Embodiments relate to MRI coils and arrays comprising transmission lines to enforce periodic conditions. An example embodiment comprises a MRI RF coil array comprising: a plurality of assemblies, wherein each assembly of the plurality of assemblies comprises: a two-port device of that assembly, wherein the two-port device of that assembly is similar to the two-port device of each other assembly of the plurality of assemblies, and wherein the two-port device of that assembly comprises at least one associated inductor configured to, in a Tx mode, generate at least a portion of a B.sub.1 field; and a transmission line of that assembly, wherein a length of the transmission line of that assembly can be similar to a length of the transmission line of each other assembly of the plurality of assemblies, wherein the plurality of assemblies are connected together in a loop.

Provided is a coil device capable of improving operability or durability thereof, being attached to a subject in a close contact state regardless of the size of a head of the subject, and obtaining a high-quality MRI image. The coil device includes at least one coil unit which has a coil element and a coil support portion which has a mechanism for attaching the coil unit to a head of a subject. The coil support portion includes a base portion, a support body which is connected to the base portion and has an elastic member, and a holder which connects the support body to the at least one coil unit and the holder has at least three contact points which are formed directly or indirectly with respect to the base portion.

The disclosure relates to a local coil, a magnetic resonance tomography scanner, a system including local coil and magnetic resonance tomography scanner, and a method for operating the system. The local coil has an active detuning facility and a passive detuning facility with substantially separate circuits. The magnetic resonance tomography scanner includes a local coil actuation for actuating the active detuning facility and a local coil monitoring for the detuning facilities, which likewise have substantially separate circuits.

According to some aspects, a low-field magnetic resonance imaging system is provided. The low-field magnetic resonance imaging system comprises a magnetics system having a plurality of magnetics components configured to produce magnetic fields for performing magnetic resonance imaging, the magnetics system comprising, a B.sub.0 magnet configured to produce a B.sub.0 field for the magnetic resonance imaging system at a low-field strength of less than 0.2 Tesla (T), a plurality of gradient coils configured to, when operated, generate magnetic fields to provide spatial encoding of magnetic resonance signals, and at least one radio frequency coil configured to, when operated, transmit radio frequency signals to a field of view of the magnetic resonance imaging system and to respond to magnetic resonance signals emitted from the field of view, a power system comprising one or more power components configured to provide power to the magnetics system to operate the magnetic resonance imaging system to perform image acquisition, and a power connection configured to connect to a single-phase outlet to receive mains electricity and deliver the mains electricity to the power system to provide power needed to operate the magnetic resonance imaging system. According to some aspects, the power system operates the low-field magnetic resonance imaging system using an average of less than 1.6 kilowatts during image acquisition.

An RF antenna element with a detuning system in which the RF antenna element comprises a resonant electrically conductive loop. The (de)tuning system comprising a switching element to (de)tune the resonant electrically conductive loop. The (de)tuning system element includes an electroluminescent element coupled to the resonant electrically conductive loop. The (de)tuning system includes a photo-electrical conversion element to detect an electro-luminescent signal from the electroluminescent element.

Various methods and systems are provided for a flexible, lightweight, low-cost radio frequency (RF) coil array of a magnetic resonance imaging (MRI) system. In one example, a posterior RF coil assembly for a MRI system includes an RF coil array including a plurality of RF coils and a deformable material housing the plurality of RF coils, each RF coil comprising a loop portion of distributed capacitance wire conductors and a coupling electronics unit coupled to each of the plurality of RF coils.

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 birdcage coil for a magnetic resonance imaging (MRI) system is provided. The birdcage coil includes: (a) a pair of conductive end rings, each having a generally domed shape in axial cross section; (b) a plurality of conductive, elongated rungs extending between the pair of conductive end rings in an axial direction; and (c) an LC delay circuit incorporated into the pair of rings and the plurality of elongated rungs, where the LC delay circuit includes a plurality of capacitive elements and a plurality of inductive elements. In the present invention circumferential spacing between adjacent elongated rungs is varied to improve homogeneity of the volume excitation. Alternatively, or in addition, LC circuit capacitance and/or inductance values are varied to improve homogeneity of the volume excitation.

Methods and systems are provided for radio frequency (RF) coils for magnetic resonance imaging (MRI) systems. In one embodiment, a system comprises: a radio frequency (RF) coil array for a magnetic resonance imaging (MRI) system, including: a flexible shell including an inner layer; and a plurality of flexible RF coils embedded within the inner layer, with each RF coil of the plurality of RF coils including two distributed capacitance wire conductors. In this way, the RF coil array may deform in order to conform to a body of a patient.

Methods and systems are provided for radio frequency (RF) coil arrays for magnetic resonance imaging (MRI) systems. In an embodiment, a RF coil array assembly for a MRI system includes a compressible body; an upper posterior RF coil array including a first plurality of RF coils embedded in the compressible body; a lower posterior RF coil array including a second plurality of RF coils embedded in the compressible body; and a head and neck RF coil array removably coupled to the upper posterior RF coil array. The head and neck RF coil array includes a third plurality of RF coils embedded in the compressible body, and one or more neck straps configured to fold over a neck of a subject to be imaged by the MRI system.