A radio-frequency (RF) coil for use in a low-field magnetic resonance imaging system and methods of making the same are provided. The RF coil may include a conductor arranged on a substrate in an arrangement such that symmetry in the arrangement cancels at least a portion of a common mode voltage when a current is passed through the conductor. The RF coil may be included in a magnetic resonance imaging (MRI) system for imaging a patient having at least one B.sub.0 magnet for generating a B.sub.0 magnetic field.

A radio frequency head coil for a magnetic resonance imaging system is provided. The radio frequency head coil includes a body operative to be disposed on a head of a patient, and an extended lip disposed on the body and operative to receive a magnetic resonance signal. At least some of the magnetic resonance signal is emitted by a region of the patient disposed between a brain stem of the patient up to and including a vertebra of the patient.

A local coil for magnetic resonance imaging is disclosed herein. The local coil includes an electrical circuit arrangement and a coaxial cable with an internal conductor and an external conductor surrounding the internal conductor. The two ends of the coaxial cable are connected to the electrical circuit arrangement and the internal conductor and the external conductor together form an antenna loop. The internal conductor and/or the external conductor has at least one interruption and the at least one interruption divides the internal conductor and/or the external conductor into at least two separate segments in each case.

Apparatus for a nuclear resonance imaging (MRI) machine (100) that includes plasma elements (104, 106, 108). The MRI machine (100) includes gradient coils (104) that generate time-dependent gradient magnetic fields, transmitting elements (106) that excite target molecules (120) with RF energy (122), and receiving elements (108) responsive to RF energy (124) emitted by the excited molecules (120). The gradient coils (104) include plasma conductors (710) in which the plasma (716) is ignited by an exciter (208). The plasma conductors (710) are electrically connected to a gradient amplifier (206) that outputs a signal to produce the gradient fields. The transmitting elements (106) are plasma devices (710) configured to emit RF energy (122). The receiving elements (108) are plasma devices (710) responsive to emitted RF energy (124). An RF exciter (218) selectively and alternatingly ignites said plasma devices (710) to avoid coupling and interference between them.

An exemplary coil arrangement can be provided, which can include, for example, coil element(s) having a parallel resonant circuit at a port, where the coil element(s) is detuned by causing a low impedance at the port. Pre-amplifier arrangements can provide a low impedance at the port of the coil element(s) to suppress the induced current on the coil element(s) thereby reducing the inductive coupling to neighboring element(s). The coil element(s) can include an inductance and a capacitance which cancel each other out. The inductance and the capacitance can cancel each other out such that an impedance of the coil element has no imaginary part at a working frequency. An impedance of the coil element(s) in free space includes a real part that can be greater than a sum of losses for the coil element(s).

A coil assembly includes: a radio frequency (RF) coil operable to be placed over a portion of a subject; a quarter-wave transformer coupled to the RF coil and configured to transform a characteristic impedance of the RF coil; and a diode placed behind the quarter-wave transformer and away from the RF coil, wherein the diode is operable to: (i) when the diode is forward biased, the diode turns the quarter-wave transformer into an open circuit such that the power amplifier drives the RF coil with sufficient electrical power for the RF coil to transmit an RF pulse into the portion of the subject; and (ii) when the diode is provided zero or revers bias, the diode turns the quarter-wave transformer into a short circuit such that the RF coil is detuned from a Lamor frequency of nuclei of interest immersed in the main magnet.

A dynamic field camera arrangement for monitoring electromagnetic field behavior in a spatial region comprises a main magnetic field and a radiofrequency (RF) field limited to a first RF band, particularly in an MRI or NMR apparatus. The arrangement comprises a magnetic field detector set comprising a plurality of low-frequency magnetic field detectors, each one of said magnetic field detectors comprising a magnetic resonance (MR) active substance, means for pulsed MR excitation of said substance and means for receiving an MR signal generated by said substance, wherein said pulsed excitation and said MR detector signal is in a second RF band that does not overlap said first RF band. The MR signal receiving means comprise a first RF filter which suppresses RF signal from said first RF band and transmits RF signal from said second RF band.

A magnetic resonance measurement apparatus according to the present invention includes a first LC circuit that forms an oscillating magnetic field that causes an object to exhibit magnetic resonance. The first LC circuit includes a parallel connection assembly including a diode. The parallel connection assembly further includes a diode connected, in parallel and in reverse direction, to the diode, or an inductor connected in parallel to the diode. In a first state in which oscillating voltage for forming the oscillating magnetic field is applied to the first LC circuit, the diode of the parallel connection assembly functions as a short-circuit such that the resonance frequency of the first LC circuit becomes a first resonance frequency. In a second state in which oscillating voltage is not applied to the first LC circuit, the diode of the parallel connection assembly functions as capacitance such that the resonance frequency of the first LC circuit becomes a second resonance frequency that is different from the first resonance frequency.

A radio frequency (RF) antenna element with a (de)tuning system, with the RF antenna element having a resonant electrically conductive loop and a (de)tuning system including a photosensitive switching element to (de)tune the resonant electrically conductive loop. The (de)tuning system comprises an injection optical source optically coupled to the photosensitive switching element.

Provided is a method and an apparatus for filtering a magnetic field induced in a coil of a magnetic resonance imaging (MRI) system. The method includes: applying an electromagnetic signal to an object, wherein the applying is performed by a transmit coil; while the electromagnetic signal is applied, emitting light toward a receive-only coil that obtains a magnetic resonance signal that is generated in the object due to the applied electromagnetic signal; and when the receive-only coil receives the emitted light, filtering a magnetic field induced in the receive-only coil due to the applied electromagnetic signal.