A low-field magnetic resonance imaging (MRI) system. The system includes a plurality of magnetics components comprising at least one first magnetics component configured to produce a low-field main magnetic field B.sub.0 and at least one second magnetics component configured to acquire magnetic resonance data when operated, and at least one controller configured to operate one or more of the plurality of magnetics components in accordance with at least one low-field zero echo time (LF-ZTE) pulse sequence.

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.

A low-field magnetic resonance imaging (MRI) system. The system includes a plurality of magnetics components comprising at least one first magnetics component configured to produce a low-field main magnetic field B.sub.0 and at least one second magnetics component configured to acquire magnetic resonance data when operated, and at least one controller configured to operate one or more of the plurality of magnetics components in accordance with at least one low-field zero echo time (LF-ZTE) pulse sequence.

An apparatus for performing a nuclear magnetic resonance (NMR) experiment in a borehole penetrating the earth includes: a carrier configured to be conveyed through the borehole; an antenna assembly disposed on the carrier and configured to receive an NMR signal; and an active gain circuit having an input coupled to the antenna and configured to apply gain to the received NMR signal and to provide an output signal comprising NMR experiment data. The apparatus also includes a feedback circuit configured to feed the output signal back to the input of the active gain circuit; wherein the signal fed back to the input of the active gain circuit is out of phase with the received NMR signal and the feedback circuit provides an electrical quality factor Q value of an antenna assembly that is less than the electrical quality factor Q value of the antenna assembly without the feedback circuit.

Systems and methods for MR siganal synchronization may be provided. The method may include determining a time difference in a local clock generator at a coil side assembly compared to a system clock generator at a system side assembly. The method may include maintaining a constant phase difference between clock signals generated by the local clock generator and by the system clock generator by correcting the local clock generator based on the time difference. The method may include acquiring MR echo signals by scanning at least a part of a subject in response to the clock signal generated by the corrected local clock generator. The method may further include digitizing the MR echo signal at the coil side assembly.

Techniques provide for passive Q switching in a bimodal resonator environment, where magnetic resonators are coupled for power transfer. A passive Q switch is responsive to a driving power from one magnetic resonator coupled to another magnetic resonator. After the driving power reaches a threshold, the passive Q switch shunts the receiving magnetic resonator, at least partially, to reduce the Q of that second resonator, which allows faster detection operation of the second resonator in some applications. The technique allows for fast Q switching in a bimodal resonator system, especially one having resonators having magnetic fields that are orthogonal to one another.

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.

A magnetic resonance tomography system includes a computer configured to implement signal processing of transmit signals and/or receive signals. The signal processing is configured to implement a mixer, an upsampler, a decimator, a filter, or any combination thereof.

An apparatus for performing a nuclear magnetic resonance (NMR) experiment in a borehole penetrating the earth includes: a carrier configured to be conveyed through the borehole; an antenna assembly disposed on the carrier and configured to receive an NMR signal; and an active gain circuit having an input coupled to the antenna and configured to apply gain to the received NMR signal and to provide an output signal comprising NMR experiment data. The apparatus also includes a feedback circuit configured to feed the output signal back to the input of the active gain circuit; wherein the signal fed back to the input of the active gain circuit is out of phase with the received NMR signal and the feedback circuit provides an electrical quality factor Q value of an antenna assembly that is less than the electrical quality factor Q value of the antenna assembly without the feedback circuit.

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.