging system is provided. The method comprising estimating a transfer function based on multiple calibration measurements obtained from the environment by at least one primary coil and at least one auxiliary sensor, respectively, estimating noise present in a magnetic resonance signal received by the at least one primary coil based at least in part on the transfer function, and suppressing noise in the magnetic resonance signal using the noise estimate.

A radio frequency receiver system for an MRI apparatus is provided which includes a receive coil for being attached to a patient to be examined by the MRI apparatus exhibits a total effective coil impedance which is composed of the coil impedance of the coil itself and the patient impedance due to the patient to who the coil is attached. An amplifier which exhibits the lowest noise impedance and which is connected to the receive coil for amplifying a signal received from the receive coil and outputting an amplified output signal. An analog-to-digital converter is connected to the amplifier for converting the amplified output signal from the amplifier to a digital signal for further processing. A matching network is interconnected between the receive coil and the amplifier and includes a matching system with an adjustable impedance for matching the total effective coil impedance to the lowest noise impedance, and a noise calculation unit which is connected to the analog-to-digital converter for receiving the digital output signal of the analog-to-digital converter and is configured to calculate the noise of the output signal of the analog-to-digital converter and for adjusting the adjustable impedance of the matching network. In this way, a possibility is provided for calibrating the matching network for every patient individually before the scanning process.

The technology disclosed in this invention belongs to both the field of Nuclear Quadrupole Resonance (NQR) and nuclear geomagnetic resonance application. Technically, a nuclear quadrupole resonance detection system and its antenna are provided. The antenna includes two coils to make a gradient antenna wherein they simultaneously receive both the signal from the target region and the external radio frequency interference. Structurally, the first coil is positioned as a regular circular coil, while the second coil is annular and evenly distributed around the first coil peripherally. These coils are on the same plane with equal areas but have opposite winding directions. The systems specific to the disclosed antenna are also included. The configuration of the invented antenna can effectively increase the capability of suppressing environmental electromagnetic radio frequency interference, thereby enhancing the detection of the NQR or geomagnetic resonance signals. Consequently, the signal-to-noise ratio of the system is improved.

A device for generating wideband signals in a local coil and a magnetic resonance tomography system with the device are provided. The device has a first analog-digital converter for digitizing a magnetic resonance signal, a signal conditioner, a pulse filter, and a transmit antenna. The signal conditioner is configured to increase a harmonic component in an output signal of the first analog-digital converter, and the pulse filter is configured to restrict an output signal of the signal conditioner to a predetermined frequency band before the output signal of the signal conditioner is emitted via the transmit antenna. The receiver is configured to receive and digitize the signal via a receive antenna, and regain a digital representation of the magnetic resonance signal by a signal processor.